journal: add dst_allocated_size parameter for compress_blob

compress_blob took src, src_size, dst and *dst_size, but dst_size
wasn't used as an input parameter with the size of dst, but only as an
output parameter. dst was implicitly assumed to be at least src_size-1.

This code wasn't *wrong*, because the only real caller in
journal-file.c got it right. But it was misleading, and the tests in
test-compress.c got it wrong, and worked only because the output
buffer happened to be the same size as input buffer. So add a seperate
dst_allocated_size parameter to make it explicit what the size of the
buffer is, and to allow test to proceed with different output buffer
sizes.

5 files changed, 26 insertions, 20 deletions

diff --git a/src/journal/compress.c b/src/journal/compress.c
index a3de0882a5..e1ab4a46f5 100644
--- a/src/journal/compress.c
+++ b/src/journal/compress.c
@@ -58,7 +58,8 @@ static const char* const object_compressed_table[_OBJECT_COMPRESSED_MAX] = {
 
 DEFINE_STRING_TABLE_LOOKUP(object_compressed, int);
 
-int compress_blob_xz(const void *src, uint64_t src_size, void *dst, size_t *dst_size) {
+int compress_blob_xz(const void *src, uint64_t src_size,
+                     void *dst, size_t dst_alloc_size, size_t *dst_size) {
 #ifdef HAVE_XZ
         static const lzma_options_lzma opt = {
                 1u << 20u, NULL, 0, LZMA_LC_DEFAULT, LZMA_LP_DEFAULT,
@@ -74,6 +75,7 @@ int compress_blob_xz(const void *src, uint64_t src_size, void *dst, size_t *dst_
         assert(src);
         assert(src_size > 0);
         assert(dst);
+        assert(dst_alloc_size > 0);
         assert(dst_size);
 
         /* Returns < 0 if we couldn't compress the data or the
@@ -83,7 +85,7 @@ int compress_blob_xz(const void *src, uint64_t src_size, void *dst, size_t *dst_
                 return -ENOBUFS;
 
         ret = lzma_stream_buffer_encode((lzma_filter*) filters, LZMA_CHECK_NONE, NULL,
-                                        src, src_size, dst, &out_pos, src_size - 1);
+                                        src, src_size, dst, &out_pos, dst_alloc_size);
         if (ret != LZMA_OK)
                 return -ENOBUFS;
 
@@ -94,13 +96,15 @@ int compress_blob_xz(const void *src, uint64_t src_size, void *dst, size_t *dst_
 #endif
 }
 
-int compress_blob_lz4(const void *src, uint64_t src_size, void *dst, size_t *dst_size) {
+int compress_blob_lz4(const void *src, uint64_t src_size,
+                      void *dst, size_t dst_alloc_size, size_t *dst_size) {
 #ifdef HAVE_LZ4
         int r;
 
         assert(src);
         assert(src_size > 0);
         assert(dst);
+        assert(dst_alloc_size > 0);
         assert(dst_size);
 
         /* Returns < 0 if we couldn't compress the data or the
@@ -109,7 +113,7 @@ int compress_blob_lz4(const void *src, uint64_t src_size, void *dst, size_t *dst
         if (src_size < 9)
                 return -ENOBUFS;
 
-        r = LZ4_compress_limitedOutput(src, dst + 8, src_size, src_size - 8 - 1);
+        r = LZ4_compress_limitedOutput(src, dst + 8, src_size, (int) dst_alloc_size - 8);
         if (r <= 0)
                 return -ENOBUFS;
 
diff --git a/src/journal/compress.h b/src/journal/compress.h
index 9a065eb763..758598730a 100644
--- a/src/journal/compress.h
+++ b/src/journal/compress.h
@@ -28,17 +28,20 @@
 const char* object_compressed_to_string(int compression);
 int object_compressed_from_string(const char *compression);
 
-int compress_blob_xz(const void *src, uint64_t src_size, void *dst, size_t *dst_size);
-int compress_blob_lz4(const void *src, uint64_t src_size, void *dst, size_t *dst_size);
+int compress_blob_xz(const void *src, uint64_t src_size,
+                     void *dst, size_t dst_alloc_size, size_t *dst_size);
+int compress_blob_lz4(const void *src, uint64_t src_size,
+                      void *dst, size_t dst_alloc_size, size_t *dst_size);
 
