libc/test/src/stdio/fgets_test.cpp

   1 //===-- Unittests for fgets -----------------------------------------------===//
   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/stdio/fclose.h"
  10 #include "src/stdio/feof.h"
  11 #include "src/stdio/ferror.h"
  12 #include "src/stdio/fgets.h"
  13 #include "src/stdio/fopen.h"
  14 #include "src/stdio/fwrite.h"
  15 #include "test/UnitTest/Test.h"
  16
  17 #include <errno.h>
  18 #include <stdio.h>
  19
  20 TEST(LlvmLibcFgetsTest, WriteAndReadCharacters) {
  21   constexpr char FILENAME[] = "testdata/fgets.test";
  22   ::FILE *file = __llvm_libc::fopen(FILENAME, "w");
  23   ASSERT_FALSE(file == nullptr);
  24   constexpr char CONTENT[] = "123456789\n"
  25                              "1234567\n"
  26                              "123456\n"
  27                              "1";
  28   constexpr size_t WRITE_SIZE = sizeof(CONTENT) - 1;
  29
  30   char buff[8];
  31   char *output;
  32
  33   ASSERT_EQ(WRITE_SIZE, __llvm_libc::fwrite(CONTENT, 1, WRITE_SIZE, file));
  34   // This is a write-only file so reads should fail.
  35   ASSERT_TRUE(__llvm_libc::fgets(buff, 8, file) == nullptr);
  36   // This is an error and not a real EOF.
  37   ASSERT_EQ(__llvm_libc::feof(file), 0);
  38   ASSERT_NE(__llvm_libc::ferror(file), 0);
  39   errno = 0;
  40
  41   ASSERT_EQ(0, __llvm_libc::fclose(file));
  42
  43   file = __llvm_libc::fopen(FILENAME, "r");
  44   ASSERT_FALSE(file == nullptr);
  45
  46   // If we request just 1 byte, it should return just a null byte and not
  47   // advance the read head. This is implementation defined.
  48   output = __llvm_libc::fgets(buff, 1, file);
  49   ASSERT_TRUE(output == buff);
  50   ASSERT_EQ(buff[0], '\0');
  51   ASSERT_EQ(errno, 0);
  52
  53   // If we request less than 1 byte, it should do nothing and return nullptr.
  54   // This is also implementation defined.
  55   output = __llvm_libc::fgets(buff, 0, file);
  56   ASSERT_TRUE(output == nullptr);
  57
  58   const char *output_arr[] = {
  59       "1234567", "89\n", "1234567", "\n", "123456\n", "1",
  60   };
  61
  62   constexpr size_t ARR_SIZE = sizeof(output_arr) / sizeof(char *);
  63
  64   for (size_t i = 0; i < ARR_SIZE; ++i) {
  65     output = __llvm_libc::fgets(buff, 8, file);
  66
  67     // This pointer comparison is intentional, fgets should return a pointer to
  68     // buff when it succeeds.
  69     ASSERT_TRUE(output == buff);
  70     ASSERT_EQ(__llvm_libc::ferror(file), 0);
  71
  72     EXPECT_STREQ(buff, output_arr[i]);
  73   }
  74
  75   // This should have hit the end of the file, but that isn't an error unless it
  76   // fails to read anything.
  77   ASSERT_NE(__llvm_libc::feof(file), 0);
  78   ASSERT_EQ(__llvm_libc::ferror(file), 0);
  79   ASSERT_EQ(errno, 0);
  80
  81   // Reading more should be an EOF, but not an error.
  82   output = __llvm_libc::fgets(buff, 8, file);
  83   ASSERT_TRUE(output == nullptr);
  84   ASSERT_NE(__llvm_libc::feof(file), 0);
  85   ASSERT_EQ(errno, 0);
  86
  87   ASSERT_EQ(0, __llvm_libc::fclose(file));
  88 }