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 18 namespace LIBC_NAMESPACE { 19 20 LLVM_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, path, buf, 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