1//===-- Unittests for ungetc ----------------------------------------------===//
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/ungetc.h"
10
11#include "hdr/stdio_macros.h"
12#include "src/stdio/fclose.h"
13#include "src/stdio/fopen.h"
14#include "src/stdio/fread.h"
15#include "src/stdio/fseek.h"
16#include "src/stdio/fwrite.h"
17#include "test/UnitTest/Test.h"
18
19TEST(LlvmLibcUngetcTest, UngetAndReadBack) {
20 constexpr char FILENAME[] = "testdata/ungetc_test.test";
21 ::FILE *file = LIBC_NAMESPACE::fopen(FILENAME, "w");
22 ASSERT_FALSE(file == nullptr);
23 constexpr char CONTENT[] = "abcdef";
24 constexpr size_t CONTENT_SIZE = sizeof(CONTENT);
25 ASSERT_EQ(CONTENT_SIZE,
26 LIBC_NAMESPACE::fwrite(CONTENT, 1, CONTENT_SIZE, file));
27#ifndef LIBC_TARGET_ARCH_IS_GPU // Behavior varies between libc implementations.
28 // Cannot unget to an un-readable file.
29 ASSERT_EQ(EOF, LIBC_NAMESPACE::ungetc('1', file));
30#endif
31 ASSERT_EQ(0, LIBC_NAMESPACE::fclose(file));
32
33 file = LIBC_NAMESPACE::fopen(FILENAME, "r+");
34 ASSERT_FALSE(file == nullptr);
35 // Calling with an EOF should always return EOF without doing anything.
36 ASSERT_EQ(EOF, LIBC_NAMESPACE::ungetc(EOF, file));
37 char c;
38 ASSERT_EQ(LIBC_NAMESPACE::fread(&c, 1, 1, file), size_t(1));
39 ASSERT_EQ(c, CONTENT[0]);
40 ASSERT_EQ(LIBC_NAMESPACE::ungetc(int(c), file), int(c));
41
42 char data[CONTENT_SIZE];
43 ASSERT_EQ(CONTENT_SIZE, LIBC_NAMESPACE::fread(data, 1, CONTENT_SIZE, file));
44 ASSERT_STREQ(CONTENT, data);
45
46 ASSERT_EQ(0, LIBC_NAMESPACE::fseek(file, 0, SEEK_SET));
47 // ungetc should not fail after a seek operation.
48 int unget_char = 'z';
49 ASSERT_EQ(unget_char, LIBC_NAMESPACE::ungetc(unget_char, file));
50#ifndef LIBC_TARGET_ARCH_IS_GPU // Behavior varies between libc implementations.
51 // Another unget should fail.
52 ASSERT_EQ(EOF, LIBC_NAMESPACE::ungetc(unget_char, file));
53#endif
54 // ungetting a char at the beginning of the file will allow us to fetch
55 // one additional character.
56 char new_data[CONTENT_SIZE + 1];
57 ASSERT_EQ(CONTENT_SIZE + 1,
58 LIBC_NAMESPACE::fread(new_data, 1, CONTENT_SIZE + 1, file));
59 ASSERT_STREQ("zabcdef", new_data);
60
61 ASSERT_EQ(size_t(1), LIBC_NAMESPACE::fwrite("x", 1, 1, file));
62#ifndef LIBC_TARGET_ARCH_IS_GPU // Behavior varies between libc implementations.
63 // unget should fail after a write operation.
64 ASSERT_EQ(EOF, LIBC_NAMESPACE::ungetc('1', file));
65#endif
66
67 ASSERT_EQ(0, LIBC_NAMESPACE::fclose(file));
68}
69

source code of libc/test/src/stdio/ungetc_test.cpp