Samuel Thibault · Julien Danjou · M Joonas Pihlaja · Julien Danjou · Julien Danjou · Julien Danjou
--- a/.gitignore
+++ b/.gitignore
@@ -29,3 +29,4 @@ stamp-h1
 *.pc
 *.tar.bz2
 *.tar.gz
+stubs.c
--- a/Makefile.am
+++ b/Makefile.am
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = pthread-stubs.pc
-
-if BUILD_LIB
-lib_LTLIBRARIES = libpthread-stubs.la
-libpthread_stubs_la_SOURCES = stubs.c
-endif
--- a/README
+++ b/README
-This library provides weak aliases for pthread functions not provided in libc
-or otherwise available by default.  Libraries like libxcb rely on pthread
-stubs to use pthreads optionally, becoming thread-safe when linked to
-libpthread, while avoiding any performance hit when running single-threaded.
-libpthread-stubs supports this behavior even on platforms which do not supply
-all the necessary pthread stubs.  On platforms which already supply all the
-necessary pthread stubs, this package ships only the pkg-config file
-pthread-stubs.pc, to allow libraries to unconditionally express a dependency
-on pthread-stubs and still obtain correct behavior.
+Project description
+-------------------
+
+Currently the project provides only a pkg-config [.pc] file, pthread-stubs.pc.
+The latter contains the Cflags/Libs flags applicable to programs/libraries
+that use only lightweight pthread API. See the next sections for the reasoning
+and implementation details.
+
+Historically this project used to provide either:
+ - a .pc file, when the C runtime was providing the pthread symbols
+or
+ - a .pc file and a library which implements weak stubs for the pthread symbols,
+which are not available in the C runtime.
+
+Since then, the latter case was found to have a fundamental design issue.
+
+
+Design
+------
+
+On platforms where the lightweight pthread symbols are provided by the runtime,
+the .pc files provides empty Cflags/Libs flags.
+
+Currently the following platforms fit the above category:
+ - GNU/Linux - GCC/Clang/GLibC/Musl
+ - Solaris 10 and later
+ - Cygwin
+ - GNU/Hurd
+ - GNU/kFreeBSD
+
+For others, each of Cflags/Libs expands to full blown pthread.
+
+For example:
+ - FreeBSD and derivatives
+ - OpenBSD - uses a heavily patched copy of pthread-stubs to workaround this
+ - other BSD platforms ?
+
+Unchecked:
+ - MSYS/MINGW
+ - Darwin - GCC/Clang - should be the same as their Linux counter part
+
+
+Many platforms have their own eccentric way of managing pthread compilation and
+linkage. The ones realistically supported by pthread-stubs [and projects that
+depend on it] work with '-pthread'.
+
+GCC supports -pthread for:
+Aarch64, ARM, Darwin, IA-64, MIPS, PowerPC, SPARC, x86
+Cygwin and x86 Windows may need a trivial patch for older GCC versions.
+See SVN rev 214161 and 171833/171834 respectively.
+
+
+Clang:
+Aarch64, ARM, x86 and likely others.
+
+SunCC/Oracle compiler:
+Requires -mt -lpthread. As of Solaris 10 (oldest currently supported version)
+all the pthread API lives in libc. Thus we'll _never_ get here.
+
+
+With previous design, one could get mismatched calls to the pthreads API.
+Consider the following scenario:
+ - Program and/or its dependencies links only against libpthread-stubs,
+since it uses lightweight API. Say pthread_mutex_lock.
+ - At a later stage the program and/or its dependencies dlopens a library
+which effectively [either directly or via any of its own dependencies] pulls a
+full blown pthread. Let's call that libB.
+ - The libpthread-stubs weak symbols get overridden by the libB ones.
+ - pthread_mutex_unlock is executed (which now originates from libB) and BOOM.
+
+Amount and severity of issues depend on a number of factors. In either case
+things go horribly wrong sooner on later.
+
+
+The symbols
+-----------
+
+The following list of symbols is taken from the libc provided by GLibC.
+
+It is deemed sufficient and reasonably accurate of what the 'lightweight'
+pthread symbols are, since GLibC is one of the few (the only) implementations
+which has the distinct split.
+
+Most/all other C runtime implementations provide all the pthread API in a
+single library.
+
+Note that the following list is incomplete wrt libc-2.24.so and that further
+symbols may be added in the future to bring the two closer. Adding symbols
+which are not available in GLibC libc is NOT allowed.
+
+   pthread_condattr_destroy
+   pthread_condattr_init
+   pthread_cond_broadcast
+   pthread_cond_destroy
+   pthread_cond_init
+   pthread_cond_signal
+   pthread_cond_timedwait
+   pthread_cond_wait
+   pthread_equal
+   pthread_exit
+   pthread_mutex_destroy
+   pthread_mutex_init
+   pthread_mutex_lock
+   pthread_mutex_unlock
+   pthread_self
--- a/autogen.sh
+++ b/autogen.sh
 #! /bin/sh

