wimlib.net Git - wimlib/blob - src/write.c

   1 /*
   2  * write.c
   3  *
   4  * Support for writing WIM files; write a WIM file, overwrite a WIM file, write
   5  * compressed file resources, etc.
   6  */
   7
   8 /*
   9  * Copyright (C) 2012, 2013 Eric Biggers
  10  *
  11  * This file is part of wimlib, a library for working with WIM files.
  12  *
  13  * wimlib is free software; you can redistribute it and/or modify it under the
  14  * terms of the GNU General Public License as published by the Free
  15  * Software Foundation; either version 3 of the License, or (at your option)
  16  * any later version.
  17  *
  18  * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
  19  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  20  * A PARTICULAR PURPOSE. See the GNU General Public License for more
  21  * details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * along with wimlib; if not, see http://www.gnu.org/licenses/.
  25  */
  26
  27 #include "config.h"
  28
  29 #if defined(HAVE_SYS_FILE_H) && defined(HAVE_FLOCK)
  30 /* On BSD, this should be included before "list.h" so that "list.h" can
  31  * overwrite the LIST_HEAD macro. */
  32 #include <sys/file.h>
  33 #endif
  34
  35 #ifdef __WIN32__
  36 #       include <windows.h>
  37 #       ifdef ERROR
  38 #               undef ERROR
  39 #       endif
  40 #endif
  41
  42 #include "list.h"
  43 #include "wimlib_internal.h"
  44 #include "buffer_io.h"
  45 #include "dentry.h"
  46 #include "lookup_table.h"
  47 #include "xml.h"
  48 #include "lzx.h"
  49 #include "xpress.h"
  50
  51 #ifdef ENABLE_MULTITHREADED_COMPRESSION
  52 #include <pthread.h>
  53 #endif
  54
  55 #include <unistd.h>
  56 #include <errno.h>
  57
  58 #ifdef WITH_NTFS_3G
  59 #include <time.h>
  60 #include <ntfs-3g/attrib.h>
  61 #include <ntfs-3g/inode.h>
  62 #include <ntfs-3g/dir.h>
  63 #endif
  64
  65 #ifdef HAVE_ALLOCA_H
  66 #include <alloca.h>
  67 #else
  68 #include <stdlib.h>
  69 #endif
  70
  71 #ifdef __WIN32__
  72 #       ifdef fsync
  73 #               undef fsync
  74 #       endif
  75 #       define fsync(fd) 0
  76 #endif
  77
  78 static int fflush_and_ftruncate(FILE *fp, off_t size)
  79 {
  80         int ret;
  81
  82         ret = fflush(fp);
  83         if (ret != 0) {
  84                 ERROR_WITH_ERRNO("Failed to flush data to output WIM file");
  85                 return WIMLIB_ERR_WRITE;
  86         }
  87         ret = ftruncate(fileno(fp), size);
  88         if (ret != 0) {
  89                 ERROR_WITH_ERRNO("Failed to truncate output WIM file to "
  90                                  "%"PRIu64" bytes", size);
  91                 return WIMLIB_ERR_WRITE;
  92         }
  93         return 0;
  94 }
  95
  96 /* Chunk table that's located at the beginning of each compressed resource in
  97  * the WIM.  (This is not the on-disk format; the on-disk format just has an
  98  * array of offsets.) */
  99 struct chunk_table {
 100         off_t file_offset;
 101         u64 num_chunks;
 102         u64 original_resource_size;
 103         u64 bytes_per_chunk_entry;
 104         u64 table_disk_size;
 105         u64 cur_offset;
 106         u64 *cur_offset_p;
 107         u64 offsets[0];
 108 };
 109
 110 /*
 111  * Allocates and initializes a chunk table, and reserves space for it in the
 112  * output file.
 113  */
 114 static int
 115 begin_wim_resource_chunk_tab(const struct wim_lookup_table_entry *lte,
 116                              FILE *out_fp,
 117                              off_t file_offset,
 118                              struct chunk_table **chunk_tab_ret)
 119 {
 120         u64 size = wim_resource_size(lte);
 121         u64 num_chunks = (size + WIM_CHUNK_SIZE - 1) / WIM_CHUNK_SIZE;
 122         size_t alloc_size = sizeof(struct chunk_table) + num_chunks * sizeof(u64);
 123         struct chunk_table *chunk_tab = CALLOC(1, alloc_size);
 124         int ret;
 125
 126         if (!chunk_tab) {
 127                 ERROR("Failed to allocate chunk table for %"PRIu64" byte "
 128                       "resource", size);
 129                 ret = WIMLIB_ERR_NOMEM;
 130                 goto out;
 131         }
 132         chunk_tab->file_offset = file_offset;
 133         chunk_tab->num_chunks = num_chunks;
 134         chunk_tab->original_resource_size = size;
 135         chunk_tab->bytes_per_chunk_entry = (size >= (1ULL << 32)) ? 8 : 4;
 136         chunk_tab->table_disk_size = chunk_tab->bytes_per_chunk_entry *
 137                                      (num_chunks - 1);
 138         chunk_tab->cur_offset = 0;
 139         chunk_tab->cur_offset_p = chunk_tab->offsets;
 140
 141         if (fwrite(chunk_tab, 1, chunk_tab->table_disk_size, out_fp) !=
 142                    chunk_tab->table_disk_size) {
 143                 ERROR_WITH_ERRNO("Failed to write chunk table in compressed "
 144                                  "file resource");
 145                 ret = WIMLIB_ERR_WRITE;
 146                 goto out;
 147         }
 148
 149         ret = 0;
 150 out:
 151         *chunk_tab_ret = chunk_tab;
 152         return ret;
 153 }
 154
 155 /*
 156  * Pointer to function to compresses a chunk of a WIM resource.
 157  *
 158  * @chunk:              Uncompressed data of the chunk.
 159  * @chunk_size:         Size of the uncompressed chunk in bytes.
 160  * @compressed_chunk:   Pointer to output buffer of size at least
 161  *                              (@chunk_size - 1) bytes.
 162  * @compressed_chunk_len_ret:   Pointer to an unsigned int into which the size
 163  *                                      of the compressed chunk will be
 164  *                                      returned.
 165  *
 166  * Returns zero if compressed succeeded, and nonzero if the chunk could not be
 167  * compressed to any smaller than @chunk_size.  This function cannot fail for
 168  * any other reasons.
 169  */
 170 typedef int (*compress_func_t)(const void *, unsigned, void *, unsigned *);
 171
 172 compress_func_t get_compress_func(int out_ctype)
 173 {
 174         if (out_ctype == WIMLIB_COMPRESSION_TYPE_LZX)
 175                 return lzx_compress;
 176         else
 177                 return xpress_compress;
 178 }
 179
 180 /*
 181  * Writes a chunk of a WIM resource to an output file.
 182  *
 183  * @chunk:        Uncompressed data of the chunk.
 184  * @chunk_size:   Size of the chunk (<= WIM_CHUNK_SIZE)
 185  * @out_fp:       FILE * to write tho chunk to.
 186  * @out_ctype:    Compression type to use when writing the chunk (ignored if no
 187  *                      chunk table provided)
 188  * @chunk_tab:    Pointer to chunk table being created.  It is updated with the
 189  *                      offset of the chunk we write.
 190  *
 191  * Returns 0 on success; nonzero on failure.
 192  */
 193 static int write_wim_resource_chunk(const u8 chunk[], unsigned chunk_size,
 194                                     FILE *out_fp, compress_func_t compress,
 195                                     struct chunk_table *chunk_tab)
 196 {
 197         const u8 *out_chunk;
 198         unsigned out_chunk_size;
 199         if (chunk_tab) {
 200                 u8 *compressed_chunk = alloca(chunk_size);
 201                 int ret;
 202
 203                 ret = compress(chunk, chunk_size, compressed_chunk,
 204                                &out_chunk_size);
 205                 if (ret == 0) {
 206                         out_chunk = compressed_chunk;
 207                 } else {
 208                         out_chunk = chunk;
 209                         out_chunk_size = chunk_size;
 210                 }
 211                 *chunk_tab->cur_offset_p++ = chunk_tab->cur_offset;
 212                 chunk_tab->cur_offset += out_chunk_size;
 213         } else {
 214                 out_chunk = chunk;
 215                 out_chunk_size = chunk_size;
 216         }
 217         if (fwrite(out_chunk, 1, out_chunk_size, out_fp) != out_chunk_size) {
 218                 ERROR_WITH_ERRNO("Failed to write WIM resource chunk");
 219                 return WIMLIB_ERR_WRITE;
 220         }
 221         return 0;
 222 }
 223
 224 /*
 225  * Finishes a WIM chunk table and writes it to the output file at the correct
 226  * offset.
 227  *
 228  * The final size of the full compressed resource is returned in the
 229  * @compressed_size_p.
