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   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 <win32.h>
  37 #endif
  38
  39 #include "list.h"
  40 #include "wimlib_internal.h"
  41 #include "buffer_io.h"
  42 #include "dentry.h"
  43 #include "lookup_table.h"
  44 #include "xml.h"
  45 #include "lzx.h"
  46 #include "xpress.h"
  47
  48 #ifdef ENABLE_MULTITHREADED_COMPRESSION
  49 #  include <pthread.h>
  50 #endif
  51
  52 #include <unistd.h>
  53 #include <errno.h>
  54
  55 #ifdef WITH_NTFS_3G
  56 #  include <time.h>
  57 #  include <ntfs-3g/attrib.h>
  58 #  include <ntfs-3g/inode.h>
  59 #  include <ntfs-3g/dir.h>
  60 #endif
  61
  62 #ifdef HAVE_ALLOCA_H
  63 #  include <alloca.h>
  64 #else
  65 #  include <stdlib.h>
  66 #endif
  67
  68 #include <limits.h>
  69
  70 static int
  71 fflush_and_ftruncate(FILE *fp, off_t size)
  72 {
  73         int ret;
  74
  75         ret = fflush(fp);
  76         if (ret != 0) {
  77                 ERROR_WITH_ERRNO("Failed to flush data to output WIM file");
  78                 return WIMLIB_ERR_WRITE;
  79         }
  80         ret = ftruncate(fileno(fp), size);
  81         if (ret != 0) {
  82                 ERROR_WITH_ERRNO("Failed to truncate output WIM file to "
  83                                  "%"PRIu64" bytes", size);
  84                 return WIMLIB_ERR_WRITE;
  85         }
  86         return 0;
  87 }
  88
  89 /* Chunk table that's located at the beginning of each compressed resource in
  90  * the WIM.  (This is not the on-disk format; the on-disk format just has an
  91  * array of offsets.) */
  92 struct chunk_table {
  93         off_t file_offset;
  94         u64 num_chunks;
  95         u64 original_resource_size;
  96         u64 bytes_per_chunk_entry;
  97         u64 table_disk_size;
  98         u64 cur_offset;
  99         u64 *cur_offset_p;
 100         u64 offsets[0];
 101 };
 102
 103 /*
 104  * Allocates and initializes a chunk table, and reserves space for it in the
 105  * output file.
 106  */
 107 static int
 108 begin_wim_resource_chunk_tab(const struct wim_lookup_table_entry *lte,
 109                              FILE *out_fp,
 110                              off_t file_offset,
 111                              struct chunk_table **chunk_tab_ret)
 112 {
 113         u64 size = wim_resource_size(lte);
 114         u64 num_chunks = (size + WIM_CHUNK_SIZE - 1) / WIM_CHUNK_SIZE;
 115         size_t alloc_size = sizeof(struct chunk_table) + num_chunks * sizeof(u64);
 116         struct chunk_table *chunk_tab = CALLOC(1, alloc_size);
 117         int ret;
 118
 119         if (!chunk_tab) {
 120                 ERROR("Failed to allocate chunk table for %"PRIu64" byte "
 121                       "resource", size);
 122                 ret = WIMLIB_ERR_NOMEM;
 123                 goto out;
 124         }
 125         chunk_tab->file_offset = file_offset;
 126         chunk_tab->num_chunks = num_chunks;
 127         chunk_tab->original_resource_size = size;
 128         chunk_tab->bytes_per_chunk_entry = (size >= (1ULL << 32)) ? 8 : 4;
 129         chunk_tab->table_disk_size = chunk_tab->bytes_per_chunk_entry *
 130                                      (num_chunks - 1);
 131         chunk_tab->cur_offset = 0;
 132         chunk_tab->cur_offset_p = chunk_tab->offsets;
 133
 134         if (fwrite(chunk_tab, 1, chunk_tab->table_disk_size, out_fp) !=
 135                    chunk_tab->table_disk_size) {
 136                 ERROR_WITH_ERRNO("Failed to write chunk table in compressed "
 137                                  "file resource");
 138                 ret = WIMLIB_ERR_WRITE;
 139                 goto out;
 140         }
 141
 142         ret = 0;
 143 out:
 144         *chunk_tab_ret = chunk_tab;
 145         return ret;
 146 }
 147
 148 /*
 149  * Pointer to function to compresses a chunk of a WIM resource.
 150  *
 151  * @chunk:              Uncompressed data of the chunk.
 152  * @chunk_size:         Size of the uncompressed chunk in bytes.
 153  * @compressed_chunk:   Pointer to output buffer of size at least
 154  *                              (@chunk_size - 1) bytes.
 155  * @compressed_chunk_len_ret:   Pointer to an unsigned int into which the size
 156  *                                      of the compressed chunk will be
 157  *                                      returned.
 158  *
 159  * Returns zero if compressed succeeded, and nonzero if the chunk could not be
 160  * compressed to any smaller than @chunk_size.  This function cannot fail for
 161  * any other reasons.
 162  */
 163 typedef int (*compress_func_t)(const void *, unsigned, void *, unsigned *);
 164
 165 compress_func_t
 166 get_compress_func(int out_ctype)
 167 {
 168         if (out_ctype == WIMLIB_COMPRESSION_TYPE_LZX)
 169                 return lzx_compress;
 170         else
 171                 return xpress_compress;
 172 }
 173
 174 /*
 175  * Writes a chunk of a WIM resource to an output file.
 176  *
 177  * @chunk:        Uncompressed data of the chunk.
 178  * @chunk_size:   Size of the chunk (<= WIM_CHUNK_SIZE)
 179  * @out_fp:       FILE * to write tho chunk to.
 180  * @out_ctype:    Compression type to use when writing the chunk (ignored if no
 181  *                      chunk table provided)
 182  * @chunk_tab:    Pointer to chunk table being created.  It is updated with the
 183  *                      offset of the chunk we write.
 184  *
 185  * Returns 0 on success; nonzero on failure.
 186  */
 187 static int
 188 write_wim_resource_chunk(const u8 chunk[], unsigned chunk_size,
 189                          FILE *out_fp, compress_func_t compress,
 190                          struct chunk_table *chunk_tab)
 191 {
 192         const u8 *out_chunk;
 193         unsigned out_chunk_size;
 194         if (chunk_tab) {
 195                 u8 *compressed_chunk = alloca(chunk_size);
 196                 int ret;
 197
 198                 ret = compress(chunk, chunk_size, compressed_chunk,
 199                                &out_chunk_size);
 200                 if (ret == 0) {
 201                         out_chunk = compressed_chunk;
 202                 } else {
 203                         out_chunk = chunk;
 204                         out_chunk_size = chunk_size;
 205                 }
 206                 *chunk_tab->cur_offset_p++ = chunk_tab->cur_offset;
 207                 chunk_tab->cur_offset += out_chunk_size;
 208         } else {
 209                 out_chunk = chunk;
 210                 out_chunk_size = chunk_size;
 211         }
 212         if (fwrite(out_chunk, 1, out_chunk_size, out_fp) != out_chunk_size) {
 213                 ERROR_WITH_ERRNO("Failed to write WIM resource chunk");
 214                 return WIMLIB_ERR_WRITE;
 215         }
 216         return 0;
 217 }
 218
 219 /*
 220  * Finishes a WIM chunk table and writes it to the output file at the correct
 221  * offset.
 222  *
 223  * The final size of the full compressed resource is returned in the
 224  * @compressed_size_p.
