lib/: get_pid(): Use the usual -1 as an error code

Signed-off-by: Alejandro Colomar <alx@kernel.org>

lib/commonio.c

@@ -195,7 +195,7 @@ static int do_lock_file (const char *file, const char *lock, bool log)
 		return 0;
 	}
 	buf[len] = '\0';
-	if (get_pid (buf, &pid) == 0) {
+	if (get_pid(buf, &pid) == -1) {
 		if (log) {
 			(void) fprintf (shadow_logfd,
 			                "%s: existing lock file %s with an invalid PID '%s'\n",

lib/get_pid.c

@@ -29,11 +29,11 @@ int get_pid (const char *pidstr, pid_t *pid)
 	    || (0 != errno)
 	    || (val < 1)
 	    || (/*@+longintegral@*/val != (pid_t)val)/*@=longintegral@*/) {
-		return 0;
+		return -1;
 	}
 
 	*pid = val;
-	return 1;
+	return 0;
 }
 
 /*
@@ -82,7 +82,7 @@ int open_pidfd(const char *pidstr)
 	char   proc_dir_name[32];
 	pid_t  target;
 
-	if (get_pid(pidstr, &target) == 0)
+	if (get_pid(pidstr, &target) == -1)
 		return -ENOENT;
 
 	/* max string length is 6 + 10 + 1 + 1 = 18, allocate 32 bytes */

lib/user_busy.c

@@ -202,7 +202,7 @@ static int user_busy_processes (const char *name, uid_t uid)
 		}
 
 		/* Check if this is a valid PID */
-		if (get_pid (tmp_d_name, &pid) == 0) {
+		if (get_pid(tmp_d_name, &pid) == -1) {
 			continue;
 		}
 
@@ -232,7 +232,7 @@ static int user_busy_processes (const char *name, uid_t uid)
 		if (task_dir != NULL) {
 			while ((ent = readdir (task_dir)) != NULL) {
 				pid_t tid;
-				if (get_pid (ent->d_name, &tid) == 0) {
+				if (get_pid(ent->d_name, &tid) == -1) {
 					continue;
 				}
 				if (tid == pid) {