Merge branch 'ti/glibc-stdio-mutex-from-signal-handler'
Allocation related functions and stdio are unsafe things to call
inside a signal handler, and indeed killing the pager can cause
glibc to deadlock waiting on allocation mutex as our signal handler
tries to free() some data structures in wait_for_pager(). Reduce
these unsafe calls.
* ti/glibc-stdio-mutex-from-signal-handler:
pager: don't use unsafe functions in signal handlers
diff --git a/pager.c b/pager.c
index 27d4c8a..e425070 100644
--- a/pager.c
+++ b/pager.c
@@ -14,19 +14,29 @@
static const char *pager_argv[] = { NULL, NULL };
static struct child_process pager_process = CHILD_PROCESS_INIT;
-static void wait_for_pager(void)
+static void wait_for_pager(int in_signal)
{
- fflush(stdout);
- fflush(stderr);
+ if (!in_signal) {
+ fflush(stdout);
+ fflush(stderr);
+ }
/* signal EOF to pager */
close(1);
close(2);
- finish_command(&pager_process);
+ if (in_signal)
+ finish_command_in_signal(&pager_process);
+ else
+ finish_command(&pager_process);
+}
+
+static void wait_for_pager_atexit(void)
+{
+ wait_for_pager(0);
}
static void wait_for_pager_signal(int signo)
{
- wait_for_pager();
+ wait_for_pager(1);
sigchain_pop(signo);
raise(signo);
}
@@ -90,7 +100,7 @@
/* this makes sure that the parent terminates after the pager */
sigchain_push_common(wait_for_pager_signal);
- atexit(wait_for_pager);
+ atexit(wait_for_pager_atexit);
}
int pager_in_use(void)
diff --git a/run-command.c b/run-command.c
index c8029f2..e17e456 100644
--- a/run-command.c
+++ b/run-command.c
@@ -18,26 +18,27 @@
static struct child_to_clean *children_to_clean;
static int installed_child_cleanup_handler;
-static void cleanup_children(int sig)
+static void cleanup_children(int sig, int in_signal)
{
while (children_to_clean) {
struct child_to_clean *p = children_to_clean;
children_to_clean = p->next;
kill(p->pid, sig);
- free(p);
+ if (!in_signal)
+ free(p);
}
}
static void cleanup_children_on_signal(int sig)
{
- cleanup_children(sig);
+ cleanup_children(sig, 1);
sigchain_pop(sig);
raise(sig);
}
static void cleanup_children_on_exit(void)
{
- cleanup_children(SIGTERM);
+ cleanup_children(SIGTERM, 0);
}
static void mark_child_for_cleanup(pid_t pid)
@@ -220,7 +221,7 @@
fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
}
-static int wait_or_whine(pid_t pid, const char *argv0)
+static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
{
int status, code = -1;
pid_t waiting;
@@ -228,6 +229,8 @@
while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
; /* nothing */
+ if (in_signal)
+ return 0;
if (waiting < 0) {
failed_errno = errno;
@@ -437,7 +440,7 @@
* At this point we know that fork() succeeded, but execvp()
* failed. Errors have been reported to our stderr.
*/
- wait_or_whine(cmd->pid, cmd->argv[0]);
+ wait_or_whine(cmd->pid, cmd->argv[0], 0);
failed_errno = errno;
cmd->pid = -1;
}
@@ -536,12 +539,18 @@
int finish_command(struct child_process *cmd)
{
- int ret = wait_or_whine(cmd->pid, cmd->argv[0]);
+ int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
argv_array_clear(&cmd->args);
argv_array_clear(&cmd->env_array);
return ret;
}
+int finish_command_in_signal(struct child_process *cmd)
+{
+ return wait_or_whine(cmd->pid, cmd->argv[0], 1);
+}
+
+
int run_command(struct child_process *cmd)
{
int code;
@@ -786,7 +795,7 @@
int finish_async(struct async *async)
{
#ifdef NO_PTHREADS
- return wait_or_whine(async->pid, "child process");
+ return wait_or_whine(async->pid, "child process", 0);
#else
void *ret = (void *)(intptr_t)(-1);
diff --git a/run-command.h b/run-command.h
index 629fab7..5428b04 100644
--- a/run-command.h
+++ b/run-command.h
@@ -50,6 +50,7 @@
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 *);
/*
