1/* Stub for readlink(). 2 Copyright (C) 2003-2007, 2009-2020 Free Software Foundation, Inc. 3 4 This program is free software: you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 3 of the License, or 7 (at your option) any later version. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program. If not, see <https://www.gnu.org/licenses/>. */ 16 17#include <config.h> 18 19/* Specification. */ 20#include <unistd.h> 21 22#include <errno.h> 23#include <string.h> 24#include <sys/stat.h> 25 26#if !HAVE_READLINK 27 28/* readlink() substitute for systems that don't have a readlink() function, 29 such as DJGPP 2.03 and mingw32. */ 30 31ssize_t 32readlink (const char *name, char *buf _GL_UNUSED, 33 size_t bufsize _GL_UNUSED) 34{ 35 struct stat statbuf; 36 37 /* In general we should use lstat() here, not stat(). But on platforms 38 without symbolic links, lstat() - if it exists - would be equivalent to 39 stat(), therefore we can use stat(). This saves us a configure check. */ 40 if (stat (name, &statbuf) >= 0) 41 errno = EINVAL; 42 return -1; 43} 44 45#else /* HAVE_READLINK */ 46 47# undef readlink 48 49/* readlink() wrapper that uses correct types, for systems like cygwin 50 1.5.x where readlink returns int, and which rejects trailing slash, 51 for Solaris 9. */ 52 53ssize_t 54rpl_readlink (const char *name, char *buf, size_t bufsize) 55{ 56# if READLINK_TRAILING_SLASH_BUG 57 size_t len = strlen (name); 58 if (len && name[len - 1] == '/') 59 { 60 /* Even if name without the slash is a symlink to a directory, 61 both lstat() and stat() must resolve the trailing slash to 62 the directory rather than the symlink. We can therefore 63 safely use stat() to distinguish between EINVAL and 64 ENOTDIR/ENOENT, avoiding extra overhead of rpl_lstat(). */ 65 struct stat st; 66 if (stat (name, &st) == 0) 67 errno = EINVAL; 68 return -1; 69 } 70# endif /* READLINK_TRAILING_SLASH_BUG */ 71 return readlink (name, buf, bufsize); 72} 73 74#endif /* HAVE_READLINK */ 75