cmd-timer

commit: c93bd81010be5bde922ad54271f53d04549b6ec1
parent 378169e980db0bf73bd4e258c686622150be6383
Author: Haelwenn (lanodan) Monnier <contact@hacktivis.me>
Date:   Wed, 18 Jun 2025 16:07:01 +0200

exits when child process returns non-zero

Diffstat:
M
timer.c
63
++++++++++++++++++++++++++++++++++++++++++++++-----------------

1 file changed, 46 insertions(+), 17 deletions(-)
diff --git a/timer.c b/timer.c
@@ -5,14 +5,15 @@
 #include "strtodur.h"
 
 #include <errno.h>
-#include <limits.h> // UINT_MAX
-#include <signal.h> // sigaction
-#include <spawn.h>  // posix_spawnp
-#include <stdio.h>  // fprintf, fputs
-#include <stdlib.h> // exit
-#include <string.h> // strerror
-#include <time.h>   // timer_create
-#include <unistd.h> // sleep
+#include <limits.h>   // UINT_MAX
+#include <signal.h>   // sigaction
+#include <spawn.h>    // posix_spawnp
+#include <stdio.h>    // fprintf, fputs
+#include <stdlib.h>   // exit
+#include <string.h>   // strerror
+#include <sys/wait.h> // waitpid
+#include <time.h>     // timer_create
+#include <unistd.h>   // sleep
 
 extern char **environ;
 static char **args;
@@ -33,6 +34,17 @@ sig_timer(int sig)
 }
 
 static void
+sig_chld(int sig)
+{
+	int chld_stat = 0;
+	waitpid((pid_t)-1, &chld_stat, WNOHANG);
+
+	if(!WIFEXITED(chld_stat)) return;
+
+	if(WEXITSTATUS(chld_stat) != 0) exit(WEXITSTATUS(chld_stat));
+}
+
+static void
 bad_usage()
 {
 	fputs("Usage: timer <interval> <command> [arguments...]\n", stderr);
@@ -67,21 +79,25 @@ main(int argc, char *argv[])
 	argc--;
 	argv++;
 
-	struct sigaction sa;
-	sa.sa_handler = &sig_timer;
-	sigemptyset(&sa.sa_mask);
-	sa.sa_flags = SA_RESTART;
+	struct sigaction sa_alrm;
+	sa_alrm.sa_handler = &sig_timer;
+	sigemptyset(&sa_alrm.sa_mask);
+	sa_alrm.sa_flags = SA_RESTART;
 
-	if(sigaction(SIGALRM, &sa, NULL) != 0)
+	if(sigaction(SIGALRM, &sa_alrm, NULL) != 0)
 	{
 		fprintf(stderr, "timer: error: Failed registering signal handler: %s\n", strerror(errno));
 		return 1;
 	}
 
-	errno = 0;
-	if(signal(SIGCHLD, SIG_IGN) == SIG_ERR)
+	struct sigaction sa_chld;
+	sa_chld.sa_handler = &sig_chld;
+	sigemptyset(&sa_chld.sa_mask);
+	sa_chld.sa_flags = SA_RESTART;
+
+	if(sigaction(SIGCHLD, &sa_chld, NULL) != 0)
 	{
-		fprintf(stderr, "timer: error: Failed setting to ignore SIGCHLD: %s\n", strerror(errno));
+		fprintf(stderr, "timer: error: Failed registering signal handler: %s\n", strerror(errno));
 		return 1;
 	}
 
@@ -109,7 +125,20 @@ main(int argc, char *argv[])
 
 	args = argv;
 
-	while(sigsuspend(&sa.sa_mask))
+	sigset_t sigmask;
+	sigfillset(&sigmask);
+	if(sigdelset(&sigmask, SIGALRM) != 0)
+	{
+		fprintf(stderr, "timer: error: Failed adding SIGALARM to new sigmask: %s\n", strerror(errno));
+		return 1;
+	}
+	if(sigdelset(&sigmask, SIGCHLD) != 0)
+	{
+		fprintf(stderr, "timer: error: Failed adding SIGCHLD to new sigmask: %s\n", strerror(errno));
+		return 1;
+	}
+
+	while(sigsuspend(&sigmask))
 		;
 
 	return 0;