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

   1 /*
   2  * write.c
   3  *
   4  * Support for writing WIM files; write a WIM file, overwrite a WIM file, write
   5  * compressed file resources, etc.
   6  */
   7
   8 /*
   9  * Copyright (C) 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 "wimlib_internal.h"
  29 #include "io.h"
  30 #include "dentry.h"
  31 #include "lookup_table.h"
  32 #include "xml.h"
  33 #include "lzx.h"
  34 #include "xpress.h"
  35 #include <unistd.h>
  36
  37 #ifdef ENABLE_MULTITHREADED_COMPRESSION
  38 #include <semaphore.h>
  39 #include <pthread.h>
  40 #include <errno.h>
  41 #endif
  42
  43 #ifdef WITH_NTFS_3G
  44 #include <time.h>
  45 #include <ntfs-3g/attrib.h>
  46 #include <ntfs-3g/inode.h>
  47 #include <ntfs-3g/dir.h>
  48 #endif
  49
  50
  51 #ifdef HAVE_ALLOCA_H
  52 #include <alloca.h>
  53 #else
  54 #include <stdlib.h>
  55 #endif
  56
  57 static int do_fflush(FILE *fp)
  58 {
  59         int ret = fflush(fp);
  60         if (ret != 0) {
  61                 ERROR_WITH_ERRNO("Failed to flush data to output WIM file");
  62                 return WIMLIB_ERR_WRITE;
  63         }
  64         return 0;
  65 }
  66
  67 static int fflush_and_ftruncate(FILE *fp, off_t size)
  68 {
  69         int ret;
  70
  71         ret = do_fflush(fp);
  72         if (ret != 0)
  73                 return ret;
  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 == WIM_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 tale 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 /*
 327  * Writes a WIM resource to a FILE * opened for writing.  The resource may be
 328  * written uncompressed or compressed depending on the @out_ctype parameter.
 329  *
 330  * If by chance the resource compresses to more than the original size (this may
 331  * happen with random data or files than are pre-compressed), the resource is
 332  * instead written uncompressed (and this is reflected in the @out_res_entry by
 333  * removing the WIM_RESHDR_FLAG_COMPRESSED flag).
 334  *
 335  * @lte:        The lookup table entry for the WIM resource.
 336  * @out_fp:     The FILE * to write the resource to.
 337  * @out_ctype:  The compression type of the resource to write.  Note: if this is
 338  *                      the same as the compression type of the WIM resource we
 339  *                      need to read, we simply copy the data (i.e. we do not
 340  *                      uncompress it, then compress it again).
 341  * @out_res_entry:  If non-NULL, a resource entry that is filled in with the
 342  *                  offset, original size, compressed size, and compression flag
 343  *                  of the output resource.
 344  *
 345  * Returns 0 on success; nonzero on failure.
 346  */
 347 int write_wim_resource(struct lookup_table_entry *lte,
 348                        FILE *out_fp, int out_ctype,
 349                        struct resource_entry *out_res_entry,
 350                        int flags)
 351 {
 352         u64 bytes_remaining;
 353         u64 original_size;
 354         u64 old_compressed_size;
 355         u64 new_compressed_size;
 356         u64 offset;
 357         int ret;
 358         struct chunk_table *chunk_tab = NULL;
 359         bool raw;
 360         off_t file_offset;
 361         compress_func_t compress;
 362 #ifdef WITH_NTFS_3G
 363         ntfs_inode *ni = NULL;
 364 #endif
 365
 366         wimlib_assert(lte);
 367
 368         /* Original size of the resource */
 369         original_size = wim_resource_size(lte);
 370
 371         /* Compressed size of the resource (as it exists now) */
 372         old_compressed_size = wim_resource_compressed_size(lte);
 373
 374         /* Current offset in output file */
 375         file_offset = ftello(out_fp);
 376         if (file_offset == -1) {
 377                 ERROR_WITH_ERRNO("Failed to get offset in output "
 378                                  "stream");
 379                 return WIMLIB_ERR_WRITE;
 380         }
 381
 382         /* Are the compression types the same?  If so, do a raw copy (copy
 383          * without decompressing and recompressing the data). */
 384         raw = (wim_resource_compression_type(lte) == out_ctype
 385                && out_ctype != WIM_COMPRESSION_TYPE_NONE);
 386
 387         if (raw) {
 388                 flags |= WIMLIB_RESOURCE_FLAG_RAW;
 389                 bytes_remaining = old_compressed_size;
 390         } else {
 391                 flags &= ~WIMLIB_RESOURCE_FLAG_RAW;
 392                 bytes_remaining = original_size;
 393         }
 394
 395         /* Empty resource; nothing needs to be done, so just return success. */
 396         if (bytes_remaining == 0)
 397                 return 0;
 398
 399         /* Buffer for reading chunks for the resource */
 400         u8 buf[min(WIM_CHUNK_SIZE, bytes_remaining)];
 401
 402         /* If we are writing a compressed resource and not doing a raw copy, we
 403          * need to initialize the chunk table */
 404         if (out_ctype != WIM_COMPRESSION_TYPE_NONE && !raw) {
 405                 ret = begin_wim_resource_chunk_tab(lte, out_fp, file_offset,
 406                                                    &chunk_tab);
 407                 if (ret != 0)
 408                         goto out;
 409         }
 410
 411         /* If the WIM resource is in an external file, open a FILE * to it so we
 412          * don't have to open a temporary one in read_wim_resource() for each
 413          * chunk. */
 414 #ifdef WITH_NTFS_3G
 415         ret = prepare_resource_for_read(lte, &ni);
 416 #else
 417         ret = prepare_resource_for_read(lte);
 418 #endif
 419         if (ret != 0)
 420                 goto out;
 421
 422         /* If we aren't doing a raw copy, we will compute the SHA1 message
 423          * digest of the resource as we read it, and verify it's the same as the
 424          * hash given in the lookup table entry once we've finished reading the
 425          * resource. */
 426         SHA_CTX ctx;
 427         if (!raw) {
 428                 sha1_init(&ctx);
 429                 compress = get_compress_func(out_ctype);
 430         }
 431         offset = 0;
 432
 433         /* While there are still bytes remaining in the WIM resource, read a
 434          * chunk of the resource, update SHA1, then write that chunk using the
 435          * desired compression type. */
 436         do {
 437                 u64 to_read = min(bytes_remaining, WIM_CHUNK_SIZE);
 438                 ret = read_wim_resource(lte, buf, to_read, offset, flags);
 439                 if (ret != 0)
 440                         goto out_fclose;
 441                 if (!raw)
 442                         sha1_update(&ctx, buf, to_read);
 443                 ret = write_wim_resource_chunk(buf, to_read, out_fp,
 444                                                compress, chunk_tab);
 445                 if (ret != 0)
 446                         goto out_fclose;
 447                 bytes_remaining -= to_read;
 448                 offset += to_read;
 449         } while (bytes_remaining);
 450
 451         /* Raw copy:  The new compressed size is the same as the old compressed
 452          * size
 453          *
 454          * Using WIM_COMPRESSION_TYPE_NONE:  The new compressed size is the
 455          * original size
 456          *
 457          * Using a different compression type:  Call
 458          * finish_wim_resource_chunk_tab() and it will provide the new
 459          * compressed size.