-srcdir=`dirname $0`
+srcdir=`dirname "$0"`
 test -z "$srcdir" && srcdir=.

 ORIGDIR=`pwd`
-cd $srcdir
+cd "$srcdir"

 autoreconf -v --install || exit 1
-cd $ORIGDIR || exit $?
+cd "$ORIGDIR" || exit $?

-$srcdir/configure --enable-maintainer-mode "$@"
+if test -z "$NOCONFIGURE"; then
+    $srcdir/configure "$@"
+fi
--- a/configure.ac
+++ b/configure.ac
 AC_INIT([libpthread-stubs],
-        0.3,
+        0.4,
        [xcb@lists.freedesktop.org])
 AC_CONFIG_SRCDIR([pthread-stubs.pc.in])
 AM_INIT_AUTOMAKE([foreign dist-bzip2])

-AC_CONFIG_HEADERS([config.h])
+dnl Check if the following functions have stubs.
+dnl See the README for specifics about the list.
+funclist="\
+pthread_condattr_destroy \
+pthread_condattr_init \
+pthread_cond_broadcast \
+pthread_cond_destroy \
+pthread_cond_init \
+pthread_cond_signal \
+pthread_cond_timedwait \
+pthread_cond_wait \
+pthread_equal \
+pthread_exit \
+pthread_mutex_destroy \
+pthread_mutex_init \
+pthread_mutex_lock \
+pthread_mutex_unlock \
+pthread_self"

-AC_PROG_LIBTOOL
-AC_PROG_CC
+AC_CHECK_FUNCS($funclist, [], [HAVE_STUBS=no])


-dnl Detection code for compilers supporting the __attribute__((weak, alias))
-dnl feature. Original code present in unieject's repository
-dnl Diego Pettenò <flameeyes@gentoo.org>
-ac_save_CFLAGS="$CFLAGS"
-CFLAGS="$CFLAGS -Werror"
-AC_CACHE_CHECK([if compiler supports __attribute__((weak, alias))],
-	[cc_cv_attribute_alias],
-	[AC_COMPILE_IFELSE([
-		void other_function(void *foo) { }
-		void some_function(void *foo) __attribute__((weak, alias("other_function")));
-		],
-		[cc_cv_attribute_alias=yes],
-		[cc_cv_attribute_alias=no])
-	])
-CFLAGS="$ac_save_CFLAGS"
-if test "x$cc_cv_attribute_alias" = "xyes"; then
-	AC_DEFINE([SUPPORT_ATTRIBUTE_ALIAS], 1, [Define this if the compiler supports the alias attribute])
+if test "x$HAVE_STUBS" != xno; then
+    PKG_CONFIG_CFLAGS=
+    PKG_CONFIG_LIBS=
+else
+    dnl See the README why '-pthread' is deemed sufficient.
+    PKG_CONFIG_CFLAGS="-pthread"
+    PKG_CONFIG_LIBS="-pthread"
 fi

