5afb937d8a
When calling setbuf(nullptr, 0) before performing file operations it should set the file to unbuffered mode. Currently the code avoids buffering internally, but the underlying stream still can buffer. This is addressed by disabling the buffering of the underlying stream. Fixes: https://github.com/llvm/llvm-project/issues/60509
121 lines
2.9 KiB
C++
121 lines
2.9 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// <fstream>
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// basic_streambuf<charT, traits>* setbuf(char_type* s, streamsize n) override;
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#include <fstream>
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#include <cstddef>
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#include <cassert>
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#include "test_macros.h"
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template <class CharT>
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static std::size_t file_size(const char* filename) {
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FILE* f = std::fopen(filename, "rb");
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std::fseek(f, 0, SEEK_END);
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long result = std::ftell(f);
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std::fclose(f);
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return result;
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}
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// Helper class to expose some protected std::basic_filebuf<CharT> members.
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template <class CharT>
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struct filebuf : public std::basic_filebuf<CharT> {
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CharT* base() { return this->pbase(); }
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CharT* ptr() { return this->pptr(); }
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};
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template <class CharT>
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static void buffered_request() {
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filebuf<CharT> buffer;
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CharT b[10] = {0};
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assert(buffer.pubsetbuf(b, 10) == &buffer);
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buffer.open("test.dat", std::ios_base::out);
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buffer.sputc(CharT('a'));
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assert(b[0] == 'a');
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buffer.close();
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assert(file_size<CharT>("test.dat") == 1);
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}
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template <class CharT>
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static void unbuffered_request_before_open() {
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filebuf<CharT> buffer;
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assert(buffer.pubsetbuf(nullptr, 0) == &buffer);
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assert(buffer.base() == nullptr);
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assert(buffer.ptr() == nullptr);
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buffer.open("test.dat", std::ios_base::out);
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assert(buffer.base() == nullptr);
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assert(buffer.ptr() == nullptr);
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buffer.sputc(CharT('a'));
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assert(buffer.base() == nullptr);
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assert(buffer.ptr() == nullptr);
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assert(file_size<CharT>("test.dat") == 1);
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}
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template <class CharT>
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static void unbuffered_request_after_open() {
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filebuf<CharT> buffer;
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buffer.open("test.dat", std::ios_base::out);
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assert(buffer.pubsetbuf(nullptr, 0) == &buffer);
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assert(buffer.base() == nullptr);
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assert(buffer.ptr() == nullptr);
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buffer.sputc(CharT('a'));
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assert(buffer.base() == nullptr);
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assert(buffer.ptr() == nullptr);
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assert(file_size<CharT>("test.dat") == 1);
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}
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template <class CharT>
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static void unbuffered_request_after_open_ate() {
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filebuf<CharT> buffer;
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buffer.open("test.dat", std::ios_base::out | std::ios_base::ate);
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assert(buffer.pubsetbuf(nullptr, 0) == &buffer);
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buffer.sputc(CharT('a'));
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assert(file_size<CharT>("test.dat") <= 1);
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// on libc++ buffering is used by default.
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LIBCPP_ASSERT(file_size<CharT>("test.dat") == 0);
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buffer.close();
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assert(file_size<CharT>("test.dat") == 1);
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}
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template <class CharT>
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static void test() {
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buffered_request<CharT>();
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unbuffered_request_before_open<CharT>();
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unbuffered_request_after_open<CharT>();
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unbuffered_request_after_open_ate<CharT>();
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}
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int main(int, char**) {
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test<char>();
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#ifndef TEST_HAS_NO_WIDE_CHARACTERS
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test<wchar_t>();
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#endif
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return 0;
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}
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