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journal/compress: remove loop in decompress_startswith_zstd()

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This should be more efficient with no downsides. Same considerations as in the
previous commit hold.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2020-07-19 10:18:46 +02:00
parent a24153279e
commit e4a321fc08
2 changed files with 19 additions and 26 deletions
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43
src/journal/compress.c
View File

@ -458,9 +458,6 @@ int decompress_startswith_zstd(
const void *prefix, size_t prefix_len,
uint8_t extra) {
#if HAVE_ZSTD
_cleanup_(ZSTD_freeDCtxp) ZSTD_DCtx *dctx = NULL;
size_t k;
assert(src);
assert(src_size > 0);
assert(buffer);
@ -468,7 +465,14 @@ int decompress_startswith_zstd(
assert(prefix);
assert(*buffer_size == 0 || *buffer);
dctx = ZSTD_createDCtx();
uint64_t size = ZSTD_getFrameContentSize(src, src_size);
if (IN_SET(size, ZSTD_CONTENTSIZE_ERROR, ZSTD_CONTENTSIZE_UNKNOWN))
return -EBADMSG;
if (size < prefix_len + 1)
return 0; /* Decompressed text too short to match the prefix and extra */
_cleanup_(ZSTD_freeDCtxp) ZSTD_DCtx *dctx = ZSTD_createDCtx();
if (!dctx)
return -ENOMEM;
@ -483,30 +487,17 @@ int decompress_startswith_zstd(
.dst = *buffer,
.size = *buffer_size,
};
size_t k;
for (;;) {
k = ZSTD_decompressStream(dctx, &output, &input);
if (ZSTD_isError(k)) {
log_debug("ZSTD decoder failed: %s", ZSTD_getErrorName(k));
return zstd_ret_to_errno(k);
}
if (output.pos >= prefix_len + 1)
return memcmp(*buffer, prefix, prefix_len) == 0 &&
((const uint8_t*) *buffer)[prefix_len] == extra;
if (input.pos >= input.size)
return 0;
if (*buffer_size > SIZE_MAX/2)
return -ENOBUFS;
if (!(greedy_realloc(buffer, buffer_size, *buffer_size * 2, 1)))
return -ENOMEM;
output.dst = *buffer;
output.size = *buffer_size;
k = ZSTD_decompressStream(dctx, &output, &input);
if (ZSTD_isError(k)) {
log_debug("ZSTD decoder failed: %s", ZSTD_getErrorName(k));
return zstd_ret_to_errno(k);
}
assert(output.pos >= prefix_len + 1);
return memcmp(*buffer, prefix, prefix_len) == 0 &&
((const uint8_t*) *buffer)[prefix_len] == extra;
#else
return -EPROTONOSUPPORT;
#endif

2
src/journal/test-compress.c
View File

@ -232,6 +232,8 @@ static void test_lz4_decompress_partial(void) {
int r;
_cleanup_free_ char *huge = NULL;
log_debug("/* %s */", __func__);
assert_se(huge = malloc(HUGE_SIZE));
memcpy(huge, "HUGE=", STRLEN("HUGE="));
memset(&huge[STRLEN("HUGE=")], 'x', HUGE_SIZE - STRLEN("HUGE=") - 1);