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Date: Sun, 8 Apr 2012 17:30:18 GMT
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To: freebsd-bugs@FreeBSD.org
From: Jilles Tjoelker <jilles@stack.nl>
Cc: 
Subject: Re: kern/166706: [libc] sem_open(3) incorrectly returns the already
 opened named semaphore handle when O_EXCL is used [regression]
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The following reply was made to PR kern/166706; it has been noted by GNATS.

From: Jilles Tjoelker <jilles@stack.nl>
To: bug-followup@FreeBSD.org, davidxu@freebsd.org
Cc: igaztanaga@gmail.com
Subject: Re: kern/166706: [libc] sem_open(3) incorrectly returns the already
 opened named semaphore handle when O_EXCL is used [regression]
Date: Sun, 8 Apr 2012 19:26:39 +0200

 > [sem_new.c may return success with O_CREAT|O_EXCL if the semaphore
 > already exists]
 
 The code in sem_new.c will happily add another reference to an already
 open semaphore, even if O_CREAT|O_EXCL were specified.
 
 The below patch fixes this by adding an extra check. It makes the
 submitter's test program pass again on head.
 
 What do you think?
 
 Index: lib/libc/gen/sem_new.c
 ===================================================================
 --- lib/libc/gen/sem_new.c	(revision 233702)
 +++ lib/libc/gen/sem_new.c	(working copy)
 @@ -162,10 +162,16 @@
  	_pthread_mutex_lock(&sem_llock);
  	LIST_FOREACH(ni, &sem_list, next) {
  		if (strcmp(name, ni->name) == 0) {
 -			ni->open_count++;
 -			sem = ni->sem;
 -			_pthread_mutex_unlock(&sem_llock);
 -			return (sem);
 +			if ((flags & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL)) {
 +				_pthread_mutex_unlock(&sem_llock);
 +				errno = EEXIST;
 +				return (SEM_FAILED);
 +			} else {
 +				ni->open_count++;
 +				sem = ni->sem;
 +				_pthread_mutex_unlock(&sem_llock);
 +				return (sem);
 +			}
  		}
  	}
  
 
 -- 
 Jilles Tjoelker