Re: Fwd: Re: error.c: "Unknown system error" should report errno value

[Jim Meyering]

Bruno Haible <address@hidden> wrote:

>> > "rm d" should fail at
>> > remove.c:1094  with   "cannot remove 'd':  Is a directory"
>> > but fails there with  "cannot remove 'd':  No such file or diectory"
>
> remove.c:1094 reads like this:
>
>           error (0, errno, _("cannot remove %s"),
>                  quote (full_filename (filename)));
>
> _() and quote() preserve errno, but full_filename () does not: it calls
> realloc() and free().

Good catch.  I've fixed that:

>From 035a5ca2b0fb83ca179ed7739e18bb60437bc525 Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Sun, 7 Oct 2007 21:55:42 +0200
Subject: [PATCH] Don't let a helper function modify errno.

* src/remove.c (full_filename_): Save and restore errno.
Spotted by Bruno Haible.

Signed-off-by: Jim Meyering <address@hidden>
---
 ChangeLog    |    4 ++++
 src/remove.c |    6 +++++-
 2 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 157f126..1c3b257 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2007-10-07  Jim Meyering  <address@hidden>

+       Don't let a helper function modify errno.
+       * src/remove.c (full_filename_): Save and restore errno.
+       Spotted by Bruno Haible.
+
        Reflect 2->3 GPL copyright version update in gnulib.
        * gl/lib/tempname.h: Update copyright from gnulib.
        * gl/lib/tempname.c: Likewise.
diff --git a/src/remove.c b/src/remove.c
index 3cbfe66..4f91dd4 100644
--- a/src/remove.c
+++ b/src/remove.c
@@ -305,7 +305,8 @@ right_justify (char *dst, size_t dst_len, const char *src, 
size_t src_len,
 /* Using the global directory name obstack, create the full name FILENAME.
    Return it in sometimes-realloc'd space that should not be freed by the
    caller.  Realloc as necessary.  If realloc fails, use a static buffer
-   and put as long a suffix in that buffer as possible.  */
+   and put as long a suffix in that buffer as possible.  Be careful not
+   to change errno.  */

 #define full_filename(Filename) full_filename_ (ds, Filename)
 static char *
@@ -313,6 +314,7 @@ full_filename_ (Dirstack_state const *ds, const char 
*filename)
 {
   static char *buf = NULL;
   static size_t n_allocated = 0;
+  int saved_errno = errno;

   size_t dir_len = obstack_object_size (&ds->dir_stack);
   char *dir_name = obstack_base (&ds->dir_stack);
@@ -350,6 +352,7 @@ full_filename_ (Dirstack_state const *ds, const char 
*filename)
              memcpy (static_buf, ELLIPSES_PREFIX,
                      sizeof (ELLIPSES_PREFIX) - 1);
            }
+         errno = saved_errno;
          return p;
        }

@@ -372,6 +375,7 @@ full_filename_ (Dirstack_state const *ds, const char 
*filename)
       assert (strlen (buf) + 1 == n_bytes_needed);
     }

+  errno = saved_errno;
   return buf;
 }

--
1.5.3.4.206.g58ba4