Re: [PATCH] Cygwin: rmdir: fail if last component is a symlink, as on Linux

[Ken Brown]

On 9/22/2019 1:18 PM, Ken Brown wrote:
[...]
> @@ -354,6 +353,25 @@ rmdir (const char *dir)
>   
> __try
>   {
> +  if (!*dir)
> + {
> +   set_errno (ENOENT);
> +   __leave;
> + }
> +
> +  /* Following Linux, do not resolve the last component of DIR if
> +  it is a symlink, even if DIR has a trailing slash.  Achieve
> +  this by stripping trailing slashes or backslashes.  */
> +  if (isdirsep (dir[strlen (dir) - 1]))
> + {
> +   /* This converts // to /, but since both give ENOTEMPTY,
> +  we're okay.  */
> +   char *buf;
> +   char *p = stpcpy (buf = tp.c_get (), dir) - 1;

I forgot to declare tp.  v2 is on the way.

Ken

[PATCH] Cygwin: rmdir: fail if last component is a symlink, as on Linux

[Ken Brown]

If the last component of the directory name is a symlink followed by a
slash, rmdir should fail, even if the symlink resolves to an existing
empty directory.

mkdir was similarly fixed in 2009 in commit
52dba6a5c45e8d8ba1e237a15213311dc11d91fb.  Modify a comment to clarify
the purpose of that commit.

Addresses https://cygwin.com/ml/cygwin/2019-09/msg00221.html.
---
 winsup/cygwin/dir.cc | 26 ++
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/winsup/cygwin/dir.cc b/winsup/cygwin/dir.cc
index b757851d5..f65c9bdad 100644
--- a/winsup/cygwin/dir.cc
+++ b/winsup/cygwin/dir.cc
@@ -305,15 +305,14 @@ mkdir (const char *dir, mode_t mode)
 
   __try
 {
-  /* POSIX says mkdir("symlink-to-missing/") should create the
-directory "missing", but Linux rejects it with EEXIST.  Copy
-Linux behavior for now.  */
-
   if (!*dir)
{
  set_errno (ENOENT);
  __leave;
}
+  /* Following Linux, do not resolve the last component of DIR if
+it is a symlink, even if DIR has a trailing slash.  Achieve
+this by stripping trailing slashes or backslashes.  */
   if (isdirsep (dir[strlen (dir) - 1]))
{
  /* This converts // to /, but since both give EEXIST, we're okay.  */
@@ -354,6 +353,25 @@ rmdir (const char *dir)
 
   __try
 {
+  if (!*dir)
+   {
+ set_errno (ENOENT);
+ __leave;
+   }
+
+  /* Following Linux, do not resolve the last component of DIR if
+it is a symlink, even if DIR has a trailing slash.  Achieve
+this by stripping trailing slashes or backslashes.  */
+  if (isdirsep (dir[strlen (dir) - 1]))
+   {
+ /* This converts // to /, but since both give ENOTEMPTY,
+we're okay.  */
+ char *buf;
+ char *p = stpcpy (buf = tp.c_get (), dir) - 1;
+ dir = buf;
+ while (p > dir && isdirsep (*p))
+   *p-- = '\0';
+   }
   if (!(fh = build_fh_name (dir, PC_SYM_NOFOLLOW)))
__leave;   /* errno already set */;
 
-- 
2.21.0