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 "src/errno/libc_errno.h"
  18
  19 TEST(LlvmLibcFgetsTest, WriteAndReadCharacters) {
  20   constexpr char FILENAME[] = "testdata/fgets.test";
  21   ::FILE *file = LIBC_NAMESPACE::fopen(FILENAME, "w");
  22   ASSERT_FALSE(file == nullptr);
  23   constexpr char CONTENT[] = "123456789\n"
  24                              "1234567\n"
  25                              "123456\n"
  26                              "1";
  27   constexpr size_t WRITE_SIZE = sizeof(CONTENT) - 1;
  28
  29   char buff[8];
  30   char *output;
  31
  32   ASSERT_EQ(WRITE_SIZE, LIBC_NAMESPACE::fwrite(CONTENT, 1, WRITE_SIZE, file));
  33   // This is a write-only file so reads should fail.
  34   ASSERT_TRUE(LIBC_NAMESPACE::fgets(buff, 8, file) == nullptr);
  35   // This is an error and not a real EOF.
  36   ASSERT_EQ(LIBC_NAMESPACE::feof(file), 0);
  37   ASSERT_NE(LIBC_NAMESPACE::ferror(file), 0);
  38   LIBC_NAMESPACE::libc_errno = 0;
  39
  40   ASSERT_EQ(0, LIBC_NAMESPACE::fclose(file));
  41
  42   file = LIBC_NAMESPACE::fopen(FILENAME, "r");
  43   ASSERT_FALSE(file == nullptr);
  44
  45   // The GPU build relies on the host C library, so this check may be different.
  46 #ifndef LIBC_TARGET_ARCH_IS_GPU
  47   // If we request just 1 byte, it should return just a null byte and not
  48   // advance the read head. This is implementation defined.
  49   output = LIBC_NAMESPACE::fgets(buff, 1, file);
  50   ASSERT_TRUE(output == buff);
  51   ASSERT_EQ(buff[0], '\0');
  52   ASSERT_ERRNO_SUCCESS();
  53
  54   // If we request less than 1 byte, it should do nothing and return nullptr.
  55   // This is also implementation defined.
  56   output = LIBC_NAMESPACE::fgets(buff, 0, file);
  57   ASSERT_TRUE(output == nullptr);
  58 #endif
  59
  60   const char *output_arr[] = {
  61       "1234567", "89\n", "1234567", "\n", "123456\n", "1",
  62   };
  63
  64   constexpr size_t ARR_SIZE = sizeof(output_arr) / sizeof(char *);
  65
  66   for (size_t i = 0; i < ARR_SIZE; ++i) {
  67     output = LIBC_NAMESPACE::fgets(buff, 8, file);
  68
  69     // This pointer comparison is intentional, fgets should return a pointer to
  70     // buff when it succeeds.
  71     ASSERT_TRUE(output == buff);
  72     ASSERT_EQ(LIBC_NAMESPACE::ferror(file), 0);
  73
  74     EXPECT_STREQ(buff, output_arr[i]);
  75   }
  76
  77   // This should have hit the end of the file, but that isn't an error unless it
  78   // fails to read anything.
  79   ASSERT_NE(LIBC_NAMESPACE::feof(file), 0);
  80   ASSERT_EQ(LIBC_NAMESPACE::ferror(file), 0);
  81   ASSERT_ERRNO_SUCCESS();
  82
  83   // Reading more should be an EOF, but not an error.
  84   output = LIBC_NAMESPACE::fgets(buff, 8, file);
  85   ASSERT_TRUE(output == nullptr);
  86   ASSERT_NE(LIBC_NAMESPACE::feof(file), 0);
  87   ASSERT_ERRNO_SUCCESS();
  88
  89   ASSERT_EQ(0, LIBC_NAMESPACE::fclose(file));
  90 }