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Disable use of PID file when running in foreground 

When running in foreground, it is likely that it is running within
systemd. In this case, a stale PID file is likely to have a PID that
corresponds to a different process, which can still be kill'ed by the
root user. This results in a false positive that the process is still
running and causes the daemon to abort prematurely.

Fixes #42
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nirenjan 2022-05-16 10:28:58 -07:00
parent 6a8dff0a17
commit 8c8f261c80
1 changed files with 30 additions and 32 deletions
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62
daemon/x52d_main.c
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@ -105,26 +105,26 @@ static void start_daemon(bool foreground, const char *pid_file)
pid_file = X52D_PID_FILE; pid_file = X52D_PID_FILE;
} }
/* Check if there is an existing daemon process running */ if (!foreground) {
pid_fd = fopen(pid_file, "r"); /* Check if there is an existing daemon process running */
if (pid_fd != NULL) { pid_fd = fopen(pid_file, "r");
int rc; if (pid_fd != NULL) {
int rc;
/* File exists, read the PID and check if it exists */ /* File exists, read the PID and check if it exists */
rc = fscanf(pid_fd, "%u", &pid); rc = fscanf(pid_fd, "%u", &pid);
fclose(pid_fd); fclose(pid_fd);
if (rc != 1) { if (rc != 1) {
perror("fscanf"); perror("fscanf");
} else { } else {
rc = kill(pid, 0); rc = kill(pid, 0);
if (rc == 0 || (rc < 0 && errno == EPERM)) { if (rc == 0 || (rc < 0 && errno == EPERM)) {
PINELOG_FATAL(_("Daemon is already running as PID %u"), pid); PINELOG_FATAL(_("Daemon is already running as PID %u"), pid);
}
} }
} }
}
if (!foreground) {
/* Fork off the parent process */ /* Fork off the parent process */
pid = fork(); pid = fork();
if (pid < 0) { if (pid < 0) {
@ -163,25 +163,23 @@ static void start_daemon(bool foreground, const char *pid_file)
/* Terminate the parent */ /* Terminate the parent */
exit(EXIT_SUCCESS); exit(EXIT_SUCCESS);
} }
}
/* Write the PID to the pid_file */ /* Write the PID to the pid_file */
pid_fd = fopen(pid_file, "w"); pid_fd = fopen(pid_file, "w");
if (pid_fd == NULL) { if (pid_fd == NULL) {
/* Unable to open PID file */ /* Unable to open PID file */
perror("fopen"); perror("fopen");
exit(EXIT_FAILURE); exit(EXIT_FAILURE);
} }
if (fprintf(pid_fd, "%u\n", getpid()) < 0) { if (fprintf(pid_fd, "%u\n", getpid()) < 0) {
perror("fprintf"); perror("fprintf");
exit(EXIT_FAILURE); exit(EXIT_FAILURE);
} }
if (fclose(pid_fd) != 0) { if (fclose(pid_fd) != 0) {
perror("fclose"); perror("fclose");
exit(EXIT_FAILURE); exit(EXIT_FAILURE);
} }
if (!foreground) {
/* Set new file permissions */ /* Set new file permissions */
umask(0); umask(0);