 230  */
 231 static int
 232 finish_wim_resource_chunk_tab(struct chunk_table *chunk_tab,
 233                               FILE *out_fp, u64 *compressed_size_p)
 234 {
 235         size_t bytes_written;
 236         if (fseeko(out_fp, chunk_tab->file_offset, SEEK_SET) != 0) {
 237                 ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" of output "
 238                                  "WIM file", chunk_tab->file_offset);
 239                 return WIMLIB_ERR_WRITE;
 240         }
 241
 242         if (chunk_tab->bytes_per_chunk_entry == 8) {
 243                 array_cpu_to_le64(chunk_tab->offsets, chunk_tab->num_chunks);
 244         } else {
 245                 for (u64 i = 0; i < chunk_tab->num_chunks; i++)
 246                         ((u32*)chunk_tab->offsets)[i] =
 247                                 cpu_to_le32(chunk_tab->offsets[i]);
 248         }
 249         bytes_written = fwrite((u8*)chunk_tab->offsets +
 250                                         chunk_tab->bytes_per_chunk_entry,
 251                                1, chunk_tab->table_disk_size, out_fp);
 252         if (bytes_written != chunk_tab->table_disk_size) {
 253                 ERROR_WITH_ERRNO("Failed to write chunk table in compressed "
 254                                  "file resource");
 255                 return WIMLIB_ERR_WRITE;
 256         }
 257         if (fseeko(out_fp, 0, SEEK_END) != 0) {
 258                 ERROR_WITH_ERRNO("Failed to seek to end of output WIM file");
 259                 return WIMLIB_ERR_WRITE;
 260         }
 261         *compressed_size_p = chunk_tab->cur_offset + chunk_tab->table_disk_size;
 262         return 0;
 263 }
 264
 265 /* Prepare for multiple reads to a resource by caching a FILE * or NTFS
 266  * attribute pointer in the lookup table entry. */
 267 static int prepare_resource_for_read(struct wim_lookup_table_entry *lte
 268
 269                                         #ifdef WITH_NTFS_3G
 270                                         , ntfs_inode **ni_ret
 271                                         #endif
 272                 )
 273 {
 274         switch (lte->resource_location) {
 275         case RESOURCE_IN_FILE_ON_DISK:
 276                 if (!lte->file_on_disk_fp) {
 277                         lte->file_on_disk_fp = fopen(lte->file_on_disk, "rb");
 278                         if (!lte->file_on_disk_fp) {
 279                                 ERROR_WITH_ERRNO("Failed to open the file "
 280                                                  "`%s'", lte->file_on_disk);
 281                                 return WIMLIB_ERR_OPEN;
 282                         }
 283                 }
 284                 break;
 285 #ifdef WITH_NTFS_3G
 286         case RESOURCE_IN_NTFS_VOLUME:
 287                 if (!lte->attr) {
 288                         struct ntfs_location *loc = lte->ntfs_loc;
 289                         ntfs_inode *ni;
 290                         wimlib_assert(loc);
 291                         ni = ntfs_pathname_to_inode(*loc->ntfs_vol_p, NULL, loc->path_utf8);
 292                         if (!ni) {
 293                                 ERROR_WITH_ERRNO("Failed to open inode `%s' in NTFS "
 294                                                  "volume", loc->path_utf8);
 295                                 return WIMLIB_ERR_NTFS_3G;
 296                         }
 297                         lte->attr = ntfs_attr_open(ni,
 298                                                    loc->is_reparse_point ? AT_REPARSE_POINT : AT_DATA,
 299                                                    (ntfschar*)loc->stream_name_utf16,
 300                                                    loc->stream_name_utf16_num_chars);
 301                         if (!lte->attr) {
 302                                 ERROR_WITH_ERRNO("Failed to open attribute of `%s' in "
 303                                                  "NTFS volume", loc->path_utf8);
 304                                 ntfs_inode_close(ni);
 305                                 return WIMLIB_ERR_NTFS_3G;
 306                         }
 307                         *ni_ret = ni;
 308                 }
 309                 break;
 310 #endif
 311 #if defined(__CYGWIN__) || defined(__WIN32__)
 312         case RESOURCE_WIN32:
 313                 if (!lte->file_on_disk_fp) {
 314                         lte->file_on_disk_fp = win32_open_file_readonly(lte->file_on_disk);
 315                         if (!lte->file_on_disk_fp)
 316                                 return WIMLIB_ERR_OPEN;
 317                 }
 318                 break;
 319 #endif
 320         default:
 321                 break;
 322         }
 323         return 0;
 324 }
 325
 326 /* Undo prepare_resource_for_read() by closing the cached FILE * or NTFS
 327  * attribute. */
 328 static void end_wim_resource_read(struct wim_lookup_table_entry *lte
 329                                 #ifdef WITH_NTFS_3G
 330                                         , ntfs_inode *ni
 331                                 #endif
 332                                         )
 333 {
 334         if (lte->resource_location == RESOURCE_IN_FILE_ON_DISK
 335             && lte->file_on_disk_fp)
 336         {
 337                 fclose(lte->file_on_disk_fp);
 338                 lte->file_on_disk_fp = NULL;
 339         }
 340 #ifdef WITH_NTFS_3G
 341         else if (lte->resource_location == RESOURCE_IN_NTFS_VOLUME) {
 342                 if (lte->attr) {
 343                         ntfs_attr_close(lte->attr);
 344                         lte->attr = NULL;
 345                 }
 346                 if (ni)
 347                         ntfs_inode_close(ni);
 348         }
 349 #endif
 350 #if defined(__CYGWIN__) || defined(__WIN32__)
 351         else if (lte->resource_location == RESOURCE_WIN32
 352                  && lte->file_on_disk_fp)
 353         {
 354                 win32_close_file(lte->file_on_disk_fp);
 355                 lte->file_on_disk_fp = NULL;
 356         }
 357 #endif
 358 }
 359
 360 static int
 361 write_uncompressed_resource_and_truncate(struct wim_lookup_table_entry *lte,
 362                                          FILE *out_fp,
 363                                          off_t file_offset,
 364                                          struct resource_entry *out_res_entry)
 365 {
 366         int ret;
 367         if (fseeko(out_fp, file_offset, SEEK_SET) != 0) {
 368                 ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" of "
 369                                  "output WIM file", file_offset);
 370                 return WIMLIB_ERR_WRITE;
 371         }
 372         ret = write_wim_resource(lte, out_fp, WIMLIB_COMPRESSION_TYPE_NONE,
 373                                  out_res_entry, 0);
 374         if (ret != 0)
 375                 return ret;
 376
 377         return fflush_and_ftruncate(out_fp,
 378                                     file_offset + wim_resource_size(lte));
 379 }
 380
 381 /*
 382  * Writes a WIM resource to a FILE * opened for writing.  The resource may be
 383  * written uncompressed or compressed depending on the @out_ctype parameter.
 384  *
 385  * If by chance the resource compresses to more than the original size (this may
 386  * happen with random data or files than are pre-compressed), the resource is
 387  * instead written uncompressed (and this is reflected in the @out_res_entry by
 388  * removing the WIM_RESHDR_FLAG_COMPRESSED flag).
 389  *
 390  * @lte:        The lookup table entry for the WIM resource.
 391  * @out_fp:     The FILE * to write the resource to.
 392  * @out_ctype:  The compression type of the resource to write.  Note: if this is
 393  *                      the same as the compression type of the WIM resource we
 394  *                      need to read, we simply copy the data (i.e. we do not
 395  *                      uncompress it, then compress it again).
 396  * @out_res_entry:  If non-NULL, a resource entry that is filled in with the
 397  *                  offset, original size, compressed size, and compression flag
 398  *                  of the output resource.
 399  *
 400  * Returns 0 on success; nonzero on failure.
 401  */
 402 int write_wim_resource(struct wim_lookup_table_entry *lte,
 403                        FILE *out_fp, int out_ctype,
 404                        struct resource_entry *out_res_entry,
 405                        int flags)
 406 {
 407         u64 bytes_remaining;
 408         u64 original_size;
 409         u64 old_compressed_size;
 410         u64 new_compressed_size;
 411         u64 offset;
 412         int ret;
 413         struct chunk_table *chunk_tab = NULL;
 414         bool raw;
 415         off_t file_offset;
 416         compress_func_t compress = NULL;
 417 #ifdef WITH_NTFS_3G
 418         ntfs_inode *ni = NULL;
 419 #endif
 420
 421         wimlib_assert(lte);
 422
 423         /* Original size of the resource */
 424         original_size = wim_resource_size(lte);
 425
 426         /* Compressed size of the resource (as it exists now) */
 427         old_compressed_size = wim_resource_compressed_size(lte);
 428
 429         /* Current offset in output file */
 430         file_offset = ftello(out_fp);
 431         if (file_offset == -1) {
 432                 ERROR_WITH_ERRNO("Failed to get offset in output "
 433                                  "stream");
 434                 return WIMLIB_ERR_WRITE;
 435         }
 436
 437         /* Are the compression types the same?  If so, do a raw copy (copy
 438          * without decompressing and recompressing the data). */
 439         raw = (wim_resource_compression_type(lte) == out_ctype
 440                && out_ctype != WIMLIB_COMPRESSION_TYPE_NONE
 441                && !(flags & WIMLIB_RESOURCE_FLAG_RECOMPRESS));
 442
 443         if (raw) {
 444                 flags |= WIMLIB_RESOURCE_FLAG_RAW;
 445                 bytes_remaining = old_compressed_size;
 446         } else {
 447                 flags &= ~WIMLIB_RESOURCE_FLAG_RAW;
 448                 bytes_remaining = original_size;
 449         }
 450
 451         /* Empty resource; nothing needs to be done, so just return success. */
 452         if (bytes_remaining == 0)
 453                 return 0;
 454
 455         /* Buffer for reading chunks for the resource */
 456         u8 buf[min(WIM_CHUNK_SIZE, bytes_remaining)];
 457
 458         /* If we are writing a compressed resource and not doing a raw copy, we
 459          * need to initialize the chunk table */
 460         if (out_ctype != WIMLIB_COMPRESSION_TYPE_NONE && !raw) {
 461                 ret = begin_wim_resource_chunk_tab(lte, out_fp, file_offset,
 462                                                    &chunk_tab);
 463                 if (ret != 0)
 464                         goto out;
 465         }
 466
 467         /* If the WIM resource is in an external file, open a FILE * to it so we
 468          * don't have to open a temporary one in read_wim_resource() for each
 469          * chunk. */
 470 #ifdef WITH_NTFS_3G
 471         ret = prepare_resource_for_read(lte, &ni);
 472 #else
 473         ret = prepare_resource_for_read(lte);
 474 #endif
 475         if (ret != 0)
 476                 goto out;
 477
 478         /* If we aren't doing a raw copy, we will compute the SHA1 message
 479          * digest of the resource as we read it, and verify it's the same as the
 480          * hash given in the lookup table entry once we've finished reading the
 481          * resource. */
 482         SHA_CTX ctx;
 483         if (!raw) {
 484                 sha1_init(&ctx);
 485                 compress = get_compress_func(out_ctype);
 486         }
 487         offset = 0;
 488
 489         /* While there are still bytes remaining in the WIM resource, read a
 490          * chunk of the resource, update SHA1, then write that chunk using the
 491          * desired compression type. */
 492         do {
 493                 u64 to_read = min(bytes_remaining, WIM_CHUNK_SIZE);
 494                 ret = read_wim_resource(lte, buf, to_read, offset, flags);
 495                 if (ret != 0)
 496                         goto out_fclose;
 497                 if (!raw)
 498                         sha1_update(&ctx, buf, to_read);
 499                 ret = write_wim_resource_chunk(buf, to_read, out_fp,
 500                                                compress, chunk_tab);
 501                 if (ret != 0)
 502                         goto out_fclose;
 503                 bytes_remaining -= to_read;
 504                 offset += to_read;
 505         } while (bytes_remaining);
 506
 507         /* Raw copy:  The new compressed size is the same as the old compressed
 508          * size
 509          *
 510          * Using WIMLIB_COMPRESSION_TYPE_NONE:  The new compressed size is the
 511          * original size
 512          *
 513          * Using a different compression type:  Call
 514          * finish_wim_resource_chunk_tab() and it will provide the new
 515          * compressed size.