-
-PKG_CONFIG_LIBS=
-AC_CHECK_FUNCS([pthread_self pthread_mutex_init pthread_mutex_destroy pthread_mutex_lock pthread_mutex_unlock pthread_cond_init pthread_cond_destroy pthread_condattr_init pthread_condattr_destroy pthread_cond_wait pthread_cond_timedwait pthread_cond_signal pthread_cond_broadcast pthread_equal pthread_exit],
-	       [], [PKG_CONFIG_LIBS='-L${libdir} -lpthread-stubs'])
+AC_SUBST([PKG_CONFIG_CFLAGS])
 AC_SUBST([PKG_CONFIG_LIBS])
-AM_CONDITIONAL(BUILD_LIB, test "x$PKG_CONFIG_LIBS" != x)

 AC_CONFIG_FILES([Makefile pthread-stubs.pc])
 AC_OUTPUT
--- a/debian/changelog
+++ b/debian/changelog
+libpthread-stubs (0.4-1) UNRELEASED; urgency=medium
+
+  * New upstream release.
+  * Change maintainer to Debian X Strike Force.
+  * Update Vcs-* URLs to point to salsa.debian.org.
+  * Bump debhelper compat to 11.
+  * Set source format to 1.0.
+  * Switch URLs to https.
+  * Bump standards version to 4.3.0.
+
+ -- Andreas Boll <aboll@debian.org>  Thu, 07 Feb 2019 23:29:46 +0100
+
 libpthread-stubs (0.3-4) unstable; urgency=low

  * Stop building libpthread-stubs0{,-udeb} (closes: 706865).

--- a/debian/compat
+++ b/debian/compat
-9
+11
--- a/debian/control
+++ b/debian/control
 Source: libpthread-stubs
 Priority: optional
 Section: libdevel
-Maintainer: XCB Developers <xcb@lists.freedesktop.org>
+Maintainer: Debian X Strike Force <debian-x@lists.debian.org>
 Uploaders: Julien Danjou <acid@debian.org>
-Build-Depends: debhelper (>= 8.1.3), dh-autoreconf
-Standards-Version: 3.8.3
-Vcs-Git: git://anonscm.debian.org/git/collab-maint/libpthread-stubs
-Vcs-Browser: http://anonscm.debian.org/gitweb/?p=collab-maint/libpthread-stubs.git
+Build-Depends: debhelper (>= 11)
+Standards-Version: 4.3.0
+Vcs-Git: https://salsa.debian.org/xorg-team/lib/libpthread-stubs.git
+Vcs-Browser: https://salsa.debian.org/xorg-team/lib/libpthread-stubs

 Package: libpthread-stubs0-dev
 Section: libdevel

--- a/debian/copyright.debian
+++ b/debian/copyright.debian
@@ -2,7 +2,7 @@ This package was debianized by Jamey Sharp <sharpone@debian.org> on
 Fri, 24 Nov 2006 01:01:49 -0800.  The package is co-maintained by the
 XCB developers via the XCB mailing list <xcb@lists.freedesktop.org>.

-It was downloaded from http://xcb.freedesktop.org/dist
+It was downloaded from https://xcb.freedesktop.org/dist

 Upstream Authors: Jamey Sharp <sharpone@debian.org>
                  Josh Triplett <josh@freedesktop.org>

--- a/debian/rules
+++ b/debian/rules
 #!/usr/bin/make -f

-DEB_HOST_ARCH_OS ?= $(shell dpkg-architecture -qDEB_HOST_ARCH_OS)
-DEB_HOST_MULTIARCH ?= $(shell dpkg-architecture -qDEB_HOST_MULTIARCH)
-
 %:
-	dh $@ --with autoreconf --builddirectory=build
+	dh $@ --builddirectory=build

 override_dh_auto_configure: debian/copyright
 	dh_auto_configure --builddirectory=build
@@ -15,4 +12,3 @@ override_dh_auto_install:

 debian/copyright: debian/copyright.debian COPYING
 	cat $+ > $@
-
--- a/debian/source/format
+++ b/debian/source/format
+1.0
--- a/debian/watch
+++ b/debian/watch
 version=3
-http://xcb.freedesktop.org/dist/libpthread-stubs-([0-9].*)\.tar\.gz
+https://xcb.freedesktop.org/dist/libpthread-stubs-([0-9].*)\.tar\.gz
--- a/pthread-stubs.pc.in
+++ b/pthread-stubs.pc.in
@@ -3,6 +3,7 @@ exec_prefix=@exec_prefix@
 libdir=@libdir@

