i386/169187: Bad sizeof(uint64_t) with -m32 compiler flag

[Eric McCorkle]

>Number:         169187
>Category:       i386
>Synopsis:       Bad sizeof(uint64_t) with -m32 compiler flag
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-i386
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Jun 18 00:40:11 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator:     Eric McCorkle
>Release:        9.0, also appears on 10.0
>Organization:
>Environment:
FreeBSD atom-edge 9.0-STABLE FreeBSD 9.0-STABLE #118 r236960M: Wed Jun 13 08:44:31 EDT 2012    root at atom-edge:/usr/obj/usr/src/sys/CUSTOM  amd64
>Description:
When compiling programs on an amd64 machine with the -m32 compiler flag, uint64_t variables are incorrectly sized, resulting in sizeof(uint64_t) == 4.  Presumably this affects int64_t as well, and any types that are typedef'ed to one of these.
>How-To-Repeat:
Compile the following program:

#include <stdio.h>
#include <stdlib.h>

int main() { printf("%d\n", sizeof(uint64_t)); return 0; }

with the following command:

gcc -m32 -o test test.c

The output will be "4" as opposed to "8" like it should be.
>Fix:
The file <machine/_types.h> defines __uint64_t as unsigned long on amd64 platforms.  When compiling with -m32, however, the compiler makes unsigned long a 32-bit integer, which seems to be the root of the problem.

A simple fix is to detect when sizeof(unsigned long) == 4, and define __uint64_t as unsigned long long instead.

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