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Re: [PATCH 03/10] pthread_sigmask: new module


From: Bruno Haible
Subject: Re: [PATCH 03/10] pthread_sigmask: new module
Date: Fri, 8 Jul 2011 02:09:05 +0200
User-agent: KMail/1.9.9

Paul Eggert wrote:
> +#if @GNULIB_PTHREAD_SIGMASK@
> +# if @REPLACE_PTHREAD_SIGMASK@
> +#  undef pthread_sigmask
> +#  define pthread_sigmask sigprocmask
> +# endif
> +#elif defined GNULIB_POSIXCHECK

When I add a signature check to the unit test

*** tests/test-signal-c++.cc.orig       Thu Jul  7 21:33:01 2011
--- tests/test-signal-c++.cc    Thu Jul  7 17:34:43 2011
***************
*** 24,29 ****
--- 24,34 ----
  #include "signature.h"
  
  
+ #if GNULIB_TEST_PTHREAD_SIGMASK
+ SIGNATURE_CHECK (GNULIB_NAMESPACE::pthread_sigmask, int,
+                  (int, const sigset_t *, sigset_t *));
+ #endif
+ 
  #if GNULIB_TEST_SIGPROCMASK
  SIGNATURE_CHECK (GNULIB_NAMESPACE::sigismember, int, (const sigset_t *, int));
  SIGNATURE_CHECK (GNULIB_NAMESPACE::sigemptyset, int, (sigset_t *));

I get a compilation error like this, already on a glibc system:

test-signal-c++.cc:28:1: error: 'pthread_sigmask' is not a member of 'gnulib'
test-signal-c++.cc:28:1: note: suggested alternative:
/usr/include/bits/sigthread.h:31:12: note:   'pthread_sigmask'

and with GCC 4.3 a different one:

In file included from /usr/include/sys/ucontext.h:23:0,
                 from /usr/include/signal.h:353,
                 from ../gllib/signal.h:41,
                 from test-signal-c++.cc:22:
../gllib/signal.h:422:1: error: '::pthread_sigmask' has not been declared
../gllib/signal.h:422:1: note: suggested alternative:
../gllib/signal.h:422:1: note:   'gnulib::pthread_sigmask'
../gllib/signal.h:424:1: error: 'pthread_sigmask' was not declared in this scope
../gllib/signal.h:424:1: note: suggested alternative:
../gllib/signal.h:422:1: note:   'gnulib::pthread_sigmask'
../gllib/signal.h:424:35: error: invalid type in declaration before ';' token
In file included from /usr/include/signal.h:389:0,
                 from ../gllib/signal.h:41,
                 from test-signal-c++.cc:22:
/usr/include/bits/sigthread.h:33:41: error: 'int pthread_sigmask(int, const 
__sigset_t*, __sigset_t*)' redeclared as different kind of symbol
../gllib/signal.h:424:1: error: previous declaration of 'int pthread_sigmask'


The reason is that the code does not use one of the known idioms for C++ safe
declaration of replacement functions. These idioms are listed in
build-aux/c++defs.h. The first idiom (for a function without known bugs, but
missing on some platforms) does it already.

There is some complication due to circular includes among glibc header files;
this can be fixed like for <stdio.h>. Here's the fix:


2011-07-07  Bruno Haible  <address@hidden>

        pthread_sigmask: Make declaration C++ safe.
        * lib/signal.in.h: In two special conditions, just do an #include_next.
        (pthread_sigmask): Test HAVE_PTHREAD_SIGMASK, not REPLACE_PTHREAD_MASK.
        Invoke _GL_CXXALIAS_SYS and _GL_CXXALIASWARN.
        * m4/signal_h.m4 (gl_SIGNAL_H_DEFAULTS): Initialize
        HAVE_PTHREAD_SIGMASK, not REPLACE_PTHREAD_MASK.
        * m4/pthread_sigmask.m4 (gl_PTHREAD_SIGMASK): Set HAVE_PTHREAD_SIGMASK,
        not REPLACE_PTHREAD_MASK.
        * modules/signal (Makefile.am): Substitute HAVE_PTHREAD_SIGMASK,
        not REPLACE_PTHREAD_MASK.
        * modules/pthread_sigmask (Depends-on, configure.ac): Update condition.

