61a29962f6916521bc1ca255ccb7b39bc2162cb0
[wimlib] / 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                && !(flags & WIMLIB_RESOURCE_FLAG_RECOMPRESS));
387
388         if (raw) {
389                 flags |= WIMLIB_RESOURCE_FLAG_RAW;
390                 bytes_remaining = old_compressed_size;
391         } else {
392                 flags &= ~WIMLIB_RESOURCE_FLAG_RAW;
393                 bytes_remaining = original_size;
394         }
395
396         /* Empty resource; nothing needs to be done, so just return success. */
397         if (bytes_remaining == 0)
398                 return 0;
399
400         /* Buffer for reading chunks for the resource */
401         u8 buf[min(WIM_CHUNK_SIZE, bytes_remaining)];
402
403         /* If we are writing a compressed resource and not doing a raw copy, we
404          * need to initialize the chunk table */
405         if (out_ctype != WIM_COMPRESSION_TYPE_NONE && !raw) {
406                 ret = begin_wim_resource_chunk_tab(lte, out_fp, file_offset,
407                                                    &chunk_tab);
408                 if (ret != 0)
409                         goto out;
410         }
411
412         /* If the WIM resource is in an external file, open a FILE * to it so we
413          * don't have to open a temporary one in read_wim_resource() for each
414          * chunk. */
415 #ifdef WITH_NTFS_3G
416         ret = prepare_resource_for_read(lte, &ni);
417 #else
418         ret = prepare_resource_for_read(lte);
419 #endif
420         if (ret != 0)
421                 goto out;
422
423         /* If we aren't doing a raw copy, we will compute the SHA1 message
424          * digest of the resource as we read it, and verify it's the same as the
425          * hash given in the lookup table entry once we've finished reading the
426          * resource. */
427         SHA_CTX ctx;
428         if (!raw) {
429                 sha1_init(&ctx);
430                 compress = get_compress_func(out_ctype);
431         }
432         offset = 0;
433
434         /* While there are still bytes remaining in the WIM resource, read a
435          * chunk of the resource, update SHA1, then write that chunk using the
436          * desired compression type. */
437         do {
438                 u64 to_read = min(bytes_remaining, WIM_CHUNK_SIZE);
439                 ret = read_wim_resource(lte, buf, to_read, offset, flags);
440                 if (ret != 0)
441                         goto out_fclose;
442                 if (!raw)
443                         sha1_update(&ctx, buf, to_read);
444                 ret = write_wim_resource_chunk(buf, to_read, out_fp,
445                                                compress, chunk_tab);
446                 if (ret != 0)
447                         goto out_fclose;
448                 bytes_remaining -= to_read;
449                 offset += to_read;
450         } while (bytes_remaining);
451
452         /* Raw copy:  The new compressed size is the same as the old compressed
453          * size
454          *
455          * Using WIM_COMPRESSION_TYPE_NONE:  The new compressed size is the
456          * original size
457          *
458          * Using a different compression type:  Call
459          * finish_wim_resource_chunk_tab() and it will provide the new
460          * compressed size.
461          */
462         if (raw) {
463                 new_compressed_size = old_compressed_size;
464         } else {
465                 if (out_ctype == WIM_COMPRESSION_TYPE_NONE)
466                         new_compressed_size = original_size;
467                 else {
468                         ret = finish_wim_resource_chunk_tab(chunk_tab, out_fp,
469                                                             &new_compressed_size);
470                         if (ret != 0)
471                                 goto out_fclose;
472                 }
473         }
474
475         /* Verify SHA1 message digest of the resource, unless we are doing a raw
476          * write (in which case we never even saw the uncompressed data).  Or,
477          * if the hash we had before is all 0's, just re-set it to be the new
478          * hash. */
479         if (!raw) {
480                 u8 md[SHA1_HASH_SIZE];
481                 sha1_final(md, &ctx);
482                 if (is_zero_hash(lte->hash)) {
483                         copy_hash(lte->hash, md);
484                 } else if (!hashes_equal(md, lte->hash)) {
485                         ERROR("WIM resource has incorrect hash!");
486                         if (lte->resource_location == RESOURCE_IN_FILE_ON_DISK) {
487                                 ERROR("We were reading it from `%s'; maybe it changed "
488                                       "while we were reading it.",
489                                       lte->file_on_disk);
490                         }
491                         ret = WIMLIB_ERR_INVALID_RESOURCE_HASH;
492                         goto out_fclose;
493                 }
494         }
495
496         if (!raw && new_compressed_size >= original_size &&
497             out_ctype != WIM_COMPRESSION_TYPE_NONE)
498         {
499                 /* Oops!  We compressed the resource to larger than the original
500                  * size.  Write the resource uncompressed instead. */
501                 if (fseeko(out_fp, file_offset, SEEK_SET) != 0) {
502                         ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" "
503                                          "of output WIM file", file_offset);
504                         ret = WIMLIB_ERR_WRITE;
505                         goto out_fclose;
506                 }
507                 ret = write_wim_resource(lte, out_fp, WIM_COMPRESSION_TYPE_NONE,
508                                          out_res_entry, flags);
509                 if (ret != 0)
510                         goto out_fclose;
511
512                 ret = fflush_and_ftruncate(out_fp, file_offset + out_res_entry->size);
513                 if (ret != 0)
514                         goto out_fclose;
515         } else {
516                 if (out_res_entry) {
517                         out_res_entry->size          = new_compressed_size;
518                         out_res_entry->original_size = original_size;
519                         out_res_entry->offset        = file_offset;
520                         out_res_entry->flags         = lte->resource_entry.flags
521                                                         & ~WIM_RESHDR_FLAG_COMPRESSED;
522                         if (out_ctype != WIM_COMPRESSION_TYPE_NONE)
523                                 out_res_entry->flags |= WIM_RESHDR_FLAG_COMPRESSED;
524                 }
525         }
526         ret = 0;
527 out_fclose:
528 #ifdef WITH_NTFS_3G
529         end_wim_resource_read(lte, ni);
530 #else
531         end_wim_resource_read(lte);
532 #endif
533 out:
534         FREE(chunk_tab);
535         return ret;
536 }
537
538 #ifdef ENABLE_MULTITHREADED_COMPRESSION
539 struct shared_queue {
540         sem_t filled_slots;
541         sem_t empty_slots;
542         pthread_mutex_t lock;
543         unsigned front;
544         unsigned back;
545         void **array;
546         unsigned size;
547 };
548
549 static int shared_queue_init(struct shared_queue *q, unsigned size)
550 {
551         q->array = CALLOC(sizeof(q->array[0]), size);
552         if (!q->array)
553                 return WIMLIB_ERR_NOMEM;
554
555         sem_init(&q->filled_slots, 0, 0);
556         sem_init(&q->empty_slots, 0, size);
557         pthread_mutex_init(&q->lock, NULL);
558         q->front = 0;
559         q->back = size - 1;
560         q->size = size;
561         return 0;
562 }
563
564 static void shared_queue_destroy(struct shared_queue *q)
565 {
566         sem_destroy(&q->filled_slots);
567         sem_destroy(&q->empty_slots);
568         pthread_mutex_destroy(&q->lock);
569         FREE(q->array);
570 }
571
572 static void shared_queue_put(struct shared_queue *q, void *obj)
573 {
574         sem_wait(&q->empty_slots);
575         pthread_mutex_lock(&q->lock);
576
577         q->back = (q->back + 1) % q->size;
578         q->array[q->back] = obj;
579
580         sem_post(&q->filled_slots);
581         pthread_mutex_unlock(&q->lock);
582 }
583
584 static void *shared_queue_get(struct shared_queue *q)
585 {
586         sem_wait(&q->filled_slots);
