libfstree: Add a filter callback to the directory scanning function

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

4 files changed, 62 insertions, 13 deletions

diff --git a/bin/gensquashfs/mkfs.c b/bin/gensquashfs/mkfs.c
index 2885d84..b25d325 100644
--- a/bin/gensquashfs/mkfs.c
+++ b/bin/gensquashfs/mkfs.c
@@ -160,8 +160,8 @@ int main(int argc, char **argv)
 	}
 
 	if (opt.infile == NULL) {
-		if (fstree_from_dir(&sqfs.fs, sqfs.fs.root,
-				    opt.packdir, opt.dirscan_flags)) {
+		if (fstree_from_dir(&sqfs.fs, sqfs.fs.root, opt.packdir,
+				    NULL, NULL, opt.dirscan_flags)) {
 			goto out;
 		}
 	} else {
diff --git a/include/fstree.h b/include/fstree.h
index e5fc966..35d6778 100644
--- a/include/fstree.h
+++ b/include/fstree.h
@@ -41,6 +41,15 @@ typedef struct file_info_t file_info_t;
 typedef struct dir_info_t dir_info_t;
 typedef struct fstree_t fstree_t;
 
+/*
+  Optionally used by fstree_from_dir and fstree_from_subdir to
+  execute custom actions for each discovered node.
+
+  If it returns a value > 0, the new node is discarded, if < 0, scanning is
+  aborted and returns a failure status.
+ */
+typedef int (*scan_node_callback)(void *user, fstree_t *fs, tree_node_t *node);
+
 /* Additional meta data stored in a tree_node_t for regular files. */
 struct file_info_t {
 	/* Linked list pointer for files in fstree_t */
@@ -252,7 +261,8 @@ int fstree_resolve_hard_link(fstree_t *fs, tree_node_t *node);
   Returns 0 on success, prints to stderr on failure.
  */
 int fstree_from_dir(fstree_t *fs, tree_node_t *root,
-		    const char *path, unsigned int flags);
+		    const char *path, scan_node_callback cb, void *user,
+		    unsigned int flags);
 
 /*
   Same as fstree_from_dir, but scans a sub-directory inside the specified path.
@@ -261,6 +271,6 @@ int fstree_from_dir(fstree_t *fs, tree_node_t *root,
  */
 int fstree_from_subdir(fstree_t *fs, tree_node_t *root,
 		       const char *path, const char *subdir,
-		       unsigned int flags);
+		       scan_node_callback cb, void *user, unsigned int flags);
 
 #endif /* FSTREE_H */
diff --git a/lib/fstree/fstree_from_dir.c b/lib/fstree/fstree_from_dir.c
index d3e188d..cb066b1 100644
--- a/lib/fstree/fstree_from_dir.c
+++ b/lib/fstree/fstree_from_dir.c
@@ -12,30 +12,53 @@
 #include <string.h>
 #include <errno.h>
 
+static void discard_node(tree_node_t *root, tree_node_t *n)
+{
+	tree_node_t *it;
+
+	if (n == root->data.dir.children) {
+		root->data.dir.children = n->next;
+	} else {
+		it = root->data.dir.children;
+
+		while (it != NULL && it->next != n)
+			it = it->next;
+
+		if (it != NULL)
+			it->next = n->next;
+	}
+
+	free(n);
+}
+
 #ifdef _WIN32
 int fstree_from_subdir(fstree_t *fs, tree_node_t *root,
 		       const char *path, const char *subdir,
+		       scan_node_callback cb, void *user,
 		       unsigned int flags)
 {
 	(void)fs; (void)root; (void)path; (void)subdir; (void)flags;
+	(void)cb; (void)user;
 	fputs("Packing a directory is not supported on Windows.\n", stderr);
 	return -1;
 }
 
 int fstree_from_dir(fstree_t *fs, tree_node_t *root,
-		    const char *path, unsigned int flags)
+		    const char *path, scan_node_callback cb,
+		    void *user, unsigned int flags)
 {
-	return fstree_from_subdir(fs, root, path, NULL, flags);
+	return fstree_from_subdir(fs, root, path, NULL, cb, user, flags);
 }
 #else
 static int populate_dir(int dir_fd, fstree_t *fs, tree_node_t *root,
-			dev_t devstart, unsigned int flags)
+			dev_t devstart, scan_node_callback cb,
+			void *user, unsigned int flags)
 {
 	char *extra = NULL;
 	struct dirent *ent;
+	int ret, childfd;
 	struct stat sb;
 	tree_node_t *n;
-	int childfd;
 	DIR *dir;
 
 	dir = fdopendir(dir_fd);
@@ -122,6 +145,8 @@ static int populate_dir(int dir_fd, fstree_t *fs, tree_node_t *root,
 						    false, false);
 			if (n == NULL)
 				continue;
+
+			ret = 0;
 		} else {
 			n = fstree_mknode(root, ent->d_name,
 					  strlen(ent->d_name), extra, &sb);
@@ -129,11 +154,21 @@ static int populate_dir(int dir_fd, fstree_t *fs, tree_node_t *root,
 				perror("creating tree node");
 				goto fail;
 			}
+
+			ret = (cb == NULL) ? 0 : cb(user, fs, n);
 		}
 
 		free(extra);
 		extra = NULL;
 
+		if (ret < 0)
+			goto fail;
+
+		if (ret > 0) {
+			discard_node(root, n);
+			continue;
+		}
+
 		if (S_ISDIR(n->mode) && !(flags & DIR_SCAN_NO_RECURSION)) {
 			childfd = openat(dir_fd, n->name, O_DIRECTORY |
 					 O_RDONLY | O_CLOEXEC);
@@ -142,8 +177,10 @@ static int populate_dir(int dir_fd, fstree_t *fs, tree_node_t *root,
 				goto fail;
 			}
 
-			if (populate_dir(childfd, fs, n, devstart, flags))
+			if (populate_dir(childfd, fs, n, devstart,
+					 cb, user, flags)) {
 				goto fail;
+			}
 		}
 	}
 
@@ -159,6 +196,7 @@ fail:
 
 int fstree_from_subdir(fstree_t *fs, tree_node_t *root,
 		       const char *path, const char *subdir,
+		       scan_node_callback cb, void *user,
 		       unsigned int flags)
 {
 	struct stat sb;
@@ -199,12 +237,13 @@ int fstree_from_subdir(fstree_t *fs, tree_node_t *root,
 		return -1;
 	}
 
-	return populate_dir(fd, fs, root, sb.st_dev, flags);
+	return populate_dir(fd, fs, root, sb.st_dev, cb, user, flags);
 }
 
 int fstree_from_dir(fstree_t *fs, tree_node_t *root,
-		    const char *path, unsigned int flags)
+		    const char *path, scan_node_callback cb,
+		    void *user, unsigned int flags)
 {
-	return fstree_from_subdir(fs, root, path, NULL, flags);
+	return fstree_from_subdir(fs, root, path, NULL, cb, user, flags);
 }
 #endif
diff --git a/tests/fstree_from_file.c b/tests/fstree_from_file.c
index f8f0892..140ffd7 100644
--- a/tests/fstree_from_file.c
+++ b/tests/fstree_from_file.c
@@ -15,7 +15,7 @@ int main(void)
 	fstree_t fs;
 
 	TEST_ASSERT(fstree_init(&fs, NULL) == 0);
-	TEST_ASSERT(fstree_from_file(&fs, TEST_PATH) == 0);
+	TEST_ASSERT(fstree_from_file(&fs, TEST_PATH, NULL) == 0);
 
 	fstree_post_process(&fs);
 	n = fs.root->data.dir.children;