--- lib/signal.in.h.orig        Fri Jul  8 02:02:44 2011
+++ lib/signal.in.h     Fri Jul  8 02:02:38 2011
@@ -20,8 +20,17 @@
 #endif
 @PRAGMA_COLUMNS@
 
-#if defined __need_sig_atomic_t || defined __need_sigset_t
-/* Special invocation convention inside glibc header files.  */
+#if defined __need_sig_atomic_t || defined __need_sigset_t || defined 
_GL_ALREADY_INCLUDING_SIGNAL_H || (defined _SIGNAL_H && !defined 
__SIZEOF_PTHREAD_MUTEX_T)
+/* Special invocation convention:
+   - Inside glibc header files.
+   - On glibc systems we have a sequence of nested includes
+     <signal.h> -> <ucontext.h> -> <signal.h>.
+     In this situation, the functions are not yet declared, therefore we cannot
+     provide the C++ aliases.
+   - On glibc systems with GCC 4.3 we have a sequence of nested includes
+     <csignal> -> </usr/include/signal.h> -> <sys/ucontext.h> -> <signal.h>.
+     In this situation, some of the functions are not yet declared, therefore
+     we cannot provide the C++ aliases.  */
 
 # @INCLUDE_NEXT@ @NEXT_SIGNAL_H@
 
@@ -30,6 +39,8 @@
 
 #ifndef address@hidden@_SIGNAL_H
 
+#define _GL_ALREADY_INCLUDING_SIGNAL_H
+
 /* Define pid_t, uid_t.
    Also, mingw defines sigset_t not in <signal.h>, but in <sys/types.h>.
    On Solaris 10, <signal.h> includes <sys/types.h>, which eventually includes
@@ -39,6 +50,8 @@
 /* The include_next requires a split double-inclusion guard.  */
 address@hidden@ @NEXT_SIGNAL_H@
 
+#undef _GL_ALREADY_INCLUDING_SIGNAL_H
+
 #ifndef address@hidden@_SIGNAL_H
 #define address@hidden@_SIGNAL_H
 
@@ -103,10 +116,13 @@
 
 
 #if @GNULIB_PTHREAD_SIGMASK@
-# if @REPLACE_PTHREAD_SIGMASK@
+# if address@hidden@
 _GL_FUNCDECL_SYS (pthread_sigmask, int,
                   (int how, const sigset_t *new_mask, sigset_t *old_mask));
 # endif
+_GL_CXXALIAS_SYS (pthread_sigmask, int,
+                  (int how, const sigset_t *new_mask, sigset_t *old_mask));
+_GL_CXXALIASWARN (pthread_sigmask);
 #elif defined GNULIB_POSIXCHECK
 # undef pthread_sigmask
 # if HAVE_RAW_DECL_PTHREAD_SIGMASK
--- m4/pthread_sigmask.m4.orig  Fri Jul  8 02:02:44 2011
+++ m4/pthread_sigmask.m4       Fri Jul  8 01:54:04 2011
@@ -1,4 +1,4 @@
-# pthread_sigmask.m4 serial 2
+# pthread_sigmask.m4 serial 3
 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,
@@ -21,6 +21,6 @@
   ])
 
