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authorwm4 <wm4@nowhere>2016-03-01 22:03:45 +0100
committerwm4 <wm4@nowhere>2016-03-01 22:03:45 +0100
commit4e53272376c546bac2e5c73f7ebfe456162d3663 (patch)
treeef4c240651e99bdd850ef3e027b39a9af24e95ed
parente0944991973c04701c830647a3f943b43d546b20 (diff)
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mpv-4e53272376c546bac2e5c73f7ebfe456162d3663.tar.xz
av_log: avoid partial lines
We want to add a prefix to the ffmpeg log message, so we called mp_msg multiple times until now. But logging such partial lines is a race condition, because there's only one internal mp_msg buffer, and no external mp_msg locks. Avoid this by building the message on a stack buffer. I might make a mp_log-local partial line buffer, but even then av_log() can be called from multiple threads, while targetting the same mp_log. (Really, ffmpeg's log API needs to be fixed.)
-rw-r--r--common/av_log.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/common/av_log.c b/common/av_log.c
index 7e0b271c81..bfd9a836e8 100644
--- a/common/av_log.c
+++ b/common/av_log.c
@@ -131,12 +131,17 @@ static void mp_msg_av_log_callback(void *ptr, int level, const char *fmt,
struct mp_log *log = get_av_log(ptr);
if (mp_msg_test(log, mp_level)) {
+ char buffer[4096] = "";
+ int pos = 0;
const char *prefix = avc ? avc->item_name(ptr) : NULL;
if (log_print_prefix && prefix)
- mp_msg(log, mp_level, "%s: ", prefix);
+ pos = snprintf(buffer, sizeof(buffer), "%s: ", prefix);
log_print_prefix = fmt[strlen(fmt) - 1] == '\n';
- mp_msg_va(log, mp_level, fmt, vl);
+ pos = MPMIN(MPMAX(pos, 0), sizeof(buffer));
+ vsnprintf(buffer + pos, sizeof(buffer) - pos, fmt, vl);
+
+ mp_msg(log, mp_level, "%s", buffer);
}
pthread_mutex_unlock(&log_lock);