sqfs2tar: add option to extract subdirectories

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

2 files changed, 161 insertions, 40 deletions

diff --git a/doc/sqfs2tar.1 b/doc/sqfs2tar.1
index c7389ed..2cf9f9c 100644
--- a/doc/sqfs2tar.1
+++ b/doc/sqfs2tar.1
@@ -13,6 +13,16 @@ work on tar archives.
 .PP
 Possible options:
 .TP
+\fB\-\-subdir\fR, \fB\-d\fR <dir>
+Unpack the given sub directory instead of the filesystem root. Can be specified
+more than once to select multiple directories. If only one is specified, it
+becomes the new root of node of the archive file system tree.
+.TP
+\fB\-\-keep\-as\-dir\fR, \fB\-k\fR
+If \fB\-\-subdir\fR is used only once, don't make the subdir the archive root,
+instead keep it as prefix for all unpacked files. Using \fB\-\-subdir\fR more
+than once implies \fB\-\-keep\-as\-dir\fR.
+.TP
 \fB\-\-no\-skip\fR, \fB\-s\fR
 Abort if file cannot be stored in a tar record instead of skipping it.
 .TP
diff --git a/tar/sqfs2tar.c b/tar/sqfs2tar.c
index 76c0d74..110c8c4 100644
--- a/tar/sqfs2tar.c
+++ b/tar/sqfs2tar.c
@@ -17,12 +17,14 @@
 #include <stdio.h>
 
 static struct option long_opts[] = {
+	{ "subdir", required_argument, NULL, 'd' },
+	{ "keep-as-dir", no_argument, NULL, 'k' },
 	{ "no-skip", no_argument, NULL, 's' },
 	{ "help", no_argument, NULL, 'h' },
 	{ "version", no_argument, NULL, 'V' },
 };
 
-static const char *short_opts = "shV";
+static const char *short_opts = "d:kshV";
 
 static const char *usagestr =
 "Usage: sqfs2tar [OPTIONS...] <sqfsfile>\n"
@@ -32,9 +34,21 @@ static const char *usagestr =
 "\n"
 "Possible options:\n"
 "\n"
+"  --subdir, -d <dir>        Unpack the given sub directory instead of the\n"
+"                            filesystem root. Can be specified more than\n"
+"                            once to select multiple directories. If only\n"
+"                            one is specified, it becomes the new root of\n"
+"                            node of the archive file system tree.\n"
+"\n"
+"  --keep-as-dir, -k         If --subdir is used only once, don't make the\n"
+"                            subdir the archive root, instead keep it as\n"
+"                            prefix for all unpacked files.\n"
+"                            Using --subdir more than once implies\n"
+"                            --keep-as-dir.\n"
+"\n"
 "  --no-skip                 Abort if a file cannot be stored in a tar\n"
 "                            archive. By default, it is simply skipped\n"
-"                            and a warning is written to stderr."
+"                            and a warning is written to stderr.\n"
 "\n"
 "  --help, -h                Print help text and exit.\n"
 "  --version, -V             Print version information and exit.\n"
@@ -49,10 +63,19 @@ static const char *usagestr =
 static const char *filename;
 static unsigned int record_counter;
 static bool dont_skip = false;
+static bool keep_as_dir = false;
+
+static const char *current_subdir = NULL;
+
+static char **subdirs = NULL;
+static size_t num_subdirs = 0;
+static size_t max_subdirs = 0;
 
 static void process_args(int argc, char **argv)
 {
-	int i;
+	size_t idx, new_count;
+	int i, ret;
+	void *new;
 
 	for (;;) {
 		i = getopt_long(argc, argv, short_opts, long_opts, NULL);
@@ -60,15 +83,41 @@ static void process_args(int argc, char **argv)
 			break;
 
 		switch (i) {
+		case 'd':
+			if (num_subdirs == max_subdirs) {
+				new_count = max_subdirs ? max_subdirs * 2 : 16;
+				new = realloc(subdirs,
+					      new_count * sizeof(subdirs[0]));
+				if (new == NULL)
+					goto fail_errno;
+
+				max_subdirs = new_count;
+				subdirs = new;
+			}
+
+			subdirs[num_subdirs] = strdup(optarg);
+			if (subdirs[num_subdirs] == NULL)
+				goto fail_errno;
+
+			if (canonicalize_name(subdirs[num_subdirs])) {
+				perror(optarg);
+				goto fail;
+			}
+
+			++num_subdirs;
+			break;
+		case 'k':
+			keep_as_dir = true;
+			break;
 		case 's':
 			dont_skip = true;
 			break;
 		case 'h':
 			fputs(usagestr, stdout);
-			exit(EXIT_SUCCESS);
+			goto out_success;
 		case 'V':
 			print_version();
-			exit(EXIT_SUCCESS);
+			goto out_success;
 		default:
 			goto fail_arg;
 		}
@@ -85,10 +134,28 @@ static void process_args(int argc, char **argv)
 		fputs("Unknown extra arguments\n", stderr);
 		goto fail_arg;
 	}
+
+	if (num_subdirs > 1)
+		keep_as_dir = true;
+
 	return;
+fail_errno:
+	perror("parsing options");
+	goto fail;
 fail_arg:
 	fputs("Try `sqfs2tar --help' for more information.\n", stderr);
-	exit(EXIT_FAILURE);
+	goto fail;
+fail:
+	ret = EXIT_FAILURE;
+	goto out_exit;
+out_success:
+	ret = EXIT_SUCCESS;
+	goto out_exit;
+out_exit:
+	for (idx = 0; idx < num_subdirs; ++idx)
+		free(subdirs[idx]);
+	free(subdirs);
+	exit(ret);
 }
 
 static int terminate_archive(void)
@@ -115,54 +182,71 @@ static int terminate_archive(void)
 
 static int write_tree_dfs(fstree_t *fs, tree_node_t *n, data_reader_t *data)
 {
+	size_t len, name_len;
 	char *name, *target;
 	struct stat sb;
 	int ret;
 
