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1 /*
2  * Copyright © 2014 Intel Corporation
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice (including the next
12  * paragraph) shall be included in all copies or substantial portions of the
13  * Software.
14  *
15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21  * IN THE SOFTWARE.
22  */
23 
24 #ifdef ENABLE_SHADER_CACHE
25 
26 #include <assert.h>
27 #include <inttypes.h>
28 #include <stdbool.h>
29 #include <stddef.h>
30 #include <stdlib.h>
31 #include <sys/types.h>
32 #include <sys/stat.h>
33 #include <dirent.h>
34 #include <fcntl.h>
35 
36 #include "zlib.h"
37 
38 #ifdef HAVE_ZSTD
39 #include "zstd.h"
40 #endif
41 
42 /* 3 is the recomended level, with 22 as the absolute maximum */
43 #define ZSTD_COMPRESSION_LEVEL 3
44 
45 /* From the zlib docs:
46  *    "If the memory is available, buffers sizes on the order of 128K or 256K
47  *    bytes should be used."
48  */
49 #define BUFSIZE 256 * 1024
50 
51 static ssize_t
52 write_all(int fd, const void *buf, size_t count);
53 
54 /**
55  * Compresses cache entry in memory and writes it to disk. Returns the size
56  * of the data written to disk.
57  */
58 static size_t
deflate_and_write_to_disk(const void * in_data,size_t in_data_size,int dest)59 deflate_and_write_to_disk(const void *in_data, size_t in_data_size, int dest)
60 {
61 #ifdef HAVE_ZSTD
62    /* from the zstd docs (https://facebook.github.io/zstd/zstd_manual.html):
63     * compression runs faster if `dstCapacity` >= `ZSTD_compressBound(srcSize)`.
64     */
65    size_t out_size = ZSTD_compressBound(in_data_size);
66    void * out = malloc(out_size);
67 
68    size_t ret = ZSTD_compress(out, out_size, in_data, in_data_size,
69                               ZSTD_COMPRESSION_LEVEL);
70    if (ZSTD_isError(ret)) {
71       free(out);
72       return 0;
73    }
74    ssize_t written = write_all(dest, out, ret);
75    if (written == -1) {
76       free(out);
77       return 0;
78    }
79    free(out);
80    return ret;
81 #else
82    unsigned char *out;
83 
84    /* allocate deflate state */
85    z_stream strm;
86    strm.zalloc = Z_NULL;
87    strm.zfree = Z_NULL;
88    strm.opaque = Z_NULL;
89    strm.next_in = (uint8_t *) in_data;
90    strm.avail_in = in_data_size;
91 
92    int ret = deflateInit(&strm, Z_BEST_COMPRESSION);
93    if (ret != Z_OK)
94        return 0;
95 
96    /* compress until end of in_data */
97    size_t compressed_size = 0;
98    int flush;
99 
100    out = malloc(BUFSIZE * sizeof(unsigned char));
101    if (out == NULL)
102       return 0;
103 
104    do {
105       int remaining = in_data_size - BUFSIZE;
106       flush = remaining > 0 ? Z_NO_FLUSH : Z_FINISH;
107       in_data_size -= BUFSIZE;
108 
109       /* Run deflate() on input until the output buffer is not full (which
110        * means there is no more data to deflate).
111        */
112       do {
113          strm.avail_out = BUFSIZE;
114          strm.next_out = out;
115 
116          ret = deflate(&strm, flush);    /* no bad return value */
117          assert(ret != Z_STREAM_ERROR);  /* state not clobbered */
118 
119          size_t have = BUFSIZE - strm.avail_out;
120          compressed_size += have;
121 
122          ssize_t written = write_all(dest, out, have);
123          if (written == -1) {
124             (void)deflateEnd(&strm);
125             free(out);
126             return 0;
127          }
128       } while (strm.avail_out == 0);
129 
130       /* all input should be used */
131       assert(strm.avail_in == 0);
132 
133    } while (flush != Z_FINISH);
134 
135    /* stream should be complete */
136    assert(ret == Z_STREAM_END);
137 
138    /* clean up and return */
139    (void)deflateEnd(&strm);
140    free(out);
141    return compressed_size;
142 # endif
143 }
144 
145 /**
146  * Decompresses cache entry, returns true if successful.
