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Re: pass by value and also snprintf()
- From: Bruce Korb <bruce dot korb at gmail dot com>
- To: Richard Henderson <rth at redhat dot com>
- Cc: libffi-discuss at sourceware dot org
- Date: Mon, 27 Apr 2015 10:37:28 -0700
- Subject: Re: pass by value and also snprintf()
- Authentication-results: sourceware.org; auth=none
- References: <CAKRnqNK1D9Wp3uedW62uVk-5FCfzGgDd0xOA2W9qMQeizV1TSw at mail dot gmail dot com> <553E6D2E dot 7060403 at redhat dot com>
Like this then:
#include <stdint.h>
#include <stdio.h>
#include <ffi.h>
#define UCONST(_p) ((void *)(uintptr_t)_p)
int
main(int argc, char ** argv)
{
char buffer[0x1000];
size_t bufsz = sizeof(buffer);
char const fmt[] = "Allocated sblock_id=%d for band_id=%d\n";
int32_t sblock = 1;
int32_t band = 1;
void * fn = sprintf;
if (sizeof(bufsz) != sizeof(uint64_t))
return 1;
ffi_type * typ[5] = {
[0] = &ffi_type_pointer,
[1] = &ffi_type_uint64,
[2] = &ffi_type_pointer,
[3] = &ffi_type_sint32,
[4] = &ffi_type_sint32 };
void * values[5] = {
[0] = buffer,
[1] = &bufsz,
[2] = UCONST(fmt),
[3] = &sblock,
[4] = &band };
ffi_cif cif;
if (ffi_prep_cif_var(&cif, FFI_DEFAULT_ABI, 3, 5,
&ffi_type_uint32, typ) == FFI_OK) {
uint32_t ret_val;
ffi_call(&cif, fn, &ret_val, values);
fputs(buffer, stdout);
return 0;
}
return 1;
}
$ cc -o ffi-test ffi-test.c -lffi
$ ./ffi-test
Segmentation fault
On Mon, Apr 27, 2015 at 10:09 AM, Richard Henderson <rth@redhat.com> wrote:
> On 04/27/2015 09:59 AM, Bruce Korb wrote:
>> I hope
>> there is an
>> obvious answer to what I am missing:
>
> Certainly there's no way we can help you further without a complete test case.
>
>
> r~