[U-Boot] [PATCH v0 01/20] fs: add fs_readdir()

[Rob Clark <robdclark@gmail.com>]

Needed to support efi file protocol.  The fallback.efi loader wants
to be able to read the contents of the /EFI directory to find an OS
to boot.

For reference, the expected EFI semantics are described in (v2.7 of UEFI
spec) in section 13.5 (page 609).  Or for convenience, see:

  http://wiki.phoenix.com/wiki/index.php/EFI_FILE_PROTOCOL#Read.28.29

The EFI level semantics are implemented in a later patch, so they are
not too important to the understanding of this patch.

Signed-off-by: Rob Clark <robdclark@gmail.com>
---
 fs/fs.c      | 25 +++++++++++++++++++++++++
 include/fs.h | 21 +++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/fs/fs.c b/fs/fs.c
index 595ff1fe69..5ac4226ece 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -69,6 +69,12 @@ static inline int fs_uuid_unsupported(char *uuid_str)
 	return -1;
 }
 
+static inline int fs_readdir_unsupported(const char *filename, loff_t offset,
+					 struct fs_dirent *dent)
+{
+	return -ENXIO;
+}
+
 struct fstype_info {
 	int fstype;
 	char *name;
@@ -92,6 +98,7 @@ struct fstype_info {
 		     loff_t len, loff_t *actwrite);
 	void (*close)(void);
 	int (*uuid)(char *uuid_str);
+	int (*readdir)(const char *filename, loff_t offset, struct fs_dirent *dent);
 };
 
 static struct fstype_info fstypes[] = {
@@ -112,6 +119,7 @@ static struct fstype_info fstypes[] = {
 		.write = fs_write_unsupported,
 #endif
 		.uuid = fs_uuid_unsupported,
+		.readdir = fs_readdir_unsupported,
 	},
 #endif
 #ifdef CONFIG_FS_EXT4
@@ -131,6 +139,7 @@ static struct fstype_info fstypes[] = {
 		.write = fs_write_unsupported,
 #endif
 		.uuid = ext4fs_uuid,
+		.readdir = fs_readdir_unsupported,
 	},
 #endif
 #ifdef CONFIG_SANDBOX
@@ -146,6 +155,7 @@ static struct fstype_info fstypes[] = {
 		.read = fs_read_sandbox,
 		.write = fs_write_sandbox,
 		.uuid = fs_uuid_unsupported,
+		.readdir = fs_readdir_unsupported,
 	},
 #endif
 #ifdef CONFIG_CMD_UBIFS
@@ -161,6 +171,7 @@ static struct fstype_info fstypes[] = {
 		.read = ubifs_read,
 		.write = fs_write_unsupported,
 		.uuid = fs_uuid_unsupported,
+		.readdir = fs_readdir_unsupported,
 	},
 #endif
 	{
@@ -175,6 +186,7 @@ static struct fstype_info fstypes[] = {
 		.read = fs_read_unsupported,
 		.write = fs_write_unsupported,
 		.uuid = fs_uuid_unsupported,
+		.readdir = fs_readdir_unsupported,
 	},
 };
 
@@ -334,6 +346,19 @@ int fs_write(const char *filename, ulong addr, loff_t offset, loff_t len,
 	return ret;
 }
 
+int fs_readdir(const char *filename, loff_t offset, struct fs_dirent *dent)
+{
+	struct fstype_info *info = fs_get_info(fs_type);
+	int ret;
+
+	memset(dent, 0, sizeof(*dent));
+
+	ret = info->readdir(filename, offset, dent);
+	fs_close();
+
+	return ret;
+}
+
 int do_size(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
 		int fstype)
 {
diff --git a/include/fs.h b/include/fs.h
index 2f2aca8378..71051d7c66 100644
--- a/include/fs.h
+++ b/include/fs.h
@@ -79,6 +79,27 @@ int fs_write(const char *filename, ulong addr, loff_t offset, loff_t len,
 	     loff_t *actwrite);
 
 /*
+ * A directory entry.
+ */
+struct fs_dirent {
+	loff_t size;
+	char name[256];
+};
+
+/*
+ * fs_readdir - Read a directory.
+ *
+ * @filename: Name of file to read from
+ * @offset: The offset into the directory to read, ie. offset of N returns
+ *    the N'th directory entry
+ * @dent: on success, filled in with directory entry
+ * @return 0 on success, -ENOTDIR if specified file is not a directory,
+ *    or -ENOENT if offset is beyond last directory entry, or -ENXIO if
+ *    operation is not supported.
+ */
+int fs_readdir(const char *filename, loff_t offset, struct fs_dirent *dent);
+
+/*
  * Common implementation for various filesystem commands, optionally limited
  * to a specific filesystem type via the fstype parameter.
  */
-- 
2.13.0