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Subject[patch] F_GETPATH for linux
I was working on some bsd/linux compatibility code, and I noticed that we 
do not have F_GETPATH. I know we can readlink /proc/PID/fd/FD (that is
what I'm doing now, under #ifdef), but I gave a patch a shot anyway.
Here it is, building but untested ...



- Davide


---
fs/fcntl.c | 27 +++++++++++++++++++++++++++
fs/proc/base.c | 26 +-------------------------
include/asm-generic/fcntl.h | 1 +
include/linux/fs.h | 1 +
4 files changed, 30 insertions(+), 25 deletions(-)

Index: linux-2.6.mod/fs/fcntl.c
===================================================================
--- linux-2.6.mod.orig/fs/fcntl.c 2008-04-13 14:17:39.000000000 -0700
+++ linux-2.6.mod/fs/fcntl.c 2008-04-13 14:54:00.000000000 -0700
@@ -316,6 +316,29 @@
return pid;
}

+int fcntl_getpath(struct path *fpath, char __user *path, int maxsize)
+{
+ int size;
+ char *buf, *pathname;
+
+ buf = (char *) __get_free_page(GFP_TEMPORARY);
+ if (!buf)
+ return -ENOMEM;
+ pathname = d_path(fpath, buf, PAGE_SIZE);
+ size = PTR_ERR(pathname);
+ if (IS_ERR(pathname))
+ goto error;
+ size = buf + PAGE_SIZE - 1 - pathname;
+ if (size > maxsize)
+ size = maxsize;
+ if (copy_to_user(path, pathname, size))
+ size = -EFAULT;
+error:
+ free_page((unsigned long) buf);
+ return size;
+}
+EXPORT_SYMBOL(fcntl_getpath);
+
static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
struct file *filp)
{
@@ -381,6 +404,10 @@
case F_NOTIFY:
err = fcntl_dirnotify(fd, filp, arg);
break;
+ case F_GETPATH:
+ err = fcntl_getpath(&filp->f_path, (char __user *) arg,
+ PATH_MAX);
+ break;
default:
break;
}
Index: linux-2.6.mod/include/asm-generic/fcntl.h
===================================================================
--- linux-2.6.mod.orig/include/asm-generic/fcntl.h 2008-04-13 14:17:33.000000000 -0700
+++ linux-2.6.mod/include/asm-generic/fcntl.h 2008-04-13 14:18:17.000000000 -0700
@@ -73,6 +73,7 @@
#define F_SETSIG 10 /* for sockets. */
#define F_GETSIG 11 /* for sockets. */
#endif
+#define F_GETPATH 12

/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
Index: linux-2.6.mod/fs/proc/base.c
===================================================================
--- linux-2.6.mod.orig/fs/proc/base.c 2008-04-13 14:41:03.000000000 -0700
+++ linux-2.6.mod/fs/proc/base.c 2008-04-13 14:42:12.000000000 -0700
@@ -1192,30 +1192,6 @@
return ERR_PTR(error);
}

-static int do_proc_readlink(struct path *path, char __user *buffer, int buflen)
-{
- char *tmp = (char*)__get_free_page(GFP_TEMPORARY);
- char *pathname;
- int len;
-
- if (!tmp)
- return -ENOMEM;
-
- pathname = d_path(path, tmp, PAGE_SIZE);
- len = PTR_ERR(pathname);
- if (IS_ERR(pathname))
- goto out;
- len = tmp + PAGE_SIZE - 1 - pathname;
-
- if (len > buflen)
- len = buflen;
- if (copy_to_user(buffer, pathname, len))
- len = -EFAULT;
- out:
- free_page((unsigned long)tmp);
- return len;
-}
-
static int proc_pid_readlink(struct dentry * dentry, char __user * buffer, int buflen)
{
int error = -EACCES;
@@ -1230,7 +1206,7 @@
if (error)
goto out;

- error = do_proc_readlink(&path, buffer, buflen);
+ error = fcntl_getpath(&path, buffer, buflen);
path_put(&path);
out:
return error;
Index: linux-2.6.mod/include/linux/fs.h
===================================================================
--- linux-2.6.mod.orig/include/linux/fs.h 2008-04-13 14:40:01.000000000 -0700
+++ linux-2.6.mod/include/linux/fs.h 2008-04-13 14:40:34.000000000 -0700
@@ -960,6 +960,7 @@
/* only for net: no internal synchronization */
extern void __kill_fasync(struct fasync_struct *, int, int);

+extern int fcntl_getpath(struct path *fpath, char __user *path, int maxsize);
extern int __f_setown(struct file *filp, struct pid *, enum pid_type, int force);
extern int f_setown(struct file *filp, unsigned long arg, int force);
extern void f_delown(struct file *filp);

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