From bbe35a6e1b54ef5cd7c1c471886c30ba85c0804e Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 27 Apr 2024 19:47:50 +0200 Subject: Adding upstream version 1.21. Signed-off-by: Daniel Baumann --- lib/readlink.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 104 insertions(+) create mode 100644 lib/readlink.c (limited to 'lib/readlink.c') diff --git a/lib/readlink.c b/lib/readlink.c new file mode 100644 index 0000000..531913e --- /dev/null +++ b/lib/readlink.c @@ -0,0 +1,104 @@ +/* Read the contents of a symbolic link. + Copyright (C) 2003-2007, 2009-2020 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program 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 General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#include + +/* Specification. */ +#include + +#include +#include +#include + +#if !HAVE_READLINK + +/* readlink() substitute for systems that don't have a readlink() function, + such as DJGPP 2.03 and mingw32. */ + +ssize_t +readlink (char const *file, char *buf _GL_UNUSED, + size_t bufsize _GL_UNUSED) +{ + struct stat statbuf; + + /* In general we should use lstat() here, not stat(). But on platforms + without symbolic links, lstat() - if it exists - would be equivalent to + stat(), therefore we can use stat(). This saves us a configure check. */ + if (stat (file, &statbuf) >= 0) + errno = EINVAL; + return -1; +} + +#else /* HAVE_READLINK */ + +# undef readlink + +/* readlink() wrapper that uses correct types, for systems like cygwin + 1.5.x where readlink returns int, and which rejects trailing slash, + for Solaris 9. */ + +ssize_t +rpl_readlink (char const *file, char *buf, size_t bufsize) +{ +# if READLINK_TRAILING_SLASH_BUG + size_t file_len = strlen (file); + if (file_len && file[file_len - 1] == '/') + { + /* Even if FILE without the slash is a symlink to a directory, + both lstat() and stat() must resolve the trailing slash to + the directory rather than the symlink. We can therefore + safely use stat() to distinguish between EINVAL and + ENOTDIR/ENOENT, avoiding extra overhead of rpl_lstat(). */ + struct stat st; + if (stat (file, &st) == 0 || errno == EOVERFLOW) + errno = EINVAL; + return -1; + } +# endif /* READLINK_TRAILING_SLASH_BUG */ + + ssize_t r = readlink (file, buf, bufsize); + +# if READLINK_TRUNCATE_BUG + if (r < 0 && errno == ERANGE) + { + /* Try again with a bigger buffer. This is just for test cases; + real code invariably discards short reads. */ + char stackbuf[4032]; + r = readlink (file, stackbuf, sizeof stackbuf); + if (r < 0) + { + if (errno == ERANGE) + { + /* Clear the buffer, which is good enough for real code. + Thankfully, no test cases try short reads of enormous + symlinks and what would be the point anyway? */ + r = bufsize; + memset (buf, 0, r); + } + } + else + { + if (bufsize < r) + r = bufsize; + memcpy (buf, stackbuf, r); + } + } +# endif + + return r; +} + +#endif /* HAVE_READLINK */ -- cgit v1.2.3