587         pthread_mutex_lock(&q->lock);
588
589         void *obj = q->array[q->front];
590         q->array[q->front] = NULL;
591         q->front = (q->front + 1) % q->size;
592
593         sem_post(&q->empty_slots);
594         pthread_mutex_unlock(&q->lock);
595         return obj;
596 }
597
598 struct compressor_thread_params {
599         struct shared_queue *res_to_compress_queue;
600         struct shared_queue *compressed_res_queue;
601         compress_func_t compress;
602 };
603
604 #define MAX_CHUNKS_PER_MSG 2
605
606 struct message {
607         struct lookup_table_entry *lte;
608         u8 *uncompressed_chunks[MAX_CHUNKS_PER_MSG];
609         u8 *out_compressed_chunks[MAX_CHUNKS_PER_MSG];
610         u8 *compressed_chunks[MAX_CHUNKS_PER_MSG];
611         unsigned uncompressed_chunk_sizes[MAX_CHUNKS_PER_MSG];
612         unsigned compressed_chunk_sizes[MAX_CHUNKS_PER_MSG];
613         unsigned num_chunks;
614         struct list_head list;
615         bool complete;
616         u64 begin_chunk;
617 };
618
619 static void compress_chunks(struct message *msg, compress_func_t compress)
620 {
621         for (unsigned i = 0; i < msg->num_chunks; i++) {
622                 DEBUG2("compress chunk %u of %u", i, msg->num_chunks);
623                 int ret = compress(msg->uncompressed_chunks[i],
624                                    msg->uncompressed_chunk_sizes[i],
625                                    msg->compressed_chunks[i],
626                                    &msg->compressed_chunk_sizes[i]);
627                 if (ret == 0) {
628                         msg->out_compressed_chunks[i] = msg->compressed_chunks[i];
629                 } else {
630                         msg->out_compressed_chunks[i] = msg->uncompressed_chunks[i];
631                         msg->compressed_chunk_sizes[i] = msg->uncompressed_chunk_sizes[i];
632                 }
633         }
634 }
635
636 static void *compressor_thread_proc(void *arg)
637 {
638         struct compressor_thread_params *params = arg;
639         struct shared_queue *res_to_compress_queue = params->res_to_compress_queue;
640         struct shared_queue *compressed_res_queue = params->compressed_res_queue;
641         compress_func_t compress = params->compress;
642         struct message *msg;
643
644         DEBUG("Compressor thread ready");
645         while ((msg = shared_queue_get(res_to_compress_queue)) != NULL) {
646                 compress_chunks(msg, compress);
647                 shared_queue_put(compressed_res_queue, msg);
648         }
649         DEBUG("Compressor thread terminating");
650 }
651 #endif
652
653 void show_stream_op_progress(u64 *cur_size, u64 *next_size,
654                              u64 total_size, u64 one_percent,
655                              unsigned *cur_percent,
656                              const struct lookup_table_entry *cur_lte,
657                              const char *op)
658 {
659         if (*cur_size >= *next_size) {
660                 printf("\r%"PRIu64" MiB of %"PRIu64" MiB "
661                        "(uncompressed) %s (%u%% done)",
662                        *cur_size >> 20,
663                        total_size >> 20, op, *cur_percent);
664                 fflush(stdout);
665                 *next_size += one_percent;
666                 (*cur_percent)++;
667         }
668         *cur_size += wim_resource_size(cur_lte);
669 }
670
671 void finish_stream_op_progress(u64 total_size, const char *op)
672 {
673         printf("\r%"PRIu64" MiB of %"PRIu64" MiB "
674                "(uncompressed) %s (100%% done)\n",
675                total_size >> 20, total_size >> 20, op);
676         fflush(stdout);
677 }
678
679 static int write_stream_list_serial(struct list_head *stream_list,
680                                     FILE *out_fp, int out_ctype,
681                                     int write_flags, u64 total_size)
682 {
683         struct lookup_table_entry *lte;
684         int ret;
685
686         u64 one_percent = total_size / 100;
687         u64 cur_size = 0;
688         u64 next_size = 0;
689         unsigned cur_percent = 0;
690         int write_resource_flags = 0;
691
692         if (write_flags & WIMLIB_WRITE_FLAG_RECOMPRESS)
693                 write_resource_flags |= WIMLIB_RESOURCE_FLAG_RECOMPRESS;
694
695         list_for_each_entry(lte, stream_list, staging_list) {
696                 if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS) {
697                         show_stream_op_progress(&cur_size, &next_size,
698                                                 total_size, one_percent,
699                                                 &cur_percent, lte, "written");
700                 }
701                 ret = write_wim_resource(lte, out_fp, out_ctype,
702                                          &lte->output_resource_entry,
703                                          write_resource_flags);
704                 if (ret != 0)
705                         return ret;
706         }
707         if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS)
708                 finish_stream_op_progress(total_size, "written");
709         return 0;
710 }
711
712 #ifdef ENABLE_MULTITHREADED_COMPRESSION
713 static int write_wim_chunks(struct message *msg, FILE *out_fp,
714                             struct chunk_table *chunk_tab)
715 {
716         for (unsigned i = 0; i < msg->num_chunks; i++) {
717                 unsigned chunk_csize = msg->compressed_chunk_sizes[i];
718
719                 DEBUG2("Write wim chunk %u of %u (csize = %u)",
720                       i, msg->num_chunks, chunk_csize);
721
722                 if (fwrite(msg->out_compressed_chunks[i], 1, chunk_csize, out_fp)
723                     != chunk_csize)
724                 {
725                         ERROR_WITH_ERRNO("Failed to write WIM chunk");
726                         return WIMLIB_ERR_WRITE;
727                 }
728
729                 *chunk_tab->cur_offset_p++ = chunk_tab->cur_offset;
730                 chunk_tab->cur_offset += chunk_csize;
731         }
732         return 0;
733 }
734
735 /*
736  * This function is executed by the main thread when the resources are being
737  * compressed in parallel.  The main thread is in change of all reading of the
738  * uncompressed data and writing of the compressed data.  The compressor threads
739  * *only* do compression from/to in-memory buffers.
740  *
741  * Each unit of work given to a compressor thread is up to MAX_CHUNKS_PER_MSG
742  * chunks of compressed data to compress, represented in a `struct message'.
743  * Each message is passed from the main thread to a worker thread through the
744  * res_to_compress_queue, and it is passed back through the
745  * compressed_res_queue.
746  */
747 static int main_writer_thread_proc(struct list_head *stream_list,
748                                    FILE *out_fp,
749                                    int out_ctype,
750                                    struct shared_queue *res_to_compress_queue,
751                                    struct shared_queue *compressed_res_queue,
752                                    size_t queue_size,
753                                    int write_flags,
754                                    u64 total_size)
755 {
756         int ret;
757
758         struct message msgs[queue_size];
759         ZERO_ARRAY(msgs);
760
761         // Initially, all the messages are available to use.
762         LIST_HEAD(available_msgs);
763         for (size_t i = 0; i < ARRAY_LEN(msgs); i++)
764                 list_add(&msgs[i].list, &available_msgs);
765
766         // outstanding_resources is the list of resources that currently have
767         // had chunks sent off for compression.
768         //
769         // The first stream in outstanding_resources is the stream that is
770         // currently being written (cur_lte).
771         //
772         // The last stream in outstanding_resources is the stream that is
773         // currently being read and chunks fed to the compressor threads
774         // (next_lte).
775         //
776         // Depending on the number of threads and the sizes of the resource,
777         // the outstanding streams list may contain streams between cur_lte and
778         // next_lte that have all their chunks compressed or being compressed,
779         // but haven't been written yet.
