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util/disk_cache: add support for detecting corrupt cache entries

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V2: fix pointer increments for writing/reading crc

Acked-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Grigori Goronzy <greg@chown.ath.cx>
This commit is contained in:
Timothy Arceri
2017-02-24 15:14:56 +11:00
parent 9fc86d4f53
commit 5afde61752
1 changed files with 34 additions and 3 deletions
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37
src/util/disk_cache.c
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@@ -38,6 +38,7 @@
#include <errno.h>
#include <dirent.h>
#include "util/crc32.h"
#include "util/u_atomic.h"
#include "util/mesa-sha1.h"
#include "util/ralloc.h"
@@ -709,6 +710,19 @@ disk_cache_put(struct disk_cache *cache,
if (*cache->size + size > cache->max_size)
evict_random_item(cache);
/* Create CRC of the data and store at the start of the file. We will
* read this when restoring the cache and use it to check for corruption.
*/
uint32_t crc32 = util_hash_crc32(data, size);
size_t crc_size = sizeof(crc32);
for (len = 0; len < crc_size; len += ret) {
ret = write(fd, ((uint8_t *) &crc32) + len, crc_size - len);
if (ret == -1) {
unlink(filename_tmp);
goto done;
}
}
/* Now, finally, write out the contents to the temporary file, then
* rename them atomically to the destination filename, and also
* perform an atomic increment of the total cache size.
@@ -723,6 +737,7 @@ disk_cache_put(struct disk_cache *cache,
rename(filename_tmp, filename);
size += crc_size;
p_atomic_add(cache->size, size);
done:
@@ -765,17 +780,33 @@ disk_cache_get(struct disk_cache *cache, cache_key key, size_t *size)
if (data == NULL)
goto fail;
for (len = 0; len < sb.st_size; len += ret) {
ret = read(fd, data + len, sb.st_size - len);
/* Load the CRC that was created when the file was written. */
uint32_t crc32;
size_t crc_size = sizeof(crc32);
assert(sb.st_size > crc_size);
for (len = 0; len < crc_size; len += ret) {
ret = read(fd, ((uint8_t *) &crc32) + len, crc_size - len);
if (ret == -1)
goto fail;
}
/* Load the actual cache data. */
size_t cache_data_size = sb.st_size - crc_size;
for (len = 0; len < cache_data_size; len += ret) {
ret = read(fd, data + len, cache_data_size - len);
if (ret == -1)
goto fail;
}
/* Check the data for corruption */
if (crc32 != util_hash_crc32(data, cache_data_size))
goto fail;
free(filename);
close(fd);
if (size)
*size = sb.st_size;
*size = cache_data_size;
return data;