Re: symlink/readlink and trailing slash

[Eric Blake]

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According to Eric Blake on 9/21/2009 4:27 PM:
> as well as audited other modules where I've recently added trailing slash 
> checks.

This is the only instance I found in my audit of existing modules touched
in the last month; and it is actually a missed optimization rather than an
out-of-bounds reference (unless anyone knows of a platform where open("")
fails to give ENOENT).

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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>From f34e1ad57eebc72dbaa7aef0181c1a7d0afff1bf Mon Sep 17 00:00:00 2001
From: Eric Blake <address@hidden>
Date: Mon, 21 Sep 2009 17:19:10 -0600
Subject: [PATCH] open, openat: minor optimization

* lib/open.c (open): If open succeeded, len is non-zero.
* lib/openat.c (rpl_openat): Likewise.

Signed-off-by: Eric Blake <address@hidden>
---
 ChangeLog    |    4 ++++
 lib/open.c   |    3 ++-
 lib/openat.c |    3 ++-
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 33dc8ae..4abbe70 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2009-09-22  Eric Blake  <address@hidden>

+       open, openat: minor optimization
+       * lib/open.c (open): If open succeeded, len is non-zero.
+       * lib/openat.c (rpl_openat): Likewise.
+
        link-follow: ensure correct result
        * m4/fcntl_h.m4 (gl_FCNTL_H): Clean up temporary file.
        * m4/link-follow.m4 (gl_FUNC_LINK_FOLLOWS_SYMLINK): Likewise, and
diff --git a/lib/open.c b/lib/open.c
index 08ecaff..7cc25bd 100644
--- a/lib/open.c
+++ b/lib/open.c
@@ -141,8 +141,9 @@ open (const char *filename, int flags, ...)
      with ENOTDIR.  */
   if (fd >= 0)
     {
+      /* We know len is positive, since open did not fail with ENOENT.  */
       size_t len = strlen (filename);
-      if (len > 0 && filename[len - 1] == '/')
+      if (filename[len - 1] == '/')
        {
          struct stat statbuf;

diff --git a/lib/openat.c b/lib/openat.c
index 7e46a26..079039f 100644
--- a/lib/openat.c
+++ b/lib/openat.c
@@ -103,8 +103,9 @@ rpl_openat (int dfd, char const *filename, int flags, ...)
      with ENOTDIR.  */
   if (fd >= 0)
     {
+      /* We know len is positive, since open did not fail with ENOENT.  */
       size_t len = strlen (filename);
-      if (len > 0 && filename[len - 1] == '/')
+      if (filename[len - 1] == '/')
        {
          struct stat statbuf;

-- 
1.6.5.rc1