 460          */
 461         if (raw) {
 462                 new_compressed_size = old_compressed_size;
 463         } else {
 464                 if (out_ctype == WIM_COMPRESSION_TYPE_NONE)
 465                         new_compressed_size = original_size;
 466                 else {
 467                         ret = finish_wim_resource_chunk_tab(chunk_tab, out_fp,
 468                                                             &new_compressed_size);
 469                         if (ret != 0)
 470                                 goto out_fclose;
 471                 }
 472         }
 473
 474         /* Verify SHA1 message digest of the resource, unless we are doing a raw
 475          * write (in which case we never even saw the uncompressed data).  Or,
 476          * if the hash we had before is all 0's, just re-set it to be the new
 477          * hash. */
 478         if (!raw) {
 479                 u8 md[SHA1_HASH_SIZE];
 480                 sha1_final(md, &ctx);
 481                 if (is_zero_hash(lte->hash)) {
 482                         copy_hash(lte->hash, md);
 483                 } else if (!hashes_equal(md, lte->hash)) {
 484                         ERROR("WIM resource has incorrect hash!");
 485                         if (lte->resource_location == RESOURCE_IN_FILE_ON_DISK) {
 486                                 ERROR("We were reading it from `%s'; maybe it changed "
 487                                       "while we were reading it.",
 488                                       lte->file_on_disk);
 489                         }
 490                         ret = WIMLIB_ERR_INVALID_RESOURCE_HASH;
 491                         goto out_fclose;
 492                 }
 493         }
 494
 495         if (!raw && new_compressed_size >= original_size &&
 496             out_ctype != WIM_COMPRESSION_TYPE_NONE)
 497         {
 498                 /* Oops!  We compressed the resource to larger than the original
 499                  * size.  Write the resource uncompressed instead. */
 500                 if (fseeko(out_fp, file_offset, SEEK_SET) != 0) {
 501                         ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" "
 502                                          "of output WIM file", file_offset);
 503                         ret = WIMLIB_ERR_WRITE;
 504                         goto out_fclose;
 505                 }
 506                 ret = write_wim_resource(lte, out_fp, WIM_COMPRESSION_TYPE_NONE,
 507                                          out_res_entry, flags);
 508                 if (ret != 0)
 509                         goto out_fclose;
 510
 511                 ret = fflush_and_ftruncate(out_fp, file_offset + out_res_entry->size);
 512                 if (ret != 0)
 513                         goto out_fclose;
 514         } else {
 515                 if (out_res_entry) {
 516                         out_res_entry->size          = new_compressed_size;
 517                         out_res_entry->original_size = original_size;
 518                         out_res_entry->offset        = file_offset;
 519                         out_res_entry->flags         = lte->resource_entry.flags
 520                                                         & ~WIM_RESHDR_FLAG_COMPRESSED;
 521                         if (out_ctype != WIM_COMPRESSION_TYPE_NONE)
 522                                 out_res_entry->flags |= WIM_RESHDR_FLAG_COMPRESSED;
 523                 }
 524         }
 525         ret = 0;
 526 out_fclose:
 527 #ifdef WITH_NTFS_3G
 528         end_wim_resource_read(lte, ni);
 529 #else
 530         end_wim_resource_read(lte);
 531 #endif
 532 out:
 533         FREE(chunk_tab);
 534         return ret;
 535 }
 536
 537 #ifdef ENABLE_MULTITHREADED_COMPRESSION
 538 struct shared_queue {
 539         sem_t filled_slots;
 540         sem_t empty_slots;
 541         pthread_mutex_t lock;
 542         unsigned front;
 543         unsigned back;
 544         void **array;
 545         unsigned size;
 546 };
 547
 548 static int shared_queue_init(struct shared_queue *q, unsigned size)
 549 {
 550         q->array = CALLOC(sizeof(q->array[0]), size);
 551         if (!q->array)
 552                 return WIMLIB_ERR_NOMEM;
 553
 554         sem_init(&q->filled_slots, 0, 0);
 555         sem_init(&q->empty_slots, 0, size);
 556         pthread_mutex_init(&q->lock, NULL);
 557         q->front = 0;
 558         q->back = size - 1;
 559         q->size = size;
 560         return 0;
 561 }
 562
 563 static void shared_queue_destroy(struct shared_queue *q)
 564 {
 565         sem_destroy(&q->filled_slots);
 566         sem_destroy(&q->empty_slots);
 567         pthread_mutex_destroy(&q->lock);
 568         FREE(q->array);
 569 }
 570
 571 static void shared_queue_put(struct shared_queue *q, void *obj)
 572 {
 573         sem_wait(&q->empty_slots);
 574         pthread_mutex_lock(&q->lock);
 575
 576         q->back = (q->back + 1) % q->size;
 577         q->array[q->back] = obj;
 578
 579         sem_post(&q->filled_slots);
 580         pthread_mutex_unlock(&q->lock);
 581 }
 582
 583 static void *shared_queue_get(struct shared_queue *q)
 584 {
 585         sem_wait(&q->filled_slots);
 586         pthread_mutex_lock(&q->lock);
 587
 588         void *obj = q->array[q->front];
 589         q->array[q->front] = NULL;
 590         q->front = (q->front + 1) % q->size;
 591
 592         sem_post(&q->empty_slots);
 593         pthread_mutex_unlock(&q->lock);
 594         return obj;
 595 }
 596
 597 struct compressor_thread_params {
 598         struct shared_queue *res_to_compress_queue;
 599         struct shared_queue *compressed_res_queue;
 600         compress_func_t compress;
 601 };
 602
 603 #define MAX_CHUNKS_PER_MSG 2
 604
 605 struct message {
 606         struct lookup_table_entry *lte;
 607         u8 *uncompressed_chunks[MAX_CHUNKS_PER_MSG];
 608         u8 *out_compressed_chunks[MAX_CHUNKS_PER_MSG];
 609         u8 *compressed_chunks[MAX_CHUNKS_PER_MSG];
 610         unsigned uncompressed_chunk_sizes[MAX_CHUNKS_PER_MSG];
 611         unsigned compressed_chunk_sizes[MAX_CHUNKS_PER_MSG];
 612         unsigned num_chunks;
 613         struct list_head list;
 614         bool complete;
 615         u64 begin_chunk;
 616 };
 617
 618 static void compress_chunks(struct message *msg, compress_func_t compress)
 619 {
 620         for (unsigned i = 0; i < msg->num_chunks; i++) {
 621                 DEBUG2("compress chunk %u of %u", i, msg->num_chunks);
 622                 int ret = compress(msg->uncompressed_chunks[i],
 623                                    msg->uncompressed_chunk_sizes[i],
 624                                    msg->compressed_chunks[i],
 625                                    &msg->compressed_chunk_sizes[i]);
 626                 if (ret == 0) {
 627                         msg->out_compressed_chunks[i] = msg->compressed_chunks[i];
 628                 } else {
 629                         msg->out_compressed_chunks[i] = msg->uncompressed_chunks[i];
 630                         msg->compressed_chunk_sizes[i] = msg->uncompressed_chunk_sizes[i];
 631                 }
 632         }
 633 }
 634
 635 static void *compressor_thread_proc(void *arg)
 636 {
 637         struct compressor_thread_params *params = arg;
 638         struct shared_queue *res_to_compress_queue = params->res_to_compress_queue;
 639         struct shared_queue *compressed_res_queue = params->compressed_res_queue;
 640         compress_func_t compress = params->compress;
 641         struct message *msg;
 642
 643         DEBUG("Compressor thread ready");
 644         while ((msg = shared_queue_get(res_to_compress_queue)) != NULL) {
 645                 compress_chunks(msg, compress);
 646                 shared_queue_put(compressed_res_queue, msg);
 647         }
 648         DEBUG("Compressor thread terminating");
 649 }
 650 #endif
 651
 652 static void show_stream_write_progress(u64 *cur_size, u64 *next_size,
 653                                        u64 total_size, u64 one_percent,
 654                                        unsigned *cur_percent,
 655                                        const struct lookup_table_entry *cur_lte)
 656 {
 657         if (*cur_size >= *next_size) {
 658                 printf("\r%"PRIu64" MiB of %"PRIu64" MiB "
 659                        "(uncompressed) written (%u%% done)",
 660                        *cur_size >> 20,
 661                        total_size >> 20, *cur_percent);
 662                 fflush(stdout);
 663                 *next_size += one_percent;
 664                 (*cur_percent)++;
 665         }
 666         *cur_size += wim_resource_size(cur_lte);
 667 }
 668
 669 static void finish_stream_write_progress(u64 total_size)
 670 {
 671         printf("\r%"PRIu64" MiB of %"PRIu64" MiB "
 672                "(uncompressed) written (100%% done)\n",
 673                total_size >> 20, total_size >> 20);
 674         fflush(stdout);
 675 }
 676
 677 static int write_stream_list_serial(struct list_head *stream_list,
 678                                     FILE *out_fp, int out_ctype,
 679                                     int write_flags, u64 total_size)
 680 {
 681         struct lookup_table_entry *lte;
 682         int ret;
 683
 684         u64 one_percent = total_size / 100;
 685         u64 cur_size = 0;
 686         u64 next_size = 0;
 687         unsigned cur_percent = 0;
 688
 689         list_for_each_entry(lte, stream_list, staging_list) {
 690                 if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS) {
 691                         show_stream_write_progress(&cur_size, &next_size,
 692                                                    total_size, one_percent,
 693                                                    &cur_percent, lte);
 694                 }
 695                 ret = write_wim_resource(lte, out_fp, out_ctype,
 696                                          &lte->output_resource_entry, 0);
 697                 if (ret != 0)
 698                         return ret;
 699         }
 700         if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS)
 701                 finish_stream_write_progress(total_size);
 702         return 0;
 703 }
 704
 705 #ifdef ENABLE_MULTITHREADED_COMPRESSION
 706 static int write_wim_chunks(struct message *msg, FILE *out_fp,
 707                             struct chunk_table *chunk_tab)
 708 {
 709         for (unsigned i = 0; i < msg->num_chunks; i++) {
 710                 unsigned chunk_csize = msg->compressed_chunk_sizes[i];
 711
 712                 DEBUG2("Write wim chunk %u of %u (csize = %u)",
 713                       i, msg->num_chunks, chunk_csize);
 714
 715                 if (fwrite(msg->out_compressed_chunks[i], 1, chunk_csize, out_fp)
 716                     != chunk_csize)
 717                 {
 718                         ERROR_WITH_ERRNO("Failed to write WIM chunk");
 719                         return WIMLIB_ERR_WRITE;
 720                 }
 721
 722                 *chunk_tab->cur_offset_p++ = chunk_tab->cur_offset;
 723                 chunk_tab->cur_offset += chunk_csize;
 724         }
 725         return 0;
 726 }
 727
 728 /*
 729  * This function is executed by the main thread when the resources are being
 730  * compressed in parallel.  The main thread is in change of all reading of the
 731  * uncompressed data and writing of the compressed data.  The compressor threads
 732  * *only* do compression from/to in-memory buffers.
