New function pid_file_read(), returns PID from a pid file

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

src/pid.c

@@ -109,6 +109,25 @@ char *pid_file(svc_t *svc)
 	return pid_runpath(fn, path, sizeof(path));
 }
 
+pid_t pid_file_read(const char *fn)
+{
+	pid_t pid = 0;
+	FILE *fp;
+	char buf[42];
+
+	fp = fopen(fn, "r");
+	if (!fp)
+		return -1;
+
+	if (fgets(buf, sizeof(buf), fp)) {
+		chomp(buf);
+		pid = atoi(buf);
+	}
+	fclose(fp);
+
+	return pid;
+}
+
 int pid_file_create(svc_t *svc)
 {
 	FILE *fp;

src/pid.h

@@ -31,6 +31,7 @@ int   pid_alive       (pid_t pid);
 char *pid_get_name    (pid_t pid, char *name, size_t len);
 
 char *pid_file        (svc_t *svc);
+pid_t pid_file_read   (const char *fn);
 int   pid_file_create (svc_t *svc);
 int   pid_file_parse  (svc_t *svc, char *arg);