[PATCH 00/18 v3] fs: add symlink and readlink support

[PATCH 00/18 v3] fs: add symlink and readlink support

[Jean-Christophe PLAGNIOL-VILLARD]

HI,

	v4:
	 drop the mounted path added to absolute symlink

	v3:
	 - fix support
	   mkdir mymount
	   mount -t ramfs none mymount/
	   ln /env/boot/net /mymount/link

	 - addres comments

	v2:
	 addres comments

please pull
The following changes since commit b77300ac6c6bbbc7eac774ff0076c7c05d39735f:

  command/mount: add autodetection support (2012-08-21 18:53:00 +0800)

are available in the git repository at:

  git://git.jcrosoft.org/barebox.git tags/fs-symlink

for you to fetch changes up to 9919df3e6c53db0edca9f0a9297b7a9e335575de:

  defautenv: add support of symlink (2012-09-03 22:46:05 +0800)

----------------------------------------------------------------
fs: add symlink and readlink support

This patch series introduce the support of symlink and readlink at

1) vfs level

2) libc API
 - symlink
 - readlink

3) commands
 - ln
 - readlink

3) filesystem
 - ramfs
 - nfs
 - envfs

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

----------------------------------------------------------------
Jean-Christophe PLAGNIOL-VILLARD (18):
      fs: add readlink support
      fs: rename stat to lstat as we implement lstat
      fs: add symlink support
      fs: implement stat
      fs: open: add symlink support
      fs: introduce get_mounted_path to get the path where a file is mounted
      ramfs: add symlink and readlink support
      nfs: add readlink support
      test: add -L support to test if it's a symbolic link
      command: add readlink support
      command: add ln support
      ls: add symlink support to -l
      dirname: add -V option to return only path related to the mountpoint
      recursive_action: add ACTION_FOLLOWLINKS support
      envfs: introduce version major and minor
      envfs: add support of variable inode size
      envfs: add support of symlink
      defautenv: add support of symlink

 MAKEALL                |    1 +
 commands/Kconfig       |   10 ++++++++
 commands/Makefile      |    2 ++
 commands/dirname.c     |   24 +++++++++++++++---
 commands/ln.c          |   51 +++++++++++++++++++++++++++++++++++++++
 commands/ls.c          |   31 ++++++++++++++++--------
 commands/readlink.c    |   80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 commands/test.c        |   11 +++++++--
 common/Makefile        |    2 +-
 common/environment.c   |  150 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----------------------------
 fs/fs.c                |  223 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------
 fs/nfs.c               |   86 ++++++++++++++++++++++++++++++++++++++++++++---------------------
 fs/ramfs.c             |   61 +++++++++++++++++++++++++++++++++++++++++-----
 include/envfs.h        |   15 ++++++++++--
 include/fs.h           |   12 +++++++++
 include/libbb.h        |    2 +-
 lib/recursive_action.c |    7 +++++-
 scripts/bareboxenv.c   |    2 +-
 18 files changed, 670 insertions(+), 100 deletions(-)
 create mode 100644 commands/ln.c
 create mode 100644 commands/readlink.c

Best Regards,
J.

_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox

[PATCH 01/18 v4] fs: add readlink support

[Jean-Christophe PLAGNIOL-VILLARD]

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
---
 fs/fs.c      |   37 +++++++++++++++++++++++++++++++++++++
 include/fs.h |    5 +++++
 2 files changed, 42 insertions(+)

diff --git a/fs/fs.c b/fs/fs.c
index 8ab1a3a..2320c3c 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -890,6 +890,43 @@ int close(int fd)
 }
 EXPORT_SYMBOL(close);
 