 733  *
 734  * Each unit of work given to a compressor thread is up to MAX_CHUNKS_PER_MSG
 735  * chunks of compressed data to compress, represented in a `struct message'.
 736  * Each message is passed from the main thread to a worker thread through the
 737  * res_to_compress_queue, and it is passed back through the
 738  * compressed_res_queue.
 739  */
 740 static int main_writer_thread_proc(struct list_head *stream_list,
 741                                    FILE *out_fp,
 742                                    int out_ctype,
 743                                    struct shared_queue *res_to_compress_queue,
 744                                    struct shared_queue *compressed_res_queue,
 745                                    size_t queue_size,
 746                                    int write_flags,
 747                                    u64 total_size)
 748 {
 749         int ret;
 750
 751
 752         struct message msgs[queue_size];
 753         ZERO_ARRAY(msgs);
 754
 755         // Initially, all the messages are available to use.
 756         LIST_HEAD(available_msgs);
 757         for (size_t i = 0; i < ARRAY_LEN(msgs); i++)
 758                 list_add(&msgs[i].list, &available_msgs);
 759
 760         // outstanding_resources is the list of resources that currently have
 761         // had chunks sent off for compression.
 762         //
 763         // The first stream in outstanding_resources is the stream that is
 764         // currently being written (cur_lte).
 765         //
 766         // The last stream in outstanding_resources is the stream that is
 767         // currently being read and chunks fed to the compressor threads
 768         // (next_lte).
 769         //
 770         // Depending on the number of threads and the sizes of the resource,
 771         // the outstanding streams list may contain streams between cur_lte and
 772         // next_lte that have all their chunks compressed or being compressed,
 773         // but haven't been written yet.
 774         //
 775         LIST_HEAD(outstanding_resources);
 776         struct list_head *next_resource = stream_list->next;
 777         struct lookup_table_entry *next_lte = container_of(next_resource,
 778                                                            struct lookup_table_entry,
 779                                                            staging_list);
 780         next_resource = next_resource->next;
 781         u64 next_chunk = 0;
 782         u64 next_num_chunks = wim_resource_chunks(next_lte);
 783         INIT_LIST_HEAD(&next_lte->msg_list);
 784         list_add_tail(&next_lte->staging_list, &outstanding_resources);
 785
 786         // As in write_wim_resource(), each resource we read is checksummed.
 787         SHA_CTX next_sha_ctx;
 788         sha1_init(&next_sha_ctx);
 789         u8 next_hash[SHA1_HASH_SIZE];
 790
 791         // Resources that don't need any chunks compressed are added to this
 792         // list and written directly by the main thread.
 793         LIST_HEAD(my_resources);
 794
 795         struct lookup_table_entry *cur_lte = next_lte;
 796         struct chunk_table *cur_chunk_tab = NULL;
 797         struct lookup_table_entry *lte;
 798         struct message *msg;
 799
 800         u64 one_percent = total_size / 100;
 801         u64 cur_size = 0;
 802         u64 next_size = 0;
 803         unsigned cur_percent = 0;
 804
 805 #ifdef WITH_NTFS_3G
 806         ntfs_inode *ni = NULL;
 807 #endif
 808
 809 #ifdef WITH_NTFS_3G
 810         ret = prepare_resource_for_read(next_lte, &ni);
 811 #else
 812         ret = prepare_resource_for_read(next_lte);
 813 #endif
 814         if (ret != 0)
 815                 goto out;
 816
 817         DEBUG("Initializing buffers for uncompressed "
 818               "and compressed data (%zu bytes needed)",
 819               queue_size * MAX_CHUNKS_PER_MSG * WIM_CHUNK_SIZE * 2);
 820
 821         // Pre-allocate all the buffers that will be needed to do the chunk
 822         // compression.
 823         for (size_t i = 0; i < ARRAY_LEN(msgs); i++) {
 824                 for (size_t j = 0; j < MAX_CHUNKS_PER_MSG; j++) {
 825                         msgs[i].compressed_chunks[j] = MALLOC(WIM_CHUNK_SIZE);
 826                         msgs[i].uncompressed_chunks[j] = MALLOC(WIM_CHUNK_SIZE);
 827                         if (msgs[i].compressed_chunks[j] == NULL ||
 828                             msgs[i].uncompressed_chunks[j] == NULL)
 829                         {
 830                                 ERROR("Could not allocate enough memory for "
 831                                       "multi-threaded compression");
 832                                 ret = WIMLIB_ERR_NOMEM;
 833                                 goto out;
 834                         }
 835                 }
 836         }
 837
 838         // This loop is executed until all resources have been written, except
 839         // possibly a few that have been added to the @my_resources list for
 840         // writing later.
 841         while (1) {
 842                 // Send chunks to the compressor threads until either (a) there
 843                 // are no more messages available since they were all sent off,
 844                 // or (b) there are no more resources that need to be
 845                 // compressed.
 846                 while (!list_empty(&available_msgs) && next_lte != NULL) {
 847
 848                         // Get a message from the available messages
 849                         // list
 850                         msg = container_of(available_msgs.next,
 851                                            struct message,
 852                                            list);
 853
 854                         // ... and delete it from the available messages
 855                         // list
 856                         list_del(&msg->list);
 857
 858                         // Initialize the message with the chunks to
 859                         // compress.
 860                         msg->num_chunks = min(next_num_chunks - next_chunk,
 861                                               MAX_CHUNKS_PER_MSG);
 862                         msg->lte = next_lte;
 863                         msg->complete = false;
 864                         msg->begin_chunk = next_chunk;
 865
 866                         unsigned size = WIM_CHUNK_SIZE;
 867                         for (unsigned i = 0; i < msg->num_chunks; i++) {
 868
 869                                 // Read chunk @next_chunk of the stream into the
 870                                 // message so that a compressor thread can
 871                                 // compress it.
