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Message-ID: <00F8D6E8AB0DD3118F1A006008186C9607C7EC@server1.axonet.com.au>
From: Andrew Dalgleish <andrewd AT axonet DOT com DOT au>
To: cygwin-developers AT sourceware DOT cygnus DOT com
Subject: symlink() bug + patch
Date: Fri, 17 Dec 1999 19:03:12 +1100
X-Priority: 3
MIME-Version: 1.0
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Content-Type: text/plain

There is a bug in symlink() if "path2" (SUSV2 docs) already exists.
If path2 is already a symlink, then the target of that symlink is
replaced instead of path2.

"ln -s" is not affected by this bug.

I first noticed this when I screwed up my gcc specs file and
re-extracted Mumit's tar file.
The symlink "libstdc++.a" contains a few "../", so tar created a file
several directories up the tree.

A simpler example is this:

bash.exe-2.02$ touch foo
bash.exe-2.02$ ln -s foo bar
bash.exe-2.02$ tar czf hum foo bar
bash.exe-2.02$ ls -l
total 2
lrw-r--r--   1 andrewd  Domain U       14 Dec 17 18:15 bar -> foo
-rw-r--r--   1 andrewd  Domain U        0 Dec 17 18:15 foo
-rw-r--r--   1 andrewd  Domain U      158 Dec 17 18:15 hum
bash.exe-2.02$ tar xzf hum
bash.exe-2.02$ ls -l
total 3
lrw-r--r--   1 andrewd  Domain U       14 Dec 17 18:15 bar -> foo
lrw-r--r--   1 andrewd  Domain U       14 Dec 17 18:15 foo -> foo
-rw-r--r--   1 andrewd  Domain U      158 Dec 17 18:15 hum
bash.exe-2.02$

Currently symlink() sets errno to EBADRQC or ELOOP (eg foo -> foo).

Here is a patch to make symlink() behave correctly.
(ie return -1 and set errno to EEXIST)

This patch is relative to cygwin-src-19991215.tar.gz

Regards,
Andrew Dalgleish



--- winsup/path.cc.orig Sun Dec 12 03:14:38 1999
+++ winsup/path.cc      Fri Dec 17 17:50:04 1999
@@ -1999,7 +1999,7 @@
       goto done;
     }

-  fd = _open (frompath, O_WRONLY | O_CREAT | O_BINARY, 0);
+  fd = _open (frompath, O_WRONLY | O_CREAT | O_EXCL | O_BINARY, 0);
   if (fd >= 0)
     {
       char buf[sizeof (SYMLINK_COOKIE) + MAX_PATH + 10];