src/test/vm_readv_writev.c

/* -*- Mode: C; tab-width: 8; c-basic-offset: 2; indent-tabs-mode: nil; -*- */

#include "util.h"

static void clear(unsigned char* p) {
  size_t i;
  size_t page_size = sysconf(_SC_PAGESIZE);
  for (i = 0; i < (unsigned)page_size; ++i) {
    p[i] = i & 0xFF;
  }
}

static void check_page1(unsigned char* p, size_t page_size, int ret) {
  if (3 == ret) {
    test_assert(p[page_size - 7] == ((page_size - 7) & 0xff));
    test_assert(p[page_size - 6] == 0);
    test_assert(p[page_size - 5] == 1);
    test_assert(p[page_size - 4] == 3);
    test_assert(p[page_size - 3] == ((page_size - 3) & 0xff));
    test_assert(p[page_size - 2] == ((page_size - 2) & 0xff));
    test_assert(p[page_size - 1] == ((page_size - 1) & 0xff));
  } else {
    test_assert(4 == ret);
    test_assert(p[page_size - 7] == ((page_size - 7) & 0xff));
    test_assert(p[page_size - 6] == 0);
    test_assert(p[page_size - 5] == 1);
    test_assert(p[page_size - 4] == 3);
    test_assert(p[page_size - 3] == ((page_size - 3) & 0xff));
    test_assert(p[page_size - 2] == ((page_size - 2) & 0xff));
    test_assert(p[page_size - 1] == 4);
  }
}

int main(void) {
  size_t page_size = sysconf(_SC_PAGESIZE);
  unsigned char* p =
      (unsigned char*)mmap(NULL, page_size * 2, PROT_READ | PROT_WRITE,
                           MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
  struct iovec in_iov[2];
  struct iovec out_iov[2];
  int ret;

  test_assert(p != MAP_FAILED);
  test_assert(0 == munmap(p + page_size, page_size));

  in_iov[0].iov_base = p;
  in_iov[0].iov_len = 2;
  in_iov[1].iov_base = p + 3;
  in_iov[1].iov_len = 3;
  out_iov[0].iov_base = p + page_size - 6;
  out_iov[0].iov_len = 3;
  out_iov[1].iov_base = p + page_size - 1;
  out_iov[1].iov_len = 2;

  clear(p);
  ret = process_vm_readv(getpid(), out_iov, 2, in_iov, 2, 0);
  test_assert(out_iov[1].iov_len == 2);
  check_page1(p, page_size, ret);
  clear(p);
  ret = process_vm_writev(getpid(), in_iov, 2, out_iov, 2, 0);
  test_assert(out_iov[1].iov_len == 2);
  check_page1(p, page_size, ret);

  out_iov[1].iov_base = p + page_size - 2;
  out_iov[1].iov_len = 3;

  clear(p);
  test_assert(5 == process_vm_readv(getpid(), out_iov, 2, in_iov, 2, 0));
  test_assert(p[page_size - 7] == ((page_size - 7) & 0xff));
  test_assert(p[page_size - 6] == 0);
  test_assert(p[page_size - 5] == 1);
  test_assert(p[page_size - 4] == 3);
  test_assert(p[page_size - 3] == ((page_size - 3) & 0xff));
  test_assert(p[page_size - 2] == 4);
  test_assert(p[page_size - 1] == 5);
  clear(p);
  ret = process_vm_writev(getpid(), in_iov, 2, out_iov, 2, 0);
  if (3 == ret) {
    test_assert(p[page_size - 7] == ((page_size - 7) & 0xff));
    test_assert(p[page_size - 6] == 0);
    test_assert(p[page_size - 5] == 1);
    test_assert(p[page_size - 4] == 3);
    test_assert(p[page_size - 3] == ((page_size - 3) & 0xff));
    test_assert(p[page_size - 2] == ((page_size - 2) & 0xff));
    test_assert(p[page_size - 1] == ((page_size - 1) & 0xff));
  } else {
    test_assert(5 == ret);
    test_assert(p[page_size - 7] == ((page_size - 7) & 0xff));
    test_assert(p[page_size - 6] == 0);
    test_assert(p[page_size - 5] == 1);
    test_assert(p[page_size - 4] == 3);
    test_assert(p[page_size - 3] == ((page_size - 3) & 0xff));
    test_assert(p[page_size - 2] == 4);
    test_assert(p[page_size - 1] == 5);
  }

  in_iov[0].iov_base = p + page_size - 1;
  in_iov[0].iov_len = 2;
  out_iov[0].iov_base = p;
  out_iov[0].iov_len = 3;

  clear(p);
  ret = process_vm_readv(getpid(), out_iov, 1, in_iov, 1, 0);
  if (ret == -1 && errno == EFAULT) {
    test_assert(p[0] == 0);
    test_assert(p[1] == 1);
  } else {
    test_assert(1 == ret);
    test_assert(p[0] == ((page_size - 1) & 0xff));
    test_assert(p[1] == 1);
  }
  clear(p);
  ret = process_vm_writev(getpid(), in_iov, 1, out_iov, 1, 0);
  if (ret == -1 && errno == EFAULT) {
    test_assert(p[0] == 0);
    test_assert(p[1] == 1);
  } else {
    test_assert(1 == ret);
    test_assert(p[0] == ((page_size - 1) & 0xff));
    /* Linux kernel bug: should be 1, but sometimes is zero ---
       extra data written. https://bugzilla.kernel.org/show_bug.cgi?id=113541 */
    if (p[1] == 0) {
      atomic_puts("Kernel bug detected!");
    }
    test_assert(p[1] == 1 || p[1] == 0);
  }

  in_iov[0].iov_base = p + page_size - 4;
  in_iov[0].iov_len = 2;
  in_iov[1].iov_base = p + page_size - 2;
  in_iov[1].iov_len = 3;
  out_iov[0].iov_base = p;
  out_iov[0].iov_len = 1;
  out_iov[1].iov_base = p + 2;
  out_iov[1].iov_len = 4;

  clear(p);
  ret = process_vm_readv(getpid(), out_iov, 2, in_iov, 2, 0);
  if (2 == ret) {
    test_assert(p[0] == ((page_size - 4) & 0xff));
    test_assert(p[1] == 1);
    test_assert(p[2] == ((page_size - 3) & 0xff));
    test_assert(p[3] == 3);
    test_assert(p[4] == 4);
    test_assert(p[5] == 5);
  } else {
    test_assert(4 == ret);
    test_assert(p[0] == ((page_size - 4) & 0xff));
    test_assert(p[1] == 1);
    test_assert(p[2] == ((page_size - 3) & 0xff));
    test_assert(p[3] == ((page_size - 2) & 0xff));
    test_assert(p[4] == ((page_size - 1) & 0xff));
    test_assert(p[5] == 5);
  }
  clear(p);
  test_assert(4 == process_vm_writev(getpid(), in_iov, 2, out_iov, 2, 0));
  test_assert(p[0] == ((page_size - 4) & 0xff));
  test_assert(p[1] == 1);
  test_assert(p[2] == ((page_size - 3) & 0xff));
  test_assert(p[3] == ((page_size - 2) & 0xff));
  test_assert(p[4] == ((page_size - 1) & 0xff));
  if (p[5] == 0) {
    atomic_puts("Kernel bug detected!");
  }
  test_assert(p[5] == 5 || p[5] == 0);

  atomic_puts("EXIT-SUCCESS");
  return 0;
}