 872
 873                                 if (next_chunk == next_num_chunks - 1 &&
 874                                      wim_resource_size(next_lte) % WIM_CHUNK_SIZE != 0)
 875                                 {
 876                                         size = wim_resource_size(next_lte) % WIM_CHUNK_SIZE;
 877                                 }
 878
 879
 880                                 DEBUG2("Read resource (size=%u, offset=%zu)",
 881                                       size, next_chunk * WIM_CHUNK_SIZE);
 882
 883                                 msg->uncompressed_chunk_sizes[i] = size;
 884
 885                                 ret = read_wim_resource(next_lte,
 886                                                         msg->uncompressed_chunks[i],
 887                                                         size,
 888                                                         next_chunk * WIM_CHUNK_SIZE,
 889                                                         0);
 890                                 if (ret != 0)
 891                                         goto out;
 892                                 sha1_update(&next_sha_ctx,
 893                                             msg->uncompressed_chunks[i], size);
 894                                 next_chunk++;
 895                         }
 896
 897                         // Send the compression request
 898                         list_add_tail(&msg->list, &next_lte->msg_list);
 899                         shared_queue_put(res_to_compress_queue, msg);
 900                         DEBUG2("Compression request sent");
 901
 902                         if (next_chunk != next_num_chunks)
 903                                 // More chunks to send for this resource
 904                                 continue;
 905
 906                         // Done sending compression requests for a resource!
 907                         // Check the SHA1 message digest.
 908                         DEBUG2("Finalize SHA1 md (next_num_chunks=%zu)", next_num_chunks);
 909                         sha1_final(next_hash, &next_sha_ctx);
 910                         if (!hashes_equal(next_lte->hash, next_hash)) {
 911                                 ERROR("WIM resource has incorrect hash!");
 912                                 if (next_lte->resource_location == RESOURCE_IN_FILE_ON_DISK) {
 913                                         ERROR("We were reading it from `%s'; maybe it changed "
 914                                               "while we were reading it.",
 915                                               next_lte->file_on_disk);
 916                                 }
 917                                 ret = WIMLIB_ERR_INVALID_RESOURCE_HASH;
 918                                 goto out;
 919                         }
 920
 921                         // Advance to the next resource.
 922                         //
 923                         // If the next resource needs no compression, just write
 924                         // it with this thread (not now though--- we could be in
 925                         // the middle of writing another resource.)  Keep doing
 926                         // this until we either get to the end of the resources
 927                         // list, or we get to a resource that needs compression.
 928
 929                         while (1) {
 930                                 if (next_resource == stream_list) {
 931                                         next_lte = NULL;
 932                                         break;
 933                                 }
 934                         #ifdef WITH_NTFS_3G
 935                                 end_wim_resource_read(next_lte, ni);
 936                                 ni = NULL;
 937                         #else
 938                                 end_wim_resource_read(next_lte);
 939                         #endif
 940
 941                                 next_lte = container_of(next_resource,
 942                                                         struct lookup_table_entry,
 943                                                         staging_list);
 944                                 next_resource = next_resource->next;
 945                                 if ((next_lte->resource_location == RESOURCE_IN_WIM
 946                                     && wimlib_get_compression_type(next_lte->wim) == out_ctype)
 947                                     || wim_resource_size(next_lte) == 0)
 948                                 {
 949                                         list_add_tail(&next_lte->staging_list,
 950                                                       &my_resources);
 951                                 } else {
 952                                         list_add_tail(&next_lte->staging_list,
 953                                                       &outstanding_resources);
 954                                         next_chunk = 0;
 955                                         next_num_chunks = wim_resource_chunks(next_lte);
 956                                         sha1_init(&next_sha_ctx);
 957                                         INIT_LIST_HEAD(&next_lte->msg_list);
 958                                 #ifdef WITH_NTFS_3G
 959                                         ret = prepare_resource_for_read(next_lte, &ni);
 960                                 #else
 961                                         ret = prepare_resource_for_read(next_lte);
 962                                 #endif
 963                                         if (ret != 0)
 964                                                 goto out;
 965                                         DEBUG2("Updated next_lte");
 966                                         break;
 967                                 }
 968                         }
 969                 }
 970
 971                 // If there are no outstanding resources, there are no more
 972                 // resources that need to be written.
 973                 if (list_empty(&outstanding_resources)) {
 974                         DEBUG("No outstanding resources! Done");
 975                         ret = 0;
 976                         goto out;
 977                 }
 978
 979                 // Get the next message from the queue and process it.
 980                 // The message will contain 1 or more data chunks that have been
 981                 // compressed.
 982                 DEBUG2("Waiting for message");
 983                 msg = shared_queue_get(compressed_res_queue);
 984                 msg->complete = true;
 985
 986                 DEBUG2("Received msg (begin_chunk=%"PRIu64")", msg->begin_chunk);
 987
 988                 list_for_each_entry(msg, &cur_lte->msg_list, list) {
 989                         DEBUG2("complete=%d", msg->complete);
 990                 }
 991
 992                 // Is this the next chunk in the current resource?  If it's not
 993                 // (i.e., an earlier chunk in a same or different resource
 994                 // hasn't been compressed yet), do nothing, and keep this
 995                 // message around until all earlier chunks are received.
 996                 //
 997                 // Otherwise, write all the chunks we can.
 998                 while (!list_empty(&cur_lte->msg_list)
 999                         && (msg = container_of(cur_lte->msg_list.next,
1000                                                struct message,
1001                                                list))->complete)
1002                 {
1003                         DEBUG2("Complete msg (begin_chunk=%"PRIu64")", msg->begin_chunk);
1004                         if (msg->begin_chunk == 0) {
1005                                 DEBUG2("Begin chunk tab");
1006                                 if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS) {
1007                                         show_stream_write_progress(&cur_size,
1008                                                                    &next_size,
1009                                                                    total_size,
1010                                                                    one_percent,
1011                                                                    &cur_percent,
1012                                                                    cur_lte);
1013                                 }
1014
1015                                 // This is the first set of chunks.  Leave space
1016                                 // for the chunk table in the output file.
1017                                 off_t cur_offset = ftello(out_fp);
1018                                 if (cur_offset == -1) {
1019                                         ret = WIMLIB_ERR_WRITE;
1020                                         goto out;
1021                                 }
1022                                 ret = begin_wim_resource_chunk_tab(cur_lte,
1023                                                                    out_fp,
1024                                                                    cur_offset,
1025                                                                    &cur_chunk_tab);
1026                                 if (ret != 0)
1027                                         goto out;
1028                         }
1029
1030                         // Write the compressed chunks from the message.
1031                         ret = write_wim_chunks(msg, out_fp, cur_chunk_tab);
1032                         if (ret != 0)
1033                                 goto out;
1034
1035                         list_del(&msg->list);
1036
1037                         // This message is available to use for different chunks
1038                         // now.
1039                         list_add(&msg->list, &available_msgs);
1040
1041                         // Was this the last chunk of the stream?  If so,
1042                         // finish it.
1043                         if (list_empty(&cur_lte->msg_list) &&
1044                             msg->begin_chunk + msg->num_chunks == cur_chunk_tab->num_chunks)
1045                         {
1046                                 DEBUG2("Finish wim chunk tab");
1047                                 u64 res_csize;
1048                                 ret = finish_wim_resource_chunk_tab(cur_chunk_tab,
1049                                                                     out_fp,
1050                                                                     &res_csize);
1051                                 if (ret != 0)
1052                                         goto out;
1053
1054
1055                                 cur_lte->output_resource_entry.size =
1056                                         res_csize;
1057
1058                                 cur_lte->output_resource_entry.original_size =
1059                                         cur_lte->resource_entry.original_size;
1060
1061                                 cur_lte->output_resource_entry.offset =
1062                                         cur_chunk_tab->file_offset;
1063
1064                                 cur_lte->output_resource_entry.flags =
1065                                         cur_lte->resource_entry.flags |
1066                                                 WIM_RESHDR_FLAG_COMPRESSED;
1067
1068                                 FREE(cur_chunk_tab);
1069                                 cur_chunk_tab = NULL;
1070
1071                                 struct list_head *next = cur_lte->staging_list.next;
1072                                 list_del(&cur_lte->staging_list);
1073
1074                                 if (next == &outstanding_resources) {
1075                                         DEBUG("No more outstanding resources");
1076                                         ret = 0;
1077                                         goto out;
1078                                 } else {
1079                                         cur_lte = container_of(cur_lte->staging_list.next,
1080                                                                struct lookup_table_entry,
1081                                                                staging_list);
1082                                 }
1083
1084                                 // Since we just finished writing a stream,
1085                                 // write any streams that have been added to the
1086                                 // my_resources list for direct writing by the
1087                                 // main thread (e.g. resources that don't need
1088                                 // to be compressed because the desired
1089                                 // compression type is the same as the previous
1090                                 // compression type).
