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-rw-r--r--gl/lib/readlink.c74
1 files changed, 74 insertions, 0 deletions
diff --git a/gl/lib/readlink.c b/gl/lib/readlink.c
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+/* Stub for readlink().
+ Copyright (C) 2003-2007, 2009-2019 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 <https://www.gnu.org/licenses/>. */
+
+#include <config.h>
+
+/* Specification. */
+#include <unistd.h>
+
+#include <errno.h>
+#include <string.h>
+#include <sys/stat.h>
+
+#if !HAVE_READLINK
+
+/* readlink() substitute for systems that don't have a readlink() function,
+ such as DJGPP 2.03 and mingw32. */
+
+ssize_t
+readlink (const char *name, 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 (name, &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 (const char *name, char *buf, size_t bufsize)
+{
+# if READLINK_TRAILING_SLASH_BUG
+ size_t len = strlen (name);
+ if (len && name[len - 1] == '/')
+ {
+ /* Even if name 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 (name, &st) == 0)
+ errno = EINVAL;
+ return -1;
+ }
+# endif /* READLINK_TRAILING_SLASH_BUG */
+ return readlink (name, buf, bufsize);
+}
+
+#endif /* HAVE_READLINK */