147  */
148 static bool
inflate_cache_data(uint8_t * in_data,size_t in_data_size,uint8_t * out_data,size_t out_data_size)149 inflate_cache_data(uint8_t *in_data, size_t in_data_size,
150                    uint8_t *out_data, size_t out_data_size)
151 {
152 #ifdef HAVE_ZSTD
153    size_t ret = ZSTD_decompress(out_data, out_data_size, in_data, in_data_size);
154    return !ZSTD_isError(ret);
155 #else
156    z_stream strm;
157 
158    /* allocate inflate state */
159    strm.zalloc = Z_NULL;
160    strm.zfree = Z_NULL;
161    strm.opaque = Z_NULL;
162    strm.next_in = in_data;
163    strm.avail_in = in_data_size;
164    strm.next_out = out_data;
165    strm.avail_out = out_data_size;
166 
167    int ret = inflateInit(&strm);
168    if (ret != Z_OK)
169       return false;
170 
171    ret = inflate(&strm, Z_NO_FLUSH);
172    assert(ret != Z_STREAM_ERROR);  /* state not clobbered */
173 
174    /* Unless there was an error we should have decompressed everything in one
175     * go as we know the uncompressed file size.
176     */
177    if (ret != Z_STREAM_END) {
178       (void)inflateEnd(&strm);
179       return false;
180    }
181    assert(strm.avail_out == 0);
182 
183    /* clean up and return */
184    (void)inflateEnd(&strm);
185    return true;
186 #endif
187 }
188 
189 #if DETECT_OS_WINDOWS
190 /* TODO: implement disk cache support on windows */
191 
192 #else
193 
194 #include <dirent.h>
195 #include <errno.h>
196 #include <pwd.h>
197 #include <stdio.h>
198 #include <string.h>
199 #include <sys/file.h>
200 #include <sys/mman.h>
201 #include <sys/types.h>
202 #include <sys/stat.h>
203 #include <unistd.h>
204 
205 #include "util/crc32.h"
206 #include "util/debug.h"
207 #include "util/disk_cache.h"
208 #include "util/disk_cache_os.h"
209 #include "util/ralloc.h"
210 #include "util/rand_xor.h"
211 
212 /* Create a directory named 'path' if it does not already exist.
213  *
214  * Returns: 0 if path already exists as a directory or if created.
215  *         -1 in all other cases.
216  */
217 static int
mkdir_if_needed(const char * path)218 mkdir_if_needed(const char *path)
219 {
220    struct stat sb;
221 
222    /* If the path exists already, then our work is done if it's a
223     * directory, but it's an error if it is not.
224     */
225    if (stat(path, &sb) == 0) {
226       if (S_ISDIR(sb.st_mode)) {
227          return 0;
228       } else {
229          fprintf(stderr, "Cannot use %s for shader cache (not a directory)"
230                          "---disabling.\n", path);
231          return -1;
232       }
233    }
234 
235    int ret = mkdir(path, 0755);
236    if (ret == 0 || (ret == -1 && errno == EEXIST))
237      return 0;
238 
239    fprintf(stderr, "Failed to create %s for shader cache (%s)---disabling.\n",
240            path, strerror(errno));
241 
242    return -1;
243 }
244 
245 /* Concatenate an existing path and a new name to form a new path.  If the new
246  * path does not exist as a directory, create it then return the resulting
247  * name of the new path (ralloc'ed off of 'ctx').