780         //
781         LIST_HEAD(outstanding_resources);
782         struct list_head *next_resource = stream_list->next;
783         struct lookup_table_entry *next_lte = container_of(next_resource,
784                                                            struct lookup_table_entry,
785                                                            staging_list);
786         next_resource = next_resource->next;
787         u64 next_chunk = 0;
788         u64 next_num_chunks = wim_resource_chunks(next_lte);
789         INIT_LIST_HEAD(&next_lte->msg_list);
790         list_add_tail(&next_lte->staging_list, &outstanding_resources);
791
792         // As in write_wim_resource(), each resource we read is checksummed.
793         SHA_CTX next_sha_ctx;
794         sha1_init(&next_sha_ctx);
795         u8 next_hash[SHA1_HASH_SIZE];
796
797         // Resources that don't need any chunks compressed are added to this
798         // list and written directly by the main thread.
799         LIST_HEAD(my_resources);
800
801         struct lookup_table_entry *cur_lte = next_lte;
802         struct chunk_table *cur_chunk_tab = NULL;
803         struct lookup_table_entry *lte;
804         struct message *msg;
805
806         u64 one_percent = total_size / 100;
807         u64 cur_size = 0;
808         u64 next_size = 0;
809         unsigned cur_percent = 0;
810
811 #ifdef WITH_NTFS_3G
812         ntfs_inode *ni = NULL;
813 #endif
814
815 #ifdef WITH_NTFS_3G
816         ret = prepare_resource_for_read(next_lte, &ni);
817 #else
818         ret = prepare_resource_for_read(next_lte);
819 #endif
820         if (ret != 0)
821                 goto out;
822
823         DEBUG("Initializing buffers for uncompressed "
824               "and compressed data (%zu bytes needed)",
825               queue_size * MAX_CHUNKS_PER_MSG * WIM_CHUNK_SIZE * 2);
826
827         // Pre-allocate all the buffers that will be needed to do the chunk
828         // compression.
829         for (size_t i = 0; i < ARRAY_LEN(msgs); i++) {
830                 for (size_t j = 0; j < MAX_CHUNKS_PER_MSG; j++) {
831                         msgs[i].compressed_chunks[j] = MALLOC(WIM_CHUNK_SIZE);
832                         msgs[i].uncompressed_chunks[j] = MALLOC(WIM_CHUNK_SIZE);
833                         if (msgs[i].compressed_chunks[j] == NULL ||
834                             msgs[i].uncompressed_chunks[j] == NULL)
835                         {
836                                 ERROR("Could not allocate enough memory for "
837                                       "multi-threaded compression");
838                                 ret = WIMLIB_ERR_NOMEM;
839                                 goto out;
840                         }
841                 }
842         }
843
844         // This loop is executed until all resources have been written, except
845         // possibly a few that have been added to the @my_resources list for
846         // writing later.
847         while (1) {
848                 // Send chunks to the compressor threads until either (a) there
849                 // are no more messages available since they were all sent off,
850                 // or (b) there are no more resources that need to be
851                 // compressed.
852                 while (!list_empty(&available_msgs) && next_lte != NULL) {
853
854                         // Get a message from the available messages
855                         // list
856                         msg = container_of(available_msgs.next,
857                                            struct message,
858                                            list);
859
860                         // ... and delete it from the available messages
861                         // list
862                         list_del(&msg->list);
863
864                         // Initialize the message with the chunks to
865                         // compress.
866                         msg->num_chunks = min(next_num_chunks - next_chunk,
867                                               MAX_CHUNKS_PER_MSG);
868                         msg->lte = next_lte;
869                         msg->complete = false;
870                         msg->begin_chunk = next_chunk;
871
872                         unsigned size = WIM_CHUNK_SIZE;
873                         for (unsigned i = 0; i < msg->num_chunks; i++) {
874
875                                 // Read chunk @next_chunk of the stream into the
876                                 // message so that a compressor thread can
877                                 // compress it.
878
879                                 if (next_chunk == next_num_chunks - 1 &&
880                                      wim_resource_size(next_lte) % WIM_CHUNK_SIZE != 0)
881                                 {
882                                         size = wim_resource_size(next_lte) % WIM_CHUNK_SIZE;
883                                 }
884
885
886                                 DEBUG2("Read resource (size=%u, offset=%zu)",
887                                       size, next_chunk * WIM_CHUNK_SIZE);
888
889                                 msg->uncompressed_chunk_sizes[i] = size;
890
891                                 ret = read_wim_resource(next_lte,
892                                                         msg->uncompressed_chunks[i],
893                                                         size,
894                                                         next_chunk * WIM_CHUNK_SIZE,
895                                                         0);
896                                 if (ret != 0)
897                                         goto out;
898                                 sha1_update(&next_sha_ctx,
899                                             msg->uncompressed_chunks[i], size);
900                                 next_chunk++;
901                         }
902
903                         // Send the compression request
904                         list_add_tail(&msg->list, &next_lte->msg_list);
905                         shared_queue_put(res_to_compress_queue, msg);
906                         DEBUG2("Compression request sent");
907
908                         if (next_chunk != next_num_chunks)
909                                 // More chunks to send for this resource
910                                 continue;
911
912                         // Done sending compression requests for a resource!
913                         // Check the SHA1 message digest.
914                         DEBUG2("Finalize SHA1 md (next_num_chunks=%zu)", next_num_chunks);
915                         sha1_final(next_hash, &next_sha_ctx);
916                         if (!hashes_equal(next_lte->hash, next_hash)) {
917                                 ERROR("WIM resource has incorrect hash!");
918                                 if (next_lte->resource_location == RESOURCE_IN_FILE_ON_DISK) {
919                                         ERROR("We were reading it from `%s'; maybe it changed "
920                                               "while we were reading it.",
921                                               next_lte->file_on_disk);
922                                 }
923                                 ret = WIMLIB_ERR_INVALID_RESOURCE_HASH;
924                                 goto out;
925                         }
926
927                         // Advance to the next resource.
928                         //
929                         // If the next resource needs no compression, just write
930                         // it with this thread (not now though--- we could be in
931                         // the middle of writing another resource.)  Keep doing
932                         // this until we either get to the end of the resources
933                         // list, or we get to a resource that needs compression.
934
935                         while (1) {
936                                 if (next_resource == stream_list) {
937                                         next_lte = NULL;
938                                         break;
939                                 }
940                         #ifdef WITH_NTFS_3G
941                                 end_wim_resource_read(next_lte, ni);
942                                 ni = NULL;
943                         #else
944                                 end_wim_resource_read(next_lte);
945                         #endif
946
947                                 next_lte = container_of(next_resource,
948                                                         struct lookup_table_entry,
949                                                         staging_list);
950                                 next_resource = next_resource->next;
951                                 if ((!(write_flags & WIMLIB_WRITE_FLAG_RECOMPRESS)
952                                       && next_lte->resource_location == RESOURCE_IN_WIM
953                                       && wimlib_get_compression_type(next_lte->wim) == out_ctype)
954                                     || wim_resource_size(next_lte) == 0)
955                                 {
956                                         list_add_tail(&next_lte->staging_list,
957                                                       &my_resources);
958                                 } else {
959                                         list_add_tail(&next_lte->staging_list,
960                                                       &outstanding_resources);
961                                         next_chunk = 0;
962                                         next_num_chunks = wim_resource_chunks(next_lte);
963                                         sha1_init(&next_sha_ctx);
964                                         INIT_LIST_HEAD(&next_lte->msg_list);
965                                 #ifdef WITH_NTFS_3G
966                                         ret = prepare_resource_for_read(next_lte, &ni);
967                                 #else
968                                         ret = prepare_resource_for_read(next_lte);
969                                 #endif
970                                         if (ret != 0)
971                                                 goto out;
972                                         DEBUG2("Updated next_lte");
973                                         break;
974                                 }
975                         }
976                 }
977
978                 // If there are no outstanding resources, there are no more
979                 // resources that need to be written.
