ports/181052: [patch] make lang/lua not hang on thread creation

[Vitaly Magerya]

>Number:         181052
>Category:       ports
>Synopsis:       [patch] make lang/lua not hang on thread creation
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-ports-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Mon Aug 05 13:50:00 UTC 2013
>Closed-Date:
>Last-Modified:
>Originator:     Vitaly Magerya
>Release:        FreeBSD 9.1 amd64
>Organization:
>Environment:
>Description:
Currently lang/lua links the 'lua' binary without -pthread flag;
this results in any call to 'pthread_create' to completely hang
the program.

Normally this wouldn't be an issue, since Lua doesn't use any
threading functions, but the problem propagates to all the C
extensions as well. For example, if you'll install devel/lgi
(the GObject/Gtk bindings), and try this simple program:

    $ lua-5.1
    Lua 5.1.5  Copyright (C) 1994-2012 Lua.org, PUC-Rio
    > lgi = require 'lgi'
    > gtk = lgi.Gtk
    > gtk.FileChooserDialog {}

.. it will hang at this point. The reason being that Gtk uses
threads internally and tries to spawn a few when you create a
FileChooser object.

That is to say, this problem makes lang/lgi basically unusable,
and prevents any kind of Lua Gtk programs working on FreeBSD.

More directly, you can create an extension that calls
'pthread_create':

    $ cat >test.c <<'EOF'
    #include <lauxlib.h>
    #include <lua.h>
    #include <pthread.h>
    #include <stdio.h>

    static void *
    thread_func(void *arg)
    {
        pthread_exit(0);
    }

    static int
    test(lua_State *L)
    {
        pthread_t thread;
        printf("PTHREAD CREATE\n");
        pthread_create(&thread, NULL, thread_func, NULL);
        printf("PTHREAD JOIN\n");
        pthread_join(thread, NULL);
        printf("DONE\n");
    }

    static const struct luaL_Reg lib[] = {
        {"test", test},
        {NULL, NULL}
    };

    LUALIB_API int
    luaopen_test(lua_State *L)
    {
    #if LUA_VERSION_NUM < 502
        luaL_register(L, "test", lib);
    #else
        luaL_newlib(L, lib);
    #endif
        return 1;
    }
    EOF

    $ cc -I/usr/local/include/lua51 -shared -pthread -fPIC -o test.so test.c

    $ lua-5.1
    Lua 5.1.5  Copyright (C) 1994-2012 Lua.org, PUC-Rio
    > test = require "test"
    > test.test()
    PTHREAD CREATE

.. and again, it hangs.
>How-To-Repeat:

>Fix:
See the attached patch. With it both 'lua' and 'lua.so' link
with -pthread.

Note that lang/lua52 and lang/luajit are affected too, but this
PR only deals with lang/lua.

Patch attached with submission follows:

diff -ruN lua.orig/Makefile lua/Makefile
--- lua.orig/Makefile	2013-04-23 17:20:25.000000000 +0300
+++ lua/Makefile	2013-08-05 16:02:33.000000000 +0300
@@ -33,7 +33,7 @@
 MAKE_ARGS=	__MAKE_CONF=${NONEXISTENT}
 # liblua.so requires libm, so make sure it has an explicit dependency
 # so that applications need not second-guess lua's dependencies.
-LDFLAGS+=	-lm
+LDFLAGS+=	-lm -pthread
 
 MAN1=		lua-${LUA_VER}.1 luac-${LUA_VER}.1
 DOCSDIR=	${PREFIX}/share/doc/${LUA_SUBDIR}
diff -ruN lua.orig/files/patch-src-Makefile lua/files/patch-src-Makefile
--- lua.orig/files/patch-src-Makefile	2012-07-14 16:54:48.000000000 +0300
+++ lua/files/patch-src-Makefile	2013-08-05 15:57:29.000000000 +0300
@@ -1,6 +1,6 @@
---- Makefile.orig	2008-01-19 17:37:58.000000000 -0200
-+++ Makefile	2008-08-10 16:00:41.000000000 -0300
-@@ -9,7 +9,8 @@
+--- Makefile.orig	2012-02-13 22:41:22.000000000 +0200
++++ Makefile	2013-08-05 15:56:32.000000000 +0300
+@@ -9,10 +9,11 @@
  
  CC= gcc
  CFLAGS= -O2 -Wall $(MYCFLAGS)
@@ -9,7 +9,11 @@
 +AR= ar
  RANLIB= ranlib
  RM= rm -f
- LIBS= -lm $(MYLIBS)
+-LIBS= -lm $(MYLIBS)
++LIBS= -lm -pthread $(MYLIBS)
+ 
+ MYCFLAGS=
+ MYLDFLAGS=
 @@ -31,12 +32,13 @@
  
  LUA_T=	lua


>Release-Note:
>Audit-Trail:
>Unformatted: