1 files changed, 68 insertions, 0 deletions
diff --git a/lib/pid_output.c b/lib/pid_output.c
new file mode 100644
index 0000000..064a7bb
--- /dev/null
+++ b/lib/pid_output.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Process id output.
+ * Copyright (C) 1998, 1999 Kunihiro Ishiguro
+ */
+
+#include <zebra.h>
+#include <fcntl.h>
+#include <log.h>
+#include "lib/version.h"
+#include "network.h"
+#include "lib_errors.h"
+
+#define PIDFILE_MASK 0644
+
+pid_t pid_output(const char *path)
+{
+	int tmp;
+	int fd;
+	pid_t pid;
+	char buf[16];
+	struct flock lock;
+	mode_t oldumask;
+
+	pid = getpid();
+
+	oldumask = umask(0777 & ~PIDFILE_MASK);
+	fd = open(path, O_RDWR | O_CREAT, PIDFILE_MASK);
+	if (fd < 0) {
+		flog_err_sys(EC_LIB_SYSTEM_CALL,
+			     "Can't create pid lock file %s (%s), exiting",
+			     path, safe_strerror(errno));
+		umask(oldumask);
+		exit(1);
+	} else {
+		size_t pidsize;
+
+		umask(oldumask);
+		memset(&lock, 0, sizeof(lock));
+
+		set_cloexec(fd);
+
+		lock.l_type = F_WRLCK;
+		lock.l_whence = SEEK_SET;
+
+		if (fcntl(fd, F_SETLK, &lock) < 0) {
+			flog_err_sys(EC_LIB_SYSTEM_CALL,
+				     "Could not lock pid_file %s (%s), exiting.  Please ensure that the daemon is not already running",
+				     path, safe_strerror(errno));
+			exit(1);
+		}
+
+		snprintf(buf, sizeof(buf), "%d\n", (int)pid);
+		pidsize = strlen(buf);
+		if ((tmp = write(fd, buf, pidsize)) != (int)pidsize)
+			flog_err_sys(
+				EC_LIB_SYSTEM_CALL,
+				"Could not write pid %d to pid_file %s, rc was %d: %s",
+				(int)pid, path, tmp, safe_strerror(errno));
+		else if (ftruncate(fd, pidsize) < 0)
+			flog_err_sys(
+				EC_LIB_SYSTEM_CALL,
+				"Could not truncate pid_file %s to %u bytes: %s",
+				path, (unsigned int)pidsize,
+				safe_strerror(errno));
+	}
+	return pid;
+}