1091                                 struct lookup_table_entry *tmp;
1092                                 list_for_each_entry_safe(lte,
1093                                                          tmp,
1094                                                          &my_resources,
1095                                                          staging_list)
1096                                 {
1097                                         if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS) {
1098                                                 show_stream_write_progress(&cur_size,
1099                                                                            &next_size,
1100                                                                            total_size,
1101                                                                            one_percent,
1102                                                                            &cur_percent,
1103                                                                            lte);
1104                                         }
1105
1106                                         ret = write_wim_resource(lte,
1107                                                                  out_fp,
1108                                                                  out_ctype,
1109                                                                  &lte->output_resource_entry,
1110                                                                  0);
1111                                         list_del(&lte->staging_list);
1112                                         if (ret != 0)
1113                                                 goto out;
1114                                 }
1115                         }
1116                 }
1117         }
1118
1119 out:
1120 #ifdef WITH_NTFS_3G
1121         end_wim_resource_read(cur_lte, ni);
1122 #else
1123         end_wim_resource_read(cur_lte);
1124 #endif
1125         if (ret == 0) {
1126                 list_for_each_entry(lte, &my_resources, staging_list) {
1127                         if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS) {
1128                                 show_stream_write_progress(&cur_size,
1129                                                            &next_size,
1130                                                            total_size,
1131                                                            one_percent,
1132                                                            &cur_percent,
1133                                                            lte);
1134                         }
1135                         ret = write_wim_resource(lte, out_fp,
1136                                                  out_ctype,
1137                                                  &lte->output_resource_entry,
1138                                                  0);
1139                         if (ret != 0)
1140                                 break;
1141                 }
1142                 if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS)
1143                         finish_stream_write_progress(total_size);
1144         } else {
1145                 size_t num_available_msgs = 0;
1146                 struct list_head *cur;
1147
1148                 list_for_each(cur, &available_msgs) {
1149                         num_available_msgs++;
1150                 }
1151
1152                 while (num_available_msgs < ARRAY_LEN(msgs)) {
1153                         shared_queue_get(compressed_res_queue);
1154                         num_available_msgs++;
1155                 }
1156         }
1157
1158         DEBUG("Freeing messages");
1159
1160         for (size_t i = 0; i < ARRAY_LEN(msgs); i++) {
1161                 for (size_t j = 0; j < MAX_CHUNKS_PER_MSG; j++) {
1162                         FREE(msgs[i].compressed_chunks[j]);
1163                         FREE(msgs[i].uncompressed_chunks[j]);
1164                 }
1165         }
1166
1167         if (cur_chunk_tab != NULL)
1168                 FREE(cur_chunk_tab);
1169         return ret;
1170 }
1171
1172
1173 static const char *get_data_type(int ctype)
1174 {
1175         switch (ctype) {
1176         case WIM_COMPRESSION_TYPE_NONE:
1177                 return "uncompressed";
1178         case WIM_COMPRESSION_TYPE_LZX:
1179                 return "LZX-compressed";
1180         case WIM_COMPRESSION_TYPE_XPRESS:
1181                 return "XPRESS-compressed";
1182         }
1183 }
1184
1185 static int write_stream_list_parallel(struct list_head *stream_list,
1186                                       FILE *out_fp, int out_ctype,
1187                                       int write_flags, u64 total_size,
1188                                       unsigned num_threads)
1189 {
1190         int ret;
1191         struct shared_queue res_to_compress_queue;
1192         struct shared_queue compressed_res_queue;
1193         pthread_t *compressor_threads = NULL;
1194
1195         if (num_threads == 0) {
1196                 long nthreads = sysconf(_SC_NPROCESSORS_ONLN);
1197                 if (nthreads < 1) {
1198                         WARNING("Could not determine number of processors! Assuming 1");
1199                         goto out_serial;
1200                 } else {
1201                         num_threads = nthreads;
1202                 }
1203         }
1204
1205         wimlib_assert(stream_list->next != stream_list);
1206
1207         static const double MESSAGES_PER_THREAD = 2.0;
1208         size_t queue_size = (size_t)(num_threads * MESSAGES_PER_THREAD);
1209
1210         DEBUG("Initializing shared queues (queue_size=%zu)", queue_size);
1211
1212         ret = shared_queue_init(&res_to_compress_queue, queue_size);
1213         if (ret != 0)
1214                 goto out_serial;
1215
1216         ret = shared_queue_init(&compressed_res_queue, queue_size);
1217         if (ret != 0)
1218                 goto out_destroy_res_to_compress_queue;
1219
1220         struct compressor_thread_params params;
1221         params.res_to_compress_queue = &res_to_compress_queue;
1222         params.compressed_res_queue = &compressed_res_queue;
1223         params.compress = get_compress_func(out_ctype);
1224
1225         compressor_threads = MALLOC(num_threads * sizeof(pthread_t));
1226
1227         for (unsigned i = 0; i < num_threads; i++) {
1228                 DEBUG("pthread_create thread %u", i);
1229                 ret = pthread_create(&compressor_threads[i], NULL,
1230                                      compressor_thread_proc, &params);
1231                 if (ret != 0) {
1232                         ret = -1;
1233                         ERROR_WITH_ERRNO("Failed to create compressor "
1234                                          "thread %u", i);
1235                         num_threads = i;
1236                         goto out_join;
1237                 }
1238         }
1239
1240         if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS) {
1241                 printf("Writing %s compressed data using %u threads...\n",
1242                        get_data_type(out_ctype), num_threads);
1243         }
1244
1245         ret = main_writer_thread_proc(stream_list,
1246                                       out_fp,
1247                                       out_ctype,
1248                                       &res_to_compress_queue,
1249                                       &compressed_res_queue,
1250                                       queue_size,
1251                                       write_flags,
1252                                       total_size);
1253
1254 out_join:
1255         for (unsigned i = 0; i < num_threads; i++)
1256                 shared_queue_put(&res_to_compress_queue, NULL);
1257
1258         for (unsigned i = 0; i < num_threads; i++) {
1259                 if (pthread_join(compressor_threads[i], NULL)) {
1260                         WARNING("Failed to join compressor thread %u: %s",
1261                                 i, strerror(errno));
1262                 }
1263         }
1264         FREE(compressor_threads);
1265         shared_queue_destroy(&compressed_res_queue);
1266 out_destroy_res_to_compress_queue:
1267         shared_queue_destroy(&res_to_compress_queue);
1268         if (ret >= 0 && ret != WIMLIB_ERR_NOMEM)
1269                 return ret;
1270 out_serial:
1271         WARNING("Falling back to single-threaded compression");
1272         return write_stream_list_serial(stream_list, out_fp,
1273                                         out_ctype, write_flags, total_size);
1274 }
1275 #endif
1276
1277 /*
1278  * Write a list of streams to a WIM (@out_fp) using the compression type
1279  * @out_ctype and up to @num_threads compressor threads.