 225  */
 226 static int
 227 finish_wim_resource_chunk_tab(struct chunk_table *chunk_tab,
 228                               FILE *out_fp, u64 *compressed_size_p)
 229 {
 230         size_t bytes_written;
 231         if (fseeko(out_fp, chunk_tab->file_offset, SEEK_SET) != 0) {
 232                 ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" of output "
 233                                  "WIM file", chunk_tab->file_offset);
 234                 return WIMLIB_ERR_WRITE;
 235         }
 236
 237         if (chunk_tab->bytes_per_chunk_entry == 8) {
 238                 array_cpu_to_le64(chunk_tab->offsets, chunk_tab->num_chunks);
 239         } else {
 240                 for (u64 i = 0; i < chunk_tab->num_chunks; i++)
 241                         ((u32*)chunk_tab->offsets)[i] =
 242                                 cpu_to_le32(chunk_tab->offsets[i]);
 243         }
 244         bytes_written = fwrite((u8*)chunk_tab->offsets +
 245                                         chunk_tab->bytes_per_chunk_entry,
 246                                1, chunk_tab->table_disk_size, out_fp);
 247         if (bytes_written != chunk_tab->table_disk_size) {
 248                 ERROR_WITH_ERRNO("Failed to write chunk table in compressed "
 249                                  "file resource");
 250                 return WIMLIB_ERR_WRITE;
 251         }
 252         if (fseeko(out_fp, 0, SEEK_END) != 0) {
 253                 ERROR_WITH_ERRNO("Failed to seek to end of output WIM file");
 254                 return WIMLIB_ERR_WRITE;
 255         }
 256         *compressed_size_p = chunk_tab->cur_offset + chunk_tab->table_disk_size;
 257         return 0;
 258 }
 259
 260 /* Prepare for multiple reads to a resource by caching a FILE * or NTFS
 261  * attribute pointer in the lookup table entry. */
 262 static int
 263 prepare_resource_for_read(struct wim_lookup_table_entry *lte
 264
 265                                 #ifdef WITH_NTFS_3G
 266                                 , ntfs_inode **ni_ret
 267                                 #endif
 268                         )
 269 {
 270         switch (lte->resource_location) {
 271         case RESOURCE_IN_FILE_ON_DISK:
 272                 if (!lte->file_on_disk_fp) {
 273                         lte->file_on_disk_fp = fopen(lte->file_on_disk, "rb");
 274                         if (!lte->file_on_disk_fp) {
 275                                 ERROR_WITH_ERRNO("Failed to open the file "
 276                                                  "`%s'", lte->file_on_disk);
 277                                 return WIMLIB_ERR_OPEN;
 278                         }
 279                 }
 280                 break;
 281 #ifdef WITH_NTFS_3G
 282         case RESOURCE_IN_NTFS_VOLUME:
 283                 if (!lte->attr) {
 284                         struct ntfs_location *loc = lte->ntfs_loc;
 285                         ntfs_inode *ni;
 286                         wimlib_assert(loc);
 287                         ni = ntfs_pathname_to_inode(*loc->ntfs_vol_p, NULL, loc->path);
 288                         if (!ni) {
 289                                 ERROR_WITH_ERRNO("Failed to open inode `%s' in NTFS "
 290                                                  "volume", loc->path);
 291                                 return WIMLIB_ERR_NTFS_3G;
 292                         }
 293                         lte->attr = ntfs_attr_open(ni,
 294                                                    loc->is_reparse_point ? AT_REPARSE_POINT : AT_DATA,
 295                                                    loc->stream_name,
 296                                                    loc->stream_name_nchars);
 297                         if (!lte->attr) {
 298                                 ERROR_WITH_ERRNO("Failed to open attribute of `%s' in "
 299                                                  "NTFS volume", loc->path);
 300                                 ntfs_inode_close(ni);
 301                                 return WIMLIB_ERR_NTFS_3G;
 302                         }
 303                         *ni_ret = ni;
 304                 }
 305                 break;
 306 #endif
 307 #ifdef __WIN32__
 308         case RESOURCE_WIN32:
 309                 if (!lte->file_on_disk_fp) {
 310                         lte->file_on_disk_fp = win32_open_file_readonly(lte->file_on_disk);
 311                         if (!lte->file_on_disk_fp)
 312                                 return WIMLIB_ERR_OPEN;
 313                 }
 314                 break;
 315 #endif
 316         default:
 317                 break;
 318         }
 319         return 0;
 320 }
 321
 322 /* Undo prepare_resource_for_read() by closing the cached FILE * or NTFS
 323  * attribute. */
 324 static void
 325 end_wim_resource_read(struct wim_lookup_table_entry *lte
 326                         #ifdef WITH_NTFS_3G
 327                                 , ntfs_inode *ni
 328                         #endif
 329                         )
 330 {
 331         if (lte->resource_location == RESOURCE_IN_FILE_ON_DISK
 332             && lte->file_on_disk_fp)
 333         {
 334                 fclose(lte->file_on_disk_fp);
 335                 lte->file_on_disk_fp = NULL;
 336         }
 337 #ifdef WITH_NTFS_3G
 338         else if (lte->resource_location == RESOURCE_IN_NTFS_VOLUME) {
 339                 if (lte->attr) {
 340                         ntfs_attr_close(lte->attr);
 341                         lte->attr = NULL;
 342                 }
 343                 if (ni)
 344                         ntfs_inode_close(ni);
 345         }
 346 #endif
 347 #ifdef __WIN32__
 348         else if (lte->resource_location == RESOURCE_WIN32
 349                  && lte->file_on_disk_fp)
 350         {
 351                 win32_close_file(lte->file_on_disk_fp);
 352                 lte->file_on_disk_fp = NULL;
 353         }
 354 #endif
 355 }
 356
 357 static int
 358 write_uncompressed_resource_and_truncate(struct wim_lookup_table_entry *lte,
 359                                          FILE *out_fp,
 360                                          off_t file_offset,
 361                                          struct resource_entry *out_res_entry)
 362 {
 363         int ret;
 364         if (fseeko(out_fp, file_offset, SEEK_SET) != 0) {
 365                 ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" of "
 366                                  "output WIM file", file_offset);
 367                 return WIMLIB_ERR_WRITE;
 368         }
 369         ret = write_wim_resource(lte, out_fp, WIMLIB_COMPRESSION_TYPE_NONE,
 370                                  out_res_entry, 0);
 371         if (ret != 0)
 372                 return ret;
 373
 374         return fflush_and_ftruncate(out_fp,
 375                                     file_offset + wim_resource_size(lte));
 376 }
 377
 378 /*
 379  * Writes a WIM resource to a FILE * opened for writing.  The resource may be
 380  * written uncompressed or compressed depending on the @out_ctype parameter.
 381  *
 382  * If by chance the resource compresses to more than the original size (this may
 383  * happen with random data or files than are pre-compressed), the resource is
 384  * instead written uncompressed (and this is reflected in the @out_res_entry by
 385  * removing the WIM_RESHDR_FLAG_COMPRESSED flag).
 386  *
 387  * @lte:        The lookup table entry for the WIM resource.
 388  * @out_fp:     The FILE * to write the resource to.
 389  * @out_ctype:  The compression type of the resource to write.  Note: if this is
 390  *                      the same as the compression type of the WIM resource we
 391  *                      need to read, we simply copy the data (i.e. we do not
 392  *                      uncompress it, then compress it again).
 393  * @out_res_entry:  If non-NULL, a resource entry that is filled in with the
 394  *                  offset, original size, compressed size, and compression flag
 395  *                  of the output resource.
 396  *
 397  * Returns 0 on success; nonzero on failure.
 398  */
 399 int
 400 write_wim_resource(struct wim_lookup_table_entry *lte,
 401                    FILE *out_fp, int out_ctype,
 402                    struct resource_entry *out_res_entry,
 403                    int flags)
 404 {
 405         u64 bytes_remaining;
 406         u64 original_size;
 407         u64 old_compressed_size;
 408         u64 new_compressed_size;
 409         u64 offset;
 410         int ret;
 411         struct chunk_table *chunk_tab = NULL;
 412         bool raw;
 413         off_t file_offset;
 414         compress_func_t compress = NULL;
 415 #ifdef WITH_NTFS_3G
 416         ntfs_inode *ni = NULL;
 417 #endif
 418
 419         wimlib_assert(lte);
 420
 421         /* Original size of the resource */
 422         original_size = wim_resource_size(lte);
 423
 424         /* Compressed size of the resource (as it exists now) */
 425         old_compressed_size = wim_resource_compressed_size(lte);
 426
 427         /* Current offset in output file */
 428         file_offset = ftello(out_fp);
 429         if (file_offset == -1) {
 430                 ERROR_WITH_ERRNO("Failed to get offset in output "
 431                                  "stream");
 432                 return WIMLIB_ERR_WRITE;
 433         }
 434
 435         /* Are the compression types the same?  If so, do a raw copy (copy
 436          * without decompressing and recompressing the data). */
 437         raw = (wim_resource_compression_type(lte) == out_ctype
 438                && out_ctype != WIMLIB_COMPRESSION_TYPE_NONE
 439                && !(flags & WIMLIB_RESOURCE_FLAG_RECOMPRESS));
 440
 441         if (raw) {
 442                 flags |= WIMLIB_RESOURCE_FLAG_RAW;
 443                 bytes_remaining = old_compressed_size;
 444         } else {
 445                 flags &= ~WIMLIB_RESOURCE_FLAG_RAW;
 446                 bytes_remaining = original_size;
 447         }
 448
 449         /* Empty resource; nothing needs to be done, so just return success. */
 450         if (bytes_remaining == 0)
 451                 return 0;
 452
 453         /* Buffer for reading chunks for the resource */
 454         u8 buf[min(WIM_CHUNK_SIZE, bytes_remaining)];
 455
 456         /* If we are writing a compressed resource and not doing a raw copy, we
 457          * need to initialize the chunk table */
 458         if (out_ctype != WIMLIB_COMPRESSION_TYPE_NONE && !raw) {
 459                 ret = begin_wim_resource_chunk_tab(lte, out_fp, file_offset,
 460                                                    &chunk_tab);
 461                 if (ret != 0)
 462                         goto out;
 463         }
 464
 465         /* If the WIM resource is in an external file, open a FILE * to it so we
 466          * don't have to open a temporary one in read_wim_resource() for each
 467          * chunk. */
 468 #ifdef WITH_NTFS_3G
 469         ret = prepare_resource_for_read(lte, &ni);
 470 #else
 471         ret = prepare_resource_for_read(lte);
 472 #endif
 473         if (ret != 0)
 474                 goto out;
 475
 476         /* If we aren't doing a raw copy, we will compute the SHA1 message
 477          * digest of the resource as we read it, and verify it's the same as the
 478          * hash given in the lookup table entry once we've finished reading the
 479          * resource. */
 480         SHA_CTX ctx;
 481         if (!raw) {
 482                 sha1_init(&ctx);
 483                 compress = get_compress_func(out_ctype);
 484         }
 485         offset = 0;
 486
 487         /* While there are still bytes remaining in the WIM resource, read a
 488          * chunk of the resource, update SHA1, then write that chunk using the
 489          * desired compression type. */
 490         do {
 491                 u64 to_read = min(bytes_remaining, WIM_CHUNK_SIZE);
 492                 ret = read_wim_resource(lte, buf, to_read, offset, flags);
 493                 if (ret != 0)
 494                         goto out_fclose;
 495                 if (!raw)
 496                         sha1_update(&ctx, buf, to_read);
 497                 ret = write_wim_resource_chunk(buf, to_read, out_fp,
 498                                                compress, chunk_tab);
 499                 if (ret != 0)
 500                         goto out_fclose;
 501                 bytes_remaining -= to_read;
 502                 offset += to_read;
 503         } while (bytes_remaining);
 504
 505         /* Raw copy:  The new compressed size is the same as the old compressed
 506          * size
 507          *
 508          * Using WIMLIB_COMPRESSION_TYPE_NONE:  The new compressed size is the
 509          * original size
 510          *
 511          * Using a different compression type:  Call
 512          * finish_wim_resource_chunk_tab() and it will provide the new
 513          * compressed size.
