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#include <stdio.h>
#include <unistd.h>
#include <sys/wait.h>
#if defined(__linux__)
#include <sys/prctl.h>
#endif
volatile int release_child_flag = 0;
int main(int argc, char const *argv[])
{
pid_t child = fork();
if (child == -1)
{
perror("fork");
return 1;
}
if (child > 0)
{ // parent
if (argc < 2)
{
fprintf(stderr, "Need pid filename.\n");
return 2;
}
// Let the test suite know the child's pid.
FILE *pid_file = fopen(argv[1], "w");
if (pid_file == NULL)
{
perror("fopen");
return 3;
}
fprintf(pid_file, "%d\n", child);
if (fclose(pid_file) == EOF)
{
perror("fclose");
return 4;
}
// And wait for the child to finish it's work.
int status = 0;
pid_t wpid = wait(&status);
if (wpid == -1)
{
perror("wait");
return 5;
}
if (wpid != child)
{
fprintf(stderr, "wait() waited for wrong child\n");
return 6;
}
if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
{
fprintf(stderr, "child did not exit correctly\n");
return 7;
}
}
else
{ // child
#if defined(__linux__)
// Immediately enable any ptracer so that we can allow the stub attach
// operation to succeed. Some Linux kernels are locked down so that
// only an ancestor process can be a ptracer of a process. This disables that
// restriction. Without it, attach-related stub tests will fail.
#if defined(PR_SET_PTRACER) && defined(PR_SET_PTRACER_ANY)
// For now we execute on best effort basis. If this fails for
// some reason, so be it.
const int prctl_result = prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY, 0, 0, 0);
(void) prctl_result;
#endif
#endif
while (! release_child_flag) // Wait for debugger to attach
sleep(1);
printf("Child's previous process group is: %d\n", getpgid(0));
setpgid(0, 0); // Set breakpoint here
printf("Child's process group set to: %d\n", getpgid(0));
}
return 0;
}
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