1280  */
1281 static int write_stream_list(struct list_head *stream_list, FILE *out_fp,
1282                              int out_ctype, int write_flags,
1283                              unsigned num_threads)
1284 {
1285         struct lookup_table_entry *lte;
1286         size_t num_streams = 0;
1287         u64 total_size = 0;
1288         bool compression_needed = false;
1289
1290         list_for_each_entry(lte, stream_list, staging_list) {
1291                 num_streams++;
1292                 total_size += wim_resource_size(lte);
1293                 if (!compression_needed
1294                     && out_ctype != WIM_COMPRESSION_TYPE_NONE
1295                     && (lte->resource_location != RESOURCE_IN_WIM
1296                         || wimlib_get_compression_type(lte->wim) != out_ctype)
1297                     && wim_resource_size(lte) != 0)
1298                         compression_needed = true;
1299         }
1300
1301         if (num_streams == 0) {
1302                 if (write_flags & WIMLIB_WRITE_FLAG_VERBOSE)
1303                         printf("No streams to write\n");
1304                 return 0;
1305         }
1306
1307         if (write_flags & WIMLIB_WRITE_FLAG_VERBOSE) {
1308                 printf("Preparing to write %zu streams "
1309                        "(%"PRIu64" total bytes uncompressed)\n",
1310                        num_streams, total_size);
1311                 printf("Using compression type %s\n",
1312                        wimlib_get_compression_type_string(out_ctype));
1313         }
1314
1315 #ifdef ENABLE_MULTITHREADED_COMPRESSION
1316         if (compression_needed && total_size >= 1000000 && num_threads != 1) {
1317                 return write_stream_list_parallel(stream_list, out_fp,
1318                                                   out_ctype, write_flags,
1319                                                   total_size, num_threads);
1320         }
1321         else
1322 #endif
1323         {
1324                 if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS) {
1325                         const char *reason = "";
1326                         if (!compression_needed)
1327                                 reason = " (no compression needed)";
1328                         printf("Writing %s data using 1 thread%s\n",
1329                                get_data_type(out_ctype), reason);
1330                 }
1331
1332                 return write_stream_list_serial(stream_list, out_fp,
1333                                                 out_ctype, write_flags,
1334                                                 total_size);
1335         }
1336 }
1337
1338
1339 static int dentry_find_streams_to_write(struct dentry *dentry,
1340                                         void *wim)
1341 {
1342         WIMStruct *w = wim;
1343         struct list_head *stream_list = w->private;
1344         struct lookup_table_entry *lte;
1345         for (unsigned i = 0; i <= dentry->d_inode->num_ads; i++) {
1346                 lte = inode_stream_lte(dentry->d_inode, i, w->lookup_table);
1347                 if (lte && ++lte->out_refcnt == 1)
1348                         list_add_tail(&lte->staging_list, stream_list);
1349         }
1350         return 0;
1351 }
1352
1353 static int find_streams_to_write(WIMStruct *w)
1354 {
1355         return for_dentry_in_tree(wim_root_dentry(w),
1356                                   dentry_find_streams_to_write, w);
1357 }
1358
1359 static int write_wim_streams(WIMStruct *w, int image, int write_flags,
1360                              unsigned num_threads)
1361 {
1362
1363         for_lookup_table_entry(w->lookup_table, lte_zero_out_refcnt, NULL);
1364         LIST_HEAD(stream_list);
1365         w->private = &stream_list;
1366         for_image(w, image, find_streams_to_write);
1367         return write_stream_list(&stream_list, w->out_fp,
1368                                  wimlib_get_compression_type(w), write_flags,
1369                                  num_threads);
1370 }
1371
1372 /*
1373  * Finish writing a WIM file: write the lookup table, xml data, and integrity
1374  * table (optional), then overwrite the WIM header.
1375  *
1376  * write_flags is a bitwise OR of the following:
1377  *
1378  *      (public)  WIMLIB_WRITE_FLAG_CHECK_INTEGRITY:
1379  *              Include an integrity table.
1380  *
1381  *      (public)  WIMLIB_WRITE_FLAG_SHOW_PROGRESS:
1382  *              Show progress information when (if) writing the integrity table.
1383  *
1384  *      (private) WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE:
1385  *              Don't write the lookup table.
1386  *
1387  *      (private) WIMLIB_WRITE_FLAG_REUSE_INTEGRITY_TABLE:
1388  *              When (if) writing the integrity table, re-use entries from the
1389  *              existing integrity table, if possible.
1390  *
1391  *      (private) WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML:
1392  *              After writing the XML data but before writing the integrity
1393  *              table, write a temporary WIM header and flush the stream so that
1394  *              the WIM is less likely to become corrupted upon abrupt program
1395  *              termination.
1396  *
1397  *      (private) WIMLIB_WRITE_FLAG_FSYNC:
1398  *              fsync() the output file before closing it.
1399  *
1400  */
1401 int finish_write(WIMStruct *w, int image, int write_flags)
1402 {
1403         int ret;
1404         struct wim_header hdr;
1405         FILE *out = w->out_fp;
1406
1407         /* @hdr will be the header for the new WIM.  First copy all the data
1408          * from the header in the WIMStruct; then set all the fields that may
1409          * have changed, including the resource entries, boot index, and image
1410          * count.  */
1411         memcpy(&hdr, &w->hdr, sizeof(struct wim_header));
1412
1413         if (!(write_flags & WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE)) {
1414                 ret = write_lookup_table(w->lookup_table, out, &hdr.lookup_table_res_entry);
1415                 if (ret != 0)
1416                         goto out;
1417         }
1418
1419         ret = write_xml_data(w->wim_info, image, out,
1420                              (write_flags & WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE) ?
1421                               wim_info_get_total_bytes(w->wim_info) : 0,
1422                              &hdr.xml_res_entry);
1423         if (ret != 0)
1424                 goto out;
1425
1426         if (write_flags & WIMLIB_WRITE_FLAG_CHECK_INTEGRITY) {
1427                 if (write_flags & WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML) {
1428                         struct wim_header checkpoint_hdr;
1429                         memcpy(&checkpoint_hdr, &hdr, sizeof(struct wim_header));
1430                         memset(&checkpoint_hdr.integrity, 0, sizeof(struct resource_entry));
1431                         if (fseeko(out, 0, SEEK_SET) != 0) {
1432                                 ret = WIMLIB_ERR_WRITE;
1433                                 goto out;
1434                         }
1435                         ret = write_header(&checkpoint_hdr, out);
1436                         if (ret != 0)
1437                                 goto out;
1438
1439                         if (fflush(out) != 0) {
1440                                 ERROR_WITH_ERRNO("Can't write data to WIM");
1441                                 ret = WIMLIB_ERR_WRITE;
1442                                 goto out;
1443                         }
1444
1445                         if (fseeko(out, 0, SEEK_END) != 0) {
1446                                 ret = WIMLIB_ERR_WRITE;
1447                                 goto out;
1448                         }
1449                 }
1450
1451                 off_t old_lookup_table_end;
1452                 off_t new_lookup_table_end;
1453                 bool show_progress;
1454                 if (write_flags & WIMLIB_WRITE_FLAG_REUSE_INTEGRITY_TABLE) {
1455                         old_lookup_table_end = w->hdr.lookup_table_res_entry.offset +
1456                                                w->hdr.lookup_table_res_entry.size;
1457                 } else {
1458                         old_lookup_table_end = 0;
1459                 }
1460                 new_lookup_table_end = hdr.lookup_table_res_entry.offset +
1461                                        hdr.lookup_table_res_entry.size;
1462                 show_progress = ((write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS) != 0);
1463
1464                 ret = write_integrity_table(out,
1465                                             &hdr.integrity,
1466                                             new_lookup_table_end,
1467                                             old_lookup_table_end,
1468                                             show_progress);
1469                 if (ret != 0)
1470                         goto out;
1471         } else {
1472                 memset(&hdr.integrity, 0, sizeof(struct resource_entry));
1473         }
1474
1475         /*
1476          * In the WIM header, there is room for the resource entry for a
1477          * metadata resource labeled as the "boot metadata".  This entry should
1478          * be zeroed out if there is no bootable image (boot_idx 0).  Otherwise,
1479          * it should be a copy of the resource entry for the image that is
1480          * marked as bootable.  This is not well documented...
