sandbox: Add a way of obtaining directory listings

This implementation uses opendir()/readdir() to access the directory
information and then puts it in a linked list for the caller's use.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@ti.com>

include/os.h

@@ -146,4 +146,52 @@ u64 os_get_nsec(void);
  */
 int os_parse_args(struct sandbox_state *state, int argc, char *argv[]);
 
+/*
+ * Types of directory entry that we support. See also os_dirent_typename in
+ * the C file.
+ */
+enum os_dirent_t {
+	OS_FILET_REG,		/* Regular file */
+	OS_FILET_LNK,		/* Symbolic link */
+	OS_FILET_DIR,		/* Directory */
+	OS_FILET_UNKNOWN,	/* Something else */
+
+	OS_FILET_COUNT,
+};
+
+/** A directory entry node, containing information about a single dirent */
+struct os_dirent_node {
+	struct os_dirent_node *next;	/* Pointer to next node, or NULL */
+	ulong size;			/* Size of file in bytes */
+	enum os_dirent_t type;		/* Type of entry */
+	char name[0];			/* Name of entry */
+};
+
+/**
+ * Get a directionry listing
+ *
+ * This allocates and returns a linked list containing the directory listing.
+ *
+ * @param dirname	Directory to examine
+ * @param headp		Returns pointer to head of linked list, or NULL if none
+ * @return 0 if ok, -ve on error
+ */
+int os_dirent_ls(const char *dirname, struct os_dirent_node **headp);
+
+/**
+ * Get the name of a directory entry type
+ *
+ * @param type		Type to cehck
+ * @return string containing the name of that type, or "???" if none/invalid
+ */
+const char *os_dirent_get_typename(enum os_dirent_t type);
+
+/**
+ * Get the size of a file
+ *
+ * @param fname		Filename to check
+ * @return size of file, or -1 if an error ocurred
+ */
+ssize_t os_get_filesize(const char *fname);
+
 #endif