116 lines · cpp
1#include <sys/types.h>2#include <sys/wait.h>3#include <assert.h>4#if defined(TEST_CLONE)5#include <sched.h>6#endif7#include <stdint.h>8#include <stdlib.h>9#include <stdio.h>10#include <unistd.h>11 12int g_val = 0;13 14void parent_func() {15 g_val = 1;16 printf("function run in parent\n");17}18 19int parent_done[2];20char parent_done_str[16];21 22void wait_for_parent() {23 char buf[2];24 // wait for the parent to finish its part25 int ret = read(parent_done[0], buf, sizeof(buf));26 assert(ret == 2);27 ret = close(parent_done[0]);28 assert(ret == 0);29}30 31// This is the function we set breakpoint on.32int child_func(const char *argv0) {33 // we need to avoid memory modifications for vfork(), yet we want34 // to be able to test watchpoints, so do the next best thing35 // and restore the original value36 g_val = 2;37 g_val = 0;38 execl(argv0, argv0, parent_done_str, NULL);39 assert(0 && "this should not be reached");40 return 1;41}42 43int child_top_func(void *argv0_ptr) {44 const char *argv0 = static_cast<char*>(argv0_ptr);45 46 int ret = close(parent_done[1]);47 assert(ret == 0);48 49 // NB: when using vfork(), the parent may be suspended while running50 // this function, so do not rely on any synchronization until we exec51#if defined(TEST_FORK)52 if (TEST_FORK != vfork)53#endif54 wait_for_parent();55 56 return child_func(argv0);57}58 59int main(int argc, char* argv[]) {60 alignas(uintmax_t) char stack[4096];61 int ret;62 63 if (argv[1]) {64 parent_done[0] = atoi(argv[1]);65 assert(parent_done[0] != 0);66 67#if defined(TEST_FORK)68 // for vfork(), we need to synchronize after exec69 if (TEST_FORK == vfork)70 wait_for_parent();71#endif72 73 fprintf(stderr, "function run in exec'd child\n");74 return 0;75 }76 77 ret = pipe(parent_done);78 assert(ret == 0);79 80 ret = snprintf(parent_done_str, sizeof(parent_done_str),81 "%d", parent_done[0]);82 assert(ret != -1);83 84#if defined(TEST_CLONE)85 pid_t pid = clone(child_top_func, &stack[sizeof(stack)], 0, argv[0]);86#elif defined(TEST_FORK)87 pid_t pid = TEST_FORK();88 // NB: this must be equivalent to the clone() call above89 if (pid == 0)90 _exit(child_top_func(argv[0]));91#endif92 assert(pid != -1);93 94 ret = close(parent_done[0]);95 assert(ret == 0);96 97 parent_func();98 99 // resume the child100 ret = write(parent_done[1], "go", 2);101 assert(ret == 2);102 ret = close(parent_done[1]);103 assert(ret == 0);104 105 int status, wait_flags = 0;106#if defined(TEST_CLONE)107 wait_flags = __WALL;108#endif109 pid_t waited = waitpid(pid, &status, wait_flags);110 assert(waited == pid);111 assert(WIFEXITED(status));112 assert(WEXITSTATUS(status) == 0);113 114 return 0;115}116