canonicalize loop-detection failure

[Jim Meyering]

Thanks to Bob's buildbot, I spotted a problem with my recent change.
Without this, the test mentioned below would fail with a diagnostic
about "../s" not being found, rather than saying that it'd detected
a symlink loop.  Here's the patch I'll push as soon as tests pass.

>From 05552c43d21f272e927663aae4bc810e17d4d785 Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Fri, 28 Sep 2007 23:26:49 +0200
Subject: [PATCH] Fix canonicalize loop-detection corner case.

Do not attempt to stat the symlink values stored via seen_triple.
Without this, coreutils' tests/misc/readlink-fp-loop test would fail
on linux-2.6.18, (but not 2.6.22).
* lib/canonicalize.c (seen_triple): Use triple_compare_ino_str, not
triple_compare.  The former compares dev,ino,filename, while the latter
would actually stat dirname(filename) when dev and ino were equal.
* lib/hash-triple.c: Install <string.h>.
(STREQ): Define.
(triple_compare_ino_str): New function.
* lib/hash-triple.h (triple_compare_ino_str): Declare it.

Signed-off-by: Jim Meyering <address@hidden>
---
 ChangeLog          |   14 ++++++++++++++
 lib/canonicalize.c |    2 +-
 lib/hash-triple.c  |   11 +++++++++++
 lib/hash-triple.h  |    1 +
 4 files changed, 27 insertions(+), 1 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 80a7159..44972ec 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+2007-09-28  Jim Meyering  <address@hidden>
+
+       Fix canonicalize loop-detection corner case.
+       Do not attempt to stat the symlink values stored via seen_triple.
+       Without this, coreutils' tests/misc/readlink-fp-loop test would fail
+       on linux-2.6.18, (but not 2.6.22).
+       * lib/canonicalize.c (seen_triple): Use triple_compare_ino_str, not
+       triple_compare.  The former compares dev,ino,filename, while the latter
+       would actually stat dirname(filename) when dev and ino were equal.
+       * lib/hash-triple.c: Install <string.h>.
+       (STREQ): Define.
+       (triple_compare_ino_str): New function.
+       * lib/hash-triple.h (triple_compare_ino_str): Declare it.
+
 2007-09-28  Eric Blake  <address@hidden>

        Enforce that AC_REPLACE_FUNCS files exist.
diff --git a/lib/canonicalize.c b/lib/canonicalize.c
index af2703c..bbf3855 100644
--- a/lib/canonicalize.c
+++ b/lib/canonicalize.c
@@ -135,7 +135,7 @@ seen_triple (Hash_table **ht, char const *filename, struct 
stat const *st)
       *ht = hash_initialize (initial_capacity,
                            NULL,
                            triple_hash,
-                           triple_compare,
+                           triple_compare_ino_str,
                            triple_free);
       if (*ht == NULL)
        xalloc_die ();
diff --git a/lib/hash-triple.c b/lib/hash-triple.c
index 2644b5f..a65a4db 100644
--- a/lib/hash-triple.c
+++ b/lib/hash-triple.c
@@ -22,11 +22,14 @@
 #include "hash-triple.h"

 #include <stdlib.h>
+#include <string.h>

 #include "hash-pjw.h"
 #include "same.h"
 #include "same-inode.h"

+#define STREQ(a, b) (strcmp ((a), (b)) == 0)
+
 /* Hash an F_triple, and *do* consider the file name.  */
 size_t
 triple_hash (void const *x, size_t table_size)
@@ -57,6 +60,14 @@ triple_compare (void const *x, void const *y)
   return (SAME_INODE (*a, *b) && same_name (a->name, b->name)) ? true : false;
 }

+bool
+triple_compare_ino_str (void const *x, void const *y)
+{
+  struct F_triple const *a = x;
+  struct F_triple const *b = y;
+  return (SAME_INODE (*a, *b) && STREQ (a->name, b->name)) ? true : false;
+}
+
 /* Free an F_triple.  */
 void
 triple_free (void *x)
diff --git a/lib/hash-triple.h b/lib/hash-triple.h
index 7abe970..51863c9 100644
--- a/lib/hash-triple.h
+++ b/lib/hash-triple.h
@@ -16,6 +16,7 @@ struct F_triple
 extern size_t triple_hash (void const *x, size_t table_size);
 extern size_t triple_hash_no_name (void const *x, size_t table_size);
 extern bool triple_compare (void const *x, void const *y);
+extern bool triple_compare_ino_str (void const *x, void const *y);
 extern void triple_free (void *x);

 #endif
--
1.5.3.2.99.ge4b2-dirty