tar 1.33 regression on OpenBSD (extrac09 getcwd)

[Christian Weisgerber]

There is a regression in tar 1.33 on OpenBSD.  Thanks to Stefan Hagen
for figuring out the details.

 89: extracting even when . and .. are unreadable    FAILED (extrac09.at:37)    

The key part of the test:

  mkdir dir
  mkdir dir/sub
  mkdir dir/sub/extract
  genfile --file dir/sub/f
  cd dir/sub

  tar -cf archive.tar f

  chmod a-r . ..
  tar -xvf archive.tar -C extract f

And the failure of the "tar -xvf ..." command:

  tar: .: Cannot getcwd: Permission denied
  tar: Error is not recoverable: exiting now

The regression has been introduced with commit 66162927ebdf,
"Check return value from xgetcwd".  Specifically, this chunk:

------------------->
@@ -922,6 +920,8 @@ chdir_arg (char const *dir)
        {
          wd[wd_count].name = ".";
          wd[wd_count].abspath = xgetcwd ();
+         if (!wd[wd_count].abspath)
+           call_arg_fatal ("getcwd", ".");
          wd[wd_count].fd = AT_FDCWD;
          wd_count++;
        }
<-------------------

A trace shows that the native system call returns EACCES, which
conforms with POSIX.

 13845 tar      CALL  __getcwd(0x3fd723c000,1024)
 13845 tar      RET   __getcwd -1 errno 13 Permission denied

-- 
Christian "naddy" Weisgerber                          naddy@mips.inka.de