> > If you trace an execve, you're going to get its syscall exit stop
> > before you get its old-style traced-exec SIGTRAP.
>
> No, you don't.
How did you come to that conclusion? My assertion was based on knowing the
kernel code. But below is a test program that illustrates the truth of it.
Here's the beginning of its output:
935 0xa7f
935 0x857f
5 0x85
59
935 0x857f
5 0x85
59
935 0x57f
5 0
59
935 0x857f
5 0x85
12
935 is the PID. 0xa7f is stopped with SIGUSR1.
Next, two syscall stops for execve (59 on x86_64), one entry and one exit.
Next, a signal stop for the post-exec SIGTRAP.
Next, a syscall entry stop for brk (12 on x86_64), the first syscall in the
new program after exec.
> > But, for exec doesn't it make sense to call it a possible ptrace stop only
> > if TCB_STARTUP?
>
> What if PTRACE_O_TRACEEXEC doesn't work? That contradicts your own
> words.
So either TCB_STARTUP will be set or TCB_WAITEXECVE will be set.
Thanks,
Roland
#include <sys/ptrace.h>
#include <asm/ptrace.h>
#include <sys/wait.h>
#include <assert.h>
#include <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
int
main ()
{
int status;
pid_t pid;
long l;
siginfo_t info;
long a = -12345;
switch (fork ())
{
case 0:
ptrace (PTRACE_TRACEME);
raise (SIGUSR1);
execl ("/bin/echo", "echo", "hello world", (char *) 0);
_exit (127);
case -1:
perror ("fork");
return 2;
}
pid = waitpid (WAIT_ANY, &status, WUNTRACED);
printf ("%d %#x\n", pid, status);
assert (WIFSTOPPED (status));
assert (WSTOPSIG (status) == SIGUSR1);
l = ptrace (PTRACE_SETOPTIONS, pid, 0, PTRACE_O_TRACESYSGOOD);
assert (l == 0);
do
{
l = ptrace (PTRACE_SYSCALL, pid, 0, 0);
if (l)
{
perror ("ptrace");
return 1;
}
pid = waitpid (WAIT_ANY, &status, WUNTRACED);
printf ("%d %#x\n", pid, status);
l = ptrace (PTRACE_GETSIGINFO, pid, 0, &info);
if (l)
perror ("PTRACE_GETSIGINFO");
else
printf ("\t%d %#x\n", info.si_signo, info.si_code);
errno = 0;
l = ptrace (PTRACE_PEEKUSER, pid, 120, &a);
if (errno)
perror ("PTRACE_PEEKUSER");
else
printf ("\t%ld\n", l);
}
while (WIFSTOPPED (status));
return 0;
}
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