 514          */
 515         if (raw) {
 516                 new_compressed_size = old_compressed_size;
 517         } else {
 518                 if (out_ctype == WIMLIB_COMPRESSION_TYPE_NONE)
 519                         new_compressed_size = original_size;
 520                 else {
 521                         ret = finish_wim_resource_chunk_tab(chunk_tab, out_fp,
 522                                                             &new_compressed_size);
 523                         if (ret != 0)
 524                                 goto out_fclose;
 525                 }
 526         }
 527
 528         /* Verify SHA1 message digest of the resource, unless we are doing a raw
 529          * write (in which case we never even saw the uncompressed data).  Or,
 530          * if the hash we had before is all 0's, just re-set it to be the new
 531          * hash. */
 532         if (!raw) {
 533                 u8 md[SHA1_HASH_SIZE];
 534                 sha1_final(md, &ctx);
 535                 if (is_zero_hash(lte->hash)) {
 536                         copy_hash(lte->hash, md);
 537                 } else if (!hashes_equal(md, lte->hash)) {
 538                         ERROR("WIM resource has incorrect hash!");
 539                         if (lte->resource_location == RESOURCE_IN_FILE_ON_DISK) {
 540                                 ERROR("We were reading it from `%s'; maybe it changed "
 541                                       "while we were reading it.",
 542                                       lte->file_on_disk);
 543                         }
 544                         ret = WIMLIB_ERR_INVALID_RESOURCE_HASH;
 545                         goto out_fclose;
 546                 }
 547         }
 548
 549         if (!raw && new_compressed_size >= original_size &&
 550             out_ctype != WIMLIB_COMPRESSION_TYPE_NONE)
 551         {
 552                 /* Oops!  We compressed the resource to larger than the original
 553                  * size.  Write the resource uncompressed instead. */
 554                 ret = write_uncompressed_resource_and_truncate(lte,
 555                                                                out_fp,
 556                                                                file_offset,
 557                                                                out_res_entry);
 558                 if (ret != 0)
 559                         goto out_fclose;
 560         } else {
 561                 if (out_res_entry) {
 562                         out_res_entry->size          = new_compressed_size;
 563                         out_res_entry->original_size = original_size;
 564                         out_res_entry->offset        = file_offset;
 565                         out_res_entry->flags         = lte->resource_entry.flags
 566                                                         & ~WIM_RESHDR_FLAG_COMPRESSED;
 567                         if (out_ctype != WIMLIB_COMPRESSION_TYPE_NONE)
 568                                 out_res_entry->flags |= WIM_RESHDR_FLAG_COMPRESSED;
 569                 }
 570         }
 571         ret = 0;
 572 out_fclose:
 573 #ifdef WITH_NTFS_3G
 574         end_wim_resource_read(lte, ni);
 575 #else
 576         end_wim_resource_read(lte);
 577 #endif
 578 out:
 579         FREE(chunk_tab);
 580         return ret;
 581 }
 582
 583 #ifdef ENABLE_MULTITHREADED_COMPRESSION
 584
 585 /* Blocking shared queue (solves the producer-consumer problem) */
 586 struct shared_queue {
 587         unsigned size;
 588         unsigned front;
 589         unsigned back;
 590         unsigned filled_slots;
 591         void **array;
 592         pthread_mutex_t lock;
 593         pthread_cond_t msg_avail_cond;
 594         pthread_cond_t space_avail_cond;
 595 };
 596
 597 static int
 598 shared_queue_init(struct shared_queue *q, unsigned size)
 599 {
 600         wimlib_assert(size != 0);
 601         q->array = CALLOC(sizeof(q->array[0]), size);
 602         if (!q->array)
 603                 return WIMLIB_ERR_NOMEM;
 604         q->filled_slots = 0;
 605         q->front = 0;
 606         q->back = size - 1;
 607         q->size = size;
 608         pthread_mutex_init(&q->lock, NULL);
 609         pthread_cond_init(&q->msg_avail_cond, NULL);
 610         pthread_cond_init(&q->space_avail_cond, NULL);
 611         return 0;
 612 }
 613
 614 static void
 615 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
 624 shared_queue_put(struct shared_queue *q, void *obj)
 625 {
 626         pthread_mutex_lock(&q->lock);
 627         while (q->filled_slots == q->size)
 628                 pthread_cond_wait(&q->space_avail_cond, &q->lock);
 629
 630         q->back = (q->back + 1) % q->size;
 631         q->array[q->back] = obj;
 632         q->filled_slots++;
 633
 634         pthread_cond_broadcast(&q->msg_avail_cond);
 635         pthread_mutex_unlock(&q->lock);
 636 }
 637
 638 static void *
 639 shared_queue_get(struct shared_queue *q)
 640 {
 641         void *obj;
 642
 643         pthread_mutex_lock(&q->lock);
 644         while (q->filled_slots == 0)
 645                 pthread_cond_wait(&q->msg_avail_cond, &q->lock);
 646
 647         obj = q->array[q->front];
 648         q->array[q->front] = NULL;
 649         q->front = (q->front + 1) % q->size;
 650         q->filled_slots--;
 651
 652         pthread_cond_broadcast(&q->space_avail_cond);
 653         pthread_mutex_unlock(&q->lock);
 654         return obj;
 655 }
 656
 657 struct compressor_thread_params {
 658         struct shared_queue *res_to_compress_queue;
 659         struct shared_queue *compressed_res_queue;
 660         compress_func_t compress;
 661 };
 662
 663 #define MAX_CHUNKS_PER_MSG 2
 664
 665 struct message {
 666         struct wim_lookup_table_entry *lte;
 667         u8 *uncompressed_chunks[MAX_CHUNKS_PER_MSG];
 668         u8 *out_compressed_chunks[MAX_CHUNKS_PER_MSG];
 669         u8 *compressed_chunks[MAX_CHUNKS_PER_MSG];
 670         unsigned uncompressed_chunk_sizes[MAX_CHUNKS_PER_MSG];
 671         unsigned compressed_chunk_sizes[MAX_CHUNKS_PER_MSG];
 672         unsigned num_chunks;
 673         struct list_head list;
 674         bool complete;
 675         u64 begin_chunk;
 676 };
 677
 678 static void
 679 compress_chunks(struct message *msg, compress_func_t compress)
 680 {
 681         for (unsigned i = 0; i < msg->num_chunks; i++) {
 682                 DEBUG2("compress chunk %u of %u", i, msg->num_chunks);
 683                 int ret = compress(msg->uncompressed_chunks[i],
 684                                    msg->uncompressed_chunk_sizes[i],
 685                                    msg->compressed_chunks[i],
 686                                    &msg->compressed_chunk_sizes[i]);
 687                 if (ret == 0) {
 688                         msg->out_compressed_chunks[i] = msg->compressed_chunks[i];
 689                 } else {
 690                         msg->out_compressed_chunks[i] = msg->uncompressed_chunks[i];
 691                         msg->compressed_chunk_sizes[i] = msg->uncompressed_chunk_sizes[i];
 692                 }
 693         }
 694 }
 695
 696 /* Compressor thread routine.  This is a lot simpler than the main thread
 697  * routine: just repeatedly get a group of chunks from the
 698  * res_to_compress_queue, compress them, and put them in the
 699  * compressed_res_queue.  A NULL pointer indicates that the thread should stop.
 700  * */
 701 static void *
 702 compressor_thread_proc(void *arg)
 703 {
 704         struct compressor_thread_params *params = arg;
 705         struct shared_queue *res_to_compress_queue = params->res_to_compress_queue;
 706         struct shared_queue *compressed_res_queue = params->compressed_res_queue;
 707         compress_func_t compress = params->compress;
 708         struct message *msg;
 709
 710         DEBUG("Compressor thread ready");
 711         while ((msg = shared_queue_get(res_to_compress_queue)) != NULL) {
 712                 compress_chunks(msg, compress);
 713                 shared_queue_put(compressed_res_queue, msg);
 714         }
 715         DEBUG("Compressor thread terminating");
 716         return NULL;
 717 }
 718 #endif /* ENABLE_MULTITHREADED_COMPRESSION */
 719
 720 static int
 721 do_write_stream_list(struct list_head *my_resources,
 722                      FILE *out_fp,
 723                      int out_ctype,
 724                      wimlib_progress_func_t progress_func,
 725                      union wimlib_progress_info *progress,
 726                      int write_resource_flags)
 727 {
 728         int ret;
 729         struct wim_lookup_table_entry *lte, *tmp;
 730
 731         list_for_each_entry_safe(lte, tmp, my_resources, staging_list) {
 732                 ret = write_wim_resource(lte,
 733                                          out_fp,
 734                                          out_ctype,
 735                                          &lte->output_resource_entry,
 736                                          write_resource_flags);
 737                 if (ret != 0)
 738                         return ret;
 739                 list_del(&lte->staging_list);
 740                 progress->write_streams.completed_bytes +=
 741                         wim_resource_size(lte);
 742                 progress->write_streams.completed_streams++;
 743                 if (progress_func) {
 744                         progress_func(WIMLIB_PROGRESS_MSG_WRITE_STREAMS,
 745                                       progress);
 746                 }
 747         }
 748         return 0;
 749 }
 750
 751 static int
 752 write_stream_list_serial(struct list_head *stream_list,
 753                          FILE *out_fp,
 754                          int out_ctype,
 755                          int write_flags,
 756                          wimlib_progress_func_t progress_func,
 757                          union wimlib_progress_info *progress)
 758 {
 759         int write_resource_flags;
 760
 761         if (write_flags & WIMLIB_WRITE_FLAG_RECOMPRESS)
 762                 write_resource_flags = WIMLIB_RESOURCE_FLAG_RECOMPRESS;
 763         else
 764                 write_resource_flags = 0;
 765         progress->write_streams.num_threads = 1;
 766         if (progress_func)
 767                 progress_func(WIMLIB_PROGRESS_MSG_WRITE_STREAMS, progress);
 768         return do_write_stream_list(stream_list, out_fp,
 769                                     out_ctype, progress_func,
 770                                     progress, write_resource_flags);
 771 }
 772
 773 #ifdef ENABLE_MULTITHREADED_COMPRESSION
 774 static int
 775 write_wim_chunks(struct message *msg, FILE *out_fp,
 776                  struct chunk_table *chunk_tab)
 777 {
 778         for (unsigned i = 0; i < msg->num_chunks; i++) {
 779                 unsigned chunk_csize = msg->compressed_chunk_sizes[i];
 780
 781                 DEBUG2("Write wim chunk %u of %u (csize = %u)",
 782                       i, msg->num_chunks, chunk_csize);
 783
 784                 if (fwrite(msg->out_compressed_chunks[i], 1, chunk_csize, out_fp)
 785                     != chunk_csize)
 786                 {
 787                         ERROR_WITH_ERRNO("Failed to write WIM chunk");
 788                         return WIMLIB_ERR_WRITE;
 789                 }
 790
 791                 *chunk_tab->cur_offset_p++ = chunk_tab->cur_offset;
 792                 chunk_tab->cur_offset += chunk_csize;
 793         }
 794         return 0;
 795 }
 796
 797 /*
 798  * This function is executed by the main thread when the resources are being
 799  * compressed in parallel.  The main thread is in change of all reading of the
 800  * uncompressed data and writing of the compressed data.  The compressor threads
 801  * *only* do compression from/to in-memory buffers.