248  *
249  * Returns NULL on any error, such as:
250  *
251  *      <path> does not exist or is not a directory
252  *      <path>/<name> exists but is not a directory
253  *      <path>/<name> cannot be created as a directory
254  */
255 static char *
concatenate_and_mkdir(void * ctx,const char * path,const char * name)256 concatenate_and_mkdir(void *ctx, const char *path, const char *name)
257 {
258    char *new_path;
259    struct stat sb;
260 
261    if (stat(path, &sb) != 0 || ! S_ISDIR(sb.st_mode))
262       return NULL;
263 
264    new_path = ralloc_asprintf(ctx, "%s/%s", path, name);
265 
266    if (mkdir_if_needed(new_path) == 0)
267       return new_path;
268    else
269       return NULL;
270 }
271 
272 /* Given a directory path and predicate function, find the entry with
273  * the oldest access time in that directory for which the predicate
274  * returns true.
275  *
276  * Returns: A malloc'ed string for the path to the chosen file, (or
277  * NULL on any error). The caller should free the string when
278  * finished.
279  */
280 static char *
choose_lru_file_matching(const char * dir_path,bool (* predicate)(const char * dir_path,const struct stat *,const char *,const size_t))281 choose_lru_file_matching(const char *dir_path,
282                          bool (*predicate)(const char *dir_path,
283                                            const struct stat *,
284                                            const char *, const size_t))
285 {
286    DIR *dir;
287    struct dirent *entry;
288    char *filename;
289    char *lru_name = NULL;
290    time_t lru_atime = 0;
291 
292    dir = opendir(dir_path);
293    if (dir == NULL)
294       return NULL;
295 
296    while (1) {
297       entry = readdir(dir);
298       if (entry == NULL)
299          break;
300 
301       struct stat sb;
302       if (fstatat(dirfd(dir), entry->d_name, &sb, 0) == 0) {
303          if (!lru_atime || (sb.st_atime < lru_atime)) {
304             size_t len = strlen(entry->d_name);
305 
306             if (!predicate(dir_path, &sb, entry->d_name, len))
307                continue;
308 
309             char *tmp = realloc(lru_name, len + 1);
310             if (tmp) {
311                lru_name = tmp;
312                memcpy(lru_name, entry->d_name, len + 1);
313                lru_atime = sb.st_atime;
314             }
315          }
316       }
317    }
318 
319    if (lru_name == NULL) {
320       closedir(dir);
321       return NULL;
322    }
323 
324    if (asprintf(&filename, "%s/%s", dir_path, lru_name) < 0)
325       filename = NULL;
326 
327    free(lru_name);
328    closedir(dir);
329 
330    return filename;
331 }
332 
333 /* Is entry a regular file, and not having a name with a trailing
334  * ".tmp"
335  */
336 static bool
is_regular_non_tmp_file(const char * path,const struct stat * sb,const char * d_name,const size_t len)337 is_regular_non_tmp_file(const char *path, const struct stat *sb,
338                         const char *d_name, const size_t len)
339 {
340    if (!S_ISREG(sb->st_mode))
341       return false;
342 
343    if (len >= 4 && strcmp(&d_name[len-4], ".tmp") == 0)
344       return false;
345 
346    return true;
347 }
348 
349 /* Returns the size of the deleted file, (or 0 on any error). */
350 static size_t
unlink_lru_file_from_directory(const char * path)351 unlink_lru_file_from_directory(const char *path)
352 {
353    struct stat sb;
354    char *filename;
355 
356    filename = choose_lru_file_matching(path, is_regular_non_tmp_file);
357    if (filename == NULL)
358       return 0;
359 
360    if (stat(filename, &sb) == -1) {
361       free (filename);
362       return 0;
363    }
364 
365    unlink(filename);
366    free (filename);
367 
368    return sb.st_blocks * 512;
369 }
370 
371 /* Is entry a directory with a two-character name, (and not the
372  * special name of ".."). We also return false if the dir is empty.
