linux: Move posix dir implementations to Linux

This generic implementation already expects a getdents API which
is Linux specific.  It also allows simplify it by assuming
_DIRENT_HAVE_D_RECLEN and _DIRENT_HAVE_D_OFF support.

The readdir are also expanded on each required implementation,
futher fixes and improvements will make parametrize the
implementation more complex.

Checked on x86_64-linux-gnu, i686-linux-gnu, and with a build
for all affected ABIs.

1 files changed, 55 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/dirstream.h b/sysdeps/unix/sysv/linux/dirstream.h
new file mode 100644
index 0000000000..a3ea2b7197
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/dirstream.h
@@ -0,0 +1,55 @@
+/* Copyright (C) 1993-2020 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, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef	_DIRSTREAM_H
+#define	_DIRSTREAM_H	1
+
+#include <sys/types.h>
+
+#include <libc-lock.h>
+
+/* Directory stream type.
+
+   The miscellaneous Unix `readdir' implementations read directory data
+   into a buffer and return `struct dirent *' pointers into it.  */
+
+struct __dirstream
+  {
+    int fd;			/* File descriptor.  */
+
+    __libc_lock_define (, lock) /* Mutex lock for this structure.  */
+
+    size_t allocation;		/* Space allocated for the block.  */
+    size_t size;		/* Total valid data in the block.  */
+    size_t offset;		/* Current offset into the block.  */
+
+    off_t filepos;		/* Position of next entry to read.  */
+
+    int errcode;		/* Delayed error code.  */
+
+    /* Directory block.  We must make sure that this block starts
+       at an address that is aligned adequately enough to store
+       dirent entries.  Using the alignment of "void *" is not
+       sufficient because dirents on 32-bit platforms can require
+       64-bit alignment.  We use "long double" here to be consistent
+       with what malloc uses.  */
+    char data[0] __attribute__ ((aligned (__alignof__ (long double))));
+  };
+
+#define _DIR_dirfd(dirp)	((dirp)->fd)
+
+#endif	/* dirstream.h */