Re: sigtrap and TF

[Rene Herman]

On 05-12-07 20:19, ninjaboy wrote:

Ehm... int3 works for me too, the TF doesn't work.
       pushf
       xor %rax, %rax
       pop %rax
       orq $0x100, %rax
       pushq %rax
       popf

the trap released here doesn't exec my handler.

Ah, I just skipped reading the bit with the fucks and the sucks. But, well, 
works for me again:

$ ./sigtrap
trap = 1
trap = 3
$

Rene.
/* gcc -W -Wall -o sigtrap sigtrap.c */

#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <sys/io.h>

volatile sig_atomic_t trap;

void sigtrap(int signum __attribute__((unused)))
{
        trap++;
}

int main(void)
{
        struct sigaction sa;

        sa.sa_handler = sigtrap;
        sigemptyset(&sa.sa_mask);
        sa.sa_flags = 0;

        if (sigaction(SIGTRAP, &sa, NULL) < 0) {
                perror("could not install handler");
                return EXIT_FAILURE;
        }

        asm(    "int3");

        printf("trap = %d\n", (int)trap);

        asm(    "pushf                  \n\t"
                "orl    $0x100, (%esp)  \n\t"
                "popf                   ");

        asm(    "nop");
        asm(    "nop");

        printf("trap = %d\n", (int)trap);

        return EXIT_SUCCESS;
}