980                 if (list_empty(&outstanding_resources)) {
981                         DEBUG("No outstanding resources! Done");
982                         ret = 0;
983                         goto out;
984                 }
985
986                 // Get the next message from the queue and process it.
987                 // The message will contain 1 or more data chunks that have been
988                 // compressed.
989                 DEBUG2("Waiting for message");
990                 msg = shared_queue_get(compressed_res_queue);
991                 msg->complete = true;
992
993                 DEBUG2("Received msg (begin_chunk=%"PRIu64")", msg->begin_chunk);
994
995                 list_for_each_entry(msg, &cur_lte->msg_list, list) {
996                         DEBUG2("complete=%d", msg->complete);
997                 }
998
999                 // Is this the next chunk in the current resource?  If it's not
1000                 // (i.e., an earlier chunk in a same or different resource
1001                 // hasn't been compressed yet), do nothing, and keep this
1002                 // message around until all earlier chunks are received.
1003                 //
1004                 // Otherwise, write all the chunks we can.
1005                 while (!list_empty(&cur_lte->msg_list)
1006                         && (msg = container_of(cur_lte->msg_list.next,
1007                                                struct message,
1008                                                list))->complete)
1009                 {
1010                         DEBUG2("Complete msg (begin_chunk=%"PRIu64")", msg->begin_chunk);
1011                         if (msg->begin_chunk == 0) {
1012                                 DEBUG2("Begin chunk tab");
1013                                 if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS) {
1014                                         show_stream_op_progress(&cur_size,
1015                                                                 &next_size,
1016                                                                 total_size,
1017                                                                 one_percent,
1018                                                                 &cur_percent,
1019                                                                 cur_lte,
1020                                                                 "written");
1021                                 }
1022
1023                                 // This is the first set of chunks.  Leave space
1024                                 // for the chunk table in the output file.
1025                                 off_t cur_offset = ftello(out_fp);
1026                                 if (cur_offset == -1) {
1027                                         ret = WIMLIB_ERR_WRITE;
1028                                         goto out;
1029                                 }
1030                                 ret = begin_wim_resource_chunk_tab(cur_lte,
1031                                                                    out_fp,
1032                                                                    cur_offset,
1033                                                                    &cur_chunk_tab);
1034                                 if (ret != 0)
1035                                         goto out;
1036                         }
1037
1038                         // Write the compressed chunks from the message.
1039                         ret = write_wim_chunks(msg, out_fp, cur_chunk_tab);
1040                         if (ret != 0)
1041                                 goto out;
1042
1043                         list_del(&msg->list);
1044
1045                         // This message is available to use for different chunks
1046                         // now.
1047                         list_add(&msg->list, &available_msgs);
1048
1049                         // Was this the last chunk of the stream?  If so,
1050                         // finish it.
1051                         if (list_empty(&cur_lte->msg_list) &&
1052                             msg->begin_chunk + msg->num_chunks == cur_chunk_tab->num_chunks)
1053                         {
1054                                 DEBUG2("Finish wim chunk tab");
1055                                 u64 res_csize;
1056                                 ret = finish_wim_resource_chunk_tab(cur_chunk_tab,
1057                                                                     out_fp,
1058                                                                     &res_csize);
1059                                 if (ret != 0)
1060                                         goto out;
1061
1062
1063                                 cur_lte->output_resource_entry.size =
1064                                         res_csize;
1065
1066                                 cur_lte->output_resource_entry.original_size =
1067                                         cur_lte->resource_entry.original_size;
1068
1069                                 cur_lte->output_resource_entry.offset =
1070                                         cur_chunk_tab->file_offset;
1071
1072                                 cur_lte->output_resource_entry.flags =
1073                                         cur_lte->resource_entry.flags |
1074                                                 WIM_RESHDR_FLAG_COMPRESSED;
1075
1076                                 FREE(cur_chunk_tab);
1077                                 cur_chunk_tab = NULL;
1078
1079                                 struct list_head *next = cur_lte->staging_list.next;
1080                                 list_del(&cur_lte->staging_list);
1081
1082                                 if (next == &outstanding_resources) {
1083                                         DEBUG("No more outstanding resources");
1084                                         ret = 0;
1085                                         goto out;
1086                                 } else {
1087                                         cur_lte = container_of(cur_lte->staging_list.next,
1088                                                                struct lookup_table_entry,
1089                                                                staging_list);
1090                                 }
1091
1092                                 // Since we just finished writing a stream,
1093                                 // write any streams that have been added to the
1094                                 // my_resources list for direct writing by the
1095                                 // main thread (e.g. resources that don't need
1096                                 // to be compressed because the desired
1097                                 // compression type is the same as the previous
1098                                 // compression type).
1099                                 struct lookup_table_entry *tmp;
1100                                 list_for_each_entry_safe(lte,
1101                                                          tmp,
1102                                                          &my_resources,
1103                                                          staging_list)
1104                                 {
1105                                         if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS) {
1106                                                 show_stream_op_progress(&cur_size,
1107                                                                         &next_size,
1108                                                                         total_size,
1109                                                                         one_percent,
1110                                                                         &cur_percent,
1111                                                                         lte,
1112                                                                         "written");
1113                                         }
1114
1115                                         ret = write_wim_resource(lte,
1116                                                                  out_fp,
1117                                                                  out_ctype,
1118                                                                  &lte->output_resource_entry,
1119                                                                  0);
1120                                         list_del(&lte->staging_list);
1121                                         if (ret != 0)
1122                                                 goto out;
1123                                 }
1124                         }
1125                 }
1126         }
1127
1128 out:
1129 #ifdef WITH_NTFS_3G
1130         end_wim_resource_read(cur_lte, ni);
1131 #else
1132         end_wim_resource_read(cur_lte);
1133 #endif
1134         if (ret == 0) {
1135                 list_for_each_entry(lte, &my_resources, staging_list) {
1136                         if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS) {
1137                                 show_stream_op_progress(&cur_size,
1138                                                         &next_size,
1139                                                         total_size,
1140                                                         one_percent,
1141                                                         &cur_percent,
1142                                                         lte,
1143                                                         "written");
1144                         }
1145                         ret = write_wim_resource(lte, out_fp,
1146                                                  out_ctype,
1147                                                  &lte->output_resource_entry,
1148                                                  0);
1149                         if (ret != 0)
1150                                 break;
1151                 }
