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Re: back into the thread....
- From: Sterling Augustine <saugustine at google dot com>
- To: Mark Manning <mark4th at gmail dot com>
- Cc: gdb at sourceware dot org
- Date: Tue, 12 Nov 2013 14:47:11 -0800
- Subject: Re: back into the thread....
- Authentication-results: sourceware.org; auth=none
- References: <CAPGNrUX7TA-4eCrrP=sD9G6oNe5Kw=eWPm_jm-D7=9ZTz-v6BA at mail dot gmail dot com> <CAEG7qUx69s2cdp4XY3cGtAakDQAoSrGnbhgvvLxUzZG+rJKC_g at mail dot gmail dot com>
On Tue, Nov 12, 2013 at 2:42 PM, Sterling Augustine
<saugustine@google.com> wrote:
> This feature clearly works.
>
.. This time with a couple of cleanups. The old example definitely
works, this just eliminates an extraneous call to malloc and an
uninitialized variable.
include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <string.h>
#include <malloc.h>
const char bytes[] = { 0x89, 0xf8, 0xc3 };
#define EXEC_BYTES sizeof(bytes)
typedef int(*function_ptr)(int);
int main(int argc, char *argv[])
{
int test_val = 5;
int return_val;
function_ptr dst;
if (posix_memalign((void **) &dst, 4096*8, EXEC_BYTES) != 0) {
printf("can't allocate.\n");
exit (-1);
}
if (mprotect(dst, EXEC_BYTES, PROT_READ|PROT_WRITE|PROT_EXEC) != 0) {
printf("can't mprotect\n");
exit (-1);
}
if (argc > 1)
test_val = atoi(argv[1]);
memcpy(dst, bytes, EXEC_BYTES);
return_val = dst(test_val);
printf("return val was %d\n", return_val);
return 0;
}