[pacman-dev] [PATCH 2/2] be_package: fallback to standard filelist loading

[Andrew Gregory]

In order to work properly, loading the filelist from an mtree file
requires a libarchive patch that has not yet been included in an
official release.[1]  Under certain circumstances, an unpatched
libarchive may refuse to read the mtree file due to inconsistencies
between it and the user's file system.  In order to allow alpm to
recover in this situation, read the mtree data into a temporary filelist
that is only copied over to the package if the entire read is
successful.

[1] https://github.com/libarchive/libarchive/commit/661684170b970ef7d6eff135b57e58a537e8bc53

Signed-off-by: Andrew Gregory <andrew.gregory.8 at gmail.com>
---

https://bbs.archlinux.org/viewtopic.php?id=194771

 lib/libalpm/be_package.c | 37 ++++++++++++++++++++++---------------
 1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/lib/libalpm/be_package.c b/lib/libalpm/be_package.c
index 37aa428..53399a3 100644
--- a/lib/libalpm/be_package.c
+++ b/lib/libalpm/be_package.c
@@ -445,17 +445,12 @@ static int build_filelist_from_mtree(alpm_handle_t *handle, alpm_pkg_t *pkg, str
 	char *mtree_data = NULL;
 	struct archive *mtree;
 	struct archive_entry *mtree_entry = NULL;
+	alpm_filelist_t filelist;
 
 	_alpm_log(handle, ALPM_LOG_DEBUG,
 			"found mtree for package %s, getting file list\n", pkg->filename);
 
-	/* throw away any files we might have already found */
-	for(i = 0; i < pkg->files.count; i++) {
-		free(pkg->files.files[i].name);
-	}
-	free(pkg->files.files);
-	pkg->files.files = NULL;
-	pkg->files.count = 0;
+	memset(&filelist, 0, sizeof(alpm_filelist_t));
 
 	/* create a new archive to parse the mtree and load it from archive into memory */
 	/* TODO: split this into a function */
@@ -478,7 +473,7 @@ static int build_filelist_from_mtree(alpm_handle_t *handle, alpm_pkg_t *pkg, str
 		size = archive_read_data(archive, mtree_data + mtree_cursize, ALPM_BUFFER_SIZE);
 
 		if(size < 0) {
-			_alpm_log(handle, ALPM_LOG_ERROR, _("error while reading package %s: %s\n"),
+			_alpm_log(handle, ALPM_LOG_DEBUG, _("error while reading package %s: %s\n"),
 					pkg->filename, archive_error_string(archive));
 			handle->pm_errno = ALPM_ERR_LIBARCHIVE;
 			goto error;
@@ -491,7 +486,7 @@ static int build_filelist_from_mtree(alpm_handle_t *handle, alpm_pkg_t *pkg, str
 	}
 
 	if(archive_read_open_memory(mtree, mtree_data, mtree_cursize)) {
-		_alpm_log(handle, ALPM_LOG_ERROR,
+		_alpm_log(handle, ALPM_LOG_DEBUG,
 				_("error while reading mtree of package %s: %s\n"),
 				pkg->filename, archive_error_string(mtree));
 		handle->pm_errno = ALPM_ERR_LIBARCHIVE;
@@ -510,23 +505,38 @@ static int build_filelist_from_mtree(alpm_handle_t *handle, alpm_pkg_t *pkg, str
 			continue;
 		}
 
-		if(add_entry_to_files_list(&pkg->files, &files_size, mtree_entry, path) < 0) {
+		if(add_entry_to_files_list(&filelist, &files_size, mtree_entry, path) < 0) {
 			goto error;
 		}
 	}
 
 	if(ret != ARCHIVE_EOF && ret != ARCHIVE_OK) { /* An error occurred */
-		_alpm_log(handle, ALPM_LOG_ERROR, _("error while reading mtree of package %s: %s\n"),
+		_alpm_log(handle, ALPM_LOG_DEBUG, _("error while reading mtree of package %s: %s\n"),
 				pkg->filename, archive_error_string(mtree));
 		handle->pm_errno = ALPM_ERR_LIBARCHIVE;
 		goto error;
 	}
 
+	/* throw away any files we loaded directly from the archive */
+	for(i = 0; i < pkg->files.count; i++) {
+		free(pkg->files.files[i].name);
+	}
+	free(pkg->files.files);
+
+	/* copy over new filelist */
+	memcpy(&pkg->files, &filelist, sizeof(alpm_filelist_t));
+
 	free(mtree_data);
 	_alpm_archive_read_free(mtree);
 	_alpm_log(handle, ALPM_LOG_DEBUG, "finished mtree reading for %s\n", pkg->filename);
 	return 0;
 error:
+	/* throw away any files we loaded from the mtree */
+	for(i = 0; i < filelist.count; i++) {
+		free(filelist.files[i].name);
+	}
+	free(filelist.files);
+
 	free(mtree_data);
 	_alpm_archive_read_free(mtree);
 	return -1;
@@ -609,10 +619,7 @@ alpm_pkg_t *_alpm_pkg_load_internal(alpm_handle_t *handle,
 			/* building the file list: cheap way
 			 * get the filelist from the mtree file rather than scanning
 			 * the whole archive  */
-			if(build_filelist_from_mtree(handle, newpkg, archive) < 0) {
-				goto error;
-			}
-			hit_mtree = 1;
+			hit_mtree = build_filelist_from_mtree(handle, newpkg, archive) == 0;
 			continue;
 		} else if(handle_simple_path(newpkg, entry_name)) {
 			continue;
-- 
2.3.4