e41ef6fd00
With lz4 1.8.3, this function can now decompress partial results into a smaller buffer. The release news don't say anything interesting, but the test case that was previously failing now works OK. Fixes #10259. A test is added. It shows that with *older* lz4, a partial decompression can occur with the returned size smaller then the requested number of bytes _and_ smaller then the size of the compressed data: (lz4-libs-1.8.2-1.fc29.x86_64) Compressed 4194304 → 16464 Decompressed → 4194304 Decompressed partial 12/4194304 → 4194304 Decompressed partial 1/1 → -2 (bad) Decompressed partial 2/2 → -2 (bad) Decompressed partial 3/3 → -2 (bad) Decompressed partial 4/4 → -2 (bad) Decompressed partial 5/5 → -2 (bad) Decompressed partial 6/6 → 6 (good) Decompressed partial 7/7 → 6 (good) Decompressed partial 8/8 → 6 (good) Decompressed partial 9/9 → 6 (good) Decompressed partial 10/10 → 6 (good) Decompressed partial 11/11 → 6 (good) Decompressed partial 12/12 → 6 (good) Decompressed partial 13/13 → 6 (good) Decompressed partial 14/14 → 6 (good) Decompressed partial 15/15 → 6 (good) Decompressed partial 16/16 → 6 (good) Decompressed partial 17/17 → 6 (good) Decompressed partial 18/18 → -16459 (bad) (lz4-libs-1.8.3-1.fc29.x86_64) Compressed 4194304 → 16464 Decompressed → 4194304 Decompressed partial 12/4194304 → 12 Decompressed partial 1/1 → 1 (good) Decompressed partial 2/2 → 2 (good) Decompressed partial 3/3 → 3 (good) Decompressed partial 4/4 → 4 (good) ... If we got such a short "successful" decompression in decompress_startswith() as implemented before this patch, we could be confused and return a false negative result. But it turns out that this only occurs with small output buffer sizes. We use greedy_realloc() to manager the buffer, so it is always at least 64 bytes. I couldn't hit a case where decompress_startswith() would actually return a bogus result. But since the lack of proof is not conclusive, the code for *older* lz4 is changed too, just to be safe. We cannot rule out that on a different architecture or with some unlucky compressed string we could hit this corner case. The fallback code is guarded by a version check. The check uses a function not the compile-time define, because there was no soversion bump in lz4 or new symbols, and we could be compiled against a newer lz4 and linked at runtime with an older one. (This happens routinely e.g. when somebody upgrades a subset of distro packages.)
342 lines
13 KiB
C
342 lines
13 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#if HAVE_LZ4
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#include <lz4.h>
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#endif
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#include "alloc-util.h"
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#include "compress.h"
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#include "fd-util.h"
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#include "fileio.h"
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#include "fs-util.h"
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#include "macro.h"
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#include "path-util.h"
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#include "random-util.h"
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#include "tests.h"
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#include "util.h"
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#if HAVE_XZ
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# define XZ_OK 0
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#else
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# define XZ_OK -EPROTONOSUPPORT
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#endif
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#if HAVE_LZ4
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# define LZ4_OK 0
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#else
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# define LZ4_OK -EPROTONOSUPPORT
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#endif
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typedef int (compress_blob_t)(const void *src, uint64_t src_size,
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void *dst, size_t dst_alloc_size, size_t *dst_size);
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typedef int (decompress_blob_t)(const void *src, uint64_t src_size,
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void **dst, size_t *dst_alloc_size,
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size_t* dst_size, size_t dst_max);
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typedef int (decompress_sw_t)(const void *src, uint64_t src_size,
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void **buffer, size_t *buffer_size,
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const void *prefix, size_t prefix_len,
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uint8_t extra);
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typedef int (compress_stream_t)(int fdf, int fdt, uint64_t max_bytes);
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typedef int (decompress_stream_t)(int fdf, int fdt, uint64_t max_size);
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#if HAVE_XZ || HAVE_LZ4
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static void test_compress_decompress(int compression,
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compress_blob_t compress,
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decompress_blob_t decompress,
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const char *data,
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size_t data_len,
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bool may_fail) {
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char compressed[512];
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size_t csize, usize = 0;
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_cleanup_free_ char *decompressed = NULL;
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int r;
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log_info("/* testing %s %s blob compression/decompression */",
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object_compressed_to_string(compression), data);
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r = compress(data, data_len, compressed, sizeof(compressed), &csize);
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if (r == -ENOBUFS) {
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log_info_errno(r, "compression failed: %m");
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assert_se(may_fail);
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} else {
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assert_se(r == 0);
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r = decompress(compressed, csize,
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(void **) &decompressed, &usize, &csize, 0);
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assert_se(r == 0);
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assert_se(decompressed);
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assert_se(memcmp(decompressed, data, data_len) == 0);
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}
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r = decompress("garbage", 7,
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(void **) &decompressed, &usize, &csize, 0);
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assert_se(r < 0);
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/* make sure to have the minimal lz4 compressed size */
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r = decompress("00000000\1g", 9,
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(void **) &decompressed, &usize, &csize, 0);
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assert_se(r < 0);
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r = decompress("\100000000g", 9,
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(void **) &decompressed, &usize, &csize, 0);
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assert_se(r < 0);
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memzero(decompressed, usize);
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}
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static void test_decompress_startswith(int compression,
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compress_blob_t compress,
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decompress_sw_t decompress_sw,
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const char *data,
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size_t data_len,
