Re: rm 8.1

[Jim Meyering]

Jim Meyering wrote:
> Ladislav Hagara wrote:
>> the behaviour of rm from last stable coreutils 8.1 is quite different
>> from previous 7.6 one.
> ....
>> Is this a bug or a new feature of rm 8.1?
>
> Thank you very much for the report!
> That is most definitely a bug.
>
> The fix has two parts:
>
> in gnulib:
>
>     The fts_open function in gnulib's fts module must not fail
>     immediately upon spotting an empty string argument.
>     That is the sole functional change.  The rest is clean-up:
>
> in coreutils:
>
>     rm: fix empty-name bug introduced with conversion to use fts
>
>     While "rm ''" would properly fail, "rm F1 '' F2" would fail
>     to remove F1 and F2, due to the empty string argument.
>     This bug was introduced on 2009-07-12, via commit 4f73ecaf,
>     "rm: rewrite to use fts".
>     * NEWS (Bug fixes): Describe it.
>     * tests/rm/empty-name: Adjust for changed diagnostic.
>     (mk_file): Define, copied from misc/ls-misc.
>     (empty-name-2): New test, for today's fix.
>     * lib/xfts.c (xfts_open): Reflect the change in fts_open, now that
>     it no longer fails immediately when one argument is the empty string.
>     Assert that the bit flags were not the cause of failure.
>     * po/POTFILES.in: Remove xfts.c.
>     * THANKS: Update.
>     Reported by Ladislav Hagara.
>
> I'll push something like the following today,
> once I've audited fts.c more closely to ensure
> that lifting the prohibition on empty names is ok.

I see no problem with zero-length names.
I suspect that the prohibition was to avoid the old SunOS4-era problem
whereby stat("",... would mistakenly succeed.  With gnulib's stat*
replacements, that can't happen now.

Here's the slightly different patch for fts.c that I've just pushed:

>From cdfe647f8d29540cdfe90cef0fa568c5d2fd4481 Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Tue, 1 Dec 2009 12:06:34 +0100
Subject: [PATCH] fts: fts_open: do not let an empty string cause immediate 
failure

This is required in support of GNU rm, for which the command
"rm A '' B" must process and remove both A and B, in spite of
the empty string argument.
* lib/fts.c (fts_open): Do not let the presence of an empty string
cause fts_open to fail immediately.  Most fts-using tools must be
able to process all arguments, in order, and can be expected to
diagnose such arguments themselves.
Also, move declaration of local, "len", "down" to initialization.
---
 ChangeLog |   11 +++++++++++
 lib/fts.c |    9 ++-------
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 07918de..6eec830 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2009-12-01  Jim Meyering  <address@hidden>
+
+       fts: fts_open: do not let an empty string cause immediate failure
+       This is required in support of GNU rm, for which the command
+       "rm A '' B" must process and remove both A and B, in spite of
+       the empty string argument.
+       * lib/fts.c (fts_open): Do not let the presence of an empty string
+       cause fts_open to fail immediately.  Most fts-using tools must be
+       able to process all arguments, in order, and can be expected to
+       diagnose such arguments themselves.
+
 2009-11-30  Eric Blake  <address@hidden>

        utimens: fix compilation error
diff --git a/lib/fts.c b/lib/fts.c
index 21c6658..39922b6 100644
--- a/lib/fts.c
+++ b/lib/fts.c
@@ -375,7 +375,6 @@ fts_open (char * const *argv,
        register size_t nitems;
        FTSENT *parent = NULL;
        FTSENT *tmp = NULL;     /* pacify gcc */
-       size_t len;
        bool defer_stat;

        /* Options check. */
@@ -474,12 +473,8 @@ fts_open (char * const *argv,

        /* Allocate/initialize root(s). */
        for (root = NULL, nitems = 0; *argv != NULL; ++argv, ++nitems) {
-               /* Don't allow zero-length file names. */
-               if ((len = strlen(*argv)) == 0) {
-                       __set_errno (ENOENT);
-                       goto mem3;
-               }
-
+               /* *Do* allow zero-length file names. */
+               size_t len = strlen(*argv);
                if ((p = fts_alloc(sp, *argv, len)) == NULL)
                        goto mem3;
                p->fts_level = FTS_ROOTLEVEL;
--
1.6.6.rc0.324.gb5bf2