journal: determine compression once, not twice

This is just paranoia: let's determine the compression to use once,
instead of twice, after all te data is in journal files which might be
corrupted any time, and it would be weird if we came to different
results here each time.

(cherry picked from commit b16cb30edd9b008f8d3dcacb6b6abe8009fa5315)

diff --git a/src/libsystemd/sd-journal/journal-file.c b/src/libsystemd/sd-journal/journal-file.c
index c67dbddaf764d35c3bfc352186c1cf5186d348af..d7dfd3049b2a8fb01ccf7f115f33e22d5d2e3d72 100644 (file)
--- a/src/libsystemd/sd-journal/journal-file.c
+++ b/src/libsystemd/sd-journal/journal-file.c
@@ -1802,17 +1802,27 @@ static int journal_file_append_field(
         return 0;
 }
 
-static int maybe_compress_payload(JournalFile *f, uint8_t *dst, const uint8_t *src, uint64_t size, size_t *rsize) {
+static int maybe_compress_payload(
+                JournalFile *f,
+                uint8_t *dst,
+                const uint8_t *src,
+                uint64_t size,
+                size_t *rsize,
+                Compression *ret_compression) {
+
         assert(f);
         assert(f->header);
+        assert(ret_compression);
 
 #if HAVE_COMPRESSION
         Compression c;
         int r;
 
         c = JOURNAL_FILE_COMPRESSION(f);
-        if (c == COMPRESSION_NONE || size < f->compress_threshold_bytes)
+        if (c == COMPRESSION_NONE || size < f->compress_threshold_bytes) {
+                *ret_compression = COMPRESSION_NONE;
                 return 0;
+        }
 
         r = compress_blob(c, src, size, dst, size - 1, rsize);
         if (r < 0)
@@ -1820,8 +1830,10 @@ static int maybe_compress_payload(JournalFile *f, uint8_t *dst, const uint8_t *s
 
         log_debug("Compressed data object %"PRIu64" -> %zu using %s", size, *rsize, compression_to_string(c));
 
+        *ret_compression = c;
         return 1; /* compressed */
 #else
+        *ret_compression = COMPRESSION_NONE;
         return 0;
 #endif
 }
@@ -1863,13 +1875,12 @@ static int journal_file_append_data(
 
         o->data.hash = htole64(hash);
 
-        r = maybe_compress_payload(f, journal_file_data_payload_field(f, o), data, size, &rsize);
+        Compression c;
+        r = maybe_compress_payload(f, journal_file_data_payload_field(f, o), data, size, &rsize, &c);
         if (r <= 0)
                 /* We don't really care failures, let's continue without compression */
                 memcpy_safe(journal_file_data_payload_field(f, o), data, size);
         else {
-                Compression c = JOURNAL_FILE_COMPRESSION(f);
-
                 assert(c >= 0 && c < _COMPRESSION_MAX && c != COMPRESSION_NONE);
 
                 o->object.size = htole64(journal_file_data_payload_offset(f) + rsize);