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bool may_fail) {
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char *compressed;
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_cleanup_free_ char *compressed1 = NULL, *compressed2 = NULL, *decompressed = NULL;
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size_t csize, usize = 0, len;
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int r;
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log_info("/* testing decompress_startswith with %s on %.20s text */",
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object_compressed_to_string(compression), data);
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#define BUFSIZE_1 512
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#define BUFSIZE_2 20000
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compressed = compressed1 = malloc(BUFSIZE_1);
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assert_se(compressed1);
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r = compress(data, data_len, compressed, BUFSIZE_1, &csize);
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if (r == -ENOBUFS) {
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log_info_errno(r, "compression failed: %m");
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assert_se(may_fail);
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compressed = compressed2 = malloc(BUFSIZE_2);
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assert_se(compressed2);
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r = compress(data, data_len, compressed, BUFSIZE_2, &csize);
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assert(r == 0);
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}
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assert_se(r == 0);
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len = strlen(data);
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r = decompress_sw(compressed, csize, (void **) &decompressed, &usize, data, len, '\0');
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assert_se(r > 0);
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r = decompress_sw(compressed, csize, (void **) &decompressed, &usize, data, len, 'w');
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assert_se(r == 0);
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r = decompress_sw(compressed, csize, (void **) &decompressed, &usize, "barbarbar", 9, ' ');
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assert_se(r == 0);
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r = decompress_sw(compressed, csize, (void **) &decompressed, &usize, data, len - 1, data[len-1]);
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assert_se(r > 0);
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r = decompress_sw(compressed, csize, (void **) &decompressed, &usize, data, len - 1, 'w');
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assert_se(r == 0);
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r = decompress_sw(compressed, csize, (void **) &decompressed, &usize, data, len, '\0');
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assert_se(r > 0);
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}
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static void test_decompress_startswith_short(int compression,
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compress_blob_t compress,
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decompress_sw_t decompress_sw) {
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#define TEXT "HUGE=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
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char buf[1024];
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size_t i, csize;
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int r;
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log_info("/* %s with %s */", __func__, object_compressed_to_string(compression));
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r = compress(TEXT, sizeof TEXT, buf, sizeof buf, &csize);
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assert_se(r == 0);
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for (i = 1; i < strlen(TEXT); i++) {
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size_t alloc_size = i;
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_cleanup_free_ void *buf2 = NULL;
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assert_se(buf2 = malloc(i));
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assert_se(decompress_sw(buf, csize, &buf2, &alloc_size, TEXT, i, TEXT[i]) == 1);
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assert_se(decompress_sw(buf, csize, &buf2, &alloc_size, TEXT, i, 'y') == 0);
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}
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}
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static void test_compress_stream(int compression,
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const char* cat,
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compress_stream_t compress,
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decompress_stream_t decompress,
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const char *srcfile) {
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_cleanup_close_ int src = -1, dst = -1, dst2 = -1;
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_cleanup_(unlink_tempfilep) char
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pattern[] = "/tmp/systemd-test.compressed.XXXXXX",
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pattern2[] = "/tmp/systemd-test.compressed.XXXXXX";
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int r;
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_cleanup_free_ char *cmd = NULL, *cmd2 = NULL;
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struct stat st = {};
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r = find_binary(cat, NULL);
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if (r < 0) {
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log_error_errno(r, "Skipping %s, could not find %s binary: %m", __func__, cat);
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return;
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}
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log_debug("/* testing %s compression */",
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object_compressed_to_string(compression));
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log_debug("/* create source from %s */", srcfile);
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assert_se((src = open(srcfile, O_RDONLY|O_CLOEXEC)) >= 0);
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log_debug("/* test compression */");
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assert_se((dst = mkostemp_safe(pattern)) >= 0);
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assert_se(compress(src, dst, -1) == 0);
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if (cat) {
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assert_se(asprintf(&cmd, "%s %s | diff %s -", cat, pattern, srcfile) > 0);
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assert_se(system(cmd) == 0);
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}
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log_debug("/* test decompression */");
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assert_se((dst2 = mkostemp_safe(pattern2)) >= 0);
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assert_se(stat(srcfile, &st) == 0);
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assert_se(lseek(dst, 0, SEEK_SET) == 0);
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r = decompress(dst, dst2, st.st_size);
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assert_se(r == 0);
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assert_se(asprintf(&cmd2, "diff %s %s", srcfile, pattern2) > 0);
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assert_se(system(cmd2) == 0);
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log_debug("/* test faulty decompression */");
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assert_se(lseek(dst, 1, SEEK_SET) == 1);
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r = decompress(dst, dst2, st.st_size);
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assert_se(IN_SET(r, 0, -EBADMSG));
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assert_se(lseek(dst, 0, SEEK_SET) == 0);
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assert_se(lseek(dst2, 0, SEEK_SET) == 0);
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r = decompress(dst, dst2, st.st_size - 1);
