[pacman-dev] [PATCH] can_remove_file: do not follow symlinks

[Joseph Burt]

The symlink itself should be checked, not its target.

Signed-off-by: Joseph Burt <caseorum at gmail.com>
---

This check also does more harm than good at the moment. If it fails once, 
the rest of the package files are silently left on the filesystem. 
Without this check, at least only the ones that failed to unlink would
be left, and the failures logged.

What if the check for removal permissions happened at the very beginning
of a package removal, and aborted it on failure? Would I step on any toes
there?

 lib/libalpm/remove.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/libalpm/remove.c b/lib/libalpm/remove.c
index 45f7c2f..48945ad 100644
--- a/lib/libalpm/remove.c
+++ b/lib/libalpm/remove.c
@@ -29,6 +29,7 @@
 #include <dirent.h>
 #include <regex.h>
 #include <unistd.h>
+#include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 
@@ -337,8 +338,8 @@ static int can_remove_file(alpm_handle_t *handle, const alpm_file_t *file)
 
 	/* If we fail write permissions due to a read-only filesystem, abort.
 	 * Assume all other possible failures are covered somewhere else */
-	if(_alpm_access(handle, NULL, filepath, W_OK) == -1) {
-		if(errno != EACCES && errno != ETXTBSY && access(filepath, F_OK) == 0) {
+	if(faccessat(AT_FDCWD, filepath, W_OK, AT_SYMLINK_NOFOLLOW) == -1) {
+		if(errno != EACCES && errno != ETXTBSY && faccessat(AT_FDCWD, filepath, F_OK, AT_SYMLINK_NOFOLLOW) == 0) {
 			/* only return failure if the file ACTUALLY exists and we can't write to
 			 * it - ignore "chmod -w" simple permission failures */
 			_alpm_log(handle, ALPM_LOG_ERROR, _("cannot remove file '%s': %s\n"),
-- 
2.9.2