 516          */
 517         if (raw) {
 518                 new_compressed_size = old_compressed_size;
 519         } else {
 520                 if (out_ctype == WIMLIB_COMPRESSION_TYPE_NONE)
 521                         new_compressed_size = original_size;
 522                 else {
 523                         ret = finish_wim_resource_chunk_tab(chunk_tab, out_fp,
 524                                                             &new_compressed_size);
 525                         if (ret != 0)
 526                                 goto out_fclose;
 527                 }
 528         }
 529
 530         /* Verify SHA1 message digest of the resource, unless we are doing a raw
 531          * write (in which case we never even saw the uncompressed data).  Or,
 532          * if the hash we had before is all 0's, just re-set it to be the new
 533          * hash. */
 534         if (!raw) {
 535                 u8 md[SHA1_HASH_SIZE];
 536                 sha1_final(md, &ctx);
 537                 if (is_zero_hash(lte->hash)) {
 538                         copy_hash(lte->hash, md);
 539                 } else if (!hashes_equal(md, lte->hash)) {
 540                         ERROR("WIM resource has incorrect hash!");
 541                         if (lte->resource_location == RESOURCE_IN_FILE_ON_DISK) {
 542                                 ERROR("We were reading it from `%s'; maybe it changed "
 543                                       "while we were reading it.",
 544                                       lte->file_on_disk);
 545                         }
 546                         ret = WIMLIB_ERR_INVALID_RESOURCE_HASH;
 547                         goto out_fclose;
 548                 }
 549         }
 550
 551         if (!raw && new_compressed_size >= original_size &&
 552             out_ctype != WIMLIB_COMPRESSION_TYPE_NONE)
 553         {
 554                 /* Oops!  We compressed the resource to larger than the original
 555                  * size.  Write the resource uncompressed instead. */
 556                 ret = write_uncompressed_resource_and_truncate(lte,
 557                                                                out_fp,
 558                                                                file_offset,
 559                                                                out_res_entry);
 560                 if (ret != 0)
 561                         goto out_fclose;
 562         } else {
 563                 if (out_res_entry) {
 564                         out_res_entry->size          = new_compressed_size;
 565                         out_res_entry->original_size = original_size;
 566                         out_res_entry->offset        = file_offset;
 567                         out_res_entry->flags         = lte->resource_entry.flags
 568                                                         & ~WIM_RESHDR_FLAG_COMPRESSED;
 569                         if (out_ctype != WIMLIB_COMPRESSION_TYPE_NONE)
 570                                 out_res_entry->flags |= WIM_RESHDR_FLAG_COMPRESSED;
 571                 }
 572         }
 573         ret = 0;
 574 out_fclose:
 575 #ifdef WITH_NTFS_3G
 576         end_wim_resource_read(lte, ni);
 577 #else
 578         end_wim_resource_read(lte);
 579 #endif
 580 out:
 581         FREE(chunk_tab);
 582         return ret;
 583 }
 584
 585 #ifdef ENABLE_MULTITHREADED_COMPRESSION
 586
 587 /* Blocking shared queue (solves the producer-consumer problem) */
 588 struct shared_queue {
 589         unsigned size;
 590         unsigned front;
 591         unsigned back;
 592         unsigned filled_slots;
 593         void **array;
 594         pthread_mutex_t lock;
 595         pthread_cond_t msg_avail_cond;
 596         pthread_cond_t space_avail_cond;
 597 };
 598
 599 static int shared_queue_init(struct shared_queue *q, unsigned size)
 600 {
 601         wimlib_assert(size != 0);
 602         q->array = CALLOC(sizeof(q->array[0]), size);
 603         if (!q->array)
 604                 return WIMLIB_ERR_NOMEM;
 605         q->filled_slots = 0;
 606         q->front = 0;
 607         q->back = size - 1;
 608         q->size = size;
 609         pthread_mutex_init(&q->lock, NULL);
 610         pthread_cond_init(&q->msg_avail_cond, NULL);
 611         pthread_cond_init(&q->space_avail_cond, NULL);
 612         return 0;
 613 }
 614
 615 static void shared_queue_destroy(struct shared_queue *q)
 616 {
 617         FREE(q->array);
 618         pthread_mutex_destroy(&q->lock);
 619         pthread_cond_destroy(&q->msg_avail_cond);
 620         pthread_cond_destroy(&q->space_avail_cond);
 621 }
 622
 623 static void shared_queue_put(struct shared_queue *q, void *obj)
 624 {
 625         pthread_mutex_lock(&q->lock);
 626         while (q->filled_slots == q->size)
 627                 pthread_cond_wait(&q->space_avail_cond, &q->lock);
 628
 629         q->back = (q->back + 1) % q->size;
 630         q->array[q->back] = obj;
 631         q->filled_slots++;
 632
 633         pthread_cond_broadcast(&q->msg_avail_cond);
 634         pthread_mutex_unlock(&q->lock);
 635 }
 636
 637 static void *shared_queue_get(struct shared_queue *q)
 638 {
 639         void *obj;
 640
 641         pthread_mutex_lock(&q->lock);
 642         while (q->filled_slots == 0)
 643                 pthread_cond_wait(&q->msg_avail_cond, &q->lock);
 644
 645         obj = q->array[q->front];
 646         q->array[q->front] = NULL;
 647         q->front = (q->front + 1) % q->size;
 648         q->filled_slots--;
 649
 650         pthread_cond_broadcast(&q->space_avail_cond);
 651         pthread_mutex_unlock(&q->lock);
 652         return obj;
 653 }
 654
 655 struct compressor_thread_params {
 656         struct shared_queue *res_to_compress_queue;
 657         struct shared_queue *compressed_res_queue;
 658         compress_func_t compress;
 659 };
 660
 661 #define MAX_CHUNKS_PER_MSG 2
 662
 663 struct message {
 664         struct wim_lookup_table_entry *lte;
 665         u8 *uncompressed_chunks[MAX_CHUNKS_PER_MSG];
 666         u8 *out_compressed_chunks[MAX_CHUNKS_PER_MSG];
 667         u8 *compressed_chunks[MAX_CHUNKS_PER_MSG];
 668         unsigned uncompressed_chunk_sizes[MAX_CHUNKS_PER_MSG];
 669         unsigned compressed_chunk_sizes[MAX_CHUNKS_PER_MSG];
 670         unsigned num_chunks;
 671         struct list_head list;
 672         bool complete;
 673         u64 begin_chunk;
 674 };
 675
 676 static void compress_chunks(struct message *msg, compress_func_t compress)
 677 {
 678         for (unsigned i = 0; i < msg->num_chunks; i++) {
 679                 DEBUG2("compress chunk %u of %u", i, msg->num_chunks);
 680                 int ret = compress(msg->uncompressed_chunks[i],
 681                                    msg->uncompressed_chunk_sizes[i],
 682                                    msg->compressed_chunks[i],
 683                                    &msg->compressed_chunk_sizes[i]);
 684                 if (ret == 0) {
 685                         msg->out_compressed_chunks[i] = msg->compressed_chunks[i];
 686                 } else {
 687                         msg->out_compressed_chunks[i] = msg->uncompressed_chunks[i];
 688                         msg->compressed_chunk_sizes[i] = msg->uncompressed_chunk_sizes[i];
 689                 }
 690         }
 691 }
 692
 693 /* Compressor thread routine.  This is a lot simpler than the main thread
 694  * routine: just repeatedly get a group of chunks from the
 695  * res_to_compress_queue, compress them, and put them in the
 696  * compressed_res_queue.  A NULL pointer indicates that the thread should stop.
 697  * */
 698 static void *compressor_thread_proc(void *arg)
 699 {
 700         struct compressor_thread_params *params = arg;
 701         struct shared_queue *res_to_compress_queue = params->res_to_compress_queue;
 702         struct shared_queue *compressed_res_queue = params->compressed_res_queue;
 703         compress_func_t compress = params->compress;
 704         struct message *msg;
 705
 706         DEBUG("Compressor thread ready");
 707         while ((msg = shared_queue_get(res_to_compress_queue)) != NULL) {
 708                 compress_chunks(msg, compress);
 709                 shared_queue_put(compressed_res_queue, msg);
 710         }
 711         DEBUG("Compressor thread terminating");
 712         return NULL;
 713 }
 714 #endif
 715
 716 static int do_write_stream_list(struct list_head *my_resources,
 717                                 FILE *out_fp,
 718                                 int out_ctype,
 719                                 wimlib_progress_func_t progress_func,
 720                                 union wimlib_progress_info *progress,
 721                                 int write_resource_flags)
 722 {
 723         int ret;
 724         struct wim_lookup_table_entry *lte, *tmp;
 725
 726         list_for_each_entry_safe(lte, tmp, my_resources, staging_list) {
 727                 ret = write_wim_resource(lte,
 728                                          out_fp,
 729                                          out_ctype,
 730                                          &lte->output_resource_entry,
 731                                          write_resource_flags);
 732                 if (ret != 0)
 733                         return ret;
 734                 list_del(&lte->staging_list);
 735                 progress->write_streams.completed_bytes +=
 736                         wim_resource_size(lte);
 737                 progress->write_streams.completed_streams++;
 738                 if (progress_func) {
 739                         progress_func(WIMLIB_PROGRESS_MSG_WRITE_STREAMS,
 740                                       progress);
 741                 }
 742         }
 743         return 0;
 744 }
 745
 746 static int write_stream_list_serial(struct list_head *stream_list,
 747                                     FILE *out_fp,
 748                                     int out_ctype,
 749                                     int write_flags,
 750                                     wimlib_progress_func_t progress_func,
 751                                     union wimlib_progress_info *progress)
 752 {
 753         int write_resource_flags;
 754
 755         if (write_flags & WIMLIB_WRITE_FLAG_RECOMPRESS)
 756                 write_resource_flags = WIMLIB_RESOURCE_FLAG_RECOMPRESS;
 757         else
 758                 write_resource_flags = 0;
 759         progress->write_streams.num_threads = 1;
 760         if (progress_func)
 761                 progress_func(WIMLIB_PROGRESS_MSG_WRITE_STREAMS, progress);
 762         return do_write_stream_list(stream_list, out_fp,
 763                                     out_ctype, progress_func,
 764                                     progress, write_resource_flags);
 765 }
 766
 767 #ifdef ENABLE_MULTITHREADED_COMPRESSION
 768 static int write_wim_chunks(struct message *msg, FILE *out_fp,
 769                             struct chunk_table *chunk_tab)
 770 {
 771         for (unsigned i = 0; i < msg->num_chunks; i++) {
 772                 unsigned chunk_csize = msg->compressed_chunk_sizes[i];
 773
 774                 DEBUG2("Write wim chunk %u of %u (csize = %u)",
 775                       i, msg->num_chunks, chunk_csize);
 776
 777                 if (fwrite(msg->out_compressed_chunks[i], 1, chunk_csize, out_fp)
 778                     != chunk_csize)
 779                 {
 780                         ERROR_WITH_ERRNO("Failed to write WIM chunk");
 781                         return WIMLIB_ERR_WRITE;
 782                 }
 783
 784                 *chunk_tab->cur_offset_p++ = chunk_tab->cur_offset;
 785                 chunk_tab->cur_offset += chunk_csize;
 786         }
 787         return 0;
 788 }
 789
 790 /*
 791  * This function is executed by the main thread when the resources are being
 792  * compressed in parallel.  The main thread is in change of all reading of the
 793  * uncompressed data and writing of the compressed data.  The compressor threads
 794  * *only* do compression from/to in-memory buffers.
