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-exception
6//
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 "src/errno/libc_errno.h"
15#include <fcntl.h>
16#include <sys/syscall.h> // For syscall numbers.
17
18namespace LIBC_NAMESPACE {
19
20LLVM_LIBC_FUNCTION(ssize_t, readlink,
21 (const char *__restrict path, char *__restrict buf,
22 size_t bufsize)) {
23#ifdef SYS_readlink
24 ssize_t ret =
25 LIBC_NAMESPACE::syscall_impl<ssize_t>(SYS_readlink, ts: path, ts: buf, ts: bufsize);
26#elif defined(SYS_readlinkat)
27 ssize_t ret = LIBC_NAMESPACE::syscall_impl<ssize_t>(SYS_readlinkat, AT_FDCWD,
28 path, buf, bufsize);
29#else
30#error "readlink or readlinkat syscalls not available."
31#endif
32 if (ret < 0) {
33 libc_errno = static_cast<int>(-ret);
34 return -1;
35 }
36 return ret;
37}
38
39} // namespace LIBC_NAMESPACE
40

source code of libc/src/unistd/linux/readlink.cpp