--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2010-03-14  Bruno Haible  <bruno@clisp.org>
+
+	* tests/test-flock.c (test_exclusive): Comment out a test that causes
+	portability problems. Instead use a simpler test.
+	(main): Check that invalid arguments are rejected only on Linux.
+
 2010-03-14  Bruno Haible  <bruno@clisp.org>
 
 	Fix bug introduced on 2009-12-31.

--- a/tests/test-flock.c
+++ b/tests/test-flock.c
@@ -58,8 +58,30 @@
   fd2 = open (file, O_RDWR, 0644);
   ASSERT (fd2 >= 0);
 
+  r = flock (fd2, LOCK_EX | LOCK_NB);
+  ASSERT (r == -1);             /* Was unable to acquire a second exclusive lock. */
+
+#if 0
+  /* The Linux manual page of flock(2) says:
+       "A process may only hold one type of lock (shared or exclusive) on a
+       file. Subsequent flock() calls on an already locked file will convert
+       an existing lock to the new lock mode."
+     So, the call below should convert the exclusive lock for fd to a shared
+     and thus succeeds.  The fact that it doesn't but instead fails is
+     apparently a bug.  */
+  /* The Solaris manual page of flock(2) says:
+       "More than one process may hold a shared lock for a file at any given
+        time, but multiple exclusive, or both shared and exclusive, locks may
+        not exist simultaneously on a file. ...
+        Requesting a lock on an object that is already locked normally causes
+        the caller to block until the lock may be acquired. If LOCK_NB is
+        included in operation, then this will not happen; instead, the call
+        will fail and the error EWOULDBLOCK will be returned."
+     So, the call below should fail and set errno to EWOULDBLOCK.  The fact
+     that it succeeds is apparently a bug.  */
   r = flock (fd2, LOCK_SH | LOCK_NB);
-  ASSERT (r == -1);             /* Was unable to acquire a second exclusive lock. */
+  ASSERT (r == -1);
+#endif
 
   ASSERT (flock (fd, LOCK_UN) == 0);
   ASSERT (close (fd2) == 0);
@@ -76,7 +98,9 @@
   ASSERT (fd >= 0);
   ASSERT (write (fd, "hello", 5) == 5);
 
-  /* Some impossible operation codes which should never be accepted. */
+#if defined __linux__
+  /* Invalid operation codes are rejected by the Linux implementation and by
+     the gnulib replacement,  but not by the MacOS X implementation.  */
   ASSERT (flock (fd, LOCK_SH | LOCK_EX) == -1);
   ASSERT (errno == EINVAL);
   ASSERT (flock (fd, LOCK_SH | LOCK_UN) == -1);
@@ -85,6 +109,7 @@
   ASSERT (errno == EINVAL);
   ASSERT (flock (fd, 0) == -1);
   ASSERT (errno == EINVAL);
+#endif
 
   test_shared (file, fd);
   test_exclusive (file, fd);