HP-UX Reference (11i v2 07/12) - 2 System Calls (vol 5)

p
ptrace(2) ptrace(2)
(PA-RISC Only; TO BE OBSOLETED)
Some or all of the actions associated with this system call reqnire the
OWNER privilege. Processes owned
by the superuser have this privilege. Processes owned by other users may have this privilege, depending on
system configuration. See privileges(5) for more information about privileged access on systems that sup-
port fine-grained privileges.
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");
HP-UX 11i Version 2: December 2007 Update − 6 − Hewlett-Packard Company 305