Around 18 o'clock on Feb 19, Juliusz Chroboczek wrote:
> Why's that? Is setjmp/longjmp verboten in modules, or is FreeType
> doing something non-portable?
Yes, it appears that setjmp/longjmp are not permitted in any XFree86 code.
Not by intent, but by implementation. Here's what I found in the
libc_wrapper code:
int
xf86setjmp(xf86jmp_buf xf86env)
{
return setjmp((void *)xf86env);
}
void
xf86longjmp(xf86jmp_buf xf86env, int val)
{
longjmp((void *)xf86env, val);
}
Given the way setjmp and longjmp work, there's no way these will ever be
useful -- the stack frame from which setjmp operates will disappear after
xf86setjmp returns, any call to xf86longjmp after that will jump into a
garbage stack frame and explode.
Here's a patch which has applications call the real setjmp/longjmp
directly (and makes xf86jmp_buf larger than jmp_buf). Testing would be
greatly appreciated.
-keith
Index: hw/xfree86/loader/xf86sym.c
===================================================================
RCS file: /home/x-cvs/xc/programs/Xserver/hw/xfree86/loader/xf86sym.c,v
retrieving revision 1.224
diff -u -r1.224 xf86sym.c
--- hw/xfree86/loader/xf86sym.c 9 Feb 2003 00:18:18 -0000 1.224
+++ hw/xfree86/loader/xf86sym.c 19 Feb 2003 19:26:32 -0000
@@ -26,6 +26,7 @@
#define INCLUDE_DEPRECATED 1
#include <fcntl.h>
+#include <setjmp.h>
#include "sym.h"
#include "misc.h"
#include "mi.h"
@@ -887,8 +888,8 @@
SYMFUNC(xf86shmat)
SYMFUNC(xf86shmdt)
SYMFUNC(xf86shmctl)
- SYMFUNC(xf86setjmp)
- SYMFUNC(xf86longjmp)
+ SYMFUNCALIAS("xf86setjmp",setjmp)
+ SYMFUNCALIAS("xf86longjmp",longjmp)
#ifdef XF86DRI
/* These may have more general uses, but
for now, they are only used by the DRI.
Index: hw/xfree86/os-support/xf86_libc.h
===================================================================
RCS file: /home/x-cvs/xc/programs/Xserver/hw/xfree86/os-support/xf86_libc.h,v
retrieving revision 3.54
diff -u -r3.54 xf86_libc.h
--- hw/xfree86/os-support/xf86_libc.h 19 Sep 2002 13:22:02 -0000 3.54
+++ hw/xfree86/os-support/xf86_libc.h 19 Feb 2003 19:25:51 -0000
@@ -71,7 +71,7 @@
typedef int xf86key_t;
/* setjmp/longjmp */
-typedef int xf86jmp_buf[20];
+typedef int xf86jmp_buf[100];
/* for setvbuf */
#define XF86_IONBF 1
Index: hw/xfree86/os-support/shared/libc_wrapper.c
===================================================================
RCS file: /home/x-cvs/xc/programs/Xserver/hw/xfree86/os-support/shared/libc_wrapper.c,v
retrieving revision 1.86
diff -u -r1.86 libc_wrapper.c
--- hw/xfree86/os-support/shared/libc_wrapper.c 31 May 2002 18:46:02 -0000 1.86
+++ hw/xfree86/os-support/shared/libc_wrapper.c 19 Feb 2003 19:25:14 -0000
@@ -1944,16 +1944,3 @@
return -1;
}
#endif /* HAVE_SYSV_IPC */
-
-int
-xf86setjmp(xf86jmp_buf xf86env)
-{
- return setjmp((void *)xf86env);
-}
-
-void
-xf86longjmp(xf86jmp_buf xf86env, int val)
-{
- longjmp((void *)xf86env, val);
-}
-
