From 0ecb606cb6cf65de1d9fc8a919bceb4be476c602 Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Thu, 12 Jul 2007 18:26:36 +0000 Subject: 2.5-18.1 --- sysdeps/unix/sysv/linux/readlinkat.c | 90 ++++++++++++++++++++++++++++++++++++ 1 file changed, 90 insertions(+) create mode 100644 sysdeps/unix/sysv/linux/readlinkat.c (limited to 'sysdeps/unix/sysv/linux/readlinkat.c') diff --git a/sysdeps/unix/sysv/linux/readlinkat.c b/sysdeps/unix/sysv/linux/readlinkat.c new file mode 100644 index 0000000000..1361596503 --- /dev/null +++ b/sysdeps/unix/sysv/linux/readlinkat.c @@ -0,0 +1,90 @@ +/* Copyright (C) 2005, 2006 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + + +/* Read the contents of the symbolic link PATH relative to FD into no + more than LEN bytes of BUF. */ +ssize_t +readlinkat (fd, path, buf, len) + int fd; + const char *path; + char *buf; + size_t len; +{ + int result; + +#ifdef __NR_readlinkat +# ifndef __ASSUME_ATFCTS + if (__have_atfcts >= 0) +# endif + { + result = INLINE_SYSCALL (readlinkat, 4, fd, path, buf, len); +# ifndef __ASSUME_ATFCTS + if (result == -1 && errno == ENOSYS) + __have_atfcts = -1; + else +# endif + return result; + } +#endif + +#ifndef __ASSUME_ATFCTS + char *pathbuf = NULL; + + if (fd != AT_FDCWD && path[0] != '/') + { + size_t pathlen = strlen (path); + static const char procfd[] = "/proc/self/fd/%d/%s"; + /* Buffer for the path name we are going to use. It consists of + - the string /proc/self/fd/ + - the file descriptor number + - the file name provided. + The final NUL is included in the sizeof. A bit of overhead + due to the format elements compensates for possible negative + numbers. */ + size_t buflen = sizeof (procfd) + sizeof (int) * 3 + pathlen; + pathbuf = __alloca (buflen); + + __snprintf (pathbuf, buflen, procfd, fd, path); + path = pathbuf; + } + + INTERNAL_SYSCALL_DECL (err); + + result = INTERNAL_SYSCALL (readlink, err, 3, path, buf, len); + + if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0)) + { + __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, pathbuf); + result = -1; + } + + return result; +#endif +} +libc_hidden_def (readlinkat) -- cgit v1.2.3