Commit 8140a500 authored by John McCutchan's avatar John McCutchan Committed by Linus Torvalds
Browse files

[PATCH] inotify: add two inotify_add_watch flags



The below patch lets userspace have more control over the inodes that
inotify will watch.  It introduces two new flags.

        IN_ONLYDIR -- only watch the inode if it is a directory.
        This is needed to avoid the race that can occur when we want to be
        sure that we are watching a directory.

        IN_DONT_FOLLOW -- don't follow a symlink.  In combination
        with IN_ONLYDIR we can make sure that we don't watch the target of
        symlinks.

The issues the flags fix came up when writing the gnome-vfs inotify
backend.  Default behaviour is unchanged.
Signed-off-by: default avatarJohn McCutchan <ttb@tentacle.dhs.org>
Acked-by: default avatarRobert Love <rml@novell.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent b4788f6d
......@@ -364,11 +364,12 @@ static int inotify_dev_get_wd(struct inotify_device *dev,
/*
* find_inode - resolve a user-given path to a specific inode and return a nd
*/
static int find_inode(const char __user *dirname, struct nameidata *nd)
static int find_inode(const char __user *dirname, struct nameidata *nd,
unsigned flags)
{
int error;
error = __user_walk(dirname, LOOKUP_FOLLOW, nd);
error = __user_walk(dirname, flags, nd);
if (error)
return error;
/* you can only watch an inode if you have read permissions on it */
......@@ -933,6 +934,7 @@ asmlinkage long sys_inotify_add_watch(int fd, const char __user *path, u32 mask)
struct file *filp;
int ret, fput_needed;
int mask_add = 0;
unsigned flags = 0;
filp = fget_light(fd, &fput_needed);
if (unlikely(!filp))
......@@ -944,7 +946,12 @@ asmlinkage long sys_inotify_add_watch(int fd, const char __user *path, u32 mask)
goto fput_and_out;
}
ret = find_inode(path, &nd);
if (!(mask & IN_DONT_FOLLOW))
flags |= LOOKUP_FOLLOW;
if (mask & IN_ONLYDIR)
flags |= LOOKUP_DIRECTORY;
ret = find_inode(path, &nd, flags);
if (unlikely(ret))
goto fput_and_out;
......
......@@ -47,6 +47,8 @@ struct inotify_event {
#define IN_MOVE (IN_MOVED_FROM | IN_MOVED_TO) /* moves */
/* special flags */
#define IN_ONLYDIR 0x01000000 /* only watch the path if it is a directory */
#define IN_DONT_FOLLOW 0x02000000 /* don't follow a sym link */
#define IN_MASK_ADD 0x20000000 /* add to the mask of an already existing watch */
#define IN_ISDIR 0x40000000 /* event occurred against dir */
#define IN_ONESHOT 0x80000000 /* only send event once */
......
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