Cleanup/fix: gensquashfs: split directory scanning from xattr scanning

On the one hand, this commit cleanes the code a bit by splitting
the "scan directory contents" code from the "scan xattrs from
directory contents" and moving the later in a seperate file.

On the other hand, the xattr scanning is now done *after* the fstree
is post processed, which includes sorting it. This way, the xattrs
are always added in a deterministic, reproducible order.

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

1 files changed, 200 insertions, 0 deletions

diff --git a/bin/gensquashfs/dirscan_xattr.c b/bin/gensquashfs/dirscan_xattr.c
new file mode 100644
index 0000000..3995a19
--- /dev/null
+++ b/bin/gensquashfs/dirscan_xattr.c
@@ -0,0 +1,200 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * dirscan_xattr.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "mkfs.h"
+
+#ifdef HAVE_SYS_XATTR_H
+static char *get_full_path(const char *prefix, tree_node_t *node)
+{
+	char *path = NULL, *new = NULL;
+	size_t path_len, prefix_len;
+	int ret;
+
+	path = fstree_get_path(node);
+	if (path == NULL)
+		goto fail;
+
+	ret = canonicalize_name(path);
+	assert(ret == 0);
+
+	path_len = strlen(path);
+	prefix_len = strlen(prefix);
+
+	while (prefix_len > 0 && prefix[prefix_len - 1] == '/')
+		--prefix_len;
+
+	if (prefix_len > 0) {
+		new = realloc(path, path_len + prefix_len + 2);
+		if (new == NULL)
+			goto fail;
+
+		path = new;
+
+		memmove(path + prefix_len + 1, path, path_len + 1);
+		memcpy(path, prefix, prefix_len);
+		path[prefix_len] = '/';
+	}
+
+	return path;
+fail:
+	perror("getting full path for xattr scan");
+	free(path);
+	return NULL;
+}
+
+static int xattr_from_path(sqfs_xattr_writer_t *xwr, const char *path)
+{
+	char *key, *value = NULL, *buffer = NULL;
+	ssize_t buflen, vallen, keylen;
+	int ret;
+
+	buflen = llistxattr(path, NULL, 0);
+	if (buflen < 0) {
+		fprintf(stderr, "llistxattr %s: %s", path, strerror(errno));
+		return -1;
+	}
+
+	if (buflen == 0)
+		return 0;
+
+	buffer = malloc(buflen);
+	if (buffer == NULL) {
+		perror("xattr name buffer");
+		return -1;
+	}
+
+	buflen = llistxattr(path, buffer, buflen);
+	if (buflen == -1) {
+		fprintf(stderr, "llistxattr %s: %s", path, strerror(errno));
+		goto fail;
+	}
+
+	key = buffer;
+	while (buflen > 0) {
+		vallen = lgetxattr(path, key, NULL, 0);
+		if (vallen == -1) {
+			fprintf(stderr, "lgetxattr %s: %s",
+				path, strerror(errno));
+			goto fail;
+		}
+
+		if (vallen > 0) {
+			value = calloc(1, vallen);
+			if (value == NULL) {
+				perror("allocating xattr value buffer");
+				goto fail;
+			}
+
+			vallen = lgetxattr(path, key, value, vallen);
+			if (vallen == -1) {
+				fprintf(stderr, "lgetxattr %s: %s\n",
+					path, strerror(errno));
+				goto fail;
+			}
+
+			ret = sqfs_xattr_writer_add(xwr, key, value, vallen);
+			if (ret) {
+				sqfs_perror(path,
+					    "storing xattr key-value pairs",
+					    ret);
+				goto fail;
+			}
+
+			free(value);
+			value = NULL;
+		}
+
+		keylen = strlen(key) + 1;
+		buflen -= keylen;
+		key += keylen;
+	}
+
+	free(buffer);
+	return 0;
+fail:
+	free(value);
+	free(buffer);
+	return -1;
+}
+#endif
+
+static int xattr_xcan_dfs(const char *path_prefix, void *selinux_handle,
+			  sqfs_xattr_writer_t *xwr, unsigned int flags,
+			  tree_node_t *node)
+{
+	char *path;
+	int ret;
+
+	ret = sqfs_xattr_writer_begin(xwr);
+	if (ret) {
+		sqfs_perror(node->name, "recoding xattr key-value pairs\n",
+			    ret);
+		return -1;
+	}
+
+#ifdef HAVE_SYS_XATTR_H
+	if (flags & DIR_SCAN_READ_XATTR) {
+		path = get_full_path(path_prefix, node);
+		if (path == NULL)
+			return -1;
+
+		ret = xattr_from_path(xwr, path);
+		free(path);
+
+		if (ret)
+			return -1;
+	}
+#else
+	(void)path_prefix;
+#endif
+
+	if (selinux_handle != NULL) {
+		path = fstree_get_path(node);
+		if (path == NULL) {
+			perror("reconstructing absolute path");
+			return -1;
+		}
+
+		ret = selinux_relable_node(selinux_handle, xwr, node, path);
+		free(path);
+
+		if (ret)
+			return -1;
+	}
+
+	if (sqfs_xattr_writer_end(xwr, &node->xattr_idx)) {
+		sqfs_perror(node->name, "completing xattr key-value pairs",
+			    ret);
+		return -1;
+	}
+
+	if (S_ISDIR(node->mode)) {
+		node = node->data.dir.children;
+
+		while (node != NULL) {
+			if (xattr_xcan_dfs(path_prefix, selinux_handle, xwr,
+					   flags, node)) {
+				return -1;
+			}
+
+			node = node->next;
+		}
+	}
+
+	return 0;
+}
+
+int xattrs_from_dir(fstree_t *fs, const char *path, void *selinux_handle,
+		    sqfs_xattr_writer_t *xwr, unsigned int flags)
+{
+	if (xwr == NULL)
+		return 0;
+
+	if (selinux_handle == NULL && !(flags & DIR_SCAN_READ_XATTR))
+		return 0;
+
+	return xattr_xcan_dfs(path, selinux_handle, xwr, flags, fs->root);
+}