373  */
374 static bool
is_two_character_sub_directory(const char * path,const struct stat * sb,const char * d_name,const size_t len)375 is_two_character_sub_directory(const char *path, const struct stat *sb,
376                                const char *d_name, const size_t len)
377 {
378    if (!S_ISDIR(sb->st_mode))
379       return false;
380 
381    if (len != 2)
382       return false;
383 
384    if (strcmp(d_name, "..") == 0)
385       return false;
386 
387    char *subdir;
388    if (asprintf(&subdir, "%s/%s", path, d_name) == -1)
389       return false;
390    DIR *dir = opendir(subdir);
391    free(subdir);
392 
393    if (dir == NULL)
394      return false;
395 
396    unsigned subdir_entries = 0;
397    struct dirent *d;
398    while ((d = readdir(dir)) != NULL) {
399       if(++subdir_entries > 2)
400          break;
401    }
402    closedir(dir);
403 
404    /* If dir only contains '.' and '..' it must be empty */
405    if (subdir_entries <= 2)
406       return false;
407 
408    return true;
409 }
410 
411 /* Create the directory that will be needed for the cache file for \key.
412  *
413  * Obviously, the implementation here must closely match
414  * _get_cache_file above.
415 */
416 static void
make_cache_file_directory(struct disk_cache * cache,const cache_key key)417 make_cache_file_directory(struct disk_cache *cache, const cache_key key)
418 {
419    char *dir;
420    char buf[41];
421 
422    _mesa_sha1_format(buf, key);
423    if (asprintf(&dir, "%s/%c%c", cache->path, buf[0], buf[1]) == -1)
424       return;
425 
426    mkdir_if_needed(dir);
427    free(dir);
428 }
429 
430 static ssize_t
read_all(int fd,void * buf,size_t count)431 read_all(int fd, void *buf, size_t count)
432 {
433    char *in = buf;
434    ssize_t read_ret;
435    size_t done;
436 
437    for (done = 0; done < count; done += read_ret) {
438       read_ret = read(fd, in + done, count - done);
439       if (read_ret == -1 || read_ret == 0)
440          return -1;
441    }
442    return done;
443 }
444 
445 static ssize_t
write_all(int fd,const void * buf,size_t count)446 write_all(int fd, const void *buf, size_t count)
447 {
448    const char *out = buf;
449    ssize_t written;
450    size_t done;
451 
452    for (done = 0; done < count; done += written) {
453       written = write(fd, out + done, count - done);
454       if (written == -1)
455          return -1;
456    }
457    return done;
458 }
459 
460 /* Evict least recently used cache item */
461 void
disk_cache_evict_lru_item(struct disk_cache * cache)462 disk_cache_evict_lru_item(struct disk_cache *cache)
463 {
464    char *dir_path;
465 
466    /* With a reasonably-sized, full cache, (and with keys generated
467     * from a cryptographic hash), we can choose two random hex digits
468     * and reasonably expect the directory to exist with a file in it.
469     * Provides pseudo-LRU eviction to reduce checking all cache files.
470     */
471    uint64_t rand64 = rand_xorshift128plus(cache->seed_xorshift128plus);
472    if (asprintf(&dir_path, "%s/%02" PRIx64 , cache->path, rand64 & 0xff) < 0)
473       return;
474 
475    size_t size = unlink_lru_file_from_directory(dir_path);
476 
477    free(dir_path);
478 
479    if (size) {
480       p_atomic_add(cache->size, - (uint64_t)size);
481       return;
482    }
483 
484    /* In the case where the random choice of directory didn't find
485     * something, we choose the least recently accessed from the
486     * existing directories.
487     *
488     * Really, the only reason this code exists is to allow the unit
489     * tests to work, (which use an artificially-small cache to be able
490     * to force a single cached item to be evicted).
