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 "hdr/fcntl_macros.h" 15 #include "src/__support/macros/config.h" 16 #include "src/errno/libc_errno.h" 17 #include <sys/syscall.h> // For syscall numbers. 18 19 namespace LIBC_NAMESPACE_DECL { 20 21 LLVM_LIBC_FUNCTION(ssize_t, readlink, 22 (const char *__restrict path, char *__restrict buf, 23 size_t bufsize)) { 24 #ifdef SYS_readlink 25 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 #else 31 #error "readlink or readlinkat syscalls not available." 32 #endif 33 if (ret < 0) { 34 libc_errno = static_cast<int>(-ret); 35 return -1; 36 } 37 return ret; 38 } 39 40 } // namespace LIBC_NAMESPACE_DECL 41