 795  *
 796  * Each unit of work given to a compressor thread is up to MAX_CHUNKS_PER_MSG
 797  * chunks of compressed data to compress, represented in a `struct message'.
 798  * Each message is passed from the main thread to a worker thread through the
 799  * res_to_compress_queue, and it is passed back through the
 800  * compressed_res_queue.
 801  */
 802 static int main_writer_thread_proc(struct list_head *stream_list,
 803                                    FILE *out_fp,
 804                                    int out_ctype,
 805                                    struct shared_queue *res_to_compress_queue,
 806                                    struct shared_queue *compressed_res_queue,
 807                                    size_t num_messages,
 808                                    int write_flags,
 809                                    wimlib_progress_func_t progress_func,
 810                                    union wimlib_progress_info *progress)
 811 {
 812         int ret;
 813         struct chunk_table *cur_chunk_tab = NULL;
 814         struct message *msgs = CALLOC(num_messages, sizeof(struct message));
 815         struct wim_lookup_table_entry *next_lte = NULL;
 816
 817         // Initially, all the messages are available to use.
 818         LIST_HEAD(available_msgs);
 819
 820         if (!msgs) {
 821                 ret = WIMLIB_ERR_NOMEM;
 822                 goto out;
 823         }
 824
 825         for (size_t i = 0; i < num_messages; i++)
 826                 list_add(&msgs[i].list, &available_msgs);
 827
 828         // outstanding_resources is the list of resources that currently have
 829         // had chunks sent off for compression.
 830         //
 831         // The first stream in outstanding_resources is the stream that is
 832         // currently being written (cur_lte).
 833         //
 834         // The last stream in outstanding_resources is the stream that is
 835         // currently being read and chunks fed to the compressor threads
 836         // (next_lte).
 837         //
 838         // Depending on the number of threads and the sizes of the resource,
 839         // the outstanding streams list may contain streams between cur_lte and
 840         // next_lte that have all their chunks compressed or being compressed,
 841         // but haven't been written yet.
 842         //
 843         LIST_HEAD(outstanding_resources);
 844         struct list_head *next_resource = stream_list->next;
 845         u64 next_chunk = 0;
 846         u64 next_num_chunks = 0;
 847
 848         // As in write_wim_resource(), each resource we read is checksummed.
 849         SHA_CTX next_sha_ctx;
 850         u8 next_hash[SHA1_HASH_SIZE];
 851
 852         // Resources that don't need any chunks compressed are added to this
 853         // list and written directly by the main thread.
 854         LIST_HEAD(my_resources);
 855
 856         struct wim_lookup_table_entry *cur_lte = NULL;
 857         struct message *msg;
 858
 859 #ifdef WITH_NTFS_3G
 860         ntfs_inode *ni = NULL;
 861 #endif
 862
 863         DEBUG("Initializing buffers for uncompressed "
 864               "and compressed data (%zu bytes needed)",
 865               num_messages * MAX_CHUNKS_PER_MSG * WIM_CHUNK_SIZE * 2);
 866
 867         // Pre-allocate all the buffers that will be needed to do the chunk
 868         // compression.
 869         for (size_t i = 0; i < num_messages; i++) {
 870                 for (size_t j = 0; j < MAX_CHUNKS_PER_MSG; j++) {
 871                         msgs[i].compressed_chunks[j] = MALLOC(WIM_CHUNK_SIZE);
 872
 873                         // The extra 8 bytes is because longest_match() in
 874                         // lz77.c may read a little bit off the end of the
 875                         // uncompressed data.  It doesn't need to be
 876                         // initialized--- we really just need to avoid accessing
 877                         // an unmapped page.
 878                         msgs[i].uncompressed_chunks[j] = MALLOC(WIM_CHUNK_SIZE + 8);
 879                         if (msgs[i].compressed_chunks[j] == NULL ||
 880                             msgs[i].uncompressed_chunks[j] == NULL)
 881                         {
 882                                 ret = WIMLIB_ERR_NOMEM;
 883                                 goto out;
 884                         }
 885                 }
 886         }
 887
 888         // This loop is executed until all resources have been written, except
 889         // possibly a few that have been added to the @my_resources list for
 890         // writing later.
 891         while (1) {
 892                 // Send chunks to the compressor threads until either (a) there
 893                 // are no more messages available since they were all sent off,
 894                 // or (b) there are no more resources that need to be
 895                 // compressed.
 896                 while (!list_empty(&available_msgs)) {
 897                         if (next_chunk == next_num_chunks) {
 898                                 // If next_chunk == next_num_chunks, there are
 899                                 // no more chunks to write in the current
 900                                 // stream.  So, check the SHA1 message digest of
 901                                 // the stream that was just finished (unless
 902                                 // next_lte == NULL, which is the case the very
 903                                 // first time this loop is entered, and also
 904                                 // near the very end of the compression when
 905                                 // there are no more streams.)  Then, advance to
 906                                 // the next stream (if there is one).
 907                                 if (next_lte != NULL) {
 908                                 #ifdef WITH_NTFS_3G
 909                                         end_wim_resource_read(next_lte, ni);
 910                                         ni = NULL;
 911                                 #else
 912                                         end_wim_resource_read(next_lte);
 913                                 #endif
 914                                         DEBUG2("Finalize SHA1 md (next_num_chunks=%zu)",
 915                                                next_num_chunks);
 916                                         sha1_final(next_hash, &next_sha_ctx);
 917                                         if (!hashes_equal(next_lte->hash, next_hash)) {
 918                                                 ERROR("WIM resource has incorrect hash!");
 919                                                 if (next_lte->resource_location ==
 920                                                     RESOURCE_IN_FILE_ON_DISK)
 921                                                 {
 922                                                         ERROR("We were reading it from `%s'; "
 923                                                               "maybe it changed while we were "
 924                                                               "reading it.",
 925                                                               next_lte->file_on_disk);
 926                                                 }
 927                                                 ret = WIMLIB_ERR_INVALID_RESOURCE_HASH;
 928                                                 goto out;
 929                                         }
 930                                 }
 931
 932                                 // Advance to the next resource.
 933                                 //
 934                                 // If the next resource needs no compression, just write
 935                                 // it with this thread (not now though--- we could be in
 936                                 // the middle of writing another resource.)  Keep doing
 937                                 // this until we either get to the end of the resources
 938                                 // list, or we get to a resource that needs compression.
 939                                 while (1) {
 940                                         if (next_resource == stream_list) {
 941                                                 // No more resources to send for
 942                                                 // compression
 943                                                 next_lte = NULL;
 944                                                 break;
 945                                         }
 946                                         next_lte = container_of(next_resource,
 947                                                                 struct wim_lookup_table_entry,
 948                                                                 staging_list);
 949                                         next_resource = next_resource->next;
 950                                         if ((!(write_flags & WIMLIB_WRITE_FLAG_RECOMPRESS)
 951                                                && wim_resource_compression_type(next_lte) == out_ctype)
 952                                             || wim_resource_size(next_lte) == 0)
 953                                         {
 954                                                 list_add_tail(&next_lte->staging_list,
 955                                                               &my_resources);
 956                                         } else {
 957                                                 list_add_tail(&next_lte->staging_list,
 958                                                               &outstanding_resources);
 959                                                 next_chunk = 0;
 960                                                 next_num_chunks = wim_resource_chunks(next_lte);
 961                                                 sha1_init(&next_sha_ctx);
 962                                                 INIT_LIST_HEAD(&next_lte->msg_list);
 963                                         #ifdef WITH_NTFS_3G
 964                                                 ret = prepare_resource_for_read(next_lte, &ni);
 965                                         #else
 966                                                 ret = prepare_resource_for_read(next_lte);
 967                                         #endif
 968
 969                                                 if (ret != 0)
 970                                                         goto out;
 971                                                 if (cur_lte == NULL) {
 972                                                         // Set cur_lte for the
 973                                                         // first time
 974                                                         cur_lte = next_lte;
 975                                                 }
 976                                                 break;
 977                                         }
 978                                 }
 979                         }
 980
 981                         if (next_lte == NULL) {
 982                                 // No more resources to send for compression
 983                                 break;
 984                         }
 985
 986                         // Get a message from the available messages
 987                         // list
 988                         msg = container_of(available_msgs.next,
 989                                            struct message,
 990                                            list);
 991
 992                         // ... and delete it from the available messages
 993                         // list
 994                         list_del(&msg->list);
 995
 996                         // Initialize the message with the chunks to
 997                         // compress.