 Name: pthread stubs
-Description: Stubs missing from libc for standard pthread functions
+Description: Meta package for pthread symbols - defaults to heavyweight ones if the C runtime does not provide lightweight ones.
 Version: @PACKAGE_VERSION@
+Cflags: @PKG_CONFIG_CFLAGS@
 Libs: @PKG_CONFIG_LIBS@
--- a/stubs.c
+++ b/stubs.c
-/* Copyright (C) 2006 Diego Pettenò
- * Inspired by libX11 code copyright (c) 1995 David E. Wexelblat.
- *
- * Permission is hereby granted, free of charge, to any person obtaining a
- * copy of this software and associated documentation files (the "Software"),
- * to deal in the Software without restriction, including without limitation
- * the rights to use, copy, modify, merge, publish, distribute, sublicense,
- * and/or sell copies of the Software, and to permit persons to whom the
- * Software is furnished to do so, subject to the following conditions:
- * 
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- * 
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
- * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
- * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- * 
- * Except as contained in this notice, the names of the authors or their
- * institutions shall not be used in advertising or otherwise to promote the
- * sale, use or other dealings in this Software without prior written
- * authorization from the authors.
- */
-
-#include <pthread.h>
-#include <stdlib.h>
-#include "config.h"
-
-#ifndef HAVE_PTHREAD_SELF
-#define NEED_ZERO_STUB
-# ifdef SUPPORT_ATTRIBUTE_ALIAS
-int pthread_self() __attribute__ ((weak, alias ("__pthread_zero_stub")));
-# else
-#  pragma weak pthread_self = __pthread_zero_stub
-# endif
-#endif
-
-#ifndef HAVE_PTHREAD_MUTEX_INIT
-#define NEED_ZERO_STUB
-# ifdef SUPPORT_ATTRIBUTE_ALIAS
-int pthread_mutex_init() __attribute__ ((weak, alias ("__pthread_zero_stub")));
-# else
-#  pragma weak pthread_mutex_init = __pthread_zero_stub
-# endif
-#endif
-
-#ifndef HAVE_PTHREAD_MUTEX_DESTROY
-#define NEED_ZERO_STUB
-# ifdef SUPPORT_ATTRIBUTE_ALIAS
-int pthread_mutex_destroy() __attribute__ ((weak, alias ("__pthread_zero_stub")));
-# else
-#  pragma weak pthread_mutex_destroy = __pthread_zero_stub
-# endif
-#endif
-
-#ifndef HAVE_PTHREAD_MUTEX_LOCK
-#define NEED_ZERO_STUB
-# ifdef SUPPORT_ATTRIBUTE_ALIAS
-int pthread_mutex_lock() __attribute__ ((weak, alias ("__pthread_zero_stub")));
-# else
-#  pragma weak pthread_mutex_lock = __pthread_zero_stub
-# endif
-#endif
-
-#ifndef HAVE_PTHREAD_MUTEX_UNLOCK
-#define NEED_ZERO_STUB
-# ifdef SUPPORT_ATTRIBUTE_ALIAS
-int pthread_mutex_unlock() __attribute__ ((weak, alias ("__pthread_zero_stub")));
-# else
-#  pragma weak pthread_mutex_unlock = __pthread_zero_stub
-# endif
-#endif
-
-#ifndef HAVE_PTHREAD_COND_INIT
-#define NEED_ZERO_STUB
-# ifdef SUPPORT_ATTRIBUTE_ALIAS