+int readlink(const char *pathname, char *buf, size_t bufsiz)
+{
+	struct fs_driver_d *fsdrv;
+	struct fs_device_d *fsdev;
+	char *p = normalise_path(pathname);
+	char *freep = p;
+	int ret;
+
+	ret = path_check_prereq(pathname, S_IFLNK);
+	if (ret)
+		goto out;
+
+	fsdev = get_fs_device_and_root_path(&p);
+	if (!fsdev) {
+		ret = -ENODEV;
+		goto out;
+	}
+	fsdrv = fsdev->driver;
+
+	if (fsdrv->readlink)
+		ret = fsdrv->readlink(&fsdev->dev, p, buf, bufsiz);
+	else
+		ret = -ENOSYS;
+
+	if (ret)
+		goto out;
+
+out:
+	free(freep);
+
+	if (ret)
+		errno = -ret;
+
+	return ret;
+}
+EXPORT_SYMBOL(readlink);
+
 static int fs_match(struct device_d *dev, struct driver_d *drv)
 {
 	return strcmp(dev->name, drv->name) ? -1 : 0;
diff --git a/include/fs.h b/include/fs.h
index 22470e6..96fe9be 100644
--- a/include/fs.h
+++ b/include/fs.h
@@ -51,6 +51,9 @@ struct fs_driver_d {
 	/* Truncate a file to given size */
 	int (*truncate)(struct device_d *dev, FILE *f, ulong size);
 
+	int (*readlink)(struct device_d *dev, const char *pathname, char *name,
+			size_t size);
+
 	int (*open)(struct device_d *dev, FILE *f, const char *pathname);
 	int (*close)(struct device_d *dev, FILE *f);
 	int (*read)(struct device_d *dev, FILE *f, void *buf, size_t size);
@@ -129,6 +132,8 @@ DIR *opendir(const char *pathname);
 struct dirent *readdir(DIR *dir);
 int closedir(DIR *dir);
 
+int readlink(const char *path, char *buf, size_t bufsiz);
+
 int mount (const char *device, const char *fsname, const char *path);
 int umount(const char *pathname);
 
-- 
1.7.10.4


_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox

Re: [PATCH 00/18 v3] fs: add symlink and readlink support

[Sascha Hauer]

On Mon, Sep 03, 2012 at 04:50:42PM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> HI,
> 
> 	v4:
> 	 drop the mounted path added to absolute symlink
> 
> 	v3:
> 	 - fix support
> 	   mkdir mymount
> 	   mount -t ramfs none mymount/
> 	   ln /env/boot/net /mymount/link
> 
> 	 - addres comments
> 
> 	v2:
> 	 addres comments
> 
> please pull
> The following changes since commit b77300ac6c6bbbc7eac774ff0076c7c05d39735f:
> 
>   command/mount: add autodetection support (2012-08-21 18:53:00 +0800)
> 
> are available in the git repository at:
> 
>   git://git.jcrosoft.org/barebox.git tags/fs-symlink

It gets better. Now we still have:

# ln bla link
# ln bla link
# ls -l
lrwxrwxrwx          3 link -> bla
lrwxrwxrwx          3 link -> bla

# ln a b
# rmdir b
unable to handle NULL pointer dereference at address 0x00000008
pc : [<a7f25fd0>]    lr : [<a7f25fb4>]
sp : a6eff948  ip : 00000003  fp : 00000000
r10: a6ffbddc  r9 : 00000000  r8 : 00000002
r7 : 00000000  r6 : 00000000  r5 : a6fe0e98  r4 : a6ffbb44
r3 : 00000000  r2 : 00000000  r1 : a6ffbdc7  r0 : 00000000
Flags: nZCv  IRQs off  FIQs off  Mode SVC_32
[<a7f25fd0>] (ramfs_rmdir+0x48/0x78) from [<a7f28660>] (rmdir+0x5c/0x88)
[<a7f28660>] (rmdir+0x5c/0x88) from [<a7f18628>] (do_rmdir+0x28/0x6c)
[<a7f18628>] (do_rmdir+0x28/0x6c) from [<a7f050b4>] (execute_command+0x38/0x7c)
[<a7f050b4>] (execute_command+0x38/0x7c) from [<a7f01efc>] (run_list_real+0x8dc/0x9dc)
[<a7f01efc>] (run_list_real+0x8dc/0x9dc) from [<a7f02144>] (parse_stream_outer+0x148/0x238)
[<a7f02144>] (parse_stream_outer+0x148/0x238) from [<a7f024cc>] (run_shell+0x3c/0x7c)
[<a7f024cc>] (run_shell+0x3c/0x7c) from [<a7f050b4>] (execute_command+0x38/0x7c)
[<a7f050b4>] (execute_command+0x38/0x7c) from [<a7f01efc>] (run_list_real+0x8dc/0x9dc)
[<a7f01efc>] (run_list_real+0x8dc/0x9dc) from [<a7f01a58>] (run_list_real+0x438/0x9dc)

