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Commit c04030e1 authored by Ulrich Drepper's avatar Ulrich Drepper Committed by Linus Torvalds
Browse files

[PATCH] flags parameter for linkat 



I'm currently at the POSIX meeting and one thing covered was the
incompatibility of Linux's link() with the POSIX definition.  The name.
Linux does not follow symlinks, POSIX requires it does.

Even if somebody thinks this is a good default behavior we cannot change this
because it would break the ABI.  But the fact remains that some application
might want this behavior.

We have one chance to help implementing this without breaking the behavior.
 For this we could use the new linkat interface which would need a new
flags parameter.  If the new parameter is AT_SYMLINK_FOLLOW the new
behavior could be invoked.

I do not want to introduce such a patch now.  But we could add the
parameter now, just don't use it.  The patch below would do this.  Can we
get this late patch applied before the release more or less fixes the
syscall API?

Signed-off-by: default avatarUlrich Drepper <drepper@redhat.com>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent ee713059

arch/mips/kernel/scall32-o32.S

+1 −1
Original line number Diff line number Diff line
@@ -626,7 +626,7 @@ einval: li v0, -EINVAL 
	sys	sys_fstatat64		4

	sys	sys_unlinkat		3

	sys	sys_renameat		4	/* 4295 */

	sys	sys_linkat		4

	sys	sys_linkat		5

	sys	sys_symlinkat		3

	sys	sys_readlinkat		4

	sys	sys_fchmodat		3

arch/s390/kernel/compat_wrapper.S

+1 −0
Original line number Diff line number Diff line
@@ -1552,6 +1552,7 @@ sys_linkat_wrapper: 
	llgtr	%r3,%r3			# const char *

	lgfr	%r4,%r4			# int

	llgtr	%r5,%r5			# const char *

	lgfr	%r6,%r6			# int

	jg	sys_linkat



	.globl sys_symlinkat_wrapper

fs/namei.c

+6 −2
Original line number Diff line number Diff line
@@ -2224,13 +2224,17 @@ int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_de 
 * and other special files.  --ADM

 */

asmlinkage long sys_linkat(int olddfd, const char __user *oldname,

			   int newdfd, const char __user *newname)

			   int newdfd, const char __user *newname,

			   int flags)

{

	struct dentry *new_dentry;

	struct nameidata nd, old_nd;

	int error;

	char * to;



	if (flags != 0)

		return -EINVAL;



	to = getname(newname);

	if (IS_ERR(to))

		return PTR_ERR(to);
@@ -2263,7 +2267,7 @@ asmlinkage long sys_linkat(int olddfd, const char __user *oldname, 


asmlinkage long sys_link(const char __user *oldname, const char __user *newname)

{

	return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname);

	return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);

}



/*

include/linux/syscalls.h

+1 −1
Original line number Diff line number Diff line
@@ -543,7 +543,7 @@ asmlinkage long sys_unlinkat(int dfd, const char __user * pathname, int flag); 
asmlinkage long sys_symlinkat(const char __user * oldname,

			      int newdfd, const char __user * newname);

asmlinkage long sys_linkat(int olddfd, const char __user *oldname,

			   int newdfd, const char __user *newname);

			   int newdfd, const char __user *newname, int flags);

asmlinkage long sys_renameat(int olddfd, const char __user * oldname,

			     int newdfd, const char __user * newname);

asmlinkage long sys_futimesat(int dfd, char __user *filename,