inittab: use more robust dev_exist() implementation

Rework the dev_exist() function to use openat() in order to resolve the device
file relative to the "/dev" directory. Drop the now unused dev_open() function.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

diff --git a/inittab.c b/inittab.c
index 622601ab3e316bebe421a53f7b3fd942bf1eb21d..528396e57534553309cdf482b87ba837772984a1 100644 (file)
--- a/inittab.c
+++ b/inittab.c
@@ -65,30 +65,23 @@ static char *ask = "/sbin/askfirst";
 
 static LIST_HEAD(actions);
 
-static int dev_open(const char *dev)
+static int dev_exist(const char *dev)
 {
-       int fd = -1;
-
-       if (dev) {
-               if (chdir("/dev"))
-                       ERROR("failed to change dir to /dev\n");
-               fd = open(dev, O_RDWR);
-               if (chdir("/"))
-                       ERROR("failed to change dir to /\n");
-       }
+       int dfd, fd;
 
-       return fd;
-}
+       dfd = open("/dev", O_PATH|O_DIRECTORY);
 
-static int dev_exist(const char *dev)
-{
-       int res;
+       if (dfd < 0)
+               return 0;
+
+       fd = openat(dfd, dev, O_RDONLY);
+       close(dfd);
 
-       res = dev_open(dev);
-       if (res != -1)
-               close(res);
+       if (fd < 0)
+               return 0;
 
-       return (res != -1);
+       close(fd);
+       return 1;
 }
 
 static void fork_worker(struct init_action *a)