 998                         msg->num_chunks = min(next_num_chunks - next_chunk,
 999                                               MAX_CHUNKS_PER_MSG);
1000                         msg->lte = next_lte;
1001                         msg->complete = false;
1002                         msg->begin_chunk = next_chunk;
1003
1004                         unsigned size = WIM_CHUNK_SIZE;
1005                         for (unsigned i = 0; i < msg->num_chunks; i++) {
1006
1007                                 // Read chunk @next_chunk of the stream into the
1008                                 // message so that a compressor thread can
1009                                 // compress it.
1010
1011                                 if (next_chunk == next_num_chunks - 1) {
1012                                         size = MODULO_NONZERO(wim_resource_size(next_lte),
1013                                                               WIM_CHUNK_SIZE);
1014                                 }
1015
1016                                 DEBUG2("Read resource (size=%u, offset=%zu)",
1017                                       size, next_chunk * WIM_CHUNK_SIZE);
1018
1019                                 msg->uncompressed_chunk_sizes[i] = size;
1020
1021                                 ret = read_wim_resource(next_lte,
1022                                                         msg->uncompressed_chunks[i],
1023                                                         size,
1024                                                         next_chunk * WIM_CHUNK_SIZE,
1025                                                         0);
1026                                 if (ret != 0)
1027                                         goto out;
1028                                 sha1_update(&next_sha_ctx,
1029                                             msg->uncompressed_chunks[i], size);
1030                                 next_chunk++;
1031                         }
1032
1033                         // Send the compression request
1034                         list_add_tail(&msg->list, &next_lte->msg_list);
1035                         shared_queue_put(res_to_compress_queue, msg);
1036                         DEBUG2("Compression request sent");
1037                 }
1038
1039                 // If there are no outstanding resources, there are no more
1040                 // resources that need to be written.
1041                 if (list_empty(&outstanding_resources)) {
1042                         ret = 0;
1043                         goto out;
1044                 }
1045
1046                 // Get the next message from the queue and process it.
1047                 // The message will contain 1 or more data chunks that have been
1048                 // compressed.
1049                 msg = shared_queue_get(compressed_res_queue);
1050                 msg->complete = true;
1051
1052                 // Is this the next chunk in the current resource?  If it's not
1053                 // (i.e., an earlier chunk in a same or different resource
1054                 // hasn't been compressed yet), do nothing, and keep this
1055                 // message around until all earlier chunks are received.
1056                 //
1057                 // Otherwise, write all the chunks we can.
1058                 while (cur_lte != NULL &&
1059                        !list_empty(&cur_lte->msg_list) &&
1060                        (msg = container_of(cur_lte->msg_list.next,
1061                                            struct message,
1062                                            list))->complete)
1063                 {
1064                         DEBUG2("Complete msg (begin_chunk=%"PRIu64")", msg->begin_chunk);
1065                         if (msg->begin_chunk == 0) {
1066                                 DEBUG2("Begin chunk tab");
1067
1068                                 // This is the first set of chunks.  Leave space
1069                                 // for the chunk table in the output file.
1070                                 off_t cur_offset = ftello(out_fp);
1071                                 if (cur_offset == -1) {
1072                                         ret = WIMLIB_ERR_WRITE;
1073                                         goto out;
1074                                 }
1075                                 ret = begin_wim_resource_chunk_tab(cur_lte,
1076                                                                    out_fp,
1077                                                                    cur_offset,
1078                                                                    &cur_chunk_tab);
1079                                 if (ret != 0)
1080                                         goto out;
1081                         }
1082
1083                         // Write the compressed chunks from the message.
1084                         ret = write_wim_chunks(msg, out_fp, cur_chunk_tab);
1085                         if (ret != 0)
1086                                 goto out;
1087
1088                         list_del(&msg->list);
1089
1090                         // This message is available to use for different chunks
1091                         // now.
1092                         list_add(&msg->list, &available_msgs);
1093
1094                         // Was this the last chunk of the stream?  If so, finish
1095                         // it.
1096                         if (list_empty(&cur_lte->msg_list) &&
1097                             msg->begin_chunk + msg->num_chunks == cur_chunk_tab->num_chunks)
1098                         {
1099                                 DEBUG2("Finish wim chunk tab");
1100                                 u64 res_csize;
1101                                 ret = finish_wim_resource_chunk_tab(cur_chunk_tab,
1102                                                                     out_fp,
1103                                                                     &res_csize);
1104                                 if (ret != 0)
1105                                         goto out;
1106
1107                                 if (res_csize >= wim_resource_size(cur_lte)) {
1108                                         /* Oops!  We compressed the resource to
1109                                          * larger than the original size.  Write
1110                                          * the resource uncompressed instead. */
1111                                         ret = write_uncompressed_resource_and_truncate(
1112                                                          cur_lte,
1113                                                          out_fp,
1114                                                          cur_chunk_tab->file_offset,
1115                                                          &cur_lte->output_resource_entry);
1116                                         if (ret != 0)
1117                                                 goto out;
1118                                 } else {
1119                                         cur_lte->output_resource_entry.size =
1120                                                 res_csize;
1121
1122                                         cur_lte->output_resource_entry.original_size =
1123                                                 cur_lte->resource_entry.original_size;
1124
1125                                         cur_lte->output_resource_entry.offset =
1126                                                 cur_chunk_tab->file_offset;
1127
1128                                         cur_lte->output_resource_entry.flags =
1129                                                 cur_lte->resource_entry.flags |
1130                                                         WIM_RESHDR_FLAG_COMPRESSED;
1131                                 }
1132
1133                                 progress->write_streams.completed_bytes +=
1134                                                 wim_resource_size(cur_lte);
1135                                 progress->write_streams.completed_streams++;
1136
1137                                 if (progress_func) {
1138                                         progress_func(WIMLIB_PROGRESS_MSG_WRITE_STREAMS,
1139                                                       progress);
1140                                 }
1141
1142                                 FREE(cur_chunk_tab);
1143                                 cur_chunk_tab = NULL;
1144
1145                                 struct list_head *next = cur_lte->staging_list.next;
1146                                 list_del(&cur_lte->staging_list);
1147
1148                                 if (next == &outstanding_resources)
1149                                         cur_lte = NULL;
1150                                 else
1151                                         cur_lte = container_of(cur_lte->staging_list.next,
1152                                                                struct wim_lookup_table_entry,
1153                                                                staging_list);
1154
1155                                 // Since we just finished writing a stream,
1156                                 // write any streams that have been added to the
1157                                 // my_resources list for direct writing by the
1158                                 // main thread (e.g. resources that don't need
1159                                 // to be compressed because the desired
1160                                 // compression type is the same as the previous
1161                                 // compression type).
1162                                 ret = do_write_stream_list(&my_resources,
1163                                                            out_fp,
1164                                                            out_ctype,
1165                                                            progress_func,
1166                                                            progress,
1167                                                            0);
1168                                 if (ret != 0)
1169                                         goto out;
1170                         }
1171                 }
1172         }
1173
1174 out:
1175         if (ret == WIMLIB_ERR_NOMEM) {
1176                 ERROR("Could not allocate enough memory for "
1177                       "multi-threaded compression");
1178         }
1179
1180         if (next_lte) {
1181 #ifdef WITH_NTFS_3G
1182                 end_wim_resource_read(next_lte, ni);
1183 #else
1184                 end_wim_resource_read(next_lte);
1185 #endif
1186         }
1187
1188         if (ret == 0) {
1189                 ret = do_write_stream_list(&my_resources, out_fp,
1190                                            out_ctype, progress_func,
1191                                            progress, 0);
1192         } else {
1193                 if (msgs) {
1194                         size_t num_available_msgs = 0;
1195                         struct list_head *cur;
1196
1197                         list_for_each(cur, &available_msgs) {
1198                                 num_available_msgs++;
1199                         }
1200
1201                         while (num_available_msgs < num_messages) {
1202                                 shared_queue_get(compressed_res_queue);
1203                                 num_available_msgs++;
1204                         }
1205                 }
1206         }
1207
1208         if (msgs) {
1209                 for (size_t i = 0; i < num_messages; i++) {
1210                         for (size_t j = 0; j < MAX_CHUNKS_PER_MSG; j++) {
1211                                 FREE(msgs[i].compressed_chunks[j]);
1212                                 FREE(msgs[i].uncompressed_chunks[j]);
1213                         }
1214                 }
1215                 FREE(msgs);
1216         }
1217
1218         FREE(cur_chunk_tab);
1219         return ret;
1220 }
1221
1222 static long get_default_num_threads()
1223 {
1224 #ifdef __WIN32__
1225         SYSTEM_INFO sysinfo;
1226         GetSystemInfo(&sysinfo);
1227         return sysinfo.dwNumberOfProcessors;
1228 #else
1229         return sysconf(_SC_NPROCESSORS_ONLN);
1230 #endif
1231 }
1232
1233 static int write_stream_list_parallel(struct list_head *stream_list,
1234                                       FILE *out_fp,
1235                                       int out_ctype,
1236                                       int write_flags,
1237                                       unsigned num_threads,
1238                                       wimlib_progress_func_t progress_func,
1239                                       union wimlib_progress_info *progress)
1240 {
1241         int ret;
1242         struct shared_queue res_to_compress_queue;
1243         struct shared_queue compressed_res_queue;
1244         pthread_t *compressor_threads = NULL;
1245
1246         if (num_threads == 0) {
1247                 long nthreads = get_default_num_threads();
1248                 if (nthreads < 1 || nthreads > UINT_MAX) {
1249                         WARNING("Could not determine number of processors! Assuming 1");
1250                         goto out_serial;
1251                 } else {
1252                         num_threads = nthreads;
1253                 }
1254         }
1255
1256         progress->write_streams.num_threads = num_threads;
1257         wimlib_assert(stream_list->next != stream_list);
1258
1259         static const double MESSAGES_PER_THREAD = 2.0;
1260         size_t queue_size = (size_t)(num_threads * MESSAGES_PER_THREAD);
1261
1262         DEBUG("Initializing shared queues (queue_size=%zu)", queue_size);
1263
1264         ret = shared_queue_init(&res_to_compress_queue, queue_size);
1265         if (ret != 0)
1266                 goto out_serial;
1267
1268         ret = shared_queue_init(&compressed_res_queue, queue_size);
1269         if (ret != 0)
1270                 goto out_destroy_res_to_compress_queue;
1271
1272         struct compressor_thread_params params;
1273         params.res_to_compress_queue = &res_to_compress_queue;
1274         params.compressed_res_queue = &compressed_res_queue;
1275         params.compress = get_compress_func(out_ctype);
1276
1277         compressor_threads = MALLOC(num_threads * sizeof(pthread_t));
1278         if (!compressor_threads) {
1279                 ret = WIMLIB_ERR_NOMEM;
1280                 goto out_destroy_compressed_res_queue;
1281         }
1282
1283         for (unsigned i = 0; i < num_threads; i++) {
1284                 DEBUG("pthread_create thread %u", i);
1285                 ret = pthread_create(&compressor_threads[i], NULL,
1286                                      compressor_thread_proc, &params);
1287                 if (ret != 0) {
1288                         ret = -1;
1289                         ERROR_WITH_ERRNO("Failed to create compressor "
1290                                          "thread %u", i);
1291                         num_threads = i;
1292                         goto out_join;
1293                 }
1294         }
1295
1296         if (progress_func)
1297                 progress_func(WIMLIB_PROGRESS_MSG_WRITE_STREAMS, progress);
1298
1299         ret = main_writer_thread_proc(stream_list,
1300                                       out_fp,
1301                                       out_ctype,
1302                                       &res_to_compress_queue,
1303                                       &compressed_res_queue,
1304                                       queue_size,
1305                                       write_flags,
1306                                       progress_func,
1307                                       progress);
1308 out_join:
1309         for (unsigned i = 0; i < num_threads; i++)
1310                 shared_queue_put(&res_to_compress_queue, NULL);
1311
1312         for (unsigned i = 0; i < num_threads; i++) {
1313                 if (pthread_join(compressor_threads[i], NULL)) {
1314                         WARNING_WITH_ERRNO("Failed to join compressor "
1315                                            "thread %u", i);
1316                 }
1317         }
1318         FREE(compressor_threads);
1319 out_destroy_compressed_res_queue:
1320         shared_queue_destroy(&compressed_res_queue);
1321 out_destroy_res_to_compress_queue:
1322         shared_queue_destroy(&res_to_compress_queue);
1323         if (ret >= 0 && ret != WIMLIB_ERR_NOMEM)
1324                 return ret;
1325 out_serial:
1326         WARNING("Falling back to single-threaded compression");
1327         return write_stream_list_serial(stream_list,
1328                                         out_fp,
1329                                         out_ctype,
1330                                         write_flags,
1331                                         progress_func,
1332                                         progress);
1333
1334 }
1335 #endif
1336
1337 /*
1338  * Write a list of streams to a WIM (@out_fp) using the compression type
1339  * @out_ctype and up to @num_threads compressor threads.
