[patch] Fix type errors in inotify interfaces

[Michael Kerrisk <mtk.manpages@googlemail.com>]

Andrew,

Vegard reminded me of an issue with the inotify interface
that I raised quite a while ago, offlist, with Robert; Robert
acknowledged that things should be fixed, but then neither of
us actually did anything :-{.

The problems lie in the types used for some inotify interfaces, both
at the kernel level and at the glibc level.  This mail addresses the
kernel problem.  I will follow up with some suggestions for glibc
changes.

For the sys_inotify_rm_watch() interface, the type of the 'wd' argument
is currently 'u32', it should be '__s32' .  That is Robert's suggestion,
and is consistent with the other declarations of watch descriptors in
the kernel source, in particular, the inotify_event structure in
include/linux/inotify.h:

struct inotify_event {
        __s32           wd;             /* watch descriptor */
        __u32           mask;           /* watch mask */
        __u32           cookie;         /* cookie to synchronize two events */
        __u32           len;            /* length (including nulls) of name */
        char            name[0];        /* stub for possible name */
};

The patch below makes the changes needed for inotify_rm_watch().

Thanks

Michael


diff --git a/fs/inotify_user.c b/fs/inotify_user.c
index d367e9b..a71f764 100644
--- a/fs/inotify_user.c
+++ b/fs/inotify_user.c
@@ -704,7 +704,7 @@ fput_and_out:
 	return ret;
 }
 
-asmlinkage long sys_inotify_rm_watch(int fd, u32 wd)
+asmlinkage long sys_inotify_rm_watch(int fd, __s32 wd)
 {
 	struct file *filp;
 	struct inotify_device *dev;
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index d6ff145..36983a5 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -550,7 +550,7 @@ asmlinkage long sys_inotify_init(void);
 asmlinkage long sys_inotify_init1(int flags);
 asmlinkage long sys_inotify_add_watch(int fd, const char __user *path,
 					u32 mask);
-asmlinkage long sys_inotify_rm_watch(int fd, u32 wd);
+asmlinkage long sys_inotify_rm_watch(int fd, __s32 wd);
 
 asmlinkage long sys_spu_run(int fd, __u32 __user *unpc,
 				 __u32 __user *ustatus);