Generate linear file list in fstree

Instead of doing DFS on the fly in gensquashfs, churn out a linked list
of all files in an archive.

Future improvements in packing strategies can go into this file.

This can also be usefull for other purposes in the future, such as file
deduplication or as a work queue for the unpacker.

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

2 files changed, 37 insertions, 0 deletions

diff --git a/lib/Makemodule.am b/lib/Makemodule.am
index c6674c0..0cc1847 100644
--- a/lib/Makemodule.am
+++ b/lib/Makemodule.am
@@ -4,6 +4,7 @@ libfstree_a_SOURCES += lib/fstree/gen_inode_table.c lib/fstree/get_path.c
 libfstree_a_SOURCES += lib/fstree/node_stat.c lib/fstree/mknode.c
 libfstree_a_SOURCES += lib/fstree/add_by_path.c lib/fstree/xattr.c
 libfstree_a_SOURCES += lib/fstree/node_from_path.c include/fstree.h
+libfstree_a_SOURCES += lib/fstree/gen_file_list.c
 libfstree_a_CFLAGS = $(AM_CFLAGS)
 libfstree_a_CPPFLAGS = $(AM_CPPFLAGS)
 
diff --git a/lib/fstree/gen_file_list.c b/lib/fstree/gen_file_list.c
new file mode 100644
index 0000000..30cd2f6
--- /dev/null
+++ b/lib/fstree/gen_file_list.c
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include "config.h"
+#include "fstree.h"
+
+static file_info_t *file_list_dfs(tree_node_t *n)
+{
+	if (S_ISREG(n->mode))
+		return n->data.file;
+
+	if (S_ISDIR(n->mode)) {
+		file_info_t *list = NULL, *last = NULL;
+
+		for (n = n->data.dir->children; n != NULL; n = n->next) {
+			if (list == NULL) {
+				list = file_list_dfs(n);
+				if (list == NULL)
+					continue;
+				last = list;
+			} else {
+				last->next = file_list_dfs(n);
+			}
+
+			while (last->next != NULL)
+				last = last->next;
+		}
+
+		return list;
+	}
+
+	return NULL;
+}
+
+void fstree_gen_file_list(fstree_t *fs)
+{
+	fs->files = file_list_dfs(fs->root);
+}