   if test $ac_cv_func_pthread_sigmask = no; then
-    REPLACE_PTHREAD_SIGMASK=1
+    HAVE_PTHREAD_SIGMASK=0
   fi
 ])
--- m4/signal_h.m4.orig Fri Jul  8 02:02:44 2011
+++ m4/signal_h.m4      Fri Jul  8 01:54:04 2011
@@ -1,4 +1,4 @@
-# signal_h.m4 serial 14
+# signal_h.m4 serial 15
 dnl Copyright (C) 2007-2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -64,6 +64,7 @@
   GNULIB_SIGACTION=0;          AC_SUBST([GNULIB_SIGACTION])
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE_POSIX_SIGNALBLOCKING=1; AC_SUBST([HAVE_POSIX_SIGNALBLOCKING])
+  HAVE_PTHREAD_SIGMASK=1;      AC_SUBST([HAVE_PTHREAD_SIGMASK])
   HAVE_SIGSET_T=1;             AC_SUBST([HAVE_SIGSET_T])
   HAVE_SIGINFO_T=1;            AC_SUBST([HAVE_SIGINFO_T])
   HAVE_SIGACTION=1;            AC_SUBST([HAVE_SIGACTION])
@@ -72,5 +73,4 @@
   HAVE_TYPE_VOLATILE_SIG_ATOMIC_T=1;
                                AC_SUBST([HAVE_TYPE_VOLATILE_SIG_ATOMIC_T])
   HAVE_SIGHANDLER_T=1;         AC_SUBST([HAVE_SIGHANDLER_T])
-  REPLACE_PTHREAD_SIGMASK=0;   AC_SUBST([REPLACE_PTHREAD_SIGMASK])
 ])
--- modules/pthread_sigmask.orig        Fri Jul  8 02:02:44 2011
+++ modules/pthread_sigmask     Fri Jul  8 01:54:25 2011
@@ -7,11 +7,11 @@
 
 Depends-on:
 signal
-sigprocmask     [test $REPLACE_PTHREAD_SIGMASK = 1]
+sigprocmask     [test $HAVE_PTHREAD_SIGMASK = 0]
 
 configure.ac:
 gl_PTHREAD_SIGMASK
-if test $REPLACE_PTHREAD_SIGMASK = 1; then
+if test $HAVE_PTHREAD_SIGMASK = 0; then
   AC_LIBOBJ([pthread_sigmask])
 fi
 gl_SIGNAL_MODULE_INDICATOR([pthread_sigmask])
--- modules/signal.orig Fri Jul  8 02:02:44 2011
+++ modules/signal      Fri Jul  8 01:54:04 2011
@@ -33,13 +33,13 @@
              -e 's/@''GNULIB_SIGPROCMASK''@/$(GNULIB_SIGPROCMASK)/g' \
              -e 's/@''GNULIB_SIGACTION''@/$(GNULIB_SIGACTION)/g' \
              -e 
's|@''HAVE_POSIX_SIGNALBLOCKING''@|$(HAVE_POSIX_SIGNALBLOCKING)|g' \
+             -e 's|@''HAVE_PTHREAD_SIGMASK''@|$(HAVE_PTHREAD_SIGMASK)|g' \
              -e 's|@''HAVE_SIGSET_T''@|$(HAVE_SIGSET_T)|g' \
              -e 's|@''HAVE_SIGINFO_T''@|$(HAVE_SIGINFO_T)|g' \
              -e 's|@''HAVE_SIGACTION''@|$(HAVE_SIGACTION)|g' \
              -e 
's|@''HAVE_STRUCT_SIGACTION_SA_SIGACTION''@|$(HAVE_STRUCT_SIGACTION_SA_SIGACTION)|g'
 \
              -e 
's|@''HAVE_TYPE_VOLATILE_SIG_ATOMIC_T''@|$(HAVE_TYPE_VOLATILE_SIG_ATOMIC_T)|g' \
              -e 's|@''HAVE_SIGHANDLER_T''@|$(HAVE_SIGHANDLER_T)|g' \
-             -e 's|@''REPLACE_PTHREAD_SIGMASK''@|$(REPLACE_PTHREAD_SIGMASK)|g' 
\
              -e '/definitions of _GL_FUNCDECL_RPL/r $(CXXDEFS_H)' \
              -e '/definition of _GL_ARG_NONNULL/r $(ARG_NONNULL_H)' \
              -e '/definition of _GL_WARN_ON_USE/r $(WARN_ON_USE_H)' \

-- 
In memoriam Georges Mandel <http://en.wikipedia.org/wiki/Georges_Mandel>



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