From 2f17f1a22f112bbc1eaa179914f0e5069f2a5ba2 Mon Sep 17 00:00:00 2001
From: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Date: Fri, 17 Aug 2012 00:48:35 +0800
Subject: [PATCH] fs: add readlink support

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 0b376a544..6a855130a 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 c0b9f71fb..906d192a7 100644
--- a/include/fs.h
+++ b/include/fs.h
@@ -50,6 +50,9 @@ 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);
@@ -124,6 +127,8 @@ 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);