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