mdev : bug corrected (patch attached)

[Souf]

Le vendredi 01 juin 2007 à 15:57 +0200, Bernhard Fischer a écrit :
> On Fri, Jun 01, 2007 at 03:15:10PM +0200, Renaud Cerrato wrote:
> >Dear,
> >
> >Using mdev, we noticed that some devices were not attached to /dev/ using
> >"mdev -s".
> >Looking at the source code, the function which walk through the /sys/ tree
> >make use of lstat, but the /sys tree can use symlink as seen here :
> >
> >$ ls -l /sys/class/misc/
> >lrwxrwxrwx    1 root     root            0 Jan  1  1970 watchdog ->
> >../../devices/platform/at91sam9x_wdt/watchdog
> >
> >Doing so, the function can't walk through symbolic links. By replacing lstat
> >by stat, the problem is corrected.
> >To avoid infinite loop, we added a walking through depth limit to 2 (see
> >udevstart.c).
> >
> >Cheers
> 
> >diff -Nru busybox-1.4.1/util-linux/mdev.c busybox-1.4.1_modified/util-linux/mdev.c
> >--- busybox-1.4.1/util-linux/mdev.c	2007-01-24 22:34:51.000000000 +0100
> >+++ busybox-1.4.1_modified/util-linux/mdev.c	2007-06-01 14:47:07.013533464 +0200
> >@@ -14,6 +14,10 @@
> > 
> > #define DEV_PATH	"/dev"
> > 
> >+#define MAX_DEPTH	3
> >+
> >+static int depth;
> >+
> > struct mdev_globals
> > {
> > 	int root_major, root_minor;
> >@@ -195,18 +199,22 @@
> > }
> > 
> > /* Recursive search of /sys/block or /sys/class.  path must be a writeable
> >- * buffer of size PATH_MAX containing the directory string to start at. */
> >+ * buffer of size PATH_MAX containing the directory string to start at. 
> >+ * The recursive depth is limited to avoid inifinite loop (circular symlinks)
> >+ */
> > 
> > static void find_dev(char *path)
> > {
> > 	DIR *dir;
> > 	size_t len = strlen(path);
> > 	struct dirent *entry;
> >-
> >+		
> > 	dir = opendir(path);
> > 	if (dir == NULL)
> > 		return;
> > 
> >+	depth++;
> >+	
> > 	while ((entry = readdir(dir)) != NULL) {
> > 		struct stat st;
> 
> recursive_action() anyone?

I had already sent a large patch to improve mdev but it does not seem to
interest many people, in any case I resend it here, it uses:

xmalloc_getline()
last_char_is()
recursive_action()
bb_make_directory()
remove_file()
bb_get_last_path_component()
xmalloc_readlink_or_warn()
xmalloc_readlink_or_warn()

all that for only 5.9 KB

RFC:
http://busybox.net/lists/busybox/2007-May/027367.html
http://busybox.net/lists/busybox/2007-May/027515.html

Malek.


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