A question about ptrace

[Ali Polatel]

I'm trying to port a program using ptrace from Linux to FreeBSD.
For this reason I'm trying to understand how ptrace on FreeBSD works.
Below is a sample program I've written which fork()'s and executes
"true" after calling PT_TRACE_ME. Having read the manual page of ptrace
I assume the printf() in parent should print SIGTRAP but it gives:
"Segmentation fault: 11"
Can someone help me figure out the problem?
TIA.

#include <assert.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <unistd.h>

int main(void)
{
    int status;
    pid_t pid;
    char *const myargv[] = { "true", NULL };

    pid = fork();
    if (0 > pid)
        abort();
    else if (!pid) {
        ptrace(PT_TRACE_ME, 0, 0, 0);
        execvp(myargv[0], myargv);
    }
    else {
        assert(0 < waitpid(pid, &status, 0));
        assert(WIFSTOPPED(status));

        assert(0 == ptrace(PT_TO_SCE, pid, 0, 0));
        assert(0 < waitpid(pid, &status, 0));

        assert(WIFSTOPPED(status));
        printf("%s\n", strsignal(WSTOPSIG(status)));
        ptrace(PT_KILL, pid, 0, 0);
        return 0;
    }
}

-- 
Regards,
Ali Polatel

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