text: #include <AK/Assertions.h>
  #include <AK/Types.h>
  #include <fcntl.h>
  #include <stdio.h>
  #include <sys/mman.h>
  #include <unistd.h>
  
  #define EXPECT_ERROR_2(err, syscall, arg1, arg2)                                                                                                                          \
      do {                                                                                                                                                                  \
          rc = syscall(arg1, arg2);                                                                                                                                         \
          if (rc >= 0 || errno != err) {                                                                                                                                    \
              fprintf(stderr, __FILE__ ":%d: Expected " #err ": " #syscall "(%p, %p), got rc=%d, errno=%d\n", __LINE__, (const void*)(arg1), (const void*)arg2, rc, errno); \
          }                                                                                                                                                                 \
      } while (0)
  
  #define EXPECT_ERROR_3(err, syscall, arg1, arg2, arg3)                                                                                                                                               \
      do {                                                                                                                                                                                             \
          rc = syscall(arg1, arg2, arg3);                                                                                                                                                              \
          if (rc >= 0 || errno != err) {                                                                                                                                                               \
              fprintf(stderr, __FILE__ ":%d: Expected " #err ": " #syscall "(%p, %p, %p), got rc=%d, errno=%d\n", __LINE__, (const void*)(arg1), (const void*)(arg2), (const void*)(arg3), rc, errno); \
          }                                                                                                                                                                                            \
      } while (0)
  
  void test_read_from_directory()
  {
      char buffer[BUFSIZ];
      int fd = open("/", O_DIRECTORY | O_RDONLY);
      ASSERT(fd >= 0);
      int rc;
      EXPECT_ERROR_3(EISDIR, read, fd, buffer, sizeof(buffer));
      rc = close(fd);
      ASSERT(rc == 0);
  }
  
  void test_write_to_directory()
  {
      char str[] = "oh frick";
      int fd = open("/", O_DIRECTORY | O_RDONLY);
      if (fd < 0)
          perror("open");
      ASSERT(fd >= 0);
      int rc;
      EXPECT_ERROR_3(EBADF, write, fd, str, sizeof(str));
      rc = close(fd);
      ASSERT(rc == 0);
  }
  
  void test_read_from_writeonly()
  {
      char buffer[BUFSIZ];
      int fd = open("/tmp/xxxx123", O_CREAT | O_WRONLY);
      ASSERT(fd >= 0);
      int rc;
      EXPECT_ERROR_3(EBADF, read, fd, buffer, sizeof(buffer));
      rc = close(fd);
      ASSERT(rc == 0);
  }
  
  void test_write_to_readonly()
  {
      char str[] = "hello";
      int fd = open("/tmp/abcd123", O_CREAT | O_RDONLY);
      ASSERT(fd >= 0);
      int rc;
      EXPECT_ERROR_3(EBADF, write, fd, str, sizeof(str));
      rc = close(fd);
      ASSERT(rc == 0);
  }
  
  void test_read_past_eof()
  {
      char buffer[BUFSIZ];
      int fd = open("/home/anon/myfile.txt", O_RDONLY);
      if (fd < 0)
          perror("open");
      ASSERT(fd >= 0);
      int rc;
      rc = lseek(fd, 9999, SEEK_SET);
      if (rc < 0)
          perror("lseek");
      rc = read(fd, buffer, sizeof(buffer));
      if (rc < 0)
          perror("read");
      if (rc > 0)
          fprintf(stderr, "read %d bytes past EOF\n", rc);
      rc = close(fd);
      ASSERT(rc == 0);
  }
  
  int main(int, char**)
  {
      int rc;
      EXPECT_ERROR_2(ENOTDIR, open, "/dev/zero", (O_DIRECTORY | O_RDONLY));
      EXPECT_ERROR_2(EINVAL, open, "/dev/zero", (O_DIRECTORY | O_CREAT | O_RDWR));
      EXPECT_ERROR_2(EEXIST, open, "/dev/zero", (O_CREAT | O_EXCL | O_RDWR));
      EXPECT_ERROR_2(EINVAL, open, "/tmp/abcdef", (O_DIRECTORY | O_CREAT | O_RDWR));
      EXPECT_ERROR_2(EACCES, open, "/proc/all", (O_RDWR));
      EXPECT_ERROR_2(ENOENT, open, "/boof/baaf/nonexistent", (O_CREAT | O_RDWR));
      EXPECT_ERROR_2(EISDIR, open, "/tmp", (O_DIRECTORY | O_RDWR));
  
      test_read_from_directory();
      test_write_to_directory();
      test_read_from_writeonly();
      test_write_to_readonly();
      test_read_past_eof();
  
      return 0;
  }
  