lldb/test/Shell/Subprocess/Inputs/fork.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 #endif
   7 #include <stdint.h>
   8 #include <stdlib.h>
   9 #include <stdio.h>
  10 #include <unistd.h>
  11
  12 int g_val = 0;
  13
  14 void parent_func() {
  15   g_val = 1;
  16   printf("function run in parent\n");
  17 }
  18
  19 int parent_done[2];
  20 char parent_done_str[16];
  21
  22 void wait_for_parent() {
  23   char buf[2];
  24   // wait for the parent to finish its part
  25   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.
  32 int child_func(const char *argv0) {
  33   // we need to avoid memory modifications for vfork(), yet we want
  34   // to be able to test watchpoints, so do the next best thing
  35   // and restore the original value
  36   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
  43 int 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 running
  50   // this function, so do not rely on any synchronization until we exec
  51 #if defined(TEST_FORK)
  52   if (TEST_FORK != vfork)
  53 #endif
  54     wait_for_parent();
  55
  56   return child_func(argv0);
  57 }
  58
  59 int 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 exec
  69     if (TEST_FORK == vfork)
  70       wait_for_parent();
  71 #endif
  72
  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 above
  89   if (pid == 0)
  90     _exit(child_top_func(argv[0]));
  91 #endif
  92   assert(pid != -1);
  93
  94   ret = close(parent_done[0]);
  95   assert(ret == 0);
  96
  97   parent_func();
  98
  99   // resume the child
 100   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 #endif
 109   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 }