HP-UX Reference (11i v2 03/08) - 2 System Calls (vol 5)

p
ptrace(2) ptrace(2)
(PA Only; TO BE OBSOLETED)
EXAMPLES
The following example illustrates the use of some of the
ptrace() calls by a tracing process.
#include <stdio.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/ptrace.h>
#define BUFSIZ 1024
#define MAXPATH 1024
pid_t npid, cpid, pid;
int status, errors=0, pathlength;
ptrace_event_t *event_addr;
ptrace_state_t *state_addr;
char *buf_addr;
size_t event_len, state_len;
int filed[2];
child()
{
int n, bar;
close(filed[1]);
/* Wait for parent to write to pipe */
while ((n = read(filed[0], &bar, BUFSIZ)) == 0);
/* Now the child can exec. */
if (execlp("ls", "ls", (char *)0) < 0) /* error during exec */
printf("Child: exec failed\n");
exit(0);
}
parent()
{
close(filed[0]);
/* Before child does an exec, attach it and set its event flag. */
if (ptrace(PT_ATTACH,pid)) /* failed to attach process */
printf("Parent: Failed to attach child\n");
if (pid != wait(&status)) /* wait failed */
printf("Parent: attach failed with wrong wait status\n");
if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
printf("Parent: SIGTRAP didn’t stop child\n");
/*
* The child process has now stopped. Set its event flag indicating
* that it needs to trigger on a PTRACE_EXEC event.
*/
event_addr->pe_set_event = PTRACE_EXEC;
if (ptrace(PT_SET_EVENT_MASK, pid, event_addr, event_len))
printf("Parent: PT_SET_EVENT_MASK ptrace request failed\n");
if (pid != wait(&status)) /* wait failed */
printf("Parent: wait() failed with wrong wait status\n");
/*
* Send the child a message so it can break out of the while loop.
* Get it running so it can exec.
*/
write(filed[1], "now run", 7);
if (ptrace(PT_CONTIN, pid, 1, 0) != 0)
printf("Parent: failed to get child process running\n");
/*
* Wait for the traced child to stop after the exec system call in
* response to an exec event set in its ptrace_event structure.
*/
if (pid != (npid = wait(&status))) /* wait failed */
printf("Parent: wait() failed with wrong status\n");
HP-UX 11i Version 2: August 2003 − 6 − Hewlett-Packard Company Section 2−−265