 802  *
 803  * Each unit of work given to a compressor thread is up to MAX_CHUNKS_PER_MSG
 804  * chunks of compressed data to compress, represented in a `struct message'.
 805  * Each message is passed from the main thread to a worker thread through the
 806  * res_to_compress_queue, and it is passed back through the
 807  * compressed_res_queue.
 808  */
 809 static int
 810 main_writer_thread_proc(struct list_head *stream_list,
 811                         FILE *out_fp,
 812                         int out_ctype,
 813                         struct shared_queue *res_to_compress_queue,
 814                         struct shared_queue *compressed_res_queue,
 815                         size_t num_messages,
 816                         int write_flags,
 817                         wimlib_progress_func_t progress_func,
 818                         union wimlib_progress_info *progress)
 819 {
 820         int ret;
 821         struct chunk_table *cur_chunk_tab = NULL;
 822         struct message *msgs = CALLOC(num_messages, sizeof(struct message));
 823         struct wim_lookup_table_entry *next_lte = NULL;
 824
 825         // Initially, all the messages are available to use.
 826         LIST_HEAD(available_msgs);
 827
 828         if (!msgs) {
 829                 ret = WIMLIB_ERR_NOMEM;
 830                 goto out;
 831         }
 832
 833         for (size_t i = 0; i < num_messages; i++)
 834                 list_add(&msgs[i].list, &available_msgs);
 835
 836         // outstanding_resources is the list of resources that currently have
 837         // had chunks sent off for compression.
 838         //
 839         // The first stream in outstanding_resources is the stream that is
 840         // currently being written (cur_lte).
 841         //
 842         // The last stream in outstanding_resources is the stream that is
 843         // currently being read and chunks fed to the compressor threads
 844         // (next_lte).
 845         //
 846         // Depending on the number of threads and the sizes of the resource,
 847         // the outstanding streams list may contain streams between cur_lte and
 848         // next_lte that have all their chunks compressed or being compressed,
 849         // but haven't been written yet.
 850         //
 851         LIST_HEAD(outstanding_resources);
 852         struct list_head *next_resource = stream_list->next;
 853         u64 next_chunk = 0;
 854         u64 next_num_chunks = 0;
 855
 856         // As in write_wim_resource(), each resource we read is checksummed.
 857         SHA_CTX next_sha_ctx;
 858         u8 next_hash[SHA1_HASH_SIZE];
 859
 860         // Resources that don't need any chunks compressed are added to this
 861         // list and written directly by the main thread.
 862         LIST_HEAD(my_resources);
 863
 864         struct wim_lookup_table_entry *cur_lte = NULL;
 865         struct message *msg;
 866
 867 #ifdef WITH_NTFS_3G
 868         ntfs_inode *ni = NULL;
 869 #endif
 870
 871         DEBUG("Initializing buffers for uncompressed "
 872               "and compressed data (%zu bytes needed)",
 873               num_messages * MAX_CHUNKS_PER_MSG * WIM_CHUNK_SIZE * 2);
 874
 875         // Pre-allocate all the buffers that will be needed to do the chunk
 876         // compression.
 877         for (size_t i = 0; i < num_messages; i++) {
 878                 for (size_t j = 0; j < MAX_CHUNKS_PER_MSG; j++) {
 879                         msgs[i].compressed_chunks[j] = MALLOC(WIM_CHUNK_SIZE);
 880
 881                         // The extra 8 bytes is because longest_match() in
 882                         // lz77.c may read a little bit off the end of the
 883                         // uncompressed data.  It doesn't need to be
 884                         // initialized--- we really just need to avoid accessing
 885                         // an unmapped page.
 886                         msgs[i].uncompressed_chunks[j] = MALLOC(WIM_CHUNK_SIZE + 8);
 887                         if (msgs[i].compressed_chunks[j] == NULL ||
 888                             msgs[i].uncompressed_chunks[j] == NULL)
 889                         {
 890                                 ret = WIMLIB_ERR_NOMEM;
 891                                 goto out;
 892                         }
 893                 }
 894         }
 895
 896         // This loop is executed until all resources have been written, except
 897         // possibly a few that have been added to the @my_resources list for
 898         // writing later.
 899         while (1) {
 900                 // Send chunks to the compressor threads until either (a) there
 901                 // are no more messages available since they were all sent off,
 902                 // or (b) there are no more resources that need to be
 903                 // compressed.
 904                 while (!list_empty(&available_msgs)) {
 905                         if (next_chunk == next_num_chunks) {
 906                                 // If next_chunk == next_num_chunks, there are
 907                                 // no more chunks to write in the current
 908                                 // stream.  So, check the SHA1 message digest of
 909                                 // the stream that was just finished (unless
 910                                 // next_lte == NULL, which is the case the very
 911                                 // first time this loop is entered, and also
 912                                 // near the very end of the compression when
 913                                 // there are no more streams.)  Then, advance to
 914                                 // the next stream (if there is one).
 915                                 if (next_lte != NULL) {
 916                                 #ifdef WITH_NTFS_3G
 917                                         end_wim_resource_read(next_lte, ni);
 918                                         ni = NULL;
 919                                 #else
 920                                         end_wim_resource_read(next_lte);
 921                                 #endif
 922                                         DEBUG2("Finalize SHA1 md (next_num_chunks=%zu)",
 923                                                next_num_chunks);
 924                                         sha1_final(next_hash, &next_sha_ctx);
 925                                         if (!hashes_equal(next_lte->hash, next_hash)) {
 926                                                 ERROR("WIM resource has incorrect hash!");
 927                                                 if (next_lte->resource_location ==
 928                                                     RESOURCE_IN_FILE_ON_DISK)
 929                                                 {
 930                                                         ERROR("We were reading it from `%s'; "
 931                                                               "maybe it changed while we were "
 932                                                               "reading it.",
 933                                                               next_lte->file_on_disk);
 934                                                 }
 935                                                 ret = WIMLIB_ERR_INVALID_RESOURCE_HASH;
 936                                                 goto out;
 937                                         }
 938                                 }
 939
 940                                 // Advance to the next resource.
 941                                 //
 942                                 // If the next resource needs no compression, just write
 943                                 // it with this thread (not now though--- we could be in
 944                                 // the middle of writing another resource.)  Keep doing
 945                                 // this until we either get to the end of the resources
 946                                 // list, or we get to a resource that needs compression.
 947                                 while (1) {
 948                                         if (next_resource == stream_list) {
 949                                                 // No more resources to send for
 950                                                 // compression
 951                                                 next_lte = NULL;
 952                                                 break;
 953                                         }
 954                                         next_lte = container_of(next_resource,
 955                                                                 struct wim_lookup_table_entry,
 956                                                                 staging_list);
 957                                         next_resource = next_resource->next;
 958                                         if ((!(write_flags & WIMLIB_WRITE_FLAG_RECOMPRESS)
 959                                                && wim_resource_compression_type(next_lte) == out_ctype)
 960                                             || wim_resource_size(next_lte) == 0)
 961                                         {
 962                                                 list_add_tail(&next_lte->staging_list,
 963                                                               &my_resources);
 964                                         } else {
 965                                                 list_add_tail(&next_lte->staging_list,
 966                                                               &outstanding_resources);
 967                                                 next_chunk = 0;
 968                                                 next_num_chunks = wim_resource_chunks(next_lte);
 969                                                 sha1_init(&next_sha_ctx);
 970                                                 INIT_LIST_HEAD(&next_lte->msg_list);
 971                                         #ifdef WITH_NTFS_3G
 972                                                 ret = prepare_resource_for_read(next_lte, &ni);
 973                                         #else
 974                                                 ret = prepare_resource_for_read(next_lte);
 975                                         #endif
 976
 977                                                 if (ret != 0)
 978                                                         goto out;
 979                                                 if (cur_lte == NULL) {
 980                                                         // Set cur_lte for the
 981                                                         // first time
 982                                                         cur_lte = next_lte;
 983                                                 }
 984                                                 break;
 985                                         }
 986                                 }
 987                         }
 988
 989                         if (next_lte == NULL) {
 990                                 // No more resources to send for compression
 991                                 break;
 992                         }
 993
 994                         // Get a message from the available messages
 995                         // list
 996                         msg = container_of(available_msgs.next,
 997                                            struct message,
 998                                            list);
 999
1000                         // ... and delete it from the available messages
1001                         // list
1002                         list_del(&msg->list);
1003
1004                         // Initialize the message with the chunks to
1005                         // compress.
1006                         msg->num_chunks = min(next_num_chunks - next_chunk,
1007                                               MAX_CHUNKS_PER_MSG);
1008                         msg->lte = next_lte;
1009                         msg->complete = false;
1010                         msg->begin_chunk = next_chunk;
1011
1012                         unsigned size = WIM_CHUNK_SIZE;
1013                         for (unsigned i = 0; i < msg->num_chunks; i++) {
1014
1015                                 // Read chunk @next_chunk of the stream into the
1016                                 // message so that a compressor thread can
1017                                 // compress it.