1340  */
1341 static int write_stream_list(struct list_head *stream_list, FILE *out_fp,
1342                              int out_ctype, int write_flags,
1343                              unsigned num_threads,
1344                              wimlib_progress_func_t progress_func)
1345 {
1346         struct wim_lookup_table_entry *lte;
1347         size_t num_streams = 0;
1348         u64 total_bytes = 0;
1349         u64 total_compression_bytes = 0;
1350         union wimlib_progress_info progress;
1351
1352         list_for_each_entry(lte, stream_list, staging_list) {
1353                 num_streams++;
1354                 total_bytes += wim_resource_size(lte);
1355                 if (out_ctype != WIMLIB_COMPRESSION_TYPE_NONE
1356                        && (wim_resource_compression_type(lte) != out_ctype ||
1357                            (write_flags & WIMLIB_WRITE_FLAG_RECOMPRESS)))
1358                 {
1359                         total_compression_bytes += wim_resource_size(lte);
1360                 }
1361         }
1362         progress.write_streams.total_bytes       = total_bytes;
1363         progress.write_streams.total_streams     = num_streams;
1364         progress.write_streams.completed_bytes   = 0;
1365         progress.write_streams.completed_streams = 0;
1366         progress.write_streams.num_threads       = num_threads;
1367         progress.write_streams.compression_type  = out_ctype;
1368
1369 #ifdef ENABLE_MULTITHREADED_COMPRESSION
1370         if (total_compression_bytes >= 1000000 && num_threads != 1)
1371                 return write_stream_list_parallel(stream_list,
1372                                                   out_fp,
1373                                                   out_ctype,
1374                                                   write_flags,
1375                                                   num_threads,
1376                                                   progress_func,
1377                                                   &progress);
1378         else
1379 #endif
1380                 return write_stream_list_serial(stream_list,
1381                                                 out_fp,
1382                                                 out_ctype,
1383                                                 write_flags,
1384                                                 progress_func,
1385                                                 &progress);
1386 }
1387
1388 struct lte_overwrite_prepare_args {
1389         WIMStruct *wim;
1390         off_t end_offset;
1391         struct list_head *stream_list;
1392 };
1393
1394 static int lte_overwrite_prepare(struct wim_lookup_table_entry *lte, void *arg)
1395 {
1396         struct lte_overwrite_prepare_args *args = arg;
1397
1398         if (lte->resource_location == RESOURCE_IN_WIM &&
1399             lte->wim == args->wim &&
1400             lte->resource_entry.offset + lte->resource_entry.size > args->end_offset)
1401         {
1402         #ifdef ENABLE_ERROR_MESSAGES
1403                 ERROR("The following resource is after the XML data:");
1404                 print_lookup_table_entry(lte, stderr);
1405         #endif
1406                 return WIMLIB_ERR_RESOURCE_ORDER;
1407         }
1408
1409         lte->out_refcnt = lte->refcnt;
1410         memcpy(&lte->output_resource_entry, &lte->resource_entry,
1411                sizeof(struct resource_entry));
1412         if (!(lte->resource_entry.flags & WIM_RESHDR_FLAG_METADATA)) {
1413                 wimlib_assert(lte->resource_location != RESOURCE_NONEXISTENT);
1414                 if (lte->resource_location != RESOURCE_IN_WIM || lte->wim != args->wim)
1415                         list_add(&lte->staging_list, args->stream_list);
1416         }
1417         return 0;
1418 }
1419
1420 static int wim_find_new_streams(WIMStruct *wim, off_t end_offset,
1421                                 struct list_head *stream_list)
1422 {
1423         struct lte_overwrite_prepare_args args = {
1424                 .wim         = wim,
1425                 .end_offset  = end_offset,
1426                 .stream_list = stream_list,
1427         };
1428
1429         return for_lookup_table_entry(wim->lookup_table,
1430                                       lte_overwrite_prepare, &args);
1431 }
1432
1433 static int inode_find_streams_to_write(struct wim_inode *inode,
1434                                        struct wim_lookup_table *table,
1435                                        struct list_head *stream_list)
1436 {
1437         struct wim_lookup_table_entry *lte;
1438         for (unsigned i = 0; i <= inode->i_num_ads; i++) {
1439                 lte = inode_stream_lte(inode, i, table);
1440                 if (lte) {
1441                         if (lte->out_refcnt == 0)
1442                                 list_add_tail(&lte->staging_list, stream_list);
1443                         lte->out_refcnt += inode->i_nlink;
1444                 }
1445         }
1446         return 0;
1447 }
1448
1449 static int image_find_streams_to_write(WIMStruct *w)
1450 {
1451         struct wim_inode *inode;
1452         struct hlist_node *cur;
1453         struct hlist_head *inode_list;
1454
1455         inode_list = &wim_get_current_image_metadata(w)->inode_list;
1456         hlist_for_each_entry(inode, cur, inode_list, i_hlist) {
1457                 inode_find_streams_to_write(inode, w->lookup_table,
1458                                             (struct list_head*)w->private);
1459         }
1460         return 0;
1461 }
1462
1463 static int write_wim_streams(WIMStruct *w, int image, int write_flags,
1464                              unsigned num_threads,
1465                              wimlib_progress_func_t progress_func)
1466 {
1467
1468         for_lookup_table_entry(w->lookup_table, lte_zero_out_refcnt, NULL);
1469         LIST_HEAD(stream_list);
1470         w->private = &stream_list;
1471         for_image(w, image, image_find_streams_to_write);
1472         return write_stream_list(&stream_list, w->out_fp,
1473                                  wimlib_get_compression_type(w), write_flags,
1474                                  num_threads, progress_func);
1475 }
1476
1477 /*
1478  * Finish writing a WIM file: write the lookup table, xml data, and integrity
1479  * table (optional), then overwrite the WIM header.
1480  *
1481  * write_flags is a bitwise OR of the following:
1482  *
1483  *      (public)  WIMLIB_WRITE_FLAG_CHECK_INTEGRITY:
1484  *              Include an integrity table.
1485  *
1486  *      (public)  WIMLIB_WRITE_FLAG_SHOW_PROGRESS:
1487  *              Show progress information when (if) writing the integrity table.
1488  *
1489  *      (private) WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE:
1490  *              Don't write the lookup table.
1491  *
1492  *      (private) WIMLIB_WRITE_FLAG_REUSE_INTEGRITY_TABLE:
1493  *              When (if) writing the integrity table, re-use entries from the
1494  *              existing integrity table, if possible.
1495  *
1496  *      (private) WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML:
1497  *              After writing the XML data but before writing the integrity
1498  *              table, write a temporary WIM header and flush the stream so that
1499  *              the WIM is less likely to become corrupted upon abrupt program
1500  *              termination.
1501  *
1502  *      (private) WIMLIB_WRITE_FLAG_FSYNC:
1503  *              fsync() the output file before closing it.
1504  *
1505  */
1506 int finish_write(WIMStruct *w, int image, int write_flags,
1507                  wimlib_progress_func_t progress_func)
1508 {
1509         int ret;
1510         struct wim_header hdr;
1511         FILE *out = w->out_fp;
1512
1513         /* @hdr will be the header for the new WIM.  First copy all the data
1514          * from the header in the WIMStruct; then set all the fields that may
1515          * have changed, including the resource entries, boot index, and image
1516          * count.  */
1517         memcpy(&hdr, &w->hdr, sizeof(struct wim_header));
1518
1519         if (!(write_flags & WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE)) {
1520                 ret = write_lookup_table(w->lookup_table, out, &hdr.lookup_table_res_entry);
1521                 if (ret != 0)
1522                         goto out;
1523         }
1524
1525         ret = write_xml_data(w->wim_info, image, out,
1526                              (write_flags & WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE) ?