[<a7f2c524>] (unwind_backtrace+0x0/0x9c) from [<a7f1bce0>] (panic+0x28/0x3c)
[<a7f1bce0>] (panic+0x28/0x3c) from [<a7f2c97c>] (do_exception+0x10/0x14)
[<a7f2c97c>] (do_exception+0x10/0x14) from [<a7f2ca08>] (do_data_abort+0x2c/0x38)
[<a7f2ca08>] (do_data_abort+0x2c/0x38) from [<a7f2c750>] (data_abort+0x50/0x60)

While you are at it, the 'ln' command should be under "file commands",
not under "scripting commands".

For links to directories I agree, this is nontrivial and can be added
later. I don't see though why links to links shouldn't be supported from
the start. All it takes is the following, right?

8<------------------------------------------------

diff --git a/fs/fs.c b/fs/fs.c
index 7c59126..447b56f 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -580,13 +580,13 @@ EXPORT_SYMBOL(unlink);
 static char *realfile(const char *pathname, struct stat *s)
 {
 	char *path = normalise_path(pathname);
-	int ret;
+	int ret, recursive = 16;
 
 	ret = lstat(path, s);
 	if (ret)
 		goto out;
 
-	if (S_ISLNK(s->st_mode)) {
+	while (S_ISLNK(s->st_mode)) {
 		char tmp[PATH_MAX];
 		char *new_path;
 
@@ -603,10 +603,16 @@ static char *realfile(const char *pathname, struct stat *s)
 		path = new_path;
 
 		ret = lstat(path, s);
+		if (ret)
+			goto out;
+
+		if (!recursive--) {
+			ret = -ELOOP;
+			goto out;
+		}
 	}
 
-	if (!ret)
-		return path;
+	return path;
 
 out:
 	free(path);

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox

Re: [PATCH 00/18 v3] fs: add symlink and readlink support

[Jean-Christophe PLAGNIOL-VILLARD]

On 15:04 Mon 03 Sep     , Sascha Hauer wrote:
> On Mon, Sep 03, 2012 at 12:04:09PM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> > HI,
> > 
> > 	v3:
> > 	 - fix support
> > 	   mkdir mymount
> > 	   mount -t ramfs none mymount/
> > 	   ln /env/boot/net /mymount/link
> > 
> > 	 - addres comments
> > 
> > 	v2:
> > 	 addres comments
> > 
> > please pull
> > The following changes since commit b77300ac6c6bbbc7eac774ff0076c7c05d39735f:
> > 
> >   command/mount: add autodetection support (2012-08-21 18:53:00 +0800)
> > 
> > are available in the git repository at:
> > 
> >   git://git.jcrosoft.org/barebox.git tags/fs-symlink
> > 
> > for you to fetch changes up to dbae117ee78df0e4110db3a3acf4f9a8bee658d0:
> > 
> >   defautenv: add support of symlink (2012-09-03 17:57:23 +0800)
> > 
> > ----------------------------------------------------------------
> > fs: add symlink and readlink support
> 
> Now we have:
> 
> > # mkdir ram
> > # mount -t ramfs none /ram/
> > # ln /env/boot/initrd ram/link
> > # ls -l ram/
> > lrwxrwxrwx         16 link -> /ram/env/boot/initrd
> > # cat ram/link
> > could not open ram/link: No such file or directory
> 
> The link should point to /env/boot/initrd instead.
> 
> This is probably related to your comment to nfs link support:
> 
> >> There is something wrong here. I do not understand what you do here, but
> >> symlinks are not supposed to bash on them with dirname/basename until
> >> you get something which fits your needs.
> > here the issue is that on nfs you need to mount the correct path >otherwise you
> > can not get the real file
> >
> > so we need to detect it and mount the correct path
> 
> This is wrong. If you put an absolute link somewhere and mount the
> filesystem a somewhere else as NFS, then yes, the link will be broken if
> the mountpoints do not match.
> 
> A symbolic link is basically just a text file, there is no magic behind
> it that fixes pathes according to mount pathes.
yes a symlink is just a file containing the path

I found why I have this on my linux ( I use a special mount to have this
feature so by default th obsolute symlink should act like this)