1018
1019                                 if (next_chunk == next_num_chunks - 1) {
1020                                         size = MODULO_NONZERO(wim_resource_size(next_lte),
1021                                                               WIM_CHUNK_SIZE);
1022                                 }
1023
1024                                 DEBUG2("Read resource (size=%u, offset=%zu)",
1025                                       size, next_chunk * WIM_CHUNK_SIZE);
1026
1027                                 msg->uncompressed_chunk_sizes[i] = size;
1028
1029                                 ret = read_wim_resource(next_lte,
1030                                                         msg->uncompressed_chunks[i],
1031                                                         size,
1032                                                         next_chunk * WIM_CHUNK_SIZE,
1033                                                         0);
1034                                 if (ret != 0)
1035                                         goto out;
1036                                 sha1_update(&next_sha_ctx,
1037                                             msg->uncompressed_chunks[i], size);
1038                                 next_chunk++;
1039                         }
1040
1041                         // Send the compression request
1042                         list_add_tail(&msg->list, &next_lte->msg_list);
1043                         shared_queue_put(res_to_compress_queue, msg);
1044                         DEBUG2("Compression request sent");
1045                 }
1046
1047                 // If there are no outstanding resources, there are no more
1048                 // resources that need to be written.
1049                 if (list_empty(&outstanding_resources)) {
1050                         ret = 0;
1051                         goto out;
1052                 }
1053
1054                 // Get the next message from the queue and process it.
1055                 // The message will contain 1 or more data chunks that have been
1056                 // compressed.
1057                 msg = shared_queue_get(compressed_res_queue);
1058                 msg->complete = true;
1059
1060                 // Is this the next chunk in the current resource?  If it's not
1061                 // (i.e., an earlier chunk in a same or different resource
1062                 // hasn't been compressed yet), do nothing, and keep this
1063                 // message around until all earlier chunks are received.
1064                 //
1065                 // Otherwise, write all the chunks we can.
1066                 while (cur_lte != NULL &&
1067                        !list_empty(&cur_lte->msg_list) &&
1068                        (msg = container_of(cur_lte->msg_list.next,
1069                                            struct message,
1070                                            list))->complete)
1071                 {
1072                         DEBUG2("Complete msg (begin_chunk=%"PRIu64")", msg->begin_chunk);
1073                         if (msg->begin_chunk == 0) {
1074                                 DEBUG2("Begin chunk tab");
1075
1076                                 // This is the first set of chunks.  Leave space
1077                                 // for the chunk table in the output file.
1078                                 off_t cur_offset = ftello(out_fp);
1079                                 if (cur_offset == -1) {
1080                                         ret = WIMLIB_ERR_WRITE;
1081                                         goto out;
1082                                 }
1083                                 ret = begin_wim_resource_chunk_tab(cur_lte,
1084                                                                    out_fp,
1085                                                                    cur_offset,
1086                                                                    &cur_chunk_tab);
1087                                 if (ret != 0)
1088                                         goto out;
1089                         }
1090
1091                         // Write the compressed chunks from the message.
1092                         ret = write_wim_chunks(msg, out_fp, cur_chunk_tab);
1093                         if (ret != 0)
1094                                 goto out;
1095
1096                         list_del(&msg->list);
1097
1098                         // This message is available to use for different chunks
1099                         // now.
1100                         list_add(&msg->list, &available_msgs);
1101
1102                         // Was this the last chunk of the stream?  If so, finish
1103                         // it.
1104                         if (list_empty(&cur_lte->msg_list) &&
1105                             msg->begin_chunk + msg->num_chunks == cur_chunk_tab->num_chunks)
1106                         {
1107                                 DEBUG2("Finish wim chunk tab");
1108                                 u64 res_csize;
1109                                 ret = finish_wim_resource_chunk_tab(cur_chunk_tab,
1110                                                                     out_fp,
1111                                                                     &res_csize);
1112                                 if (ret != 0)
1113                                         goto out;
1114
1115                                 if (res_csize >= wim_resource_size(cur_lte)) {
1116                                         /* Oops!  We compressed the resource to
1117                                          * larger than the original size.  Write
1118                                          * the resource uncompressed instead. */
1119                                         ret = write_uncompressed_resource_and_truncate(
1120                                                          cur_lte,
1121                                                          out_fp,
1122                                                          cur_chunk_tab->file_offset,
1123                                                          &cur_lte->output_resource_entry);
1124                                         if (ret != 0)
1125                                                 goto out;
1126                                 } else {
1127                                         cur_lte->output_resource_entry.size =
1128                                                 res_csize;
1129
1130                                         cur_lte->output_resource_entry.original_size =
1131                                                 cur_lte->resource_entry.original_size;
1132
1133                                         cur_lte->output_resource_entry.offset =
1134                                                 cur_chunk_tab->file_offset;
1135
1136                                         cur_lte->output_resource_entry.flags =
1137                                                 cur_lte->resource_entry.flags |
1138                                                         WIM_RESHDR_FLAG_COMPRESSED;
1139                                 }
1140
1141                                 progress->write_streams.completed_bytes +=
1142                                                 wim_resource_size(cur_lte);
1143                                 progress->write_streams.completed_streams++;
1144
1145                                 if (progress_func) {
1146                                         progress_func(WIMLIB_PROGRESS_MSG_WRITE_STREAMS,
1147                                                       progress);
1148                                 }
1149
1150                                 FREE(cur_chunk_tab);
1151                                 cur_chunk_tab = NULL;
1152
1153                                 struct list_head *next = cur_lte->staging_list.next;
1154                                 list_del(&cur_lte->staging_list);
1155
1156                                 if (next == &outstanding_resources)
1157                                         cur_lte = NULL;
1158                                 else
1159                                         cur_lte = container_of(cur_lte->staging_list.next,
1160                                                                struct wim_lookup_table_entry,
1161                                                                staging_list);
1162
1163                                 // Since we just finished writing a stream,
1164                                 // write any streams that have been added to the
1165                                 // my_resources list for direct writing by the
1166                                 // main thread (e.g. resources that don't need
1167                                 // to be compressed because the desired
1168                                 // compression type is the same as the previous
1169                                 // compression type).
1170                                 ret = do_write_stream_list(&my_resources,
1171                                                            out_fp,
1172                                                            out_ctype,
1173                                                            progress_func,
1174                                                            progress,
1175                                                            0);
1176                                 if (ret != 0)
1177                                         goto out;
1178                         }
1179                 }
1180         }
1181
1182 out:
1183         if (ret == WIMLIB_ERR_NOMEM) {
1184                 ERROR("Could not allocate enough memory for "
1185                       "multi-threaded compression");
1186         }
1187
1188         if (next_lte) {
1189 #ifdef WITH_NTFS_3G
1190                 end_wim_resource_read(next_lte, ni);
1191 #else
1192                 end_wim_resource_read(next_lte);
1193 #endif
1194         }
1195
1196         if (ret == 0) {
1197                 ret = do_write_stream_list(&my_resources, out_fp,
1198                                            out_ctype, progress_func,
1199                                            progress, 0);
1200         } else {
1201                 if (msgs) {
1202                         size_t num_available_msgs = 0;
1203                         struct list_head *cur;
1204
1205                         list_for_each(cur, &available_msgs) {
1206                                 num_available_msgs++;
1207                         }
1208
1209                         while (num_available_msgs < num_messages) {
1210                                 shared_queue_get(compressed_res_queue);
1211                                 num_available_msgs++;
1212                         }
1213                 }
1214         }
1215
1216         if (msgs) {
1217                 for (size_t i = 0; i < num_messages; i++) {
1218                         for (size_t j = 0; j < MAX_CHUNKS_PER_MSG; j++) {
1219                                 FREE(msgs[i].compressed_chunks[j]);
1220                                 FREE(msgs[i].uncompressed_chunks[j]);
1221                         }
1222                 }
1223                 FREE(msgs);
1224         }
1225
1226         FREE(cur_chunk_tab);
1227         return ret;
1228 }
1229
1230 static long
1231 get_default_num_threads()
1232 {
1233 #ifdef __WIN32__
1234         return win32_get_number_of_processors();
1235 #else
1236         return sysconf(_SC_NPROCESSORS_ONLN);
1237 #endif
1238 }
1239
1240 static int
1241 write_stream_list_parallel(struct list_head *stream_list,
1242                            FILE *out_fp,
1243                            int out_ctype,
1244                            int write_flags,
1245                            unsigned num_threads,
1246                            wimlib_progress_func_t progress_func,
1247                            union wimlib_progress_info *progress)
1248 {
1249         int ret;
1250         struct shared_queue res_to_compress_queue;
1251         struct shared_queue compressed_res_queue;
1252         pthread_t *compressor_threads = NULL;
1253
1254         if (num_threads == 0) {
1255                 long nthreads = get_default_num_threads();
1256                 if (nthreads < 1 || nthreads > UINT_MAX) {
1257                         WARNING("Could not determine number of processors! Assuming 1");
1258                         goto out_serial;
1259                 } else {
1260                         num_threads = nthreads;
1261                 }
1262         }
1263
1264         progress->write_streams.num_threads = num_threads;
1265         wimlib_assert(stream_list->next != stream_list);
1266
1267         static const double MESSAGES_PER_THREAD = 2.0;
1268         size_t queue_size = (size_t)(num_threads * MESSAGES_PER_THREAD);
1269
1270         DEBUG("Initializing shared queues (queue_size=%zu)", queue_size);
1271
1272         ret = shared_queue_init(&res_to_compress_queue, queue_size);
1273         if (ret != 0)
1274                 goto out_serial;
1275
1276         ret = shared_queue_init(&compressed_res_queue, queue_size);
1277         if (ret != 0)
1278                 goto out_destroy_res_to_compress_queue;
1279
1280         struct compressor_thread_params params;
1281         params.res_to_compress_queue = &res_to_compress_queue;
1282         params.compressed_res_queue = &compressed_res_queue;
1283         params.compress = get_compress_func(out_ctype);
1284
1285         compressor_threads = MALLOC(num_threads * sizeof(pthread_t));
1286         if (!compressor_threads) {
1287                 ret = WIMLIB_ERR_NOMEM;
1288                 goto out_destroy_compressed_res_queue;
1289         }
1290
1291         for (unsigned i = 0; i < num_threads; i++) {
1292                 DEBUG("pthread_create thread %u", i);
1293                 ret = pthread_create(&compressor_threads[i], NULL,
1294                                      compressor_thread_proc, &params);
1295                 if (ret != 0) {
1296                         ret = -1;
1297                         ERROR_WITH_ERRNO("Failed to create compressor "
1298                                          "thread %u", i);
1299                         num_threads = i;
1300                         goto out_join;
1301                 }
1302         }
1303
1304         if (progress_func)
1305                 progress_func(WIMLIB_PROGRESS_MSG_WRITE_STREAMS, progress);
1306
1307         ret = main_writer_thread_proc(stream_list,
1308                                       out_fp,
1309                                       out_ctype,
1310                                       &res_to_compress_queue,
1311                                       &compressed_res_queue,
1312                                       queue_size,
1313                                       write_flags,
1314                                       progress_func,
1315                                       progress);
1316 out_join:
1317         for (unsigned i = 0; i < num_threads; i++)
1318                 shared_queue_put(&res_to_compress_queue, NULL);
1319
1320         for (unsigned i = 0; i < num_threads; i++) {
1321                 if (pthread_join(compressor_threads[i], NULL)) {
1322                         WARNING_WITH_ERRNO("Failed to join compressor "
1323                                            "thread %u", i);
1324                 }
1325         }
1326         FREE(compressor_threads);
1327 out_destroy_compressed_res_queue:
1328         shared_queue_destroy(&compressed_res_queue);
1329 out_destroy_res_to_compress_queue:
1330         shared_queue_destroy(&res_to_compress_queue);
1331         if (ret >= 0 && ret != WIMLIB_ERR_NOMEM)
1332                 return ret;
1333 out_serial:
1334         WARNING("Falling back to single-threaded compression");
1335         return write_stream_list_serial(stream_list,
1336                                         out_fp,
1337                                         out_ctype,
1338                                         write_flags,
1339                                         progress_func,
1340                                         progress);
1341
1342 }
1343 #endif
1344
1345 /*
1346  * Write a list of streams to a WIM (@out_fp) using the compression type
1347  * @out_ctype and up to @num_threads compressor threads.
