libc/test/src/string/strncpy_test.cpp

   1 //===-- Unittests for strncpy ---------------------------------------------===//
   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/__support/CPP/span.h"
  10 #include "src/string/strncpy.h"
  11 #include "test/UnitTest/Test.h"
  12 #include <stddef.h> // For size_t.
  13
  14 class LlvmLibcStrncpyTest : public LIBC_NAMESPACE::testing::Test {
  15 public:
  16   void check_strncpy(LIBC_NAMESPACE::cpp::span<char> dst,
  17                      const LIBC_NAMESPACE::cpp::span<const char> src, size_t n,
  18                      const LIBC_NAMESPACE::cpp::span<const char> expected) {
  19     // Making sure we don't overflow buffer.
  20     ASSERT_GE(dst.size(), n);
  21     // Making sure strncpy returns dst.
  22     ASSERT_EQ(LIBC_NAMESPACE::strncpy(dst.data(), src.data(), n), dst.data());
  23     // Expected must be of the same size as dst.
  24     ASSERT_EQ(dst.size(), expected.size());
  25     // Expected and dst are the same.
  26     for (size_t i = 0; i < expected.size(); ++i)
  27       ASSERT_EQ(expected[i], dst[i]);
  28   }
  29 };
  30
  31 TEST_F(LlvmLibcStrncpyTest, Untouched) {
  32   char dst[] = {'a', 'b'};
  33   const char src[] = {'x', '\0'};
  34   const char expected[] = {'a', 'b'};
  35   check_strncpy(dst, src, 0, expected);
  36 }
  37
  38 TEST_F(LlvmLibcStrncpyTest, CopyOne) {
  39   char dst[] = {'a', 'b'};
  40   const char src[] = {'x', 'y'};
  41   const char expected[] = {'x', 'b'}; // no \0 is appended
  42   check_strncpy(dst, src, 1, expected);
  43 }
  44
  45 TEST_F(LlvmLibcStrncpyTest, CopyNull) {
  46   char dst[] = {'a', 'b'};
  47   const char src[] = {'\0', 'y'};
  48   const char expected[] = {'\0', 'b'};
  49   check_strncpy(dst, src, 1, expected);
  50 }
  51
  52 TEST_F(LlvmLibcStrncpyTest, CopyPastSrc) {
  53   char dst[] = {'a', 'b'};
  54   const char src[] = {'\0', 'y'};
  55   const char expected[] = {'\0', '\0'};
  56   check_strncpy(dst, src, 2, expected);
  57 }