491     */
492    dir_path = choose_lru_file_matching(cache->path,
493                                        is_two_character_sub_directory);
494    if (dir_path == NULL)
495       return;
496 
497    size = unlink_lru_file_from_directory(dir_path);
498 
499    free(dir_path);
500 
501    if (size)
502       p_atomic_add(cache->size, - (uint64_t)size);
503 }
504 
505 void
disk_cache_evict_item(struct disk_cache * cache,char * filename)506 disk_cache_evict_item(struct disk_cache *cache, char *filename)
507 {
508    struct stat sb;
509    if (stat(filename, &sb) == -1) {
510       free(filename);
511       return;
512    }
513 
514    unlink(filename);
515    free(filename);
516 
517    if (sb.st_blocks)
518       p_atomic_add(cache->size, - (uint64_t)sb.st_blocks * 512);
519 }
520 
521 void *
disk_cache_load_item(struct disk_cache * cache,char * filename,size_t * size)522 disk_cache_load_item(struct disk_cache *cache, char *filename, size_t *size)
523 {
524    int fd = -1, ret;
525    struct stat sb;
526    uint8_t *data = NULL;
527    uint8_t *uncompressed_data = NULL;
528    uint8_t *file_header = NULL;
529 
530    fd = open(filename, O_RDONLY | O_CLOEXEC);
531    if (fd == -1)
532       goto fail;
533 
534    if (fstat(fd, &sb) == -1)
535       goto fail;
536 
537    data = malloc(sb.st_size);
538    if (data == NULL)
539       goto fail;
540 
541    size_t ck_size = cache->driver_keys_blob_size;
542    file_header = malloc(ck_size);
543    if (!file_header)
544       goto fail;
545 
546    if (sb.st_size < ck_size)
547       goto fail;
548 
549    ret = read_all(fd, file_header, ck_size);
550    if (ret == -1)
551       goto fail;
552 
553    /* Check for extremely unlikely hash collisions */
554    if (memcmp(cache->driver_keys_blob, file_header, ck_size) != 0) {
555       assert(!"Mesa cache keys mismatch!");
556       goto fail;
557    }
558 
559    size_t cache_item_md_size = sizeof(uint32_t);
560    uint32_t md_type;
561    ret = read_all(fd, &md_type, cache_item_md_size);
562    if (ret == -1)
563       goto fail;
564 
565    if (md_type == CACHE_ITEM_TYPE_GLSL) {
566       uint32_t num_keys;
567       cache_item_md_size += sizeof(uint32_t);
568       ret = read_all(fd, &num_keys, sizeof(uint32_t));
569       if (ret == -1)
570          goto fail;
571 
572       /* The cache item metadata is currently just used for distributing
573        * precompiled shaders, they are not used by Mesa so just skip them for
574        * now.
575        * TODO: pass the metadata back to the caller and do some basic
576        * validation.
577        */
578       cache_item_md_size += num_keys * sizeof(cache_key);
579       ret = lseek(fd, num_keys * sizeof(cache_key), SEEK_CUR);
580       if (ret == -1)
581          goto fail;
582    }
583 
584    /* Load the CRC that was created when the file was written. */
585    struct cache_entry_file_data cf_data;
586    size_t cf_data_size = sizeof(cf_data);
587    ret = read_all(fd, &cf_data, cf_data_size);
588    if (ret == -1)
589       goto fail;
590 
591    /* Load the actual cache data. */
592    size_t cache_data_size =
593       sb.st_size - cf_data_size - ck_size - cache_item_md_size;
594    ret = read_all(fd, data, cache_data_size);
595    if (ret == -1)
596       goto fail;
597 
598    /* Uncompress the cache data */
599    uncompressed_data = malloc(cf_data.uncompressed_size);
600    if (!inflate_cache_data(data, cache_data_size, uncompressed_data,
601                            cf_data.uncompressed_size))
602       goto fail;
603 
604    /* Check the data for corruption */
605    if (cf_data.crc32 != util_hash_crc32(uncompressed_data,
606                                         cf_data.uncompressed_size))
607       goto fail;
608 
609    free(data);
610    free(filename);
611    free(file_header);
612    close(fd);
613 
614    if (size)
615       *size = cf_data.uncompressed_size;
616 
617    return uncompressed_data;
618 
619  fail:
620    if (data)
621       free(data);
622    if (filename)
623       free(filename);
624    if (uncompressed_data)
625       free(uncompressed_data);
626    if (file_header)
627       free(file_header);
628    if (fd != -1)
629       close(fd);
630 
631    return NULL;
632 }
633 
634 /* Return a filename within the cache's directory corresponding to 'key'.