1527                               wim_info_get_total_bytes(w->wim_info) : 0,
1528                              &hdr.xml_res_entry);
1529         if (ret != 0)
1530                 goto out;
1531
1532         if (write_flags & WIMLIB_WRITE_FLAG_CHECK_INTEGRITY) {
1533                 if (write_flags & WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML) {
1534                         struct wim_header checkpoint_hdr;
1535                         memcpy(&checkpoint_hdr, &hdr, sizeof(struct wim_header));
1536                         memset(&checkpoint_hdr.integrity, 0, sizeof(struct resource_entry));
1537                         if (fseeko(out, 0, SEEK_SET) != 0) {
1538                                 ERROR_WITH_ERRNO("Failed to seek to beginning "
1539                                                  "of WIM being written");
1540                                 ret = WIMLIB_ERR_WRITE;
1541                                 goto out;
1542                         }
1543                         ret = write_header(&checkpoint_hdr, out);
1544                         if (ret != 0)
1545                                 goto out;
1546
1547                         if (fflush(out) != 0) {
1548                                 ERROR_WITH_ERRNO("Can't write data to WIM");
1549                                 ret = WIMLIB_ERR_WRITE;
1550                                 goto out;
1551                         }
1552
1553                         if (fseeko(out, 0, SEEK_END) != 0) {
1554                                 ERROR_WITH_ERRNO("Failed to seek to end "
1555                                                  "of WIM being written");
1556                                 ret = WIMLIB_ERR_WRITE;
1557                                 goto out;
1558                         }
1559                 }
1560
1561                 off_t old_lookup_table_end;
1562                 off_t new_lookup_table_end;
1563                 if (write_flags & WIMLIB_WRITE_FLAG_REUSE_INTEGRITY_TABLE) {
1564                         old_lookup_table_end = w->hdr.lookup_table_res_entry.offset +
1565                                                w->hdr.lookup_table_res_entry.size;
1566                 } else {
1567                         old_lookup_table_end = 0;
1568                 }
1569                 new_lookup_table_end = hdr.lookup_table_res_entry.offset +
1570                                        hdr.lookup_table_res_entry.size;
1571
1572                 ret = write_integrity_table(out,
1573                                             &hdr.integrity,
1574                                             new_lookup_table_end,
1575                                             old_lookup_table_end,
1576                                             progress_func);
1577                 if (ret != 0)
1578                         goto out;
1579         } else {
1580                 memset(&hdr.integrity, 0, sizeof(struct resource_entry));
1581         }
1582
1583         /*
1584          * In the WIM header, there is room for the resource entry for a
1585          * metadata resource labeled as the "boot metadata".  This entry should
1586          * be zeroed out if there is no bootable image (boot_idx 0).  Otherwise,
1587          * it should be a copy of the resource entry for the image that is
1588          * marked as bootable.  This is not well documented...
1589          */
1590
1591         /* Set image count and boot index correctly for single image writes */
1592         if (image != WIMLIB_ALL_IMAGES) {
1593                 hdr.image_count = 1;
1594                 if (hdr.boot_idx == image)
1595                         hdr.boot_idx = 1;
1596                 else
1597                         hdr.boot_idx = 0;
1598         }
1599
1600         if (hdr.boot_idx == 0) {
1601                 memset(&hdr.boot_metadata_res_entry, 0,
1602                        sizeof(struct resource_entry));
1603         } else {
1604                 memcpy(&hdr.boot_metadata_res_entry,
1605                        &w->image_metadata[
1606                           hdr.boot_idx - 1].metadata_lte->output_resource_entry,
1607                        sizeof(struct resource_entry));
1608         }
1609
1610         if (fseeko(out, 0, SEEK_SET) != 0) {
1611                 ERROR_WITH_ERRNO("Failed to seek to beginning of WIM "
1612                                  "being written");
1613                 ret = WIMLIB_ERR_WRITE;
1614                 goto out;
1615         }
1616
1617         ret = write_header(&hdr, out);
1618         if (ret != 0)
1619                 goto out;
1620
1621         if (write_flags & WIMLIB_WRITE_FLAG_FSYNC) {
1622                 if (fflush(out) != 0
1623                     || fsync(fileno(out)) != 0)
1624                 {
1625                         ERROR_WITH_ERRNO("Error flushing data to WIM file");
1626                         ret = WIMLIB_ERR_WRITE;
1627                 }
1628         }
1629 out:
1630         if (fclose(out) != 0) {
1631                 ERROR_WITH_ERRNO("Failed to close the WIM file");
1632                 if (ret == 0)
1633                         ret = WIMLIB_ERR_WRITE;
1634         }
1635         w->out_fp = NULL;
1636         return ret;
1637 }
1638
1639 #if defined(HAVE_SYS_FILE_H) && defined(HAVE_FLOCK)
1640 int lock_wim(WIMStruct *w, FILE *fp)
1641 {
1642         int ret = 0;
1643         if (fp && !w->wim_locked) {
1644                 ret = flock(fileno(fp), LOCK_EX | LOCK_NB);
1645                 if (ret != 0) {
1646                         if (errno == EWOULDBLOCK) {
1647                                 ERROR("`%s' is already being modified or has been "
1648                                       "mounted read-write\n"
1649                                       "        by another process!", w->filename);
1650                                 ret = WIMLIB_ERR_ALREADY_LOCKED;
1651                         } else {
1652                                 WARNING_WITH_ERRNO("Failed to lock `%s'",
1653                                                    w->filename);
1654                                 ret = 0;
1655                         }
1656                 } else {
1657                         w->wim_locked = 1;
1658                 }
1659         }
1660         return ret;
1661 }
1662 #endif
1663
1664 static int open_wim_writable(WIMStruct *w, const char *path,
1665                              bool trunc, bool readable)
1666 {
1667         const char *mode;
1668         if (trunc)
1669                 if (readable)
1670                         mode = "w+b";
1671                 else
1672                         mode = "wb";
1673         else
1674                 mode = "r+b";
1675
1676         wimlib_assert(w->out_fp == NULL);
1677         w->out_fp = fopen(path, mode);
1678         if (w->out_fp) {
1679                 return 0;
1680         } else {
1681                 ERROR_WITH_ERRNO("Failed to open `%s' for writing", path);
1682                 return WIMLIB_ERR_OPEN;
1683         }
1684 }
1685
1686
1687 void close_wim_writable(WIMStruct *w)
1688 {
1689         if (w->out_fp) {
1690                 if (fclose(w->out_fp) != 0) {
1691                         WARNING_WITH_ERRNO("Failed to close output WIM");
1692                 }
1693                 w->out_fp = NULL;
1694         }
1695 }
1696
1697 /* Open file stream and write dummy header for WIM. */
1698 int begin_write(WIMStruct *w, const char *path, int write_flags)
1699 {
1700         int ret;
1701         ret = open_wim_writable(w, path, true,
1702                                 (write_flags & WIMLIB_WRITE_FLAG_CHECK_INTEGRITY) != 0);
1703         if (ret != 0)
1704                 return ret;
1705         /* Write dummy header. It will be overwritten later. */
1706         return write_header(&w->hdr, w->out_fp);
1707 }
1708
1709 /* Writes a stand-alone WIM to a file.  */
1710 WIMLIBAPI int wimlib_write(WIMStruct *w, const char *path,
1711                            int image, int write_flags, unsigned num_threads,
1712                            wimlib_progress_func_t progress_func)
1713 {
1714         int ret;
1715
1716         if (!path)
1717                 return WIMLIB_ERR_INVALID_PARAM;
1718
1719         write_flags &= WIMLIB_WRITE_MASK_PUBLIC;
1720
1721         if (image != WIMLIB_ALL_IMAGES &&
1722              (image < 1 || image > w->hdr.image_count))
1723                 return WIMLIB_ERR_INVALID_IMAGE;
1724
1725         if (w->hdr.total_parts != 1) {
1726                 ERROR("Cannot call wimlib_write() on part of a split WIM");
1727                 return WIMLIB_ERR_SPLIT_UNSUPPORTED;
1728         }
1729
1730         ret = begin_write(w, path, write_flags);
1731         if (ret != 0)
1732                 goto out;
1733
1734         ret = write_wim_streams(w, image, write_flags, num_threads,
1735                                 progress_func);
1736         if (ret != 0)
1737                 goto out;
1738
1739         if (progress_func)
1740                 progress_func(WIMLIB_PROGRESS_MSG_WRITE_METADATA_BEGIN, NULL);
1741
1742         ret = for_image(w, image, write_metadata_resource);
1743         if (ret != 0)
1744                 goto out;
1745
1746         if (progress_func)
1747                 progress_func(WIMLIB_PROGRESS_MSG_WRITE_METADATA_END, NULL);
1748
1749         ret = finish_write(w, image, write_flags, progress_func);
1750 out:
1751         close_wim_writable(w);
1752         DEBUG("wimlib_write(path=%s) = %d", path, ret);
1753         return ret;
1754 }
1755
1756 static bool any_images_modified(WIMStruct *w)
1757 {
1758         for (int i = 0; i < w->hdr.image_count; i++)
1759                 if (w->image_metadata[i].modified)
1760                         return true;
1761         return false;
1762 }
1763
1764 /*
1765  * Overwrite a WIM, possibly appending streams to it.
1766  *
1767  * A WIM looks like (or is supposed to look like) the following:
1768  *
1769  *                   Header (212 bytes)
1770  *                   Streams and metadata resources (variable size)
1771  *                   Lookup table (variable size)
1772  *                   XML data (variable size)
1773  *                   Integrity table (optional) (variable size)
1774  *
1775  * If we are not adding any streams or metadata resources, the lookup table is
1776  * unchanged--- so we only need to overwrite the XML data, integrity table, and
1777  * header.  This operation is potentially unsafe if the program is abruptly
1778  * terminated while the XML data or integrity table are being overwritten, but
1779  * before the new header has been written.  To partially alleviate this problem,
1780  * a special flag (WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML) is passed to
1781  * finish_write() to cause a temporary WIM header to be written after the XML
1782  * data has been written.  This may prevent the WIM from becoming corrupted if
1783  * the program is terminated while the integrity table is being calculated (but
1784  * no guarantees, due to write re-ordering...).
