fs: Add a new command to create symbolic links

The command line is:
ln <interface> <dev[:part]> target linkname

Currently symbolic links are supported only in ext4 and only if the option
CMD_EXT4_WRITE is enabled.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

cmd/fs.c

@@ -76,6 +76,20 @@ U_BOOT_CMD(
 	"      device type 'interface' instance 'dev'."
 )
 
+static int do_ln_wrapper(cmd_tbl_t *cmdtp, int flag, int argc,
+			 char * const argv[])
+{
+	return do_ln(cmdtp, flag, argc, argv, FS_TYPE_ANY);
+}
+
+U_BOOT_CMD(
+	ln,	5,	1,	do_ln_wrapper,
+	"Create a symbolic link",
+	"<interface> <dev[:part]> target linkname\n"
+	"    - create a symbolic link to 'target' with the name 'linkname' on\n"
+	"      device type 'interface' instance 'dev'."
+)
+
 static int do_fstype_wrapper(cmd_tbl_t *cmdtp, int flag, int argc,
 				char * const argv[])
 {

fs/fs.c

@@ -90,6 +90,11 @@ static inline int fs_write_unsupported(const char *filename, void *buf,
 	return -1;
 }
 
+static inline int fs_ln_unsupported(const char *filename, const char *target)
+{
+	return -1;
+}
+
 static inline void fs_close_unsupported(void)
 {
 }
@@ -154,6 +159,7 @@ struct fstype_info {
 	void (*closedir)(struct fs_dir_stream *dirs);
 	int (*unlink)(const char *filename);
 	int (*mkdir)(const char *dirname);
+	int (*ln)(const char *filename, const char *target);
 };
 
 static struct fstype_info fstypes[] = {
@@ -181,6 +187,7 @@ static struct fstype_info fstypes[] = {
 		.opendir = fat_opendir,
 		.readdir = fat_readdir,
 		.closedir = fat_closedir,
+		.ln = fs_ln_unsupported,
 	},
 #endif
 
@@ -197,8 +204,10 @@ static struct fstype_info fstypes[] = {
 		.read = ext4_read_file,
 #ifdef CONFIG_CMD_EXT4_WRITE
 		.write = ext4_write_file,
+		.ln = ext4fs_create_link,
 #else
 		.write = fs_write_unsupported,
+		.ln = fs_ln_unsupported,
 #endif
 		.uuid = ext4fs_uuid,
 		.opendir = fs_opendir_unsupported,
@@ -222,6 +231,7 @@ static struct fstype_info fstypes[] = {
 		.opendir = fs_opendir_unsupported,
 		.unlink = fs_unlink_unsupported,
 		.mkdir = fs_mkdir_unsupported,
+		.ln = fs_ln_unsupported,
 	},
 #endif
 #ifdef CONFIG_CMD_UBIFS
@@ -240,6 +250,7 @@ static struct fstype_info fstypes[] = {
 		.opendir = fs_opendir_unsupported,
 		.unlink = fs_unlink_unsupported,
 		.mkdir = fs_mkdir_unsupported,
+		.ln = fs_ln_unsupported,
 	},
 #endif
 #ifdef CONFIG_FS_BTRFS
@@ -258,6 +269,7 @@ static struct fstype_info fstypes[] = {
 		.opendir = fs_opendir_unsupported,
 		.unlink = fs_unlink_unsupported,
 		.mkdir = fs_mkdir_unsupported,
+		.ln = fs_ln_unsupported,
 	},
 #endif
 	{
@@ -275,6 +287,7 @@ static struct fstype_info fstypes[] = {
 		.opendir = fs_opendir_unsupported,
 		.unlink = fs_unlink_unsupported,
 		.mkdir = fs_mkdir_unsupported,
+		.ln = fs_ln_unsupported,
 	},
 };
 
@@ -602,6 +615,22 @@ int fs_mkdir(const char *dirname)
 	return ret;
 }
 
+int fs_ln(const char *fname, const char *target)
+{
+	struct fstype_info *info = fs_get_info(fs_type);
+	int ret;
+
+	ret = info->ln(fname, target);
+
+	if (ret < 0) {
+		printf("** Unable to create link %s -> %s **\n", fname, target);
+		ret = -1;
+	}
+	fs_close();
+
+	return ret;
+}
+
 int do_size(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
 		int fstype)
 {
@@ -840,3 +869,18 @@ int do_mkdir(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
 
 	return 0;
 }
+
+int do_ln(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
+	  int fstype)
+{
+	if (argc != 5)
+		return CMD_RET_USAGE;
+
+	if (fs_set_blk_dev(argv[1], argv[2], fstype))
+		return 1;
+
+	if (fs_ln(argv[3], argv[4]))
+		return 1;
+
+	return 0;
+}

include/fs.h

@@ -191,6 +191,8 @@ int do_rm(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
 		int fstype);
 int do_mkdir(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
 		int fstype);
+int do_ln(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
+	  int fstype);
 
 /*
  * Determine the UUID of the specified filesystem and print it. Optionally it is