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authorJosh Steadmon <steadmon@google.com>2021-11-18 14:01:41 -0800
committerJunio C Hamano <gitster@pobox.com>2021-11-18 22:38:15 -0800
commit538ac746048fab0ed32b972e34eaabb9fb3f15b9 (patch)
tree6f179087022b1e51fa3d140510a4c7809948eea6 /trace2/tr2_dst.c
parent5fbd2fc5997dfa4d4593a862fe729b1e7a89bcf8 (diff)
downloadgit-538ac746048fab0ed32b972e34eaabb9fb3f15b9.tar.gz
trace2: disable tr2_dst before warning on write errors
If writing a trace2 message fails, we optionally warn the user of this fact. However, in 0ee10fd (usage: add trace2 entry upon warning(), 2020-11-23), we added a trace entry to the warning() function. This means that we can enter an infinite loop of failing trace2 writes and warnings. Fix this by disabling the failing trace2 destination before issuing the warning. Additionally, trace2 sets a default SIGPIPE handler (tr2main_signal_handler) when it is initialized. This handler generates its own trace2 messages when a signal is received. If a trace2 write fails due to a broken pipe, this handler will run and then cause another failed write. Fix this by temporarily ignoring SIGPIPE while writing trace2 messages. This is safe because the write will still fail, and we will disable the failing destination. Signed-off-by: Josh Steadmon <steadmon@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'trace2/tr2_dst.c')
-rw-r--r--trace2/tr2_dst.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/trace2/tr2_dst.c b/trace2/tr2_dst.c
index bda283e7f4..8a21dd2972 100644
--- a/trace2/tr2_dst.c
+++ b/trace2/tr2_dst.c
@@ -1,4 +1,5 @@
#include "cache.h"
+#include "sigchain.h"
#include "trace2/tr2_dst.h"
#include "trace2/tr2_sid.h"
#include "trace2/tr2_sysenv.h"
@@ -360,6 +361,7 @@ int tr2_dst_trace_want(struct tr2_dst *dst)
void tr2_dst_write_line(struct tr2_dst *dst, struct strbuf *buf_line)
{
int fd = tr2_dst_get_trace_fd(dst);
+ ssize_t bytes;
strbuf_complete_line(buf_line); /* ensure final NL on buffer */
@@ -378,12 +380,15 @@ void tr2_dst_write_line(struct tr2_dst *dst, struct strbuf *buf_line)
*
* If we get an IO error, just close the trace dst.
*/
- if (write(fd, buf_line->buf, buf_line->len) >= 0)
+ sigchain_push(SIGPIPE, SIG_IGN);
+ bytes = write(fd, buf_line->buf, buf_line->len);
+ sigchain_pop(SIGPIPE);
+ if (bytes >= 0)
return;
+ tr2_dst_trace_disable(dst);
if (tr2_dst_want_warning())
warning("unable to write trace to '%s': %s",
tr2_sysenv_display_name(dst->sysenv_var),
strerror(errno));
- tr2_dst_trace_disable(dst);
}