1348  */
1349 static int
1350 write_stream_list(struct list_head *stream_list, FILE *out_fp,
1351                   int out_ctype, int write_flags,
1352                   unsigned num_threads,
1353                   wimlib_progress_func_t progress_func)
1354 {
1355         struct wim_lookup_table_entry *lte;
1356         size_t num_streams = 0;
1357         u64 total_bytes = 0;
1358         u64 total_compression_bytes = 0;
1359         union wimlib_progress_info progress;
1360
1361         list_for_each_entry(lte, stream_list, staging_list) {
1362                 num_streams++;
1363                 total_bytes += wim_resource_size(lte);
1364                 if (out_ctype != WIMLIB_COMPRESSION_TYPE_NONE
1365                        && (wim_resource_compression_type(lte) != out_ctype ||
1366                            (write_flags & WIMLIB_WRITE_FLAG_RECOMPRESS)))
1367                 {
1368                         total_compression_bytes += wim_resource_size(lte);
1369                 }
1370         }
1371         progress.write_streams.total_bytes       = total_bytes;
1372         progress.write_streams.total_streams     = num_streams;
1373         progress.write_streams.completed_bytes   = 0;
1374         progress.write_streams.completed_streams = 0;
1375         progress.write_streams.num_threads       = num_threads;
1376         progress.write_streams.compression_type  = out_ctype;
1377
1378 #ifdef ENABLE_MULTITHREADED_COMPRESSION
1379         if (total_compression_bytes >= 1000000 && num_threads != 1)
1380                 return write_stream_list_parallel(stream_list,
1381                                                   out_fp,
1382                                                   out_ctype,
1383                                                   write_flags,
1384                                                   num_threads,
1385                                                   progress_func,
1386                                                   &progress);
1387         else
1388 #endif
1389                 return write_stream_list_serial(stream_list,
1390                                                 out_fp,
1391                                                 out_ctype,
1392                                                 write_flags,
1393                                                 progress_func,
1394                                                 &progress);
1395 }
1396
1397 struct lte_overwrite_prepare_args {
1398         WIMStruct *wim;
1399         off_t end_offset;
1400         struct list_head *stream_list;
1401 };
1402
1403 static int
1404 lte_overwrite_prepare(struct wim_lookup_table_entry *lte, void *arg)
1405 {
1406         struct lte_overwrite_prepare_args *args = arg;
1407
1408         if (lte->resource_location == RESOURCE_IN_WIM &&
1409             lte->wim == args->wim &&
1410             lte->resource_entry.offset + lte->resource_entry.size > args->end_offset)
1411         {
1412         #ifdef ENABLE_ERROR_MESSAGES
1413                 ERROR("The following resource is after the XML data:");
1414                 print_lookup_table_entry(lte, stderr);
1415         #endif
1416                 return WIMLIB_ERR_RESOURCE_ORDER;
1417         }
1418
1419         lte->out_refcnt = lte->refcnt;
1420         memcpy(&lte->output_resource_entry, &lte->resource_entry,
1421                sizeof(struct resource_entry));
1422         if (!(lte->resource_entry.flags & WIM_RESHDR_FLAG_METADATA)) {
1423                 wimlib_assert(lte->resource_location != RESOURCE_NONEXISTENT);
1424                 if (lte->resource_location != RESOURCE_IN_WIM || lte->wim != args->wim)
1425                         list_add(&lte->staging_list, args->stream_list);
1426         }
1427         return 0;
1428 }
1429
1430 static int
1431 wim_find_new_streams(WIMStruct *wim, off_t end_offset,
1432                      struct list_head *stream_list)
1433 {
1434         struct lte_overwrite_prepare_args args = {
1435                 .wim         = wim,
1436                 .end_offset  = end_offset,
1437                 .stream_list = stream_list,
1438         };
1439
1440         return for_lookup_table_entry(wim->lookup_table,
1441                                       lte_overwrite_prepare, &args);
1442 }
1443
1444 static int
1445 inode_find_streams_to_write(struct wim_inode *inode,
1446                             struct wim_lookup_table *table,
1447                             struct list_head *stream_list)
1448 {
1449         struct wim_lookup_table_entry *lte;
1450         for (unsigned i = 0; i <= inode->i_num_ads; i++) {
1451                 lte = inode_stream_lte(inode, i, table);
1452                 if (lte) {
1453                         if (lte->out_refcnt == 0)
1454                                 list_add_tail(&lte->staging_list, stream_list);
1455                         lte->out_refcnt += inode->i_nlink;
1456                 }
1457         }
1458         return 0;
1459 }
1460
1461 static int
1462 image_find_streams_to_write(WIMStruct *w)
1463 {
1464         struct wim_inode *inode;
1465         struct hlist_node *cur;
1466         struct hlist_head *inode_list;
1467
1468         inode_list = &wim_get_current_image_metadata(w)->inode_list;
1469         hlist_for_each_entry(inode, cur, inode_list, i_hlist) {
1470                 inode_find_streams_to_write(inode, w->lookup_table,
1471                                             (struct list_head*)w->private);
1472         }
1473         return 0;
1474 }
1475
1476 static int
1477 write_wim_streams(WIMStruct *w, int image, int write_flags,
1478                              unsigned num_threads,
1479                              wimlib_progress_func_t progress_func)
1480 {
1481
1482         for_lookup_table_entry(w->lookup_table, lte_zero_out_refcnt, NULL);
1483         LIST_HEAD(stream_list);
1484         w->private = &stream_list;
1485         for_image(w, image, image_find_streams_to_write);
1486         return write_stream_list(&stream_list, w->out_fp,
1487                                  wimlib_get_compression_type(w), write_flags,
1488                                  num_threads, progress_func);
1489 }
1490
1491 /*
1492  * Finish writing a WIM file: write the lookup table, xml data, and integrity
1493  * table (optional), then overwrite the WIM header.
1494  *
1495  * write_flags is a bitwise OR of the following:
1496  *
1497  *      (public)  WIMLIB_WRITE_FLAG_CHECK_INTEGRITY:
1498  *              Include an integrity table.
1499  *
1500  *      (public)  WIMLIB_WRITE_FLAG_SHOW_PROGRESS:
1501  *              Show progress information when (if) writing the integrity table.
1502  *
1503  *      (private) WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE:
1504  *              Don't write the lookup table.
1505  *
1506  *      (private) WIMLIB_WRITE_FLAG_REUSE_INTEGRITY_TABLE:
1507  *              When (if) writing the integrity table, re-use entries from the
1508  *              existing integrity table, if possible.
1509  *
1510  *      (private) WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML:
1511  *              After writing the XML data but before writing the integrity
1512  *              table, write a temporary WIM header and flush the stream so that
1513  *              the WIM is less likely to become corrupted upon abrupt program
1514  *              termination.
1515  *
1516  *      (private) WIMLIB_WRITE_FLAG_FSYNC:
1517  *              fsync() the output file before closing it.
1518  *
1519  */
1520 int
1521 finish_write(WIMStruct *w, int image, int write_flags,
1522              wimlib_progress_func_t progress_func)
1523 {
1524         int ret;
1525         struct wim_header hdr;
1526         FILE *out = w->out_fp;
1527
1528         /* @hdr will be the header for the new WIM.  First copy all the data
1529          * from the header in the WIMStruct; then set all the fields that may
1530          * have changed, including the resource entries, boot index, and image
1531          * count.  */
1532         memcpy(&hdr, &w->hdr, sizeof(struct wim_header));
1533
1534         if (!(write_flags & WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE)) {
1535                 ret = write_lookup_table(w->lookup_table, out, &hdr.lookup_table_res_entry);
1536                 if (ret != 0)
1537                         goto out;
1538         }
1539
1540         ret = write_xml_data(w->wim_info, image, out,
1541                              (write_flags & WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE) ?