-static inline int compress_blob(const void *src, uint64_t src_size, void *dst, size_t *dst_size) {
+static inline int compress_blob(const void *src, uint64_t src_size,
+                                void *dst, size_t dst_alloc_size, size_t *dst_size) {
         int r;
 #ifdef HAVE_LZ4
-        r = compress_blob_lz4(src, src_size, dst, dst_size);
+        r = compress_blob_lz4(src, src_size, dst, dst_alloc_size, dst_size);
         if (r == 0)
                 return OBJECT_COMPRESSED_LZ4;
 #else
-        r = compress_blob_xz(src, src_size, dst, dst_size);
+        r = compress_blob_xz(src, src_size, dst, dst_alloc_size, dst_size);
         if (r == 0)
                 return OBJECT_COMPRESSED_XZ;
 #endif
diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
index f9ff9545dd..751e1423fc 100644
--- a/src/journal/journal-file.c
+++ b/src/journal/journal-file.c
@@ -1085,7 +1085,7 @@ static int journal_file_append_data(
         if (JOURNAL_FILE_COMPRESS(f) && size >= COMPRESSION_SIZE_THRESHOLD) {
                 size_t rsize = 0;
 
-                compression = compress_blob(data, size, o->data.payload, &rsize);
+                compression = compress_blob(data, size, o->data.payload, size - 1, &rsize);
 
                 if (compression >= 0) {
                         o->object.size = htole64(offsetof(Object, data.payload) + rsize);
diff --git a/src/journal/test-compress-benchmark.c b/src/journal/test-compress-benchmark.c
index 93ea9c6318..baed0d82a4 100644
--- a/src/journal/test-compress-benchmark.c
+++ b/src/journal/test-compress-benchmark.c
@@ -27,7 +27,8 @@
 #include "string-util.h"
 #include "util.h"
 
-typedef int (compress_t)(const void *src, uint64_t src_size, void *dst, size_t *dst_size);
+typedef int (compress_t)(const void *src, uint64_t src_size, void *dst,
+                         size_t dst_alloc_size, size_t *dst_size);
 typedef int (decompress_t)(const void *src, uint64_t src_size,
                            void **dst, size_t *dst_alloc_size, size_t* dst_size, size_t dst_max);
 
@@ -111,8 +112,8 @@ static void test_compress_decompress(const char* label, const char* type,
 
                 memzero(buf, MIN(size + 1000, MAX_SIZE));
 
-                r = compress(text, size, buf, &j);
-                /* assume compression must be successful except for small inputs */
+                r = compress(text, size, buf, size, &j);
+                /* assume compression must be successful except for small or random inputs */
                 assert_se(r == 0 || (size < 2048 && r == -ENOBUFS) || streq(type, "random"));
 
                 /* check for overwrites */
diff --git a/src/journal/test-compress.c b/src/journal/test-compress.c
index b9d90a8988..62b5a508be 100644
--- a/src/journal/test-compress.c
+++ b/src/journal/test-compress.c
@@ -38,7 +38,7 @@
 #endif
 
 typedef int (compress_blob_t)(const void *src, uint64_t src_size,
-                              void *dst, size_t *dst_size);
+                              void *dst, size_t dst_alloc_size, size_t *dst_size);
 typedef int (decompress_blob_t)(const void *src, uint64_t src_size,
                                 void **dst, size_t *dst_alloc_size,
                                 size_t* dst_size, size_t dst_max);
@@ -57,15 +57,14 @@ static void test_compress_decompress(int compression,
                                      size_t data_len,
                                      bool may_fail) {
         char compressed[512];
-        size_t csize = 512;
-        size_t usize = 0;
+        size_t csize, usize = 0;
         _cleanup_free_ char *decompressed = NULL;
         int r;
 
         log_info("/* testing %s %s blob compression/decompression */",
                  object_compressed_to_string(compression), data);
 
-        r = compress(data, data_len, compressed, &csize);
+        r = compress(data, data_len, compressed, sizeof(compressed), &csize);
         if (r == -ENOBUFS) {
                 log_info_errno(r, "compression failed: %m");
                 assert_se(may_fail);
@@ -102,15 +101,14 @@ static void test_decompress_startswith(int compression,
                                        bool may_fail) {
 
         char compressed[512];
-        size_t csize = 512;
-        size_t usize = 0;
+        size_t csize, usize = 0;
         _cleanup_free_ char *decompressed = NULL;
         int r;
 
         log_info("/* testing decompress_startswith with %s on %s text*/",
                  object_compressed_to_string(compression), data);
 
-        r = compress(data, data_len, compressed, &csize);
+        r = compress(data, data_len, compressed, sizeof(compressed), &csize);
         if (r == -ENOBUFS) {
                 log_info_errno(r, "compression failed: %m");
                 assert_se(may_fail);