41 lines · cpp
1//===-- Linux implementation of readlink ----------------------------------===//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/unistd/readlink.h"10 11#include "src/__support/OSUtil/syscall.h" // For internal syscall function.12#include "src/__support/common.h"13 14#include "hdr/fcntl_macros.h"15#include "src/__support/libc_errno.h"16#include "src/__support/macros/config.h"17#include <sys/syscall.h> // For syscall numbers.18 19namespace LIBC_NAMESPACE_DECL {20 21LLVM_LIBC_FUNCTION(ssize_t, readlink,22 (const char *__restrict path, char *__restrict buf,23 size_t bufsize)) {24#ifdef SYS_readlink25 ssize_t ret =26 LIBC_NAMESPACE::syscall_impl<ssize_t>(SYS_readlink, path, buf, bufsize);27#elif defined(SYS_readlinkat)28 ssize_t ret = LIBC_NAMESPACE::syscall_impl<ssize_t>(SYS_readlinkat, AT_FDCWD,29 path, buf, bufsize);30#else31#error "readlink or readlinkat syscalls not available."32#endif33 if (ret < 0) {34 libc_errno = static_cast<int>(-ret);35 return -1;36 }37 return ret;38}39 40} // namespace LIBC_NAMESPACE_DECL41