1152                 if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS)
1153                         finish_stream_op_progress(total_size, "written");
1154         } else {
1155                 size_t num_available_msgs = 0;
1156                 struct list_head *cur;
1157
1158                 list_for_each(cur, &available_msgs) {
1159                         num_available_msgs++;
1160                 }
1161
1162                 while (num_available_msgs < ARRAY_LEN(msgs)) {
1163                         shared_queue_get(compressed_res_queue);
1164                         num_available_msgs++;
1165                 }
1166         }
1167
1168         DEBUG("Freeing messages");
1169
1170         for (size_t i = 0; i < ARRAY_LEN(msgs); i++) {
1171                 for (size_t j = 0; j < MAX_CHUNKS_PER_MSG; j++) {
1172                         FREE(msgs[i].compressed_chunks[j]);
1173                         FREE(msgs[i].uncompressed_chunks[j]);
1174                 }
1175         }
1176
1177         if (cur_chunk_tab != NULL)
1178                 FREE(cur_chunk_tab);
1179         return ret;
1180 }
1181
1182
1183 static const char *get_data_type(int ctype)
1184 {
1185         switch (ctype) {
1186         case WIM_COMPRESSION_TYPE_NONE:
1187                 return "uncompressed";
1188         case WIM_COMPRESSION_TYPE_LZX:
1189                 return "LZX-compressed";
1190         case WIM_COMPRESSION_TYPE_XPRESS:
1191                 return "XPRESS-compressed";
1192         }
1193 }
1194
1195 static int write_stream_list_parallel(struct list_head *stream_list,
1196                                       FILE *out_fp, int out_ctype,
1197                                       int write_flags, u64 total_size,
1198                                       unsigned num_threads)
1199 {
1200         int ret;
1201         struct shared_queue res_to_compress_queue;
1202         struct shared_queue compressed_res_queue;
1203         pthread_t *compressor_threads = NULL;
1204
1205         if (num_threads == 0) {
1206                 long nthreads = sysconf(_SC_NPROCESSORS_ONLN);
1207                 if (nthreads < 1) {
1208                         WARNING("Could not determine number of processors! Assuming 1");
1209                         goto out_serial;
1210                 } else {
1211                         num_threads = nthreads;
1212                 }
1213         }
1214
1215         wimlib_assert(stream_list->next != stream_list);
1216
1217         static const double MESSAGES_PER_THREAD = 2.0;
1218         size_t queue_size = (size_t)(num_threads * MESSAGES_PER_THREAD);
1219
1220         DEBUG("Initializing shared queues (queue_size=%zu)", queue_size);
1221
1222         ret = shared_queue_init(&res_to_compress_queue, queue_size);
1223         if (ret != 0)
1224                 goto out_serial;
1225
1226         ret = shared_queue_init(&compressed_res_queue, queue_size);
1227         if (ret != 0)
1228                 goto out_destroy_res_to_compress_queue;
1229
1230         struct compressor_thread_params params;
1231         params.res_to_compress_queue = &res_to_compress_queue;
1232         params.compressed_res_queue = &compressed_res_queue;
1233         params.compress = get_compress_func(out_ctype);
1234
1235         compressor_threads = MALLOC(num_threads * sizeof(pthread_t));
1236
1237         for (unsigned i = 0; i < num_threads; i++) {
1238                 DEBUG("pthread_create thread %u", i);
1239                 ret = pthread_create(&compressor_threads[i], NULL,
1240                                      compressor_thread_proc, &params);
1241                 if (ret != 0) {
1242                         ret = -1;
1243                         ERROR_WITH_ERRNO("Failed to create compressor "
1244                                          "thread %u", i);
1245                         num_threads = i;
1246                         goto out_join;
1247                 }
1248         }
1249
1250         if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS) {
1251                 printf("Writing %s data using %u threads...\n",
1252                        get_data_type(out_ctype), num_threads);
1253         }
1254
1255         ret = main_writer_thread_proc(stream_list,
1256                                       out_fp,
1257                                       out_ctype,
1258                                       &res_to_compress_queue,
1259                                       &compressed_res_queue,
1260                                       queue_size,
1261                                       write_flags,
1262                                       total_size);
1263
1264 out_join:
1265         for (unsigned i = 0; i < num_threads; i++)
1266                 shared_queue_put(&res_to_compress_queue, NULL);
1267
1268         for (unsigned i = 0; i < num_threads; i++) {
1269                 if (pthread_join(compressor_threads[i], NULL)) {
1270                         WARNING("Failed to join compressor thread %u: %s",
1271                                 i, strerror(errno));
1272                 }
1273         }
1274         FREE(compressor_threads);
1275         shared_queue_destroy(&compressed_res_queue);
1276 out_destroy_res_to_compress_queue:
1277         shared_queue_destroy(&res_to_compress_queue);
1278         if (ret >= 0 && ret != WIMLIB_ERR_NOMEM)
1279                 return ret;
1280 out_serial:
1281         WARNING("Falling back to single-threaded compression");
1282         return write_stream_list_serial(stream_list, out_fp,
1283                                         out_ctype, write_flags, total_size);
1284 }
1285 #endif
1286
1287 /*
1288  * Write a list of streams to a WIM (@out_fp) using the compression type
1289  * @out_ctype and up to @num_threads compressor threads.
1290  */
1291 static int write_stream_list(struct list_head *stream_list, FILE *out_fp,
1292                              int out_ctype, int write_flags,
1293                              unsigned num_threads)
1294 {
1295         struct lookup_table_entry *lte;
1296         size_t num_streams = 0;
1297         u64 total_size = 0;
1298         bool compression_needed = false;
1299
1300         list_for_each_entry(lte, stream_list, staging_list) {
1301                 num_streams++;
1302                 total_size += wim_resource_size(lte);
1303                 if (!compression_needed
1304                     &&
1305                     (out_ctype != WIM_COMPRESSION_TYPE_NONE
1306                        && (lte->resource_location != RESOURCE_IN_WIM
1307                            || wimlib_get_compression_type(lte->wim) != out_ctype
1308                            || (write_flags & WIMLIB_WRITE_FLAG_REBUILD)))
1309                     && wim_resource_size(lte) != 0)
1310                         compression_needed = true;
1311         }
1312
1313         if (num_streams == 0) {
1314                 if (write_flags & WIMLIB_WRITE_FLAG_VERBOSE)
1315                         printf("No streams to write\n");
1316                 return 0;
1317         }
1318
1319         if (write_flags & WIMLIB_WRITE_FLAG_VERBOSE) {
1320                 printf("Preparing to write %zu streams "
1321                        "(%"PRIu64" total bytes uncompressed)\n",
1322                        num_streams, total_size);
1323                 printf("Using compression type %s\n",
1324                        wimlib_get_compression_type_string(out_ctype));
1325         }
1326
1327 #ifdef ENABLE_MULTITHREADED_COMPRESSION
1328         if (compression_needed && total_size >= 1000000 && num_threads != 1) {
1329                 return write_stream_list_parallel(stream_list, out_fp,
1330                                                   out_ctype, write_flags,
1331                                                   total_size, num_threads);
1332         }
1333         else
1334 #endif
1335         {
1336                 if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS) {
1337                         const char *reason = "";
1338                         if (!compression_needed)
1339                                 reason = " (no compression needed)";
1340                         printf("Writing %s data using 1 thread%s\n",
1341                                get_data_type(out_ctype), reason);
1342                 }
1343
1344                 return write_stream_list_serial(stream_list, out_fp,
1345                                                 out_ctype, write_flags,
1346                                                 total_size);
1347         }
1348 }
1349
1350
1351 static int dentry_find_streams_to_write(struct dentry *dentry,
1352                                         void *wim)
1353 {
1354         WIMStruct *w = wim;
1355         struct list_head *stream_list = w->private;
1356         struct lookup_table_entry *lte;
1357         for (unsigned i = 0; i <= dentry->d_inode->num_ads; i++) {
1358                 lte = inode_stream_lte(dentry->d_inode, i, w->lookup_table);
1359                 if (lte && ++lte->out_refcnt == 1)
1360                         list_add_tail(&lte->staging_list, stream_list);
1361         }
1362         return 0;
1363 }
1364
1365 static int find_streams_to_write(WIMStruct *w)
1366 {
1367         return for_dentry_in_tree(wim_root_dentry(w),
1368                                   dentry_find_streams_to_write, w);
1369 }
1370
1371 static int write_wim_streams(WIMStruct *w, int image, int write_flags,
1372                              unsigned num_threads)
1373 {
1374
1375         for_lookup_table_entry(w->lookup_table, lte_zero_out_refcnt, NULL);
1376         LIST_HEAD(stream_list);
1377         w->private = &stream_list;
1378         for_image(w, image, find_streams_to_write);
1379         return write_stream_list(&stream_list, w->out_fp,
1380                                  wimlib_get_compression_type(w), write_flags,
1381                                  num_threads);
1382 }
1383
1384 /*
1385  * Finish writing a WIM file: write the lookup table, xml data, and integrity
1386  * table (optional), then overwrite the WIM header.