-int pthread_cond_init() __attribute__ ((weak, alias ("__pthread_zero_stub")));
-# else
-#  pragma weak pthread_cond_init = __pthread_zero_stub
-# endif
-#endif
-
-#ifndef HAVE_PTHREAD_COND_DESTROY
-#define NEED_ZERO_STUB
-# ifdef SUPPORT_ATTRIBUTE_ALIAS
-int pthread_cond_destroy() __attribute__ ((weak, alias ("__pthread_zero_stub")));
-# else
-#  pragma weak pthread_cond_destroy = __pthread_zero_stub
-# endif
-#endif
-
-#ifndef HAVE_PTHREAD_CONDATTR_INIT
-#define NEED_ZERO_STUB
-# ifdef SUPPORT_ATTRIBUTE_ALIAS
-int pthread_condattr_init() __attribute__ ((weak, alias ("__pthread_zero_stub")));
-# else
-#  pragma weak pthread_condattr_init = __pthread_zero_stub
-# endif
-#endif
-
-#ifndef HAVE_PTHREAD_CONDATTR_DESTROY
-#define NEED_ZERO_STUB
-# ifdef SUPPORT_ATTRIBUTE_ALIAS
-int pthread_condattr_destroy() __attribute__ ((weak, alias ("__pthread_zero_stub")));
-# else
-#  pragma weak pthread_condattr_destroy = __pthread_zero_stub
-# endif
-#endif
-
-#ifndef HAVE_PTHREAD_COND_WAIT
-#define NEED_ABORT_STUB
-# ifdef SUPPORT_ATTRIBUTE_ALIAS
-int pthread_cond_wait() __attribute__ ((weak, alias ("__pthread_abort_stub")));
-# else
-#  pragma weak pthread_cond_wait = __pthread_abort_stub
-# endif
-#endif
-
-#ifndef HAVE_PTHREAD_COND_TIMEDWAIT
-#define NEED_ABORT_STUB
-# ifdef SUPPORT_ATTRIBUTE_ALIAS
-int pthread_cond_timedwait() __attribute__ ((weak, alias ("__pthread_abort_stub")));
-# else
-#  pragma weak pthread_cond_timedwait = __pthread_abort_stub
-# endif
-#endif
-
-#ifndef HAVE_PTHREAD_COND_SIGNAL
-#define NEED_ZERO_STUB
-# ifdef SUPPORT_ATTRIBUTE_ALIAS
-int pthread_cond_signal() __attribute__ ((weak, alias ("__pthread_zero_stub")));
-# else
-#  pragma weak pthread_cond_signal = __pthread_zero_stub
-# endif
-#endif
-
-#ifndef HAVE_PTHREAD_COND_BROADCAST
-#define NEED_ZERO_STUB
-# ifdef SUPPORT_ATTRIBUTE_ALIAS
-int pthread_cond_broadcast() __attribute__ ((weak, alias ("__pthread_zero_stub")));
-# else
-#  pragma weak pthread_cond_broadcast = __pthread_zero_stub
-# endif
-#endif
-
-#ifndef HAVE_PTHREAD_EQUAL
-#define NEED_EQUAL_STUB
-# ifdef SUPPORT_ATTRIBUTE_ALIAS
-int pthread_equal() __attribute__ ((weak, alias ("__pthread_equal_stub")));
-# else
-#  pragma weak pthread_equal = __pthread_equal_stub
-# endif
-#endif
-
-#ifndef HAVE_PTHREAD_EXIT
-#define NEED_EXIT_STUB
-# ifdef SUPPORT_ATTRIBUTE_ALIAS
-void pthread_exit() __attribute__ ((weak, alias ("__pthread_exit_stub")));
-# else
-#  pragma weak pthread_exit = __pthread_exit_stub
-# endif
-#endif
-
-#ifdef NEED_ZERO_STUB
-static int __pthread_zero_stub()
-{
-    return 0;
-}
-#endif
-
-#ifdef NEED_ABORT_STUB
-static int __pthread_abort_stub()
-{
-    abort();
-}
-#endif
-
-#ifdef NEED_EQUAL_STUB
-static int __pthread_equal_stub(pthread_t t1, pthread_t t2)
-{
-    return (t1 == t2);
-}
-#endif
-
-#ifdef NEED_EXIT_STUB
-static void __pthread_exit_stub(void *ret)
-{
-    exit(EXIT_SUCCESS);
-}
-#endif