Re: invalid assumption of m4/getcwd-path-max.m4

[Eric Blake]

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According to Jim Meyering on 3/26/2005 7:17 AM:
> Thanks for reporting that.
> So the test program goes wrong on cygwin because of a
> mkdir failure when the would-be cwd_len exceeds PATH_MAX.
...
> If mkdir fails in a way (what errno value?) that cannot be confused
> with e.g., disk full, then it should be easy to adjust the test program.
> Just test for the combination of a too-large cwd_len and failed mkdir
> with that errno value.

Through cygwin 1.5.13, mkdir was failing with EINVAL, but since that does
not match POSIX, I proposed a patch to cygwin to make it fail with
ENAMETOOLONG in CVS (and the future cygwin 1.5.14).  I don't see any
reason to check for EINVAL in this patch, as I already maintain a
cygwin-specific patch to the cygwin distribution of coreutils; but there
might be other systems where ENAMETOOLONG is worth checking, making the
patch below a good idea for coreutils and gnulib.

> 
> Can you propose/test a patch?
> 

2005-03-28  Eric Blake  <address@hidden>  (tiny change)

        * getcwd-path-max.m4: Return success on systems such as cygwin
        where no absolute path name can exceed PATH_MAX.

- --
Life is short - so eat dessert first!

Eric Blake             address@hidden
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Index: m4/getcwd-path-max.m4
===================================================================
RCS file: /cvsroot/coreutils/coreutils/m4/getcwd-path-max.m4,v
retrieving revision 1.15
diff -u -p -r1.15 getcwd-path-max.m4
--- m4/getcwd-path-max.m4       23 Jan 2005 09:07:57 -0000      1.15
+++ m4/getcwd-path-max.m4       28 Mar 2005 20:05:56 -0000
@@ -98,11 +98,15 @@ main (void)
       char *c = NULL;
 
       cwd_len += DIR_NAME_SIZE;
-      /* If mkdir or chdir fails, be pessimistic and consider that
-        as a failure, too.  */
+      /* If mkdir or chdir fails, it could be that this system cannot create
+        any file with an absolute name longer than PATH_MAX, such as cygwin.
+        If so, leave fail as 0, because the current working directory can't
+        be too long for getcwd if it can't even be created.  For other
+        errors, be pessimistic and consider that as a failure, too.  */
       if (mkdir (DIR_NAME, S_IRWXU) < 0 || chdir (DIR_NAME) < 0)
        {
-         fail = 2;
+         if (! (errno == ERANGE || is_ENAMETOOLONG (errno)))
+           fail = 2;
          break;
        }