1387  *
1388  * write_flags is a bitwise OR of the following:
1389  *
1390  *      (public)  WIMLIB_WRITE_FLAG_CHECK_INTEGRITY:
1391  *              Include an integrity table.
1392  *
1393  *      (public)  WIMLIB_WRITE_FLAG_SHOW_PROGRESS:
1394  *              Show progress information when (if) writing the integrity table.
1395  *
1396  *      (private) WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE:
1397  *              Don't write the lookup table.
1398  *
1399  *      (private) WIMLIB_WRITE_FLAG_REUSE_INTEGRITY_TABLE:
1400  *              When (if) writing the integrity table, re-use entries from the
1401  *              existing integrity table, if possible.
1402  *
1403  *      (private) WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML:
1404  *              After writing the XML data but before writing the integrity
1405  *              table, write a temporary WIM header and flush the stream so that
1406  *              the WIM is less likely to become corrupted upon abrupt program
1407  *              termination.
1408  *
1409  *      (private) WIMLIB_WRITE_FLAG_FSYNC:
1410  *              fsync() the output file before closing it.
1411  *
1412  */
1413 int finish_write(WIMStruct *w, int image, int write_flags)
1414 {
1415         int ret;
1416         struct wim_header hdr;
1417         FILE *out = w->out_fp;
1418
1419         /* @hdr will be the header for the new WIM.  First copy all the data
1420          * from the header in the WIMStruct; then set all the fields that may
1421          * have changed, including the resource entries, boot index, and image
1422          * count.  */
1423         memcpy(&hdr, &w->hdr, sizeof(struct wim_header));
1424
1425         if (!(write_flags & WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE)) {
1426                 ret = write_lookup_table(w->lookup_table, out, &hdr.lookup_table_res_entry);
1427                 if (ret != 0)
1428                         goto out;
1429         }
1430
1431         ret = write_xml_data(w->wim_info, image, out,
1432                              (write_flags & WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE) ?
1433                               wim_info_get_total_bytes(w->wim_info) : 0,
1434                              &hdr.xml_res_entry);
1435         if (ret != 0)
1436                 goto out;
1437
1438         if (write_flags & WIMLIB_WRITE_FLAG_CHECK_INTEGRITY) {
1439                 if (write_flags & WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML) {
1440                         struct wim_header checkpoint_hdr;
1441                         memcpy(&checkpoint_hdr, &hdr, sizeof(struct wim_header));
1442                         memset(&checkpoint_hdr.integrity, 0, sizeof(struct resource_entry));
1443                         if (fseeko(out, 0, SEEK_SET) != 0) {
1444                                 ret = WIMLIB_ERR_WRITE;
1445                                 goto out;
1446                         }
1447                         ret = write_header(&checkpoint_hdr, out);
1448                         if (ret != 0)
1449                                 goto out;
1450
1451                         if (fflush(out) != 0) {
1452                                 ERROR_WITH_ERRNO("Can't write data to WIM");
1453                                 ret = WIMLIB_ERR_WRITE;
1454                                 goto out;
1455                         }
1456
1457                         if (fseeko(out, 0, SEEK_END) != 0) {
1458                                 ret = WIMLIB_ERR_WRITE;
1459                                 goto out;
1460                         }
1461                 }
1462
1463                 off_t old_lookup_table_end;
1464                 off_t new_lookup_table_end;
1465                 bool show_progress;
1466                 if (write_flags & WIMLIB_WRITE_FLAG_REUSE_INTEGRITY_TABLE) {
1467                         old_lookup_table_end = w->hdr.lookup_table_res_entry.offset +
1468                                                w->hdr.lookup_table_res_entry.size;
1469                 } else {
1470                         old_lookup_table_end = 0;
1471                 }
1472                 new_lookup_table_end = hdr.lookup_table_res_entry.offset +
1473                                        hdr.lookup_table_res_entry.size;
1474                 show_progress = ((write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS) != 0);
1475
1476                 ret = write_integrity_table(out,
1477                                             &hdr.integrity,
1478                                             new_lookup_table_end,
1479                                             old_lookup_table_end,
1480                                             show_progress);
1481                 if (ret != 0)
1482                         goto out;
1483         } else {
1484                 memset(&hdr.integrity, 0, sizeof(struct resource_entry));
1485         }
1486
1487         /*
1488          * In the WIM header, there is room for the resource entry for a
1489          * metadata resource labeled as the "boot metadata".  This entry should
1490          * be zeroed out if there is no bootable image (boot_idx 0).  Otherwise,
1491          * it should be a copy of the resource entry for the image that is
1492          * marked as bootable.  This is not well documented...
1493          */
1494         if (hdr.boot_idx == 0 || !w->image_metadata
1495                         || (image != WIM_ALL_IMAGES && image != hdr.boot_idx)) {
1496                 memset(&hdr.boot_metadata_res_entry, 0,
1497                        sizeof(struct resource_entry));
1498         } else {
1499                 memcpy(&hdr.boot_metadata_res_entry,
1500                        &w->image_metadata[
1501                           hdr.boot_idx - 1].metadata_lte->output_resource_entry,
1502                        sizeof(struct resource_entry));
1503         }
1504
1505         /* Set image count and boot index correctly for single image writes */
1506         if (image != WIM_ALL_IMAGES) {
1507                 hdr.image_count = 1;
1508                 if (hdr.boot_idx == image)
1509                         hdr.boot_idx = 1;
1510                 else
1511                         hdr.boot_idx = 0;
1512         }
1513
1514         if (fseeko(out, 0, SEEK_SET) != 0) {
1515                 ret = WIMLIB_ERR_WRITE;
1516                 goto out;
1517         }
1518
1519         ret = write_header(&hdr, out);
1520         if (ret != 0)
1521                 goto out;
1522
1523         if (write_flags & WIMLIB_WRITE_FLAG_FSYNC) {
1524                 if (fflush(out) != 0
1525                     || fsync(fileno(out)) != 0)
1526                 {
1527                         ERROR_WITH_ERRNO("Error flushing data to WIM file");
1528                         ret = WIMLIB_ERR_WRITE;
1529                 }
1530         }
1531 out:
1532         if (fclose(out) != 0) {
1533                 ERROR_WITH_ERRNO("Failed to close the WIM file");
1534                 if (ret == 0)
1535                         ret = WIMLIB_ERR_WRITE;
1536         }
1537         w->out_fp = NULL;
1538         return ret;
1539 }
1540
1541 static void close_wim_writable(WIMStruct *w)
1542 {
1543         if (w->out_fp) {