-	if (n->parent != NULL || !S_ISDIR(n->mode)) {
-		name = fstree_get_path(n);
-		if (name == NULL) {
-			perror("resolving tree node path");
-			return -1;
-		}
-
-		assert(canonicalize_name(name) == 0);
+	if (n->parent == NULL && S_ISDIR(n->mode))
+		goto skip_hdr;
 
-		fstree_node_stat(fs, n, &sb);
+	name = fstree_get_path(n);
+	if (name == NULL) {
+		perror("resolving tree node path");
+		return -1;
+	}
 
-		target = S_ISLNK(sb.st_mode) ? n->data.slink_target : NULL;
-		ret = write_tar_header(STDOUT_FILENO, &sb, name, target,
-				       record_counter++);
+	assert(canonicalize_name(name) == 0);
 
-		if (ret > 0) {
-			if (dont_skip) {
-				fputs("Not allowed to skip files, aborting!\n",
-				      stderr);
-				ret = -1;
-			} else {
-				fprintf(stderr, "Skipping %s\n", name);
-				ret = 0;
-			}
+	if (current_subdir != NULL && !keep_as_dir) {
+		if (strcmp(name, current_subdir) == 0) {
 			free(name);
-			return ret;
+			goto skip_hdr;
 		}
 
-		free(name);
+		len = strlen(current_subdir);
+		name_len = strlen(name);
 
-		if (ret < 0)
-			return -1;
+		assert(name_len > len);
+		assert(name[len] == '/');
 
-		if (S_ISREG(n->mode)) {
-			if (data_reader_dump_file(data, n->data.file,
-						  STDOUT_FILENO, false)) {
-				return -1;
-			}
+		memmove(name, name + len + 1, name_len - len);
+	}
 
-			if (padd_file(STDOUT_FILENO, n->data.file->size, 512))
-				return -1;
+	fstree_node_stat(fs, n, &sb);
+
+	target = S_ISLNK(sb.st_mode) ? n->data.slink_target : NULL;
+	ret = write_tar_header(STDOUT_FILENO, &sb, name, target,
+			       record_counter++);
+
+	if (ret > 0) {
+		if (dont_skip) {
+			fputs("Not allowed to skip files, aborting!\n",
+			      stderr);
+			ret = -1;
+		} else {
+			fprintf(stderr, "Skipping %s\n", name);
+			ret = 0;
 		}
+		free(name);
+		return ret;
 	}
 
+	free(name);
+
+	if (ret < 0)
+		return -1;
+
+	if (S_ISREG(n->mode)) {
+		if (data_reader_dump_file(data, n->data.file,
+					  STDOUT_FILENO, false)) {
+			return -1;
+		}
+
+		if (padd_file(STDOUT_FILENO, n->data.file->size, 512))
+			return -1;
+	}
+skip_hdr:
 	if (S_ISDIR(n->mode)) {
 		for (n = n->data.dir->children; n != NULL; n = n->next) {
 			if (write_tree_dfs(fs, n, data))
@@ -179,8 +263,10 @@ int main(int argc, char **argv)
 	int status = EXIT_FAILURE;
 	sqfs_super_t super;
 	compressor_t *cmp;
+	tree_node_t *root;
 	fstree_t fs;
 	int sqfsfd;
+	size_t i;
 
 	process_args(argc, argv);
 
@@ -216,8 +302,30 @@ int main(int argc, char **argv)
 	if (data == NULL)
 		goto out_fs;
 
-	if (write_tree_dfs(&fs, fs.root, data))
-		goto out_data;
+	for (i = 0; i < num_subdirs; ++i) {
+		root = fstree_node_from_path(&fs, subdirs[i]);
+		if (root == NULL) {
+			perror(subdirs[i]);
+			goto out_data;
+		}
+
+		if (!S_ISDIR(root->mode)) {
+			fprintf(stderr, "%s is not a directory\n", subdirs[i]);
+			goto out_data;
+		}
+
+		current_subdir = subdirs[i];
+
+		if (write_tree_dfs(&fs, root, data))
+			goto out_data;
+	}
+
+	current_subdir = NULL;
+
+	if (num_subdirs == 0) {
+		if (write_tree_dfs(&fs, fs.root, data))
+			goto out_data;
+	}
 
 	if (terminate_archive())
 		goto out_data;
@@ -231,5 +339,8 @@ out_cmp:
 	cmp->destroy(cmp);
 out_fd:
 	close(sqfsfd);
+	for (i = 0; i < num_subdirs; ++i)
+		free(subdirs[i]);
+	free(subdirs);
 	return status;
 }