Added readlinkat().

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@33978 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/posix/unistd.h

@@ -138,6 +138,8 @@ extern int		unlink(const char *name);
 extern int		rmdir(const char *path);
 
 extern ssize_t  readlink(const char *path, char *buffer, size_t bufferSize);
+extern ssize_t	readlinkat(int fd, const char *path, char *buffer,
+					size_t bufferSize);
 extern int      symlink(const char *from, const char *to);
 
 extern int      ftruncate(int fd, off_t newSize);

src/system/libroot/posix/unistd/link.c

@@ -19,9 +19,16 @@
 
 ssize_t
 readlink(const char *path, char *buffer, size_t bufferSize)
+{
+	return readlinkat(AT_FDCWD, path, buffer, bufferSize);
+}
+
+
+ssize_t
+readlinkat(int fd, const char *path, char *buffer, size_t bufferSize)
 {
 	size_t linkLen = bufferSize;
-	status_t status = _kern_read_link(-1, path, buffer, &linkLen);
+	status_t status = _kern_read_link(fd, path, buffer, &linkLen);
 	if (status < B_OK) {
 		errno = status;
 		return -1;
@@ -49,7 +56,7 @@ int
 unlink(const char *path)
 {
 	int status = _kern_unlink(-1, path);
-	
+
 	RETURN_AND_SET_ERRNO(status);
 }