From 3beb6b44062811ce7c87c13331899b9f3be9e348 Mon Sep 17 00:00:00 2001 From: Michael Stapelberg Date: Sun, 19 May 2013 19:58:51 +0200 Subject: [PATCH] signal handler: set flag because directly calling fprintf() is unsafe --- i3status.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) diff --git a/i3status.c b/i3status.c index 5311ca9..c6973f7 100644 --- a/i3status.c +++ b/i3status.c @@ -45,19 +45,19 @@ /* socket file descriptor for general purposes */ int general_socket; +static bool exit_upon_signal = false; + cfg_t *cfg, *cfg_general, *cfg_section; /* - * Exit upon SIGPIPE because when we have nowhere to write to, gathering system - * information is pointless. Also exit explicitly on SIGTERM and SIGINT because - * only this will trigger a reset of the cursor in the terminal output-format. + * Set the exit_upon_signal flag, because one cannot do anything in a safe + * manner in a signal handler (e.g. fprintf, which we really want to do for + * debugging purposes), see + * https://www.securecoding.cert.org/confluence/display/seccode/SIG30-C.+Call+only+asynchronous-safe+functions+within+signal+handlers * */ void fatalsig(int signum) { - fprintf(stderr, "Received SIG%s, exiting\n", signum == SIGPIPE ? "PIPE" : - signum == SIGTERM ? "TERM" : - "INT"); - exit(1); + exit_upon_signal = true; } /* @@ -325,6 +325,11 @@ int main(int argc, char *argv[]) { struct sigaction action; memset(&action, 0, sizeof(struct sigaction)); action.sa_handler = fatalsig; + + /* Exit upon SIGPIPE because when we have nowhere to write to, gathering system + * information is pointless. Also exit explicitly on SIGTERM and SIGINT because + * only this will trigger a reset of the cursor in the terminal output-format. + */ sigaction(SIGPIPE, &action, NULL); sigaction(SIGTERM, &action, NULL); sigaction(SIGINT, &action, NULL); @@ -428,6 +433,10 @@ int main(int argc, char *argv[]) { char buffer[4096]; while (1) { + if (exit_upon_signal) { + fprintf(stderr, "Exiting due to signal.\n"); + exit(1); + } struct timeval tv; gettimeofday(&tv, NULL); if (output_format == O_I3BAR) -- 2.39.5