1481          */
1482         if (hdr.boot_idx == 0 || !w->image_metadata
1483                         || (image != WIM_ALL_IMAGES && image != hdr.boot_idx)) {
1484                 memset(&hdr.boot_metadata_res_entry, 0,
1485                        sizeof(struct resource_entry));
1486         } else {
1487                 memcpy(&hdr.boot_metadata_res_entry,
1488                        &w->image_metadata[
1489                           hdr.boot_idx - 1].metadata_lte->output_resource_entry,
1490                        sizeof(struct resource_entry));
1491         }
1492
1493         /* Set image count and boot index correctly for single image writes */
1494         if (image != WIM_ALL_IMAGES) {
1495                 hdr.image_count = 1;
1496                 if (hdr.boot_idx == image)
1497                         hdr.boot_idx = 1;
1498                 else
1499                         hdr.boot_idx = 0;
1500         }
1501
1502         if (fseeko(out, 0, SEEK_SET) != 0) {
1503                 ret = WIMLIB_ERR_WRITE;
1504                 goto out;
1505         }
1506
1507         ret = write_header(&hdr, out);
1508         if (ret != 0)
1509                 goto out;
1510
1511         if (write_flags & WIMLIB_WRITE_FLAG_FSYNC) {
1512                 if (fflush(out) != 0
1513                     || fsync(fileno(out)) != 0)
1514                 {
1515                         ERROR_WITH_ERRNO("Error flushing data to WIM file");
1516                         ret = WIMLIB_ERR_WRITE;
1517                 }
1518         }
1519 out:
1520         if (fclose(out) != 0) {
1521                 ERROR_WITH_ERRNO("Failed to close the WIM file");
1522                 if (ret == 0)
1523                         ret = WIMLIB_ERR_WRITE;
1524         }
1525         w->out_fp = NULL;
1526         return ret;
1527 }
1528
1529 static void close_wim_writable(WIMStruct *w)
1530 {
1531         if (w->out_fp) {
1532                 if (fclose(w->out_fp) != 0) {
1533                         WARNING("Failed to close output WIM: %s",
1534                                 strerror(errno));
1535                 }
1536                 w->out_fp = NULL;
1537         }
1538 }
1539
1540 /* Open file stream and write dummy header for WIM. */
1541 int begin_write(WIMStruct *w, const char *path, int write_flags)
1542 {
1543         int ret;
1544         bool need_readable = false;
1545         bool trunc = true;
1546         if (write_flags & WIMLIB_WRITE_FLAG_CHECK_INTEGRITY)
1547                 need_readable = true;
1548
1549         ret = open_wim_writable(w, path, trunc, need_readable);
1550         if (ret != 0)
1551                 return ret;
1552         /* Write dummy header. It will be overwritten later. */
1553         return write_header(&w->hdr, w->out_fp);
1554 }
1555
1556 /* Writes a stand-alone WIM to a file.  */
1557 WIMLIBAPI int wimlib_write(WIMStruct *w, const char *path,
1558                            int image, int write_flags, unsigned num_threads)
1559 {
1560         int ret;
1561
1562         if (!w || !path)
1563                 return WIMLIB_ERR_INVALID_PARAM;
1564
1565         write_flags &= WIMLIB_WRITE_MASK_PUBLIC;
1566
1567         if (image != WIM_ALL_IMAGES &&
1568              (image < 1 || image > w->hdr.image_count))
1569                 return WIMLIB_ERR_INVALID_IMAGE;
1570
1571         if (w->hdr.total_parts != 1) {
1572                 ERROR("Cannot call wimlib_write() on part of a split WIM");
1573                 return WIMLIB_ERR_SPLIT_UNSUPPORTED;
1574         }
1575
1576         if (image == WIM_ALL_IMAGES)
1577                 DEBUG("Writing all images to `%s'.", path);
1578         else
1579                 DEBUG("Writing image %d to `%s'.", image, path);
1580
1581         ret = begin_write(w, path, write_flags);
1582         if (ret != 0)
1583                 goto out;
1584
1585         ret = write_wim_streams(w, image, write_flags, num_threads);
1586         if (ret != 0)
1587                 goto out;
1588
1589         if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS)
1590                 printf("Writing image metadata...\n");
1591
1592         ret = for_image(w, image, write_metadata_resource);
1593         if (ret != 0)
1594                 goto out;
1595
1596         ret = finish_write(w, image, write_flags);
1597         if (ret == 0 && (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS))
1598                 printf("Successfully wrote `%s'\n", path);
1599 out:
1600         close_wim_writable(w);
1601         return ret;
1602 }
1603
1604 static int lte_overwrite_prepare(struct lookup_table_entry *lte,
1605                                  void *ignore)
1606 {
1607         memcpy(&lte->output_resource_entry, &lte->resource_entry,
1608                sizeof(struct resource_entry));
1609         lte->out_refcnt = 0;
1610         return 0;
1611 }
1612
1613 static int check_resource_offset(struct lookup_table_entry *lte, void *arg)
1614 {
1615         off_t end_offset = *(u64*)arg;
1616
1617         wimlib_assert(lte->out_refcnt <= lte->refcnt);
1618         if (lte->out_refcnt < lte->refcnt) {
1619                 if (lte->resource_entry.offset + lte->resource_entry.size > end_offset) {
1620                         ERROR("The following resource is after the XML data:");
1621                         print_lookup_table_entry(lte);
1622                         return WIMLIB_ERR_RESOURCE_ORDER;
1623                 }
1624         }
1625         return 0;
1626 }
1627
1628 static int find_new_streams(struct lookup_table_entry *lte, void *arg)
1629 {
1630         if (lte->out_refcnt == lte->refcnt)
1631                 list_add(&lte->staging_list, (struct list_head*)arg);
1632         else
1633                 lte->out_refcnt = lte->refcnt;
1634         return 0;
1635 }
1636
1637 /*
1638  * Overwrite a WIM, possibly appending streams to it.
1639  *
1640  * A WIM looks like (or is supposed to look like) the following:
1641  *
1642  *                   Header (212 bytes)
1643  *                   Streams and metadata resources (variable size)
1644  *                   Lookup table (variable size)
1645  *                   XML data (variable size)
1646  *                   Integrity table (optional) (variable size)
1647  *
1648  * If we are not adding any streams or metadata resources, the lookup table is
1649  * unchanged--- so we only need to overwrite the XML data, integrity table, and
1650  * header.  This operation is potentially unsafe if the program is abruptly
1651  * terminated while the XML data or integrity table are being overwritten, but
1652  * before the new header has been written.  To partially alleviate this problem,
1653  * a special flag (WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML) is passed to
1654  * finish_write() to cause a temporary WIM header to be written after the XML
1655  * data has been written.  This may prevent the WIM from becoming corrupted if
1656  * the program is terminated while the integrity table is being calculated (but
1657  * no guarantees, due to write re-ordering...).
1658  *
1659  * If we are adding new streams or images (metadata resources), the lookup table
1660  * needs to be changed, and those streams need to be written.  In this case, we
1661  * try to perform a safe update of the WIM file by writing the streams *after*
1662  * the end of the previous WIM, then writing the new lookup table, XML data, and
1663  * (optionally) integrity table following the new streams.  This will produce a
1664  * layout like the following:
1665  *
1666  *                   Header (212 bytes)
1667  *                   (OLD) Streams and metadata resources (variable size)
1668  *                   (OLD) Lookup table (variable size)
1669  *                   (OLD) XML data (variable size)
1670  *                   (OLD) Integrity table (optional) (variable size)
1671  *                   (NEW) Streams and metadata resources (variable size)
1672  *                   (NEW) Lookup table (variable size)
1673  *                   (NEW) XML data (variable size)
1674  *                   (NEW) Integrity table (optional) (variable size)
1675  *
1676  * At all points, the WIM is valid as nothing points to the new data yet.  Then,
1677  * the header is overwritten to point to the new lookup table, XML data, and
1678  * integrity table, to produce the following layout:
1679  *
1680  *                   Header (212 bytes)
1681  *                   Streams and metadata resources (variable size)
1682  *                   Nothing (variable size)
1683  *                   More Streams and metadata resources (variable size)
1684  *                   Lookup table (variable size)
1685  *                   XML data (variable size)
1686  *                   Integrity table (optional) (variable size)
1687  *
1688  * This method allows an image to be appended to a large WIM very quickly, and
1689  * is is crash-safe except in the case of write re-ordering, but the
1690  * disadvantage is that a small hole is left in the WIM where the old lookup
1691  * table, xml data, and integrity table were.  (These usually only take up a
1692  * small amount of space compared to the streams, however.