1542                               wim_info_get_total_bytes(w->wim_info) : 0,
1543                              &hdr.xml_res_entry);
1544         if (ret != 0)
1545                 goto out;
1546
1547         if (write_flags & WIMLIB_WRITE_FLAG_CHECK_INTEGRITY) {
1548                 if (write_flags & WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML) {
1549                         struct wim_header checkpoint_hdr;
1550                         memcpy(&checkpoint_hdr, &hdr, sizeof(struct wim_header));
1551                         memset(&checkpoint_hdr.integrity, 0, sizeof(struct resource_entry));
1552                         if (fseeko(out, 0, SEEK_SET) != 0) {
1553                                 ERROR_WITH_ERRNO("Failed to seek to beginning "
1554                                                  "of WIM being written");
1555                                 ret = WIMLIB_ERR_WRITE;
1556                                 goto out;
1557                         }
1558                         ret = write_header(&checkpoint_hdr, out);
1559                         if (ret != 0)
1560                                 goto out;
1561
1562                         if (fflush(out) != 0) {
1563                                 ERROR_WITH_ERRNO("Can't write data to WIM");
1564                                 ret = WIMLIB_ERR_WRITE;
1565                                 goto out;
1566                         }
1567
1568                         if (fseeko(out, 0, SEEK_END) != 0) {
1569                                 ERROR_WITH_ERRNO("Failed to seek to end "
1570                                                  "of WIM being written");
1571                                 ret = WIMLIB_ERR_WRITE;
1572                                 goto out;
1573                         }
1574                 }
1575
1576                 off_t old_lookup_table_end;
1577                 off_t new_lookup_table_end;
1578                 if (write_flags & WIMLIB_WRITE_FLAG_REUSE_INTEGRITY_TABLE) {
1579                         old_lookup_table_end = w->hdr.lookup_table_res_entry.offset +
1580                                                w->hdr.lookup_table_res_entry.size;
1581                 } else {
1582                         old_lookup_table_end = 0;
1583                 }
1584                 new_lookup_table_end = hdr.lookup_table_res_entry.offset +
1585                                        hdr.lookup_table_res_entry.size;
1586
1587                 ret = write_integrity_table(out,
1588                                             &hdr.integrity,
1589                                             new_lookup_table_end,
1590                                             old_lookup_table_end,
1591                                             progress_func);
1592                 if (ret != 0)
1593                         goto out;
1594         } else {
1595                 memset(&hdr.integrity, 0, sizeof(struct resource_entry));
1596         }
1597
1598         /*
1599          * In the WIM header, there is room for the resource entry for a
1600          * metadata resource labeled as the "boot metadata".  This entry should
1601          * be zeroed out if there is no bootable image (boot_idx 0).  Otherwise,
1602          * it should be a copy of the resource entry for the image that is
1603          * marked as bootable.  This is not well documented...
1604          */
1605
1606         /* Set image count and boot index correctly for single image writes */
1607         if (image != WIMLIB_ALL_IMAGES) {
1608                 hdr.image_count = 1;
1609                 if (hdr.boot_idx == image)
1610                         hdr.boot_idx = 1;
1611                 else
1612                         hdr.boot_idx = 0;
1613         }
1614
1615         if (hdr.boot_idx == 0) {
1616                 memset(&hdr.boot_metadata_res_entry, 0,
1617                        sizeof(struct resource_entry));
1618         } else {
1619                 memcpy(&hdr.boot_metadata_res_entry,
1620                        &w->image_metadata[
1621                           hdr.boot_idx - 1].metadata_lte->output_resource_entry,
1622                        sizeof(struct resource_entry));
1623         }
1624
1625         if (fseeko(out, 0, SEEK_SET) != 0) {
1626                 ERROR_WITH_ERRNO("Failed to seek to beginning of WIM "
1627                                  "being written");
1628                 ret = WIMLIB_ERR_WRITE;
1629                 goto out;
1630         }
1631
1632         ret = write_header(&hdr, out);
1633         if (ret != 0)
1634                 goto out;
1635
1636         if (write_flags & WIMLIB_WRITE_FLAG_FSYNC) {
1637                 if (fflush(out) != 0
1638                     || fsync(fileno(out)) != 0)
1639                 {
1640                         ERROR_WITH_ERRNO("Error flushing data to WIM file");
1641                         ret = WIMLIB_ERR_WRITE;
1642                 }
1643         }
1644 out:
1645         if (fclose(out) != 0) {
1646                 ERROR_WITH_ERRNO("Failed to close the WIM file");
1647                 if (ret == 0)
1648                         ret = WIMLIB_ERR_WRITE;
1649         }
1650         w->out_fp = NULL;
1651         return ret;
1652 }
1653
1654 #if defined(HAVE_SYS_FILE_H) && defined(HAVE_FLOCK)
1655 int
1656 lock_wim(WIMStruct *w, FILE *fp)
1657 {
1658         int ret = 0;
1659         if (fp && !w->wim_locked) {
1660                 ret = flock(fileno(fp), LOCK_EX | LOCK_NB);
1661                 if (ret != 0) {
1662                         if (errno == EWOULDBLOCK) {
1663                                 ERROR("`%s' is already being modified or has been "
1664                                       "mounted read-write\n"
1665                                       "        by another process!", w->filename);
1666                                 ret = WIMLIB_ERR_ALREADY_LOCKED;
1667                         } else {
1668                                 WARNING_WITH_ERRNO("Failed to lock `%s'",
1669                                                    w->filename);
1670                                 ret = 0;
1671                         }
1672                 } else {
1673                         w->wim_locked = 1;
1674                 }
1675         }
1676         return ret;
1677 }
1678 #endif
1679
1680 static int
1681 open_wim_writable(WIMStruct *w, const mbchar *path,
1682                   bool trunc, bool readable)
1683 {
1684         const char *mode;
1685         if (trunc)
1686                 if (readable)
1687                         mode = "w+b";
1688                 else
1689                         mode = "wb";
1690         else
1691                 mode = "r+b";
1692
1693         wimlib_assert(w->out_fp == NULL);
1694         w->out_fp = fopen(path, mode);
1695         if (w->out_fp) {
1696                 return 0;
1697         } else {
1698                 ERROR_WITH_ERRNO("Failed to open `%s' for writing", path);
1699                 return WIMLIB_ERR_OPEN;
1700         }
1701 }
1702
1703
1704 void
1705 close_wim_writable(WIMStruct *w)
1706 {
1707         if (w->out_fp) {
1708                 if (fclose(w->out_fp) != 0) {
1709                         WARNING_WITH_ERRNO("Failed to close output WIM");
1710                 }
1711                 w->out_fp = NULL;
1712         }
1713 }
1714
1715 /* Open file stream and write dummy header for WIM. */
1716 int
1717 begin_write(WIMStruct *w, const mbchar *path, int write_flags)
1718 {
1719         int ret;
1720         ret = open_wim_writable(w, path, true,
1721                                 (write_flags & WIMLIB_WRITE_FLAG_CHECK_INTEGRITY) != 0);
1722         if (ret != 0)
1723                 return ret;
1724         /* Write dummy header. It will be overwritten later. */
1725         return write_header(&w->hdr, w->out_fp);
1726 }
1727
1728 /* Writes a stand-alone WIM to a file.  */
1729 WIMLIBAPI int
1730 wimlib_write(WIMStruct *w, const mbchar *path,
1731              int image, int write_flags, unsigned num_threads,
1732              wimlib_progress_func_t progress_func)
1733 {
1734         int ret;
1735
1736         if (!path)
1737                 return WIMLIB_ERR_INVALID_PARAM;
1738
1739         write_flags &= WIMLIB_WRITE_MASK_PUBLIC;
1740
1741         if (image != WIMLIB_ALL_IMAGES &&
1742              (image < 1 || image > w->hdr.image_count))
1743                 return WIMLIB_ERR_INVALID_IMAGE;
1744
1745         if (w->hdr.total_parts != 1) {
1746                 ERROR("Cannot call wimlib_write() on part of a split WIM");
1747                 return WIMLIB_ERR_SPLIT_UNSUPPORTED;
1748         }
1749
1750         ret = begin_write(w, path, write_flags);
1751         if (ret != 0)
1752                 goto out;
1753
1754         ret = write_wim_streams(w, image, write_flags, num_threads,
1755                                 progress_func);
1756         if (ret != 0)
1757                 goto out;
1758
1759         if (progress_func)
1760                 progress_func(WIMLIB_PROGRESS_MSG_WRITE_METADATA_BEGIN, NULL);
1761
1762         ret = for_image(w, image, write_metadata_resource);
1763         if (ret != 0)
1764                 goto out;
1765
1766         if (progress_func)
1767                 progress_func(WIMLIB_PROGRESS_MSG_WRITE_METADATA_END, NULL);
1768
1769         ret = finish_write(w, image, write_flags, progress_func);
1770 out:
1771         close_wim_writable(w);
1772         DEBUG("wimlib_write(path=%s) = %d", path, ret);
1773         return ret;
1774 }
1775
1776 static bool
1777 any_images_modified(WIMStruct *w)
1778 {
1779         for (int i = 0; i < w->hdr.image_count; i++)
1780                 if (w->image_metadata[i].modified)
1781                         return true;
1782         return false;
1783 }
1784
1785 /*
1786  * Overwrite a WIM, possibly appending streams to it.
1787  *
1788  * A WIM looks like (or is supposed to look like) the following:
1789  *
1790  *                   Header (212 bytes)
1791  *                   Streams and metadata resources (variable size)
1792  *                   Lookup table (variable size)
1793  *                   XML data (variable size)
1794  *                   Integrity table (optional) (variable size)
1795  *
1796  * If we are not adding any streams or metadata resources, the lookup table is
1797  * unchanged--- so we only need to overwrite the XML data, integrity table, and
1798  * header.  This operation is potentially unsafe if the program is abruptly
1799  * terminated while the XML data or integrity table are being overwritten, but
1800  * before the new header has been written.  To partially alleviate this problem,
1801  * a special flag (WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML) is passed to
1802  * finish_write() to cause a temporary WIM header to be written after the XML
1803  * data has been written.  This may prevent the WIM from becoming corrupted if
1804  * the program is terminated while the integrity table is being calculated (but
1805  * no guarantees, due to write re-ordering...).