1785  *
1786  * If we are adding new streams or images (metadata resources), the lookup table
1787  * needs to be changed, and those streams need to be written.  In this case, we
1788  * try to perform a safe update of the WIM file by writing the streams *after*
1789  * the end of the previous WIM, then writing the new lookup table, XML data, and
1790  * (optionally) integrity table following the new streams.  This will produce a
1791  * layout like the following:
1792  *
1793  *                   Header (212 bytes)
1794  *                   (OLD) Streams and metadata resources (variable size)
1795  *                   (OLD) Lookup table (variable size)
1796  *                   (OLD) XML data (variable size)
1797  *                   (OLD) Integrity table (optional) (variable size)
1798  *                   (NEW) Streams and metadata resources (variable size)
1799  *                   (NEW) Lookup table (variable size)
1800  *                   (NEW) XML data (variable size)
1801  *                   (NEW) Integrity table (optional) (variable size)
1802  *
1803  * At all points, the WIM is valid as nothing points to the new data yet.  Then,
1804  * the header is overwritten to point to the new lookup table, XML data, and
1805  * integrity table, to produce the following layout:
1806  *
1807  *                   Header (212 bytes)
1808  *                   Streams and metadata resources (variable size)
1809  *                   Nothing (variable size)
1810  *                   More Streams and metadata resources (variable size)
1811  *                   Lookup table (variable size)
1812  *                   XML data (variable size)
1813  *                   Integrity table (optional) (variable size)
1814  *
1815  * This method allows an image to be appended to a large WIM very quickly, and
1816  * is is crash-safe except in the case of write re-ordering, but the
1817  * disadvantage is that a small hole is left in the WIM where the old lookup
1818  * table, xml data, and integrity table were.  (These usually only take up a
1819  * small amount of space compared to the streams, however.)
1820  */
1821 static int overwrite_wim_inplace(WIMStruct *w, int write_flags,
1822                                  unsigned num_threads,
1823                                  wimlib_progress_func_t progress_func)
1824 {
1825         int ret;
1826         struct list_head stream_list;
1827         off_t old_wim_end;
1828         bool found_modified_image;
1829
1830         DEBUG("Overwriting `%s' in-place", w->filename);
1831
1832         /* Make sure that the integrity table (if present) is after the XML
1833          * data, and that there are no stream resources, metadata resources, or
1834          * lookup tables after the XML data.  Otherwise, these data would be
1835          * overwritten. */
1836         if (w->hdr.integrity.offset != 0 &&
1837             w->hdr.integrity.offset < w->hdr.xml_res_entry.offset) {
1838                 ERROR("Didn't expect the integrity table to be before the XML data");
1839                 return WIMLIB_ERR_RESOURCE_ORDER;
1840         }
1841
1842         if (w->hdr.lookup_table_res_entry.offset > w->hdr.xml_res_entry.offset) {
1843                 ERROR("Didn't expect the lookup table to be after the XML data");
1844                 return WIMLIB_ERR_RESOURCE_ORDER;
1845         }
1846
1847
1848         if (w->hdr.integrity.offset)
1849                 old_wim_end = w->hdr.integrity.offset + w->hdr.integrity.size;
1850         else
1851                 old_wim_end = w->hdr.xml_res_entry.offset + w->hdr.xml_res_entry.size;
1852
1853         if (!w->deletion_occurred && !any_images_modified(w)) {
1854                 /* If no images have been modified and no images have been
1855                  * deleted, a new lookup table does not need to be written. */
1856                 old_wim_end = w->hdr.lookup_table_res_entry.offset +
1857                               w->hdr.lookup_table_res_entry.size;
1858                 write_flags |= WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE |
1859                                WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML;
1860         }
1861         INIT_LIST_HEAD(&stream_list);
1862         ret = wim_find_new_streams(w, old_wim_end, &stream_list);
1863         if (ret != 0)
1864                 return ret;
1865
1866         ret = open_wim_writable(w, w->filename, false,
1867                                 (write_flags & WIMLIB_WRITE_FLAG_CHECK_INTEGRITY) != 0);
1868         if (ret != 0)
1869                 return ret;
1870
1871         ret = lock_wim(w, w->out_fp);
1872         if (ret != 0) {
1873                 fclose(w->out_fp);
1874                 w->out_fp = NULL;
1875                 return ret;
1876         }
1877
1878         if (fseeko(w->out_fp, old_wim_end, SEEK_SET) != 0) {
1879                 ERROR_WITH_ERRNO("Can't seek to end of WIM");
1880                 fclose(w->out_fp);
1881                 w->out_fp = NULL;
1882                 w->wim_locked = 0;
1883                 return WIMLIB_ERR_WRITE;
1884         }
1885
1886         if (!list_empty(&stream_list)) {
1887                 DEBUG("Writing newly added streams (offset = %"PRIu64")",
1888                       old_wim_end);
1889                 ret = write_stream_list(&stream_list, w->out_fp,
1890                                         wimlib_get_compression_type(w),
1891                                         write_flags, num_threads,
1892                                         progress_func);
1893                 if (ret != 0)
1894                         goto out_ftruncate;
1895         } else {
1896                 DEBUG("No new streams were added");
1897         }
1898
1899         found_modified_image = false;
1900         for (int i = 0; i < w->hdr.image_count; i++) {
1901                 if (!found_modified_image)
1902                         found_modified_image = w->image_metadata[i].modified;
1903                 if (found_modified_image) {
1904                         select_wim_image(w, i + 1);
1905                         ret = write_metadata_resource(w);
1906                         if (ret != 0)
1907                                 goto out_ftruncate;
1908                 }
1909         }
1910         write_flags |= WIMLIB_WRITE_FLAG_REUSE_INTEGRITY_TABLE;
1911         ret = finish_write(w, WIMLIB_ALL_IMAGES, write_flags,
1912                            progress_func);
1913 out_ftruncate:
1914         close_wim_writable(w);
1915         if (ret != 0 && !(write_flags & WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE)) {
1916                 WARNING("Truncating `%s' to its original size (%"PRIu64" bytes)",
1917                         w->filename, old_wim_end);
1918                 /* Return value of truncate() is ignored because this is already
1919                  * an error path. */
1920                 (void)truncate(w->filename, old_wim_end);
1921         }
1922         w->wim_locked = 0;
1923         return ret;
1924 }
1925
1926 static int overwrite_wim_via_tmpfile(WIMStruct *w, int write_flags,
1927                                      unsigned num_threads,
1928                                      wimlib_progress_func_t progress_func)
1929 {
1930         size_t wim_name_len;
1931         int ret;
1932
1933         DEBUG("Overwriting `%s' via a temporary file", w->filename);
1934
1935         /* Write the WIM to a temporary file in the same directory as the
1936          * original WIM. */
1937         wim_name_len = strlen(w->filename);
1938         char tmpfile[wim_name_len + 10];
1939         memcpy(tmpfile, w->filename, wim_name_len);
1940         randomize_char_array_with_alnum(tmpfile + wim_name_len, 9);
1941         tmpfile[wim_name_len + 9] = '\0';
1942
1943         ret = wimlib_write(w, tmpfile, WIMLIB_ALL_IMAGES,
1944                            write_flags | WIMLIB_WRITE_FLAG_FSYNC,
1945                            num_threads, progress_func);
1946         if (ret != 0) {
1947                 ERROR("Failed to write the WIM file `%s'", tmpfile);
1948                 goto err;
1949         }
1950
1951         DEBUG("Renaming `%s' to `%s'", tmpfile, w->filename);
1952
1953         /* Rename the new file to the old file .*/
1954         if (rename(tmpfile, w->filename) != 0) {
1955                 ERROR_WITH_ERRNO("Failed to rename `%s' to `%s'",
1956                                  tmpfile, w->filename);
1957                 ret = WIMLIB_ERR_RENAME;
1958                 goto err;
1959         }
1960
1961         if (progress_func) {
1962                 union wimlib_progress_info progress;
1963                 progress.rename.from = tmpfile;
1964                 progress.rename.to = w->filename;
1965                 progress_func(WIMLIB_PROGRESS_MSG_RENAME, &progress);
1966         }
1967
1968         /* Close the original WIM file that was opened for reading. */
1969         if (w->fp != NULL) {
1970                 fclose(w->fp);
1971                 w->fp = NULL;
1972         }
1973
1974         /* Re-open the WIM read-only. */
1975         w->fp = fopen(w->filename, "rb");
1976         if (w->fp == NULL) {
1977                 ret = WIMLIB_ERR_REOPEN;
1978                 WARNING_WITH_ERRNO("Failed to re-open `%s' read-only",
1979                                    w->filename);
1980                 FREE(w->filename);
1981                 w->filename = NULL;
1982         }
1983         return ret;
1984 err:
1985         /* Remove temporary file. */
1986         if (unlink(tmpfile) != 0)
1987                 WARNING_WITH_ERRNO("Failed to remove `%s'", tmpfile);
1988         return ret;
1989 }
1990
1991 /*
1992  * Writes a WIM file to the original file that it was read from, overwriting it.
1993  */
1994 WIMLIBAPI int wimlib_overwrite(WIMStruct *w, int write_flags,
1995                                unsigned num_threads,
1996                                wimlib_progress_func_t progress_func)
1997 {
1998         write_flags &= WIMLIB_WRITE_MASK_PUBLIC;
1999
2000         if (!w->filename)
2001                 return WIMLIB_ERR_NO_FILENAME;
2002
2003         if (w->hdr.total_parts != 1) {
2004                 ERROR("Cannot modify a split WIM");
2005                 return WIMLIB_ERR_SPLIT_UNSUPPORTED;
2006         }
2007
2008         if ((!w->deletion_occurred || (write_flags & WIMLIB_WRITE_FLAG_SOFT_DELETE))
2009             && !(write_flags & WIMLIB_WRITE_FLAG_REBUILD))
2010         {
2011                 int ret;
2012                 ret = overwrite_wim_inplace(w, write_flags, num_threads,
2013                                             progress_func);
2014                 if (ret == WIMLIB_ERR_RESOURCE_ORDER)
2015                         WARNING("Falling back to re-building entire WIM");
2016                 else
2017                         return ret;
2018         }
2019         return overwrite_wim_via_tmpfile(w, write_flags, num_threads,
2020                                          progress_func);
2021 }