635  *
636  * Returns NULL if out of memory.
637  */
638 char *
disk_cache_get_cache_filename(struct disk_cache * cache,const cache_key key)639 disk_cache_get_cache_filename(struct disk_cache *cache, const cache_key key)
640 {
641    char buf[41];
642    char *filename;
643 
644    if (cache->path_init_failed)
645       return NULL;
646 
647    _mesa_sha1_format(buf, key);
648    if (asprintf(&filename, "%s/%c%c/%s", cache->path, buf[0],
649                 buf[1], buf + 2) == -1)
650       return NULL;
651 
652    return filename;
653 }
654 
655 void
disk_cache_write_item_to_disk(struct disk_cache_put_job * dc_job,struct cache_entry_file_data * cf_data,char * filename)656 disk_cache_write_item_to_disk(struct disk_cache_put_job *dc_job,
657                               struct cache_entry_file_data *cf_data,
658                               char *filename)
659 {
660    int fd = -1, fd_final = -1;
661 
662    /* Write to a temporary file to allow for an atomic rename to the
663     * final destination filename, (to prevent any readers from seeing
664     * a partially written file).
665     */
666    char *filename_tmp = NULL;
667    if (asprintf(&filename_tmp, "%s.tmp", filename) == -1)
668       goto done;
669 
670    fd = open(filename_tmp, O_WRONLY | O_CLOEXEC | O_CREAT, 0644);
671 
672    /* Make the two-character subdirectory within the cache as needed. */
673    if (fd == -1) {
674       if (errno != ENOENT)
675          goto done;
676 
677       make_cache_file_directory(dc_job->cache, dc_job->key);
678 
679       fd = open(filename_tmp, O_WRONLY | O_CLOEXEC | O_CREAT, 0644);
680       if (fd == -1)
681          goto done;
682    }
683 
684    /* With the temporary file open, we take an exclusive flock on
685     * it. If the flock fails, then another process still has the file
686     * open with the flock held. So just let that file be responsible
687     * for writing the file.
688     */
689 #ifdef HAVE_FLOCK
690    int err = flock(fd, LOCK_EX | LOCK_NB);
691 #else
692    struct flock lock = {
693       .l_start = 0,
694       .l_len = 0, /* entire file */
695       .l_type = F_WRLCK,
696       .l_whence = SEEK_SET
697    };
698    int err = fcntl(fd, F_SETLK, &lock);
699 #endif
700    if (err == -1)
701       goto done;
702 
703    /* Now that we have the lock on the open temporary file, we can
704     * check to see if the destination file already exists. If so,
705     * another process won the race between when we saw that the file
706     * didn't exist and now. In this case, we don't do anything more,
707     * (to ensure the size accounting of the cache doesn't get off).
708     */
709    fd_final = open(filename, O_RDONLY | O_CLOEXEC);
710    if (fd_final != -1) {
711       unlink(filename_tmp);
712       goto done;
713    }
714 
715    /* OK, we're now on the hook to write out a file that we know is
716     * not in the cache, and is also not being written out to the cache
717     * by some other process.
718     */
719 
720    /* Write the driver_keys_blob, this can be used find information about the
721     * mesa version that produced the entry or deal with hash collisions,
722     * should that ever become a real problem.
723     */
724    int ret = write_all(fd, dc_job->cache->driver_keys_blob,
725                        dc_job->cache->driver_keys_blob_size);
726    if (ret == -1) {
727       unlink(filename_tmp);
728       goto done;
729    }
730 
731    /* Write the cache item metadata. This data can be used to deal with
732     * hash collisions, as well as providing useful information to 3rd party
733     * tools reading the cache files.
