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