debuginfod: Use gmtime_r instead of gmtime to avoid data race
Commit Message
Since we are multi-threaded using gmtime might cause a data race
because gmtime reuses a global struct to write data into. Make
sure that each thread uses their own struct tm and use gmtime_r
instead.
Signed-off-by: Mark Wielaard <mark@klomp.org>
---
debuginfod/ChangeLog | 5 +++++
debuginfod/debuginfod.cxx | 15 +++++++++------
2 files changed, 14 insertions(+), 6 deletions(-)
Comments
Hi,
On Wed, 2021-12-01 at 08:26 -0500, Frank Ch. Eigler wrote:
> Since we are multi-threaded using gmtime might cause a data race
> > because gmtime reuses a global struct to write data into. Make
> > sure that each thread uses their own struct tm and use gmtime_r
> > instead.
>
> (thanks, lgtm)
Thanks, pushed.
Cheers,
Mark
@@ -1,3 +1,8 @@
+2021-12-01 Mark Wielaard <mark@klomp.org>
+
+ * debuginfod-client.c (timestamp): Use gmtime_r instead of gmtime.
+ (add_mhd_last_modified): Likewise.
+
2021-12-01 Mark Wielaard <mark@klomp.org>
* debuginfod-client.c (debuginfod_query_server): Free tmp_url on
@@ -855,10 +855,11 @@ timestamp (ostream &o)
char datebuf[80];
char *now2 = NULL;
time_t now_t = time(NULL);
- struct tm *now = gmtime (&now_t);
- if (now)
+ struct tm now;
+ struct tm *nowp = gmtime_r (&now_t, &now);
+ if (nowp)
{
- (void) strftime (datebuf, sizeof (datebuf), "%c", now);
+ (void) strftime (datebuf, sizeof (datebuf), "%c", nowp);
now2 = datebuf;
}
@@ -1076,11 +1077,13 @@ conninfo (struct MHD_Connection * conn)
static bool
add_mhd_last_modified (struct MHD_Response *resp, time_t mtime)
{
- struct tm *now = gmtime (&mtime);
- if (now != NULL)
+ struct tm now;
+ struct tm *nowp = gmtime_r (&mtime, &now);
+ if (nowp != NULL)
{
char datebuf[80];
- size_t rc = strftime (datebuf, sizeof (datebuf), "%a, %d %b %Y %T GMT", now);
+ size_t rc = strftime (datebuf, sizeof (datebuf), "%a, %d %b %Y %T GMT",
+ nowp);
if (rc > 0 && rc < sizeof (datebuf))
if (MHD_add_response_header (resp, "Last-Modified", datebuf) == MHD_NO)
return false;