734     */
735    ret = write_all(fd, &dc_job->cache_item_metadata.type,
736                    sizeof(uint32_t));
737    if (ret == -1) {
738       unlink(filename_tmp);
739       goto done;
740    }
741 
742    if (dc_job->cache_item_metadata.type == CACHE_ITEM_TYPE_GLSL) {
743       ret = write_all(fd, &dc_job->cache_item_metadata.num_keys,
744                       sizeof(uint32_t));
745       if (ret == -1) {
746          unlink(filename_tmp);
747          goto done;
748       }
749 
750       ret = write_all(fd, dc_job->cache_item_metadata.keys[0],
751                       dc_job->cache_item_metadata.num_keys *
752                       sizeof(cache_key));
753       if (ret == -1) {
754          unlink(filename_tmp);
755          goto done;
756       }
757    }
758 
759    size_t cf_data_size = sizeof(*cf_data);
760    ret = write_all(fd, cf_data, cf_data_size);
761    if (ret == -1) {
762       unlink(filename_tmp);
763       goto done;
764    }
765 
766    /* Now, finally, write out the contents to the temporary file, then
767     * rename them atomically to the destination filename, and also
768     * perform an atomic increment of the total cache size.
769     */
770    size_t file_size = deflate_and_write_to_disk(dc_job->data, dc_job->size,
771                                                 fd);
772    if (file_size == 0) {
773       unlink(filename_tmp);
774       goto done;
775    }
776    ret = rename(filename_tmp, filename);
777    if (ret == -1) {
778       unlink(filename_tmp);
779       goto done;
780    }
781 
782    struct stat sb;
783    if (stat(filename, &sb) == -1) {
784       /* Something went wrong remove the file */
785       unlink(filename);
786       goto done;
787    }
788 
789    p_atomic_add(dc_job->cache->size, sb.st_blocks * 512);
790 
791  done:
792    if (fd_final != -1)
793       close(fd_final);
794    /* This close finally releases the flock, (now that the final file
795     * has been renamed into place and the size has been added).
796     */
797    if (fd != -1)
798       close(fd);
799    free(filename_tmp);
800 }
801 
802 /* Determine path for cache based on the first defined name as follows:
803  *
804  *   $MESA_GLSL_CACHE_DIR
805  *   $XDG_CACHE_HOME/mesa_shader_cache
806  *   <pwd.pw_dir>/.cache/mesa_shader_cache
807  */
808 char *
disk_cache_generate_cache_dir(void * mem_ctx)809 disk_cache_generate_cache_dir(void *mem_ctx)
810 {
811    char *path = getenv("MESA_GLSL_CACHE_DIR");
812    if (path) {
813       if (mkdir_if_needed(path) == -1)
814          return NULL;
815 
816       path = concatenate_and_mkdir(mem_ctx, path, CACHE_DIR_NAME);
817       if (!path)
818          return NULL;
819    }
820 
821    if (path == NULL) {
822       char *xdg_cache_home = getenv("XDG_CACHE_HOME");
823 
824       if (xdg_cache_home) {
825          if (mkdir_if_needed(xdg_cache_home) == -1)
826             return NULL;
827 
828          path = concatenate_and_mkdir(mem_ctx, xdg_cache_home, CACHE_DIR_NAME);
829          if (!path)
830             return NULL;
831       }
832    }
833 
834    if (!path) {
835       char *buf;
836       size_t buf_size;
837       struct passwd pwd, *result;
838 
839       buf_size = sysconf(_SC_GETPW_R_SIZE_MAX);
840       if (buf_size == -1)
841          buf_size = 512;
842 
843       /* Loop until buf_size is large enough to query the directory */
844       while (1) {
845          buf = ralloc_size(mem_ctx, buf_size);
846 
847          getpwuid_r(getuid(), &pwd, buf, buf_size, &result);
848          if (result)
849             break;
