57 lines · cpp
1//===-- Implementation of 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-exception6//7//===----------------------------------------------------------------------===//8 9#include "src/stdio/fgets.h"10#include "src/__support/File/file.h"11 12#include "hdr/types/FILE.h"13#include "src/__support/libc_errno.h"14#include "src/__support/macros/config.h"15#include <stddef.h>16 17namespace LIBC_NAMESPACE_DECL {18 19LLVM_LIBC_FUNCTION(char *, fgets,20 (char *__restrict str, int count,21 ::FILE *__restrict raw_stream)) {22 if (count < 1)23 return nullptr;24 25 unsigned char c = '\0';26 auto stream = reinterpret_cast<LIBC_NAMESPACE::File *__restrict>(raw_stream);27 stream->lock();28 29 // i is an int because it's frequently compared to count, which is also int.30 int i = 0;31 32 for (; i < (count - 1) && c != '\n'; ++i) {33 auto result = stream->read_unlocked(&c, 1);34 size_t r = result.value;35 if (result.has_error())36 libc_errno = result.error;37 38 if (r != 1)39 break;40 str[i] = c;41 }42 43 bool has_error = stream->error_unlocked();44 bool has_eof = stream->iseof_unlocked();45 stream->unlock();46 47 // If the requested read size makes no sense, an error occured, or no bytes48 // were read due to an EOF, then return nullptr and don't write the null byte.49 if (has_error || (i == 0 && has_eof))50 return nullptr;51 52 str[i] = '\0';53 return str;54}55 56} // namespace LIBC_NAMESPACE_DECL57