1544                 if (fclose(w->out_fp) != 0) {
1545                         WARNING("Failed to close output WIM: %s",
1546                                 strerror(errno));
1547                 }
1548                 w->out_fp = NULL;
1549         }
1550 }
1551
1552 /* Open file stream and write dummy header for WIM. */
1553 int begin_write(WIMStruct *w, const char *path, int write_flags)
1554 {
1555         int ret;
1556         bool need_readable = false;
1557         bool trunc = true;
1558         if (write_flags & WIMLIB_WRITE_FLAG_CHECK_INTEGRITY)
1559                 need_readable = true;
1560
1561         ret = open_wim_writable(w, path, trunc, need_readable);
1562         if (ret != 0)
1563                 return ret;
1564         /* Write dummy header. It will be overwritten later. */
1565         return write_header(&w->hdr, w->out_fp);
1566 }
1567
1568 /* Writes a stand-alone WIM to a file.  */
1569 WIMLIBAPI int wimlib_write(WIMStruct *w, const char *path,
1570                            int image, int write_flags, unsigned num_threads)
1571 {
1572         int ret;
1573
1574         if (!w || !path)
1575                 return WIMLIB_ERR_INVALID_PARAM;
1576
1577         write_flags &= WIMLIB_WRITE_MASK_PUBLIC;
1578
1579         if (image != WIM_ALL_IMAGES &&
1580              (image < 1 || image > w->hdr.image_count))
1581                 return WIMLIB_ERR_INVALID_IMAGE;
1582
1583         if (w->hdr.total_parts != 1) {
1584                 ERROR("Cannot call wimlib_write() on part of a split WIM");
1585                 return WIMLIB_ERR_SPLIT_UNSUPPORTED;
1586         }
1587
1588         if (image == WIM_ALL_IMAGES)
1589                 DEBUG("Writing all images to `%s'.", path);
1590         else
1591                 DEBUG("Writing image %d to `%s'.", image, path);
1592
1593         ret = begin_write(w, path, write_flags);
1594         if (ret != 0)
1595                 goto out;
1596
1597         ret = write_wim_streams(w, image, write_flags, num_threads);
1598         if (ret != 0)
1599                 goto out;
1600
1601         if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS)
1602                 printf("Writing image metadata...\n");
1603
1604         ret = for_image(w, image, write_metadata_resource);
1605         if (ret != 0)
1606                 goto out;
1607
1608         ret = finish_write(w, image, write_flags);
1609         if (ret == 0 && (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS))
1610                 printf("Successfully wrote `%s'\n", path);
1611 out:
1612         close_wim_writable(w);
1613         return ret;
1614 }
1615
1616 static int lte_overwrite_prepare(struct lookup_table_entry *lte,
1617                                  void *ignore)
1618 {
1619         memcpy(&lte->output_resource_entry, &lte->resource_entry,
1620                sizeof(struct resource_entry));
1621         lte->out_refcnt = 0;
1622         return 0;
1623 }
1624
1625 static int check_resource_offset(struct lookup_table_entry *lte, void *arg)
1626 {
1627         off_t end_offset = *(u64*)arg;
1628
1629         wimlib_assert(lte->out_refcnt <= lte->refcnt);
1630         if (lte->out_refcnt < lte->refcnt) {
1631                 if (lte->resource_entry.offset + lte->resource_entry.size > end_offset) {
1632                         ERROR("The following resource is after the XML data:");
1633                         print_lookup_table_entry(lte);
1634                         return WIMLIB_ERR_RESOURCE_ORDER;
1635                 }
1636         }
1637         return 0;
1638 }
1639
1640 static int find_new_streams(struct lookup_table_entry *lte, void *arg)
1641 {
1642         if (lte->out_refcnt == lte->refcnt)
1643                 list_add(&lte->staging_list, (struct list_head*)arg);
1644         else
1645                 lte->out_refcnt = lte->refcnt;
1646         return 0;
1647 }
1648
1649 /*
1650  * Overwrite a WIM, possibly appending streams to it.
1651  *
1652  * A WIM looks like (or is supposed to look like) the following:
1653  *
1654  *                   Header (212 bytes)
1655  *                   Streams and metadata resources (variable size)
1656  *                   Lookup table (variable size)
1657  *                   XML data (variable size)
1658  *                   Integrity table (optional) (variable size)
1659  *
1660  * If we are not adding any streams or metadata resources, the lookup table is
1661  * unchanged--- so we only need to overwrite the XML data, integrity table, and
1662  * header.  This operation is potentially unsafe if the program is abruptly
1663  * terminated while the XML data or integrity table are being overwritten, but
1664  * before the new header has been written.  To partially alleviate this problem,
1665  * a special flag (WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML) is passed to
1666  * finish_write() to cause a temporary WIM header to be written after the XML
1667  * data has been written.  This may prevent the WIM from becoming corrupted if
1668  * the program is terminated while the integrity table is being calculated (but
1669  * no guarantees, due to write re-ordering...).
1670  *
1671  * If we are adding new streams or images (metadata resources), the lookup table
1672  * needs to be changed, and those streams need to be written.  In this case, we
1673  * try to perform a safe update of the WIM file by writing the streams *after*
1674  * the end of the previous WIM, then writing the new lookup table, XML data, and
1675  * (optionally) integrity table following the new streams.  This will produce a
1676  * layout like the following:
1677  *
1678  *                   Header (212 bytes)
1679  *                   (OLD) Streams and metadata resources (variable size)
1680  *                   (OLD) Lookup table (variable size)
1681  *                   (OLD) XML data (variable size)
1682  *                   (OLD) Integrity table (optional) (variable size)
1683  *                   (NEW) Streams and metadata resources (variable size)
1684  *                   (NEW) Lookup table (variable size)
1685  *                   (NEW) XML data (variable size)
1686  *                   (NEW) Integrity table (optional) (variable size)
1687  *
1688  * At all points, the WIM is valid as nothing points to the new data yet.  Then,
1689  * the header is overwritten to point to the new lookup table, XML data, and
1690  * integrity table, to produce the following layout:
1691  *
1692  *                   Header (212 bytes)
1693  *                   Streams and metadata resources (variable size)
1694  *                   Nothing (variable size)
1695  *                   More Streams and metadata resources (variable size)
1696  *                   Lookup table (variable size)
1697  *                   XML data (variable size)
1698  *                   Integrity table (optional) (variable size)
1699  *
1700  * This method allows an image to be appended to a large WIM very quickly, and
1701  * is is crash-safe except in the case of write re-ordering, but the
1702  * disadvantage is that a small hole is left in the WIM where the old lookup
1703  * table, xml data, and integrity table were.  (These usually only take up a
1704  * small amount of space compared to the streams, however.
