From 4c82b9247b29f31814e7ee5f77c745db659e27ac Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Sat, 24 Oct 2015 13:17:54 +0200
Subject: [PATCH] journal: fix error handling when compressing journal objects

Let's make sure we handle compression errors properly, and don't
misunderstand an error for success.

Also, let's actually compress things if lz4 is enabled.

Fixes #1662.

Cherry-picked from: d1afbcd22170e95c79261340071d376fe41fc3af
Resolves: #1292447
---
 src/journal/journal-file.c | 12 +++++++-----
 src/journal/journal-file.h |  5 +++++
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
index f500568..a8f92e2 100644
--- a/src/journal/journal-file.c
+++ b/src/journal/journal-file.c
@@ -1051,23 +1051,25 @@ static int journal_file_append_data(
         o->data.hash = htole64(hash);
 
 #if defined(HAVE_XZ) || defined(HAVE_LZ4)
-        if (f->compress_xz &&
-            size >= COMPRESSION_SIZE_THRESHOLD) {
+        if (JOURNAL_FILE_COMPRESS(f) && size >= COMPRESSION_SIZE_THRESHOLD) {
                 size_t rsize;
 
                 compression = compress_blob(data, size, o->data.payload, &rsize);
 
-                if (compression) {
+                if (compression >= 0) {
                         o->object.size = htole64(offsetof(Object, data.payload) + rsize);
                         o->object.flags |= compression;
 
                         log_debug("Compressed data object %"PRIu64" -> %zu using %s",
                                   size, rsize, object_compressed_to_string(compression));
-                }
+                } else
+                        /* Compression didn't work, we don't really care why, let's continue without compression */
+                        compression = 0;
+
         }
 #endif
 
-        if (!compression && size > 0)
+        if (compression == 0 && size > 0)
                 memcpy(o->data.payload, data, size);
 
         r = journal_file_link_data(f, o, p, hash);
diff --git a/src/journal/journal-file.h b/src/journal/journal-file.h
index 403c8f7..0f29b09 100644
--- a/src/journal/journal-file.h
+++ b/src/journal/journal-file.h
@@ -229,3 +229,8 @@ int journal_file_get_cutoff_realtime_usec(JournalFile *f, usec_t *from, usec_t *
 int journal_file_get_cutoff_monotonic_usec(JournalFile *f, sd_id128_t boot, usec_t *from, usec_t *to);
 
 bool journal_file_rotate_suggested(JournalFile *f, usec_t max_file_usec);
+
+static inline bool JOURNAL_FILE_COMPRESS(JournalFile *f) {
+        assert(f);
+        return f->compress_xz || f->compress_lz4;
+}