Re: lock: more tests

[Bruno Haible]

The new test-once1 test crashes on FreeBSD 11, through abort().
This is because newer versions of FreeBSD now have pthread_cancel
in libc (older versions had it only in libthread, libthr), thus
the macro pthread_in_use() produces the value 1, but pthread_once()
returns ENOSYS. (Cf.
https://github.com/freebsd/freebsd/blob/master/lib/libc/gen/_pthread_stubs.c )

This fixes it.

I considered adding an autoconf test for the presence of pthread_cancel
versus pthread_create in libc vs. libpthread (rather than a #ifdef __FreeBSD__).
But we want binaries built with older versions of FreeBSD to work with newer
versions of FreeBSD as well; an autoconf test cannot do this.


2018-02-17  Bruno Haible  <address@hidden>

        lock: Fix test-once1 crash on FreeBSD11.
        * lib/glthread/lock.h: On FreeBSD, test the weak value of the symbol
        'pthread_create', not 'pthread_cancel'.

diff --git a/lib/glthread/lock.h b/lib/glthread/lock.h
index 87d9df1..dd8e1f8 100644
--- a/lib/glthread/lock.h
+++ b/lib/glthread/lock.h
@@ -149,8 +149,18 @@ extern int glthread_in_use (void);
 #  endif
 
 #  if !PTHREAD_IN_USE_DETECTION_HARD
-#   pragma weak pthread_cancel
-#   define pthread_in_use() (pthread_cancel != NULL)
+    /* On most platforms, pthread_cancel or pthread_kill can be used to
+       determine whether libpthread is in use.
+       On newer versions of FreeBSD, however, this is no longer possible,
+       because pthread_cancel and pthread_kill got added to libc.  Therefore
+       use pthread_create to test whether libpthread is in use.  */
+#   if defined __FreeBSD__ || defined __DragonFly__ /* FreeBSD */
+#    pragma weak pthread_create
+#    define pthread_in_use() (pthread_create != NULL)
+#   else /* glibc, NetBSD, OpenBSD, IRIX, OSF/1, Solaris */
+#    pragma weak pthread_cancel
+#    define pthread_in_use() (pthread_cancel != NULL)
+#   endif
 #  endif
 
 # else