Hey guys,
I'm trying to get started with basic ptrace functionality with the
following:
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
int main(int argc, char **argv)
{
int pid, status, ret;
if((pid = fork()) == 0)
{
ptrace(PT_TRACE_ME,0,0,0);
execl(argv[1],argv[1],0);
printf("exec failed\n");
}
else{
wait(&status);
if(WIFSTOPPED(status))
printf("child has stopped. child pid: %d\n", pid);
errno = 0;
ret = ptrace(PT_CONTINUE, pid, (caddr_t)1, 0);
printf("ret: %d\n", ret);
printf("errno: %s\n", strerror(errno));
}
}
>From my basic understanding, what the above should do is fork a
child process which will stop at exec and cause the parent-tracing
process to exit wait(). The parent process should then have the child
process continue execution normally by calling ptrace() with
PT_CONTINUE.
When I run the code, The child process is created, however, ptrace()
with PT_CONTINUE seems to fail as the child process does not continue
normal execution. ptrace's return value is 0 and errno is "Unknown
error: 0".
Running output:
aronzvis-macbook:ptrace_test aronzvi$ ./ptrace ../voidinc
child has stopped. child pid: 37959
ret: 0
errno: Unknown error: 0
I'm running OS X 10.5.7 and building the code with the 10.5 SDK.
Your help is much appreciated,
Aron-Zvi