# mkdir ram
# mount -t ramfs none /ram/
# ln /env/boot/net ram/link
# ls -l ram/
lrwxrwxrwx         16 link -> /env/boot/net
# cat ram/link
#!/bin/sh

if [ "$1" = menu ]; then
	boot-menu-add-entry "$0" "network (tftp, nfs)"
	exit
fi

path="/mnt/tftp"

# to get the dhcp info (global.dhcp.rootpath, global.dhcp.bootfile, global.dhcp.oftree_file)
ifup eth0

global.bootm.image="${path}/${global.user}-linux-${global.hostname}"
#global.bootm.oftree="${path}/${global.user}-oftree-${global.hostname}"

if [ -n "${global.dhcp.rootpath}" ]; then
	bootp=1
	nfsroot="${global.dhcp.rootpath}"
else
	nfsroot="/home/${global.user}/nfsroot/${global.hostname}"
fi

if [ -n "${global.dhcp.bootfile}" -o -n "${global.dhcp.oftree_file}" ]; then
	bootp=1
	path="/mnt/dhcp"

	if [ -d "${path}" ]; then
		umount "${path}"
	else
		mkdir "${path}"
	fi
	mount -t tftp $eth0.serverip "${path}"

	[ -n "${global.dhcp.bootfile}" ] && global.bootm.image="${path}/${global.dhcp.bootfile}"
	[ -n "${global.dhcp.oftree_file}" ] && global.bootm.oftree="${path}/${global.dhcp.oftree_file}"
fi

if [ x${bootp} = x1 ]; then
	echo "Boot via bootp/dhcp on server ${eth0.serverip}"
	[ -n "${global.dhcp.bootfile}" ] && echo "bootm.image => ${global.dhcp.bootfile}"
	[ -n "${global.dhcp.oftree_file}" ] && echo "bootm.oftree => ${global.dhcp.oftree_file}"
	[ -n "${global.dhcp.rootpath}" ] && echo "nfsroot => ${global.dhcp.rootpath}"
fi

bootargs-ip
bootargs-root-nfs -n "$nfsroot"

I update the patch series with this patch to act as suppsoed

---
diff --git a/fs/fs.c b/fs/fs.c
index 53d8316..7c59126 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -1005,12 +1005,6 @@ int readlink(const char *pathname, char *buf, size_t bufsiz)
        char *p = normalise_path(pathname);
        char *freep = p;
        int ret;
-       size_t len = 0;
-       char tmp[PATH_MAX];
-
-       memset(tmp, 0, PATH_MAX);
-
-       buf[0] = 0;
 
        ret = path_check_prereq(pathname, S_IFLNK);
        if (ret)
@@ -1023,29 +1017,14 @@ int readlink(const char *pathname, char *buf, size_t bufsiz)
        }
        fsdrv = fsdev->driver;
 
-       len = min(bufsiz, (size_t)(PATH_MAX - 1));
        if (fsdrv->readlink)
-               ret = fsdrv->readlink(&fsdev->dev, p, tmp, len);
+               ret = fsdrv->readlink(&fsdev->dev, p, buf, bufsiz);
        else
                ret = -ENOSYS;
 
        if (ret)
                goto out;
 
-       if (tmp[0] == '/') {
-               int l = strlen(fsdev->path);
-
-               if (fsdev->path[l - 1] == '/')
-                       l--;
-
-               if (l) {
-                       len -= l;
-                       strncat(buf, fsdev->path, l);
-               }
-       }
-
-       strncat(buf, tmp, len);
-
 out:
        free(freep);
 

Best Regards,
J.

_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox

Re: [PATCH 00/18 v3] fs: add symlink and readlink support

[Sascha Hauer]

On Mon, Sep 03, 2012 at 12:04:09PM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> HI,
> 
> 	v3:
> 	 - fix support
> 	   mkdir mymount
> 	   mount -t ramfs none mymount/
> 	   ln /env/boot/net /mymount/link
> 
> 	 - addres comments
> 
> 	v2:
> 	 addres comments
> 
> please pull
> The following changes since commit b77300ac6c6bbbc7eac774ff0076c7c05d39735f:
> 
>   command/mount: add autodetection support (2012-08-21 18:53:00 +0800)
> 
> are available in the git repository at:
> 
>   git://git.jcrosoft.org/barebox.git tags/fs-symlink
> 
> for you to fetch changes up to dbae117ee78df0e4110db3a3acf4f9a8bee658d0:
> 
>   defautenv: add support of symlink (2012-09-03 17:57:23 +0800)
> 
> ----------------------------------------------------------------
> fs: add symlink and readlink support