850 
851          if (errno == ERANGE) {
852             ralloc_free(buf);
853             buf = NULL;
854             buf_size *= 2;
855          } else {
856             return NULL;
857          }
858       }
859 
860       path = concatenate_and_mkdir(mem_ctx, pwd.pw_dir, ".cache");
861       if (!path)
862          return NULL;
863 
864       path = concatenate_and_mkdir(mem_ctx, path, CACHE_DIR_NAME);
865       if (!path)
866          return NULL;
867    }
868 
869    return path;
870 }
871 
872 bool
disk_cache_enabled()873 disk_cache_enabled()
874 {
875    /* If running as a users other than the real user disable cache */
876    if (geteuid() != getuid())
877       return false;
878 
879    /* At user request, disable shader cache entirely. */
880 #ifdef SHADER_CACHE_DISABLE_BY_DEFAULT
881    bool disable_by_default = true;
882 #else
883    bool disable_by_default = false;
884 #endif
885    if (env_var_as_boolean("MESA_GLSL_CACHE_DISABLE", disable_by_default))
886       return false;
887 
888    return true;
889 }
890 
891 bool
disk_cache_mmap_cache_index(void * mem_ctx,struct disk_cache * cache,char * path)892 disk_cache_mmap_cache_index(void *mem_ctx, struct disk_cache *cache,
893                             char *path)
894 {
895    int fd = -1;
896    bool mapped = false;
897 
898    cache->path = ralloc_strdup(cache, path);
899    if (cache->path == NULL)
900       goto path_fail;
901 
902    path = ralloc_asprintf(mem_ctx, "%s/index", cache->path);
903    if (path == NULL)
904       goto path_fail;
905 
906    fd = open(path, O_RDWR | O_CREAT | O_CLOEXEC, 0644);
907    if (fd == -1)
908       goto path_fail;
909 
910    struct stat sb;
911    if (fstat(fd, &sb) == -1)
912       goto path_fail;
913 
914    /* Force the index file to be the expected size. */
915    size_t size = sizeof(*cache->size) + CACHE_INDEX_MAX_KEYS * CACHE_KEY_SIZE;
916    if (sb.st_size != size) {
917       if (ftruncate(fd, size) == -1)
918          goto path_fail;
919    }
920 
921    /* We map this shared so that other processes see updates that we
922     * make.
923     *
924     * Note: We do use atomic addition to ensure that multiple
925     * processes don't scramble the cache size recorded in the
926     * index. But we don't use any locking to prevent multiple
927     * processes from updating the same entry simultaneously. The idea
928     * is that if either result lands entirely in the index, then
929     * that's equivalent to a well-ordered write followed by an
930     * eviction and a write. On the other hand, if the simultaneous
931     * writes result in a corrupt entry, that's not really any
932     * different than both entries being evicted, (since within the
933     * guarantees of the cryptographic hash, a corrupt entry is
934     * unlikely to ever match a real cache key).
935     */
936    cache->index_mmap = mmap(NULL, size, PROT_READ | PROT_WRITE,
937                             MAP_SHARED, fd, 0);
938    if (cache->index_mmap == MAP_FAILED)
939       goto path_fail;
940    cache->index_mmap_size = size;
941 
942    cache->size = (uint64_t *) cache->index_mmap;
943    cache->stored_keys = cache->index_mmap + sizeof(uint64_t);
944    mapped = true;
945 
946 path_fail:
947    if (fd != -1)
948       close(fd);
949 
950    return mapped;
951 }
952 
953 void
disk_cache_destroy_mmap(struct disk_cache * cache)954 disk_cache_destroy_mmap(struct disk_cache *cache)
955 {
956    munmap(cache->index_mmap, cache->index_mmap_size);
957 }
958 #endif
959 
960 #endif /* ENABLE_SHADER_CACHE */
961