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-rw-r--r--sysdeps/unix/sysv/linux/readlinkat.c90
1 files changed, 90 insertions, 0 deletions
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 <errno.h>
+#include <fcntl.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysdep.h>
+#include <unistd.h>
+#include <kernel-features.h>
+
+
+/* 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)