Now we have:

> # mkdir ram
> # mount -t ramfs none /ram/
> # ln /env/boot/initrd ram/link
> # ls -l ram/
> lrwxrwxrwx         16 link -> /ram/env/boot/initrd
> # cat ram/link
> could not open ram/link: No such file or directory

The link should point to /env/boot/initrd instead.

This is probably related to your comment to nfs link support:

>> There is something wrong here. I do not understand what you do here, but
>> symlinks are not supposed to bash on them with dirname/basename until
>> you get something which fits your needs.
> here the issue is that on nfs you need to mount the correct path >otherwise you
> can not get the real file
>
> so we need to detect it and mount the correct path

This is wrong. If you put an absolute link somewhere and mount the
filesystem a somewhere else as NFS, then yes, the link will be broken if
the mountpoints do not match.

A symbolic link is basically just a text file, there is no magic behind
it that fixes pathes according to mount pathes.

Sascha


-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox

[PATCH 00/18 v3] fs: add symlink and readlink support

[Jean-Christophe PLAGNIOL-VILLARD]

HI,

	v3:
	 - fix support
	   mkdir mymount
	   mount -t ramfs none mymount/
	   ln /env/boot/net /mymount/link

	 - addres comments

	v2:
	 addres comments

please pull
The following changes since commit b77300ac6c6bbbc7eac774ff0076c7c05d39735f:

  command/mount: add autodetection support (2012-08-21 18:53:00 +0800)

are available in the git repository at:

  git://git.jcrosoft.org/barebox.git tags/fs-symlink

for you to fetch changes up to dbae117ee78df0e4110db3a3acf4f9a8bee658d0:

  defautenv: add support of symlink (2012-09-03 17:57:23 +0800)

----------------------------------------------------------------
fs: add symlink and readlink support

This patch series introduce the support of symlink and readlink at

1) vfs level

2) libc API
 - symlink
 - readlink

3) commands
 - ln
 - readlink

3) filesystem
 - ramfs
 - nfs
 - envfs

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

----------------------------------------------------------------
Jean-Christophe PLAGNIOL-VILLARD (18):
      fs: add readlink support
      fs: rename stat to lstat as we implement lstat
      fs: add symlink support
      fs: implement stat
      fs: open: add symlink support
      fs: introduce get_mounted_path to get the path where a file is mounted
      ramfs: add symlink and readlink support
      nfs: add readlink support
      test: add -L support to test if it's a symbolic link
      command: add readlink support
      command: add ln support
      ls: add symlink support to -l
      dirname: add -V option to return only path related to the mountpoint
      recursive_action: add ACTION_FOLLOWLINKS support
      envfs: introduce version major and minor
      envfs: add support of variable inode size
      envfs: add support of symlink
      defautenv: add support of symlink

 MAKEALL                |    1 +
 commands/Kconfig       |   10 +++++++
 commands/Makefile      |    2 ++
 commands/dirname.c     |   24 ++++++++++++++---
 commands/ln.c          |   51 +++++++++++++++++++++++++++++++++++
 commands/ls.c          |   31 +++++++++++++++-------
 commands/readlink.c    |   80 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 commands/test.c        |   11 ++++++--
 common/Makefile        |    2 +-
 common/environment.c   |  150 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---------------------------
 fs/fs.c                |  244 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 fs/nfs.c               |   86 +++++++++++++++++++++++++++++++++++++++--------------------
 fs/ramfs.c             |   61 +++++++++++++++++++++++++++++++++++++-----
 include/envfs.h        |   15 +++++++++--
 include/fs.h           |   12 +++++++++
 include/libbb.h        |    2 +-
 lib/recursive_action.c |    7 ++++-
 scripts/bareboxenv.c   |    2 +-
 18 files changed, 691 insertions(+), 100 deletions(-)
 create mode 100644 commands/ln.c
 create mode 100644 commands/readlink.c

Best Regards,
J.

_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox