Attachment 223712 Details for Bug 254661 – fbsd-fork-dbreg.c

fbsd-fork-dbreg.c

fbsd-fork-dbreg.c (text/plain), 2.49 KB, created by Michał Górny on 2021-03-30 15:31:03 UTC

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Creator: Michał Górny

Created: 2021-03-30 15:31:03 UTC

Size: 2.49 KB

patch

obsolete

>#include <sys/types.h>
>#include <sys/ptrace.h>
>#include <sys/wait.h>
>
>#include <assert.h>
>#include <signal.h>
>#include <spawn.h>
>#include <stdio.h>
>#include <stdlib.h>
>#include <string.h>
>#include <unistd.h>
>
>#include <cpuid.h>
>
>volatile int g_val = 0;
>
>int main() {
>    int ret;
>    pid_t pid = fork();
>    assert(pid != -1);
>
>    if (pid == 0) {
>        /* child -- debugged program */
>        /* request tracing */
>        ret = ptrace(PT_TRACE_ME, 0, NULL, 0);
>        assert(ret != -1);
>        ret = raise(SIGSTOP);
>        assert(ret != -1);
>
>	ret = fork();
>	assert(ret != -1);
>        _exit(0);
>    }
>
>    /* parent -- the debugger */
>    pid_t waited;
>
>    /* 1. SIGSTOP for the process */
>    waited = waitpid(pid, &ret, 0);
>    assert(waited == pid);
>    assert(WIFSTOPPED(ret));
>    assert(WSTOPSIG(ret) == SIGSTOP);
>
>    /* set the event mask */
>    int event_mask = PTRACE_FORK;
>    ret = ptrace(PT_SET_EVENT_MASK, waited,
>                 (void*)&event_mask,
>                 sizeof(event_mask));
>    assert(ret == 0);
>
>    /* set dbregs */
>    struct dbreg dbregs = {0};
>    dbregs.dr[0] = (uintptr_t) &g_val;
>    dbregs.dr[7] = 0x13;
>
>    printf("dr0 = %p\n", (void*)dbregs.dr[0]);
>    printf("dr7 = %08lx\n", dbregs.dr[7]);
>
>    ret = ptrace(PT_SETDBREGS, waited, (void*)&dbregs, 0);
>    assert(ret == 0);
>
>    ret = ptrace(PT_CONTINUE, waited, (void*)1, 0);
>    assert(ret == 0);
>
>    /* 2. SIGTRAP for fork */
>    waited = waitpid(pid, &ret, 0);
>    assert(waited == pid);
>    assert(WIFSTOPPED(ret));
>    assert(WSTOPSIG(ret) == SIGTRAP);
>
>    struct ptrace_lwpinfo info;
>    ret = ptrace(PT_LWPINFO, waited, (void*)&info, sizeof(info));
>    assert(ret == 0);
>    assert(info.pl_flags & PL_FLAG_FORKED);
>
>    ret = ptrace(PT_CONTINUE, waited, (void*)1, 0);
>    assert(ret == 0);
>
>    /* 3. SIGCHLD for the child */
>    waited = waitpid(info.pl_child_pid, &ret, 0);
>    assert(waited != pid);
>    assert(WIFSTOPPED(ret));
>    assert(WSTOPSIG(ret) == SIGSTOP);
>
>    /* grab dbregs */
>    ret = ptrace(PT_GETDBREGS, waited, (void*)&dbregs, 0);
>    assert(ret == 0);
>
>    printf("dr0 = %p\n", (void*)dbregs.dr[0]);
>    printf("dr7 = %08lx\n", dbregs.dr[7]);
>
>    ret = ptrace(PT_CONTINUE, waited, (void*)1, 0);
>    assert(ret == 0);
>
>    /* 4. exit for both */
>    waited = waitpid(pid, &ret, 0);
>    assert(waited == pid);
>    assert(WIFEXITED(ret));
>    assert(WEXITSTATUS(ret) == 0);
>
>    waited = waitpid(-1, &ret, 0);
>    assert(waited != pid);
>    assert(WIFEXITED(ret));
>    assert(WEXITSTATUS(ret) == 0);
>
>    return 0;
>}

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Attachments on bug 254661: 223712