1806  *
1807  * If we are adding new streams or images (metadata resources), the lookup table
1808  * needs to be changed, and those streams need to be written.  In this case, we
1809  * try to perform a safe update of the WIM file by writing the streams *after*
1810  * the end of the previous WIM, then writing the new lookup table, XML data, and
1811  * (optionally) integrity table following the new streams.  This will produce a
1812  * layout like the following:
1813  *
1814  *                   Header (212 bytes)
1815  *                   (OLD) Streams and metadata resources (variable size)
1816  *                   (OLD) Lookup table (variable size)
1817  *                   (OLD) XML data (variable size)
1818  *                   (OLD) Integrity table (optional) (variable size)
1819  *                   (NEW) Streams and metadata resources (variable size)
1820  *                   (NEW) Lookup table (variable size)
1821  *                   (NEW) XML data (variable size)
1822  *                   (NEW) Integrity table (optional) (variable size)
1823  *
1824  * At all points, the WIM is valid as nothing points to the new data yet.  Then,
1825  * the header is overwritten to point to the new lookup table, XML data, and
1826  * integrity table, to produce the following layout:
1827  *
1828  *                   Header (212 bytes)
1829  *                   Streams and metadata resources (variable size)
1830  *                   Nothing (variable size)
1831  *                   More Streams and metadata resources (variable size)
1832  *                   Lookup table (variable size)
1833  *                   XML data (variable size)
1834  *                   Integrity table (optional) (variable size)
1835  *
1836  * This method allows an image to be appended to a large WIM very quickly, and
1837  * is is crash-safe except in the case of write re-ordering, but the
1838  * disadvantage is that a small hole is left in the WIM where the old lookup
1839  * table, xml data, and integrity table were.  (These usually only take up a
1840  * small amount of space compared to the streams, however.)
1841  */
1842 static int
1843 overwrite_wim_inplace(WIMStruct *w, int write_flags,
1844                       unsigned num_threads,
1845                       wimlib_progress_func_t progress_func)
1846 {
1847         int ret;
1848         struct list_head stream_list;
1849         off_t old_wim_end;
1850         bool found_modified_image;
1851
1852         DEBUG("Overwriting `%s' in-place", w->filename);
1853
1854         /* Make sure that the integrity table (if present) is after the XML
1855          * data, and that there are no stream resources, metadata resources, or
1856          * lookup tables after the XML data.  Otherwise, these data would be
1857          * overwritten. */
1858         if (w->hdr.integrity.offset != 0 &&
1859             w->hdr.integrity.offset < w->hdr.xml_res_entry.offset) {
1860                 ERROR("Didn't expect the integrity table to be before the XML data");
1861                 return WIMLIB_ERR_RESOURCE_ORDER;
1862         }
1863
1864         if (w->hdr.lookup_table_res_entry.offset > w->hdr.xml_res_entry.offset) {
1865                 ERROR("Didn't expect the lookup table to be after the XML data");
1866                 return WIMLIB_ERR_RESOURCE_ORDER;
1867         }
1868
1869
1870         if (w->hdr.integrity.offset)
1871                 old_wim_end = w->hdr.integrity.offset + w->hdr.integrity.size;
1872         else
1873                 old_wim_end = w->hdr.xml_res_entry.offset + w->hdr.xml_res_entry.size;
1874
1875         if (!w->deletion_occurred && !any_images_modified(w)) {
1876                 /* If no images have been modified and no images have been
1877                  * deleted, a new lookup table does not need to be written. */
1878                 old_wim_end = w->hdr.lookup_table_res_entry.offset +
1879                               w->hdr.lookup_table_res_entry.size;
1880                 write_flags |= WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE |
1881                                WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML;
1882         }
1883         INIT_LIST_HEAD(&stream_list);
1884         ret = wim_find_new_streams(w, old_wim_end, &stream_list);
1885         if (ret != 0)
1886                 return ret;
1887
1888         ret = open_wim_writable(w, w->filename, false,
1889                                 (write_flags & WIMLIB_WRITE_FLAG_CHECK_INTEGRITY) != 0);
1890         if (ret != 0)
1891                 return ret;
1892
1893         ret = lock_wim(w, w->out_fp);
1894         if (ret != 0) {
1895                 fclose(w->out_fp);
1896                 w->out_fp = NULL;
1897                 return ret;
1898         }
1899
1900         if (fseeko(w->out_fp, old_wim_end, SEEK_SET) != 0) {
1901                 ERROR_WITH_ERRNO("Can't seek to end of WIM");
1902                 fclose(w->out_fp);
1903                 w->out_fp = NULL;
1904                 w->wim_locked = 0;
1905                 return WIMLIB_ERR_WRITE;
1906         }
1907
1908         if (!list_empty(&stream_list)) {
1909                 DEBUG("Writing newly added streams (offset = %"PRIu64")",
1910                       old_wim_end);
1911                 ret = write_stream_list(&stream_list, w->out_fp,
1912                                         wimlib_get_compression_type(w),
1913                                         write_flags, num_threads,
1914                                         progress_func);
1915                 if (ret != 0)
1916                         goto out_ftruncate;
1917         } else {
1918                 DEBUG("No new streams were added");
1919         }
1920
1921         found_modified_image = false;
1922         for (int i = 0; i < w->hdr.image_count; i++) {
1923                 if (!found_modified_image)
1924                         found_modified_image = w->image_metadata[i].modified;
1925                 if (found_modified_image) {
1926                         select_wim_image(w, i + 1);
1927                         ret = write_metadata_resource(w);
1928                         if (ret != 0)
1929                                 goto out_ftruncate;
1930                 }
1931         }
1932         write_flags |= WIMLIB_WRITE_FLAG_REUSE_INTEGRITY_TABLE;
1933         ret = finish_write(w, WIMLIB_ALL_IMAGES, write_flags,
1934                            progress_func);
1935 out_ftruncate:
1936         close_wim_writable(w);
1937         if (ret != 0 && !(write_flags & WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE)) {
1938                 WARNING("Truncating `%s' to its original size (%"PRIu64" bytes)",
1939                         w->filename, old_wim_end);
1940                 /* Return value of truncate() is ignored because this is already
1941                  * an error path. */
1942                 (void)truncate(w->filename, old_wim_end);
1943         }
1944         w->wim_locked = 0;
1945         return ret;
1946 }
1947
1948 static int
1949 overwrite_wim_via_tmpfile(WIMStruct *w, int write_flags,
1950                           unsigned num_threads,
1951                           wimlib_progress_func_t progress_func)
1952 {
1953         size_t wim_name_len;
1954         int ret;
1955
1956         DEBUG("Overwriting `%s' via a temporary file", w->filename);
1957
1958         /* Write the WIM to a temporary file in the same directory as the
1959          * original WIM. */
1960         wim_name_len = strlen(w->filename);
1961         mbchar tmpfile[wim_name_len + 10];
1962         memcpy(tmpfile, w->filename, wim_name_len);
1963         randomize_char_array_with_alnum(tmpfile + wim_name_len, 9);
1964         tmpfile[wim_name_len + 9] = '\0';
1965
1966         ret = wimlib_write(w, tmpfile, WIMLIB_ALL_IMAGES,
1967                            write_flags | WIMLIB_WRITE_FLAG_FSYNC,
1968                            num_threads, progress_func);
1969         if (ret != 0) {
1970                 ERROR("Failed to write the WIM file `%s'", tmpfile);
1971                 goto err;
1972         }
1973
1974         DEBUG("Renaming `%s' to `%s'", tmpfile, w->filename);
1975
1976         /* Rename the new file to the old file .*/
1977         if (rename(tmpfile, w->filename) != 0) {
1978                 ERROR_WITH_ERRNO("Failed to rename `%s' to `%s'",
1979                                  tmpfile, w->filename);
1980                 ret = WIMLIB_ERR_RENAME;
1981                 goto err;
1982         }
1983
1984         if (progress_func) {
1985                 union wimlib_progress_info progress;
1986                 progress.rename.from = tmpfile;
1987                 progress.rename.to = w->filename;
1988                 progress_func(WIMLIB_PROGRESS_MSG_RENAME, &progress);
1989         }
1990
1991         /* Close the original WIM file that was opened for reading. */
1992         if (w->fp != NULL) {
1993                 fclose(w->fp);
1994                 w->fp = NULL;
1995         }
1996
1997         /* Re-open the WIM read-only. */
1998         w->fp = fopen(w->filename, "rb");
1999         if (w->fp == NULL) {
2000                 ret = WIMLIB_ERR_REOPEN;
2001                 WARNING_WITH_ERRNO("Failed to re-open `%s' read-only",
2002                                    w->filename);
2003                 FREE(w->filename);
2004                 w->filename = NULL;
2005         }
2006         return ret;
2007 err:
2008         /* Remove temporary file. */
2009         if (unlink(tmpfile) != 0)
2010                 WARNING_WITH_ERRNO("Failed to remove `%s'", tmpfile);
2011         return ret;
2012 }
2013
2014 /*
2015  * Writes a WIM file to the original file that it was read from, overwriting it.
2016  */
2017 WIMLIBAPI int
2018 wimlib_overwrite(WIMStruct *w, int write_flags,
2019                  unsigned num_threads,
2020                  wimlib_progress_func_t progress_func)
2021 {
2022         write_flags &= WIMLIB_WRITE_MASK_PUBLIC;
2023
2024         if (!w->filename)
2025                 return WIMLIB_ERR_NO_FILENAME;
2026
2027         if (w->hdr.total_parts != 1) {
2028                 ERROR("Cannot modify a split WIM");
2029                 return WIMLIB_ERR_SPLIT_UNSUPPORTED;
2030         }
2031
2032         if ((!w->deletion_occurred || (write_flags & WIMLIB_WRITE_FLAG_SOFT_DELETE))
2033             && !(write_flags & WIMLIB_WRITE_FLAG_REBUILD))
2034         {
2035                 int ret;
2036                 ret = overwrite_wim_inplace(w, write_flags, num_threads,
2037                                             progress_func);
2038                 if (ret == WIMLIB_ERR_RESOURCE_ORDER)
2039                         WARNING("Falling back to re-building entire WIM");
2040                 else
2041                         return ret;
2042         }
2043         return overwrite_wim_via_tmpfile(w, write_flags, num_threads,
2044                                          progress_func);
2045 }