1693  */
1694 static int overwrite_wim_inplace(WIMStruct *w, int write_flags,
1695                                  unsigned num_threads,
1696                                  int modified_image_idx)
1697 {
1698         int ret;
1699         struct list_head stream_list;
1700         off_t old_wim_end;
1701
1702         DEBUG("Overwriting `%s' in-place", w->filename);
1703
1704         /* Make sure that the integrity table (if present) is after the XML
1705          * data, and that there are no stream resources, metadata resources, or
1706          * lookup tables after the XML data.  Otherwise, these data would be
1707          * overwritten. */
1708         if (w->hdr.integrity.offset != 0 &&
1709             w->hdr.integrity.offset < w->hdr.xml_res_entry.offset) {
1710                 ERROR("Didn't expect the integrity table to be before the XML data");
1711                 return WIMLIB_ERR_RESOURCE_ORDER;
1712         }
1713
1714         if (w->hdr.lookup_table_res_entry.offset > w->hdr.xml_res_entry.offset) {
1715                 ERROR("Didn't expect the lookup table to be after the XML data");
1716                 return WIMLIB_ERR_RESOURCE_ORDER;
1717         }
1718
1719         DEBUG("Identifying newly added streams");
1720         for_lookup_table_entry(w->lookup_table, lte_overwrite_prepare, NULL);
1721         INIT_LIST_HEAD(&stream_list);
1722         for (int i = modified_image_idx; i < w->hdr.image_count; i++) {
1723                 DEBUG("Identifiying streams in image %d", i + 1);
1724                 wimlib_assert(w->image_metadata[i].modified);
1725                 wimlib_assert(!w->image_metadata[i].has_been_mounted_rw);
1726                 wimlib_assert(w->image_metadata[i].root_dentry != NULL);
1727                 wimlib_assert(w->image_metadata[i].metadata_lte != NULL);
1728                 w->private = &stream_list;
1729                 for_dentry_in_tree(w->image_metadata[i].root_dentry,
1730                                    dentry_find_streams_to_write, w);
1731         }
1732
1733         if (w->hdr.integrity.offset)
1734                 old_wim_end = w->hdr.integrity.offset + w->hdr.integrity.size;
1735         else
1736                 old_wim_end = w->hdr.xml_res_entry.offset + w->hdr.xml_res_entry.size;
1737
1738         ret = for_lookup_table_entry(w->lookup_table, check_resource_offset,
1739                                      &old_wim_end);
1740         if (ret != 0)
1741                 return ret;
1742
1743         if (modified_image_idx == w->hdr.image_count) {
1744                 /* If no images are modified, a new lookup table does not need
1745                  * to be written. */
1746                 wimlib_assert(list_empty(&stream_list));
1747                 old_wim_end = w->hdr.lookup_table_res_entry.offset +
1748                               w->hdr.lookup_table_res_entry.size;
1749                 write_flags |= WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE |
1750                                WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML;
1751         }
1752
1753         INIT_LIST_HEAD(&stream_list);
1754         for_lookup_table_entry(w->lookup_table, find_new_streams,
1755                                &stream_list);
1756
1757         ret = open_wim_writable(w, w->filename, false,
1758                                 (write_flags & WIMLIB_WRITE_FLAG_CHECK_INTEGRITY) != 0);
1759         if (ret != 0)
1760                 return ret;
1761
1762         if (fseeko(w->out_fp, old_wim_end, SEEK_SET) != 0) {
1763                 ERROR_WITH_ERRNO("Can't seek to end of WIM");
1764                 return WIMLIB_ERR_WRITE;
1765         }
1766
1767         if (!list_empty(&stream_list)) {
1768                 DEBUG("Writing newly added streams (offset = %"PRIu64")",
1769                       old_wim_end);
1770                 ret = write_stream_list(&stream_list, w->out_fp,
1771                                         wimlib_get_compression_type(w),
1772                                         write_flags, num_threads);
1773                 if (ret != 0)
1774                         goto out_ftruncate;
1775         } else {
1776                 DEBUG("No new streams were added");
1777         }
1778
1779         for (int i = modified_image_idx; i < w->hdr.image_count; i++) {
1780                 select_wim_image(w, i + 1);
1781                 ret = write_metadata_resource(w);
1782                 if (ret != 0)
1783                         goto out_ftruncate;
1784         }
1785         write_flags |= WIMLIB_WRITE_FLAG_REUSE_INTEGRITY_TABLE;
1786         ret = finish_write(w, WIM_ALL_IMAGES, write_flags);
1787 out_ftruncate:
1788         close_wim_writable(w);
1789         if (ret != 0) {
1790                 WARNING("Truncating `%s' to its original size (%"PRIu64" bytes)",
1791                         w->filename, old_wim_end);
1792                 truncate(w->filename, old_wim_end);
1793         }
1794         return ret;
1795 }
1796
1797 static int overwrite_wim_via_tmpfile(WIMStruct *w, int write_flags,
1798                                      unsigned num_threads)
1799 {
1800         size_t wim_name_len;
1801         int ret;
1802
1803         DEBUG("Overwrining `%s' via a temporary file", w->filename);
1804
1805         /* Write the WIM to a temporary file in the same directory as the
1806          * original WIM. */
1807         wim_name_len = strlen(w->filename);
1808         char tmpfile[wim_name_len + 10];
1809         memcpy(tmpfile, w->filename, wim_name_len);
1810         randomize_char_array_with_alnum(tmpfile + wim_name_len, 9);
1811         tmpfile[wim_name_len + 9] = '\0';
1812
1813         ret = wimlib_write(w, tmpfile, WIM_ALL_IMAGES,
1814                            write_flags | WIMLIB_WRITE_FLAG_FSYNC,
1815                            num_threads);
1816         if (ret != 0) {
1817                 ERROR("Failed to write the WIM file `%s'", tmpfile);
1818                 goto err;
1819         }
1820
1821         /* Close the original WIM file that was opened for reading. */
1822         if (w->fp != NULL) {
1823                 fclose(w->fp);
1824                 w->fp = NULL;
1825         }
1826
1827         DEBUG("Renaming `%s' to `%s'", tmpfile, w->filename);
1828
1829         /* Rename the new file to the old file .*/
1830         if (rename(tmpfile, w->filename) != 0) {
1831                 ERROR_WITH_ERRNO("Failed to rename `%s' to `%s'",
1832                                  tmpfile, w->filename);
1833                 ret = WIMLIB_ERR_RENAME;
1834                 goto err;
1835         }
1836
1837         if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS)
1838                 printf("Successfully renamed `%s' to `%s'\n", tmpfile, w->filename);
1839
1840         /* Re-open the WIM read-only. */
1841         w->fp = fopen(w->filename, "rb");
1842         if (w->fp == NULL) {
1843                 ret = WIMLIB_ERR_REOPEN;
1844                 WARNING("Failed to re-open `%s' read-only: %s",
1845                         w->filename, strerror(errno));
1846         }
1847         return ret;
1848 err:
1849         /* Remove temporary file. */
1850         if (unlink(tmpfile) != 0)
1851                 WARNING("Failed to remove `%s': %s", tmpfile, strerror(errno));
1852         return ret;
1853 }
1854
1855 /*
1856  * Writes a WIM file to the original file that it was read from, overwriting it.
1857  */
1858 WIMLIBAPI int wimlib_overwrite(WIMStruct *w, int write_flags,
1859                                unsigned num_threads)
1860 {
1861         if (!w)
1862                 return WIMLIB_ERR_INVALID_PARAM;
1863
1864         write_flags &= WIMLIB_WRITE_MASK_PUBLIC;
1865
1866         if (!w->filename)
1867                 return WIMLIB_ERR_NO_FILENAME;
1868
1869         if (w->hdr.total_parts != 1) {
1870                 ERROR("Cannot modify a split WIM");
1871                 return WIMLIB_ERR_SPLIT_UNSUPPORTED;
1872         }
1873
1874         if (!w->deletion_occurred && !(write_flags & WIMLIB_WRITE_FLAG_REBUILD)) {
1875                 int i, modified_image_idx;
1876                 for (i = 0; i < w->hdr.image_count && !w->image_metadata[i].modified; i++)
1877                         ;
1878                 modified_image_idx = i;
1879                 for (; i < w->hdr.image_count && w->image_metadata[i].modified &&
1880                         !w->image_metadata[i].has_been_mounted_rw; i++)
1881                         ;
1882                 if (i == w->hdr.image_count) {
1883                         return overwrite_wim_inplace(w, write_flags, num_threads,
1884                                                      modified_image_idx);
1885                 }
1886         }
1887         return overwrite_wim_via_tmpfile(w, write_flags, num_threads);
1888 }
1889
1890 /* Deprecated */
1891 WIMLIBAPI int wimlib_overwrite_xml_and_header(WIMStruct *wim, int write_flags)
1892 {
1893         return wimlib_overwrite(wim, write_flags, 1);
1894 }