[bug #35671] Wrong error from -[NSFileManager createDirectoryAtPath:...]

[Jens Alfke]

URL:
  <http://savannah.gnu.org/bugs/?35671>

                 Summary: Wrong error from -[NSFileManager
createDirectoryAtPath:...]
                 Project: GNUstep
            Submitted by: snej
            Submitted on: Wed 29 Feb 2012 08:07:47 PM GMT
                Category: None
                Severity: 3 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any

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Details:

Calling -[NSFileManager createDirectoryAtPath: withIntermediateDirectories:
attributes: error:] with an already-existing directory whose path is (at
least?) two levels deep, returns the wrong error code. The output NSError has
code 2 (ENOENT), when it should be EEXIST. (It may be possible for other
incorrect error codes to be returned too.)

STEPS TO REPRODUCE

$ mkdir /tmp/foobar

NSError* error = nil;
[[NSFIleManager defaultManager] createDirectoryAtPath: @"/tmp/foobar"
withIntermediateDirectories: NO attributes: nil error: &error];
NSAssert(error.code == EEXIST, @"Wrong error %@", error);

DIAGNOSIS
The above method calls the older method -createDirectoryAtPath:attributes:,
and if that fails it calls -[NSError _lastError] to generate the NSError to be
returned. This assumes the relevant error code is contained in errno.

However, in the case where the directory already exists, the older method
returns NO after a successful stat() call, so errno never actually gets set to
EEXIST. Instead the value from the previous error (whatever that was) is left
behind.

The best fix appears to be to manually set errno=EEXIST in this situation.
(See patch below.)

There may be other code paths in that method that have similar issues; I
haven't checked.

CONFIGURATION 
URL: http://svn.gna.org/svn/gnustep/libs/base/trunk/Source 
Repository Root: http://svn.gna.org/svn/gnustep 
Repository UUID: 72102866-910b-0410-8b05-ffd578937521 
Revision: 34837 
My OS is Ubuntu 11 (current according to software update). 
I'm compiling with Clang 3.1 (trunk 151546). 

PATCH

Index: NSFileManager.m
===================================================================
--- NSFileManager.m     (revision 34837)
+++ NSFileManager.m     (working copy)
@@ -854,6 +854,7 @@
            {
              ASSIGN(_lastError,
                @"Could not create directory - already exists");
+             errno = EEXIST;
              return NO;
            }
        }





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