libc/test/src/sys/select/select_ui_test.cpp

   1 //===-- Interactive unittests for select ----------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "src/errno/libc_errno.h"
  10 #include "src/sys/select/select.h"
  11 #include "src/unistd/read.h"
  12 #include "test/UnitTest/Test.h"
  13
  14 #include <sys/select.h>
  15 #include <unistd.h>
  16
  17 // This test is not be run automatically as part of the libc testsuite.
  18 // Instead, one has to run it manually and press a key on the keyboard
  19 // to make the test succeed.
  20 TEST(LlvmLibcSelectTest, ReadStdinAfterSelect) {
  21   LIBC_NAMESPACE::libc_errno = 0;
  22   constexpr int STDIN_FD = 0;
  23   fd_set set;
  24   FD_ZERO(&set);
  25   FD_SET(STDIN_FD, &set);
  26   struct timeval zero {
  27     0, 0
  28   }; // No wait
  29   struct timeval hr {
  30     3600, 0
  31   }; // Wait for an hour.
  32
  33   // Zero timeout means we don't wait for input. So, select should return
  34   // immediately.
  35   int count =
  36       LIBC_NAMESPACE::select(STDIN_FD + 1, &set, nullptr, nullptr, &zero);
  37   // The set should indicate that stdin is NOT ready for reading.
  38   ASSERT_EQ(0, FD_ISSET(STDIN_FD, &set));
  39
  40   FD_SET(STDIN_FD, &set);
  41   // Wait for an hour and give the user a chance to hit a key.
  42   count = LIBC_NAMESPACE::select(STDIN_FD + 1, &set, nullptr, nullptr, &hr);
  43   ASSERT_EQ(count, 1);
  44   // The set should indicate that stdin is ready for reading.
  45   ASSERT_EQ(1, FD_ISSET(STDIN_FD, &set));
  46
  47   // Verify that atleast one character can be read.
  48   char c;
  49   ASSERT_EQ(LIBC_NAMESPACE::read(STDIN_FD, &c, 1), ssize_t(1));
  50 }