Re: pthread_sigmask and glibc

[Bruno Haible]

Hi Eric,

> doc/posix-functions/pthread_sigmask.texi does not mention any issues 
> with glibc, but the pthread_sigmask module ends up replacing 
> pthread_sigmask anyways:
> 
> configure:7526: checking for pthread_sigmask
> configure:7526: gcc -o conftest -g -O2   conftest.c  >&5
> /tmp/ccRmi1Nr.o: In function `main':
> /home/remote/eblake/gnulib/testdir20236/build/conftest.c:76: undefined 
> reference to `pthread_sigmask'
> 
> GNULIB_PTHREAD_SIGMASK='1'
> HAVE_PTHREAD_SIGMASK='0'
> LIB_PTHREAD_SIGMASK=''
> REPLACE_PTHREAD_SIGMASK='1'

I reproduce the issue with
  $ ./gnulib-tool --create-testdir --dir=/tmp/testdir --with-tests 
--single-configure pthread_sigmask

> Why? Because AC_CHECK_FUNCS_ONCE does not add the mandatory -pthread 
> compiler switch, and glibc only provides pthread_sigmask when compiling 
> for threads.  This seems fishy to me; it seems like we have a bug in 
> pthread_sigmask.m4 for not recognizing glibc's version, and populating 
> $(LIB_PTHREAD_SIGMASK) with -pthread as appropriate.

Yes. Looking at the generated configure shows

                    if test $ac_cv_func_pthread_sigmask = yes; then
                  :
    else
            HAVE_PTHREAD_SIGMASK=0
                        REPLACE_PTHREAD_SIGMASK=1
    fi

That is, the  m4_ifdef([gl_[]THREADLIB]  test evaluated to false, although
it was meant to evaluate to true. I'm applying this fix. With it, I get
in config.status:

S["GNULIB_PTHREAD_SIGMASK"]="1"
S["HAVE_PTHREAD_SIGMASK"]="1"
S["LIB_PTHREAD_SIGMASK"]="-lpthread"
S["REPLACE_PTHREAD_SIGMASK"]="0"

which is as expected.


2011-08-02  Bruno Haible  <address@hidden>

        pthread_sigmask: Actually use results of gl_THREADLIB.
        * m4/pthread_sigmask.m4 (gl_FUNC_PTHREAD_SIGMASK): Test and require
        gl_THREADLIB, not gl_[]THREADLIB.
        Reported by Eric Blake.

--- m4/pthread_sigmask.m4.orig  Wed Aug  3 01:01:53 2011
+++ m4/pthread_sigmask.m4       Wed Aug  3 01:01:52 2011
@@ -1,4 +1,4 @@
-# pthread_sigmask.m4 serial 11
+# pthread_sigmask.m4 serial 12
 dnl Copyright (C) 2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -13,8 +13,8 @@
   dnl Some packages like Emacs use --avoid=threadlib.
   dnl Write the symbol in such a way that it does not cause 'aclocal' to pick
   dnl the threadlib.m4 file that is installed in $PREFIX/share/aclocal/.
-  m4_ifdef([gl_[]THREADLIB], [
-    AC_REQUIRE([gl_[]THREADLIB])
+  m4_ifdef([gl_][THREADLIB], [
+    AC_REQUIRE([gl_][THREADLIB])
 
     if test "$gl_threads_api" = posix; then
       if test $ac_cv_func_pthread_sigmask = yes; then
-- 
In memoriam Amatore Sciesa <http://it.wikipedia.org/wiki/Amatore_Sciesa>