1705  */
1706 static int overwrite_wim_inplace(WIMStruct *w, int write_flags,
1707                                  unsigned num_threads,
1708                                  int modified_image_idx)
1709 {
1710         int ret;
1711         struct list_head stream_list;
1712         off_t old_wim_end;
1713
1714         DEBUG("Overwriting `%s' in-place", w->filename);
1715
1716         /* Make sure that the integrity table (if present) is after the XML
1717          * data, and that there are no stream resources, metadata resources, or
1718          * lookup tables after the XML data.  Otherwise, these data would be
1719          * overwritten. */
1720         if (w->hdr.integrity.offset != 0 &&
1721             w->hdr.integrity.offset < w->hdr.xml_res_entry.offset) {
1722                 ERROR("Didn't expect the integrity table to be before the XML data");
1723                 return WIMLIB_ERR_RESOURCE_ORDER;
1724         }
1725
1726         if (w->hdr.lookup_table_res_entry.offset > w->hdr.xml_res_entry.offset) {
1727                 ERROR("Didn't expect the lookup table to be after the XML data");
1728                 return WIMLIB_ERR_RESOURCE_ORDER;
1729         }
1730
1731         DEBUG("Identifying newly added streams");
1732         for_lookup_table_entry(w->lookup_table, lte_overwrite_prepare, NULL);
1733         INIT_LIST_HEAD(&stream_list);
1734         for (int i = modified_image_idx; i < w->hdr.image_count; i++) {
1735                 DEBUG("Identifiying streams in image %d", i + 1);
1736                 wimlib_assert(w->image_metadata[i].modified);
1737                 wimlib_assert(!w->image_metadata[i].has_been_mounted_rw);
1738                 wimlib_assert(w->image_metadata[i].root_dentry != NULL);
1739                 wimlib_assert(w->image_metadata[i].metadata_lte != NULL);
1740                 w->private = &stream_list;
1741                 for_dentry_in_tree(w->image_metadata[i].root_dentry,
1742                                    dentry_find_streams_to_write, w);
1743         }
1744
1745         if (w->hdr.integrity.offset)
1746                 old_wim_end = w->hdr.integrity.offset + w->hdr.integrity.size;
1747         else
1748                 old_wim_end = w->hdr.xml_res_entry.offset + w->hdr.xml_res_entry.size;
1749
1750         ret = for_lookup_table_entry(w->lookup_table, check_resource_offset,
1751                                      &old_wim_end);
1752         if (ret != 0)
1753                 return ret;
1754
1755         if (modified_image_idx == w->hdr.image_count && !w->deletion_occurred) {
1756                 /* If no images have been modified and no images have been
1757                  * deleted, a new lookup table does not need to be written. */
1758                 wimlib_assert(list_empty(&stream_list));
1759                 old_wim_end = w->hdr.lookup_table_res_entry.offset +
1760                               w->hdr.lookup_table_res_entry.size;
1761                 write_flags |= WIMLIB_WRITE_FLAG_NO_LOOKUP_TABLE |
1762                                WIMLIB_WRITE_FLAG_CHECKPOINT_AFTER_XML;
1763         }
1764
1765         INIT_LIST_HEAD(&stream_list);
1766         for_lookup_table_entry(w->lookup_table, find_new_streams,
1767                                &stream_list);
1768
1769         ret = open_wim_writable(w, w->filename, false,
1770                                 (write_flags & WIMLIB_WRITE_FLAG_CHECK_INTEGRITY) != 0);
1771         if (ret != 0)
1772                 return ret;
1773
1774         if (fseeko(w->out_fp, old_wim_end, SEEK_SET) != 0) {
1775                 ERROR_WITH_ERRNO("Can't seek to end of WIM");
1776                 return WIMLIB_ERR_WRITE;
1777         }
1778
1779         if (!list_empty(&stream_list)) {
1780                 DEBUG("Writing newly added streams (offset = %"PRIu64")",
1781                       old_wim_end);
1782                 ret = write_stream_list(&stream_list, w->out_fp,
1783                                         wimlib_get_compression_type(w),
1784                                         write_flags, num_threads);
1785                 if (ret != 0)
1786                         goto out_ftruncate;
1787         } else {
1788                 DEBUG("No new streams were added");
1789         }
1790
1791         for (int i = modified_image_idx; i < w->hdr.image_count; i++) {
1792                 select_wim_image(w, i + 1);
1793                 ret = write_metadata_resource(w);
1794                 if (ret != 0)
1795                         goto out_ftruncate;
1796         }
1797         write_flags |= WIMLIB_WRITE_FLAG_REUSE_INTEGRITY_TABLE;
1798         ret = finish_write(w, WIM_ALL_IMAGES, write_flags);
1799 out_ftruncate:
1800         close_wim_writable(w);
1801         if (ret != 0) {
1802                 WARNING("Truncating `%s' to its original size (%"PRIu64" bytes)",
1803                         w->filename, old_wim_end);
1804                 truncate(w->filename, old_wim_end);
1805         }
1806         return ret;
1807 }
1808
1809 static int overwrite_wim_via_tmpfile(WIMStruct *w, int write_flags,
1810                                      unsigned num_threads)
1811 {
1812         size_t wim_name_len;
1813         int ret;
1814
1815         DEBUG("Overwrining `%s' via a temporary file", w->filename);
1816
1817         /* Write the WIM to a temporary file in the same directory as the
1818          * original WIM. */
1819         wim_name_len = strlen(w->filename);
1820         char tmpfile[wim_name_len + 10];
1821         memcpy(tmpfile, w->filename, wim_name_len);
1822         randomize_char_array_with_alnum(tmpfile + wim_name_len, 9);
1823         tmpfile[wim_name_len + 9] = '\0';
1824
1825         ret = wimlib_write(w, tmpfile, WIM_ALL_IMAGES,
1826                            write_flags | WIMLIB_WRITE_FLAG_FSYNC,
1827                            num_threads);
1828         if (ret != 0) {
1829                 ERROR("Failed to write the WIM file `%s'", tmpfile);
1830                 goto err;
1831         }
1832
1833         /* Close the original WIM file that was opened for reading. */
1834         if (w->fp != NULL) {
1835                 fclose(w->fp);
1836                 w->fp = NULL;
1837         }
1838
1839         DEBUG("Renaming `%s' to `%s'", tmpfile, w->filename);
1840
1841         /* Rename the new file to the old file .*/
1842         if (rename(tmpfile, w->filename) != 0) {
1843                 ERROR_WITH_ERRNO("Failed to rename `%s' to `%s'",
1844                                  tmpfile, w->filename);
1845                 ret = WIMLIB_ERR_RENAME;
1846                 goto err;
1847         }
1848
1849         if (write_flags & WIMLIB_WRITE_FLAG_SHOW_PROGRESS)
1850                 printf("Successfully renamed `%s' to `%s'\n", tmpfile, w->filename);
1851
1852         /* Re-open the WIM read-only. */
1853         w->fp = fopen(w->filename, "rb");
1854         if (w->fp == NULL) {
1855                 ret = WIMLIB_ERR_REOPEN;
1856                 WARNING("Failed to re-open `%s' read-only: %s",
1857                         w->filename, strerror(errno));
1858         }
1859         return ret;
1860 err:
1861         /* Remove temporary file. */
1862         if (unlink(tmpfile) != 0)
1863                 WARNING("Failed to remove `%s': %s", tmpfile, strerror(errno));
1864         return ret;
1865 }
1866
1867 /*
1868  * Writes a WIM file to the original file that it was read from, overwriting it.
1869  */
1870 WIMLIBAPI int wimlib_overwrite(WIMStruct *w, int write_flags,
1871                                unsigned num_threads)
1872 {
1873         if (!w)
1874                 return WIMLIB_ERR_INVALID_PARAM;
1875
1876         write_flags &= WIMLIB_WRITE_MASK_PUBLIC;
1877
1878         if (!w->filename)
1879                 return WIMLIB_ERR_NO_FILENAME;
1880
1881         if (w->hdr.total_parts != 1) {
1882                 ERROR("Cannot modify a split WIM");
1883                 return WIMLIB_ERR_SPLIT_UNSUPPORTED;
1884         }
1885
1886         if ((!w->deletion_occurred || (write_flags & WIMLIB_WRITE_FLAG_SOFT_DELETE))
1887             && !(write_flags & WIMLIB_WRITE_FLAG_REBUILD))
1888         {
1889                 int i, modified_image_idx;
1890                 for (i = 0; i < w->hdr.image_count && !w->image_metadata[i].modified; i++)
1891                         ;
1892                 modified_image_idx = i;
1893                 for (; i < w->hdr.image_count && w->image_metadata[i].modified &&
1894                         !w->image_metadata[i].has_been_mounted_rw; i++)
1895                         ;
1896                 if (i == w->hdr.image_count) {
1897                         return overwrite_wim_inplace(w, write_flags, num_threads,
1898                                                      modified_image_idx);
1899                 }
1900         }
1901         return overwrite_wim_via_tmpfile(w, write_flags, num_threads);
1902 }
1903
1904 /* Deprecated */
1905 WIMLIBAPI int wimlib_overwrite_xml_and_header(WIMStruct *wim, int write_flags)
1906 {
1907         return wimlib_overwrite(wim, write_flags, 1);
1908 }