[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Hurd libc implementations of *xattr calls
|
From: |
Roland McGrath |
|
Subject: |
Hurd libc implementations of *xattr calls |
|
Date: |
Sun, 22 Feb 2004 14:17:53 -0800 |
Hey, that's so trivial I implemented it last weekend and forgot I'd done
so! :-)
Naturally, this patch is wholly untested. It does compile, though. I
would appreciate some testing. (Remember, this is just about Unixish
access to the existing author and translator data, not any new kind of
attributes being stored with Hurd files.)
Caveats:
1. Setting "gnu.author" to empty is not fully atomic.
The semantics I've defined for this is that empty/lack-of-attribute
corresponds to st_author == st_uid. This is the desireable choice so
that files with no interesting author information don't store any extra
details in attributes; otherwise there would always be a gnu.author
attribute record for every file in an archive. However, the
implementation of *setxattr has to do an io_stat to get the st_uid value
to pass to file_chauthor; between those two calls, a chown could come in
between those RPCs and then setxattr(,"gnu.author",0,0) results in a new
gnu.author attribute (showing the pre-chown st_uid value) even if there
was never any request to set it that way.
2. The XATTR_CREATE and XATTR_REPLACE flags are not fully atomic as
they are in monolithic kernel system call versions of these calls.
That is, atomic with respect to other *setxattr calls or the underlying
equivalents (which are file_chauthor and file_set_translator).
The only case that actually does full atomicity is setting
gnu.translator with XATTR_CREATE. It would be easy to add a new