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assert_se(r == -EFBIG);
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}
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#endif
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#if HAVE_LZ4
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static void test_lz4_decompress_partial(void) {
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char buf[20000], buf2[100];
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size_t buf_size = sizeof(buf), compressed;
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int r;
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_cleanup_free_ char *huge = NULL;
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#define HUGE_SIZE (4096*1024)
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assert_se(huge = malloc(HUGE_SIZE));
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memset(huge, 'x', HUGE_SIZE);
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memcpy(huge, "HUGE=", 5);
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r = LZ4_compress_default(huge, buf, HUGE_SIZE, buf_size);
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assert_se(r >= 0);
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compressed = r;
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log_info("Compressed %i → %zu", HUGE_SIZE, compressed);
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r = LZ4_decompress_safe(buf, huge, r, HUGE_SIZE);
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assert_se(r >= 0);
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log_info("Decompressed → %i", r);
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r = LZ4_decompress_safe_partial(buf, huge,
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compressed,
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12, HUGE_SIZE);
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assert_se(r >= 0);
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log_info("Decompressed partial %i/%i → %i", 12, HUGE_SIZE, r);
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for (size_t size = 1; size < sizeof(buf2); size++) {
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/* This failed in older lz4s but works in newer ones. */
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r = LZ4_decompress_safe_partial(buf, buf2, compressed, size, size);
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log_info("Decompressed partial %zu/%zu → %i (%s)", size, size, r,
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r < 0 ? "bad" : "good");
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if (r >= 0 && LZ4_versionNumber() >= 10803)
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/* lz4 <= 1.8.2 should fail that test, let's only check for newer ones */
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assert_se(memcmp(buf2, huge, r) == 0);
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}
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}
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#endif
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int main(int argc, char *argv[]) {
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#if HAVE_XZ || HAVE_LZ4
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const char text[] =
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"text\0foofoofoofoo AAAA aaaaaaaaa ghost busters barbarbar FFF"
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"foofoofoofoo AAAA aaaaaaaaa ghost busters barbarbar FFF";
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/* The file to test compression on can be specified as the first argument */
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const char *srcfile = argc > 1 ? argv[1] : argv[0];
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char data[512] = "random\0";
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char huge[4096*1024];
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memset(huge, 'x', sizeof(huge));
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memcpy(huge, "HUGE=", 5);
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char_array_0(huge);
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test_setup_logging(LOG_DEBUG);
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random_bytes(data + 7, sizeof(data) - 7);
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#if HAVE_XZ
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test_compress_decompress(OBJECT_COMPRESSED_XZ, compress_blob_xz, decompress_blob_xz,
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text, sizeof(text), false);
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test_compress_decompress(OBJECT_COMPRESSED_XZ, compress_blob_xz, decompress_blob_xz,
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data, sizeof(data), true);
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test_decompress_startswith(OBJECT_COMPRESSED_XZ,
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compress_blob_xz, decompress_startswith_xz,
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text, sizeof(text), false);
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test_decompress_startswith(OBJECT_COMPRESSED_XZ,
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compress_blob_xz, decompress_startswith_xz,
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data, sizeof(data), true);
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test_decompress_startswith(OBJECT_COMPRESSED_XZ,
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compress_blob_xz, decompress_startswith_xz,
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huge, sizeof(huge), true);
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test_compress_stream(OBJECT_COMPRESSED_XZ, "xzcat",
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compress_stream_xz, decompress_stream_xz, srcfile);
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test_decompress_startswith_short(OBJECT_COMPRESSED_XZ, compress_blob_xz, decompress_startswith_xz);
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#else
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log_info("/* XZ test skipped */");
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#endif
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#if HAVE_LZ4
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test_compress_decompress(OBJECT_COMPRESSED_LZ4, compress_blob_lz4, decompress_blob_lz4,
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text, sizeof(text), false);
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test_compress_decompress(OBJECT_COMPRESSED_LZ4, compress_blob_lz4, decompress_blob_lz4,
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data, sizeof(data), true);
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test_decompress_startswith(OBJECT_COMPRESSED_LZ4,
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compress_blob_lz4, decompress_startswith_lz4,
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text, sizeof(text), false);
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test_decompress_startswith(OBJECT_COMPRESSED_LZ4,
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compress_blob_lz4, decompress_startswith_lz4,
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data, sizeof(data), true);
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test_decompress_startswith(OBJECT_COMPRESSED_LZ4,
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compress_blob_lz4, decompress_startswith_lz4,
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huge, sizeof(huge), true);
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test_compress_stream(OBJECT_COMPRESSED_LZ4, "lz4cat",
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compress_stream_lz4, decompress_stream_lz4, srcfile);
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test_lz4_decompress_partial();
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test_decompress_startswith_short(OBJECT_COMPRESSED_LZ4, compress_blob_lz4, decompress_startswith_lz4);
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#else
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log_info("/* LZ4 test skipped */");
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#endif
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return 0;
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#else
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log_info("/* XZ and LZ4 tests skipped */");
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return EXIT_TEST_SKIP;
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#endif
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}
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