Add helper function for reading dir entries to meta reader

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

3 files changed, 63 insertions, 0 deletions

diff --git a/include/meta_reader.h b/include/meta_reader.h
index d7ab732..1fb527a 100644
--- a/include/meta_reader.h
+++ b/include/meta_reader.h
@@ -28,4 +28,8 @@ sqfs_inode_generic_t *meta_reader_read_inode(meta_reader_t *ir,
 					     uint64_t block_start,
 					     size_t offset);
 
+int meta_reader_read_dir_header(meta_reader_t *m, sqfs_dir_header_t *hdr);
+
+sqfs_dir_entry_t *meta_reader_read_dir_ent(meta_reader_t *m);
+
 #endif /* META_READER_H */
diff --git a/lib/Makemodule.am b/lib/Makemodule.am
index b521a7e..a1bf0f2 100644
--- a/lib/Makemodule.am
+++ b/lib/Makemodule.am
@@ -14,6 +14,7 @@ libsquashfs_a_SOURCES += lib/sqfs/table.c include/table.h
 libsquashfs_a_SOURCES += lib/sqfs/read_super.c lib/sqfs/meta_reader.c
 libsquashfs_a_SOURCES += include/meta_reader.h lib/sqfs/id_table_write.c
 libsquashfs_a_SOURCES += lib/sqfs/id_table_read.c lib/sqfs/read_inode.c
+libsquashfs_a_SOURCES += lib/sqfs/readdir.c
 
 libutil_a_SOURCES = lib/util/canonicalize_name.c lib/util/write_retry.c
 libutil_a_SOURCES += lib/util/read_retry.c include/util.h
diff --git a/lib/sqfs/readdir.c b/lib/sqfs/readdir.c
new file mode 100644
index 0000000..142bafb
--- /dev/null
+++ b/lib/sqfs/readdir.c
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include "meta_reader.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+int meta_reader_read_dir_header(meta_reader_t *m, sqfs_dir_header_t *hdr)
+{
+	if (meta_reader_read(m, hdr, sizeof(*hdr)))
+		return -1;
+
+	hdr->count = le32toh(hdr->count);
+	hdr->start_block = le32toh(hdr->start_block);
+	hdr->inode_number = le32toh(hdr->inode_number);
+	return 0;
+}
+
+sqfs_dir_entry_t *meta_reader_read_dir_ent(meta_reader_t *m)
+{
+	sqfs_dir_entry_t ent, *out;
+
+	if (meta_reader_read(m, &ent, sizeof(ent)))
+		return NULL;
+
+	ent.offset = le16toh(ent.offset);
+	ent.inode_number = le16toh(ent.inode_number);
+	ent.type = le16toh(ent.type);
+	ent.size = le16toh(ent.size);
+
+	out = calloc(1, sizeof(*out) + ent.size + 2);
+	if (out == NULL) {
+		perror("reading dir entry");
+		return NULL;
+	}
+
+	*out = ent;
+	if (meta_reader_read(m, out->name, ent.size + 1)) {
+		free(out);
+		return NULL;
+	}
+
+	if (strchr((char *)out->name, '/') != NULL ||
+	    strchr((char *)out->name, '\\') != NULL) {
+		fputs("Found a file name that contains slashes\n", stderr);
+		free(out);
+		return NULL;
+	}
+
+	if (strcmp((char *)out->name, "..") == 0 ||
+	    strcmp((char *)out->name, ".") == 0) {
+		fputs("Found '..' or '.' in file names\n", stderr);
+		free(out);
+		return NULL;
+	}
+
+	return out;
+}