Date: Mon, 16 Jun 1997 19:36:20 +0200 (MEST) From: arnej@mail.math.ntnu.no To: FreeBSD-gnats-submit@FreeBSD.ORG Subject: bin/3884: stdarg.h fails for data types < 4 bytes Message-ID: <199706161736.TAA15725@frida.math.ntnu.no> Resent-Message-ID: <199706161740.KAA18177@hub.freebsd.org>
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>Number: 3884
>Category: bin
>Synopsis: stdarg.h fails for data types < 4 bytes
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Mon Jun 16 10:40:01 PDT 1997
>Last-Modified:
>Originator: Arne Henrik Juul
>Organization:
Norwegian University of Technology and Science
>Release: FreeBSD 2.2-STABLE i386
>Environment:
2.2 branch and -current.
>Description:
The standard include file <stdarg.h> #defines va_arg to
make an explicit abort() when asked to get an argument
with sizeof(type) < sizeof(int). Probably stdarg.h should
follow the conventions of the C compiler instead.
>How-To-Repeat:
Inspect <stdarg.h>, or compile and run the following test
program, gotten from c-torture.
#include <stdarg.h>
struct tiny
{
short c;
};
f (int n, ...)
{
struct tiny x;
int i;
va_list ap;
va_start (ap,n);
for (i = 0; i < n; i++)
{
x = va_arg (ap,struct tiny);
if (x.c != i + 10)
abort();
}
{
long x = va_arg (ap, long);
if (x != 123)
abort();
}
va_end (ap);
}
main ()
{
struct tiny x[3];
x[0].c = 10;
x[1].c = 11;
x[2].c = 12;
f (3, x[0], x[1], x[2], (long) 123);
exit(0);
}
>Fix:
Apply following patch:
--- /usr/src/sys/i386/include/stdarg.h Wed Apr 2 14:31:20 1997
+++ ./stdarg.h Mon Jun 16 19:16:48 1997
@@ -39,13 +39,13 @@
typedef char *va_list;
+#define __va_promote(type) \
+ (((sizeof(type) + sizeof(int) - 1) / sizeof(int)) * sizeof(int))
+
#ifdef __GNUC__
#define va_start(AP, LASTARG) \
(AP = ((va_list) __builtin_next_arg (LASTARG)))
#else
-#define __va_promote(type) \
- (((sizeof(type) + sizeof(int) - 1) / sizeof(int)) * sizeof(int))
-
#define va_start(ap, last) \
(ap = ((va_list)&(last) + __va_promote(last)))
#endif
@@ -55,8 +55,7 @@
((type *)(ap += sizeof(type)))[-1]
#else
#define va_arg(ap, type) \
- ((type *)(ap += sizeof(type) < sizeof(int) ? \
- (abort(), 0) : sizeof(type)))[-1]
+ (*((type *)(ap += __va_promote(type), ap - __va_promote(type))))
#endif
#define va_end(ap)
>Audit-Trail:
>Unformatted:
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