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authorTakashi Iwai <tiwai@suse.de>2015-09-04 09:35:57 (GMT)
committerJunio C Hamano <gitster@pobox.com>2015-09-04 21:57:51 (GMT)
commit507d7804c0b094889cd20f23ad9a48e2b76791f3 (patch)
treeb84dec20adb88cbaaceade47df81dc30f90fd50a /run-command.h
parenta17c56c056d5fea0843b429132904c429a900229 (diff)
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pager: don't use unsafe functions in signal handlers
Since the commit a3da8821208d (pager: do wait_for_pager on signal death), we call wait_for_pager() in the pager's signal handler. The recent bug report revealed that this causes a deadlock in glibc at aborting "git log" [*1*]. When this happens, git process is left unterminated, and it can't be killed by SIGTERM but only by SIGKILL. The problem is that wait_for_pager() function does more than waiting for pager process's termination, but it does cleanups and printing errors. Unfortunately, the functions that may be used in a signal handler are very limited [*2*]. Particularly, malloc(), free() and the variants can't be used in a signal handler because they take a mutex internally in glibc. This was the cause of the deadlock above. Other than the direct calls of malloc/free, many functions calling malloc/free can't be used. strerror() is such one, either. Also the usage of fflush() and printf() in a signal handler is bad, although it seems working so far. In a safer side, we should avoid them, too. This patch tries to reduce the calls of such functions in signal handlers. wait_for_signal() takes a flag and avoids the unsafe calls. Also, finish_command_in_signal() is introduced for the same reason. There the free() calls are removed, and only waits for the children without whining at errors. [*1*] https://bugzilla.opensuse.org/show_bug.cgi?id=942297 [*2*] http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04_03 Signed-off-by: Takashi Iwai <tiwai@suse.de> Reviewed-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'run-command.h')
-rw-r--r--run-command.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/run-command.h b/run-command.h
index 1103805..518663e 100644
--- a/run-command.h
+++ b/run-command.h
@@ -50,6 +50,7 @@ void child_process_init(struct child_process *);
int start_command(struct child_process *);
int finish_command(struct child_process *);
+int finish_command_in_signal(struct child_process *);
int run_command(struct child_process *);
extern const char *find_hook(const char *name);