Handle removal of empty directories properly

This addresses FS#25141. We shouldn't remove every empty directory we
come across during the removal process unless it is truly not known to
any other package. This will prevent removal of essential directories
such as '/var/lock/'.

This is accomplished by first checking the empty/non-empty status of a
directory, which was previously done implicitly by calling rmdir() and
ignoring errors. We do this to avoid the next (new) check in most cases,
which is to look at all local packages to see if the to-be-removed
directory is present in another packages' filelist. If we do not find it
anywhere, then we remove it, else we keep the file around.

The pactest has been updated to test more cases, as well as finding a
flaw in the original expected to fail case- we need separate DIR and
FILE based EXIST rules.

Signed-off-by: Dan McGee <dan@archlinux.org>

1 files changed, 39 insertions, 6 deletions

diff --git a/lib/libalpm/remove.c b/lib/libalpm/remove.c
index b15dbaa5..c2a8ad2c 100644
--- a/lib/libalpm/remove.c
+++ b/lib/libalpm/remove.c
@@ -232,8 +232,8 @@ static void unlink_file(alpm_handle_t *handle, alpm_pkg_t *info,
 	 * see the big comment block in db_find_fileconflicts() for an
 	 * explanation. */
 	if(alpm_list_find_str(skip_remove, fileobj->name)) {
-		_alpm_log(handle, ALPM_LOG_DEBUG, "%s is in skip_remove, skipping removal\n",
-				file);
+		_alpm_log(handle, ALPM_LOG_DEBUG,
+				"%s is in skip_remove, skipping removal\n", file);
 		return;
 	}
 
@@ -247,11 +247,44 @@ static void unlink_file(alpm_handle_t *handle, alpm_pkg_t *info,
 	}
 
 	if(S_ISDIR(buf.st_mode)) {
-		if(rmdir(file)) {
-			/* this is okay, other packages are probably using it (like /usr) */
-			_alpm_log(handle, ALPM_LOG_DEBUG, "keeping directory %s\n", file);
+		ssize_t files = _alpm_files_in_directory(handle, file, 0);
+		/* if we have files, no need to remove the directory */
+		if(files > 0) {
+			_alpm_log(handle, ALPM_LOG_DEBUG, "keeping directory %s (contains files)\n",
+					file);
+		} else if(files < 0) {
+			_alpm_log(handle, ALPM_LOG_DEBUG,
+					"keeping directory %s (could not count files)\n", file);
 		} else {
-			_alpm_log(handle, ALPM_LOG_DEBUG, "removing directory %s\n", file);
+			/* one last check- does any other package own this file? */
+			alpm_list_t *local, *local_pkgs;
+			int found = 0;
+			local_pkgs = _alpm_db_get_pkgcache(handle->db_local);
+			for(local = local_pkgs; local && !found; local = local->next) {
+				alpm_pkg_t *local_pkg = local->data;
+				alpm_list_t *files;
+
+				/* we duplicated the package when we put it in the removal list, so we
+				 * so we can't use direct pointer comparison here. */
+				if(_alpm_pkg_cmp(info, local_pkg) == 0) {
+					continue;
+				}
+				files = alpm_pkg_get_files(local_pkg);
+				if(_alpm_filelist_contains(files, fileobj->name)) {
+					_alpm_log(handle, ALPM_LOG_DEBUG,
+							"keeping directory %s (owned by %s)\n", file, local_pkg->name);
+					found = 1;
+				}
+			}
+			if(!found) {
+				if(rmdir(file)) {
+					_alpm_log(handle, ALPM_LOG_DEBUG,
+							"directory removal of %s failed: %s\n", file, strerror(errno));
+				} else {
+					_alpm_log(handle, ALPM_LOG_DEBUG,
+							"removed directory %s (no remaining owners)\n", file);
+				}
+			}
 		}
 	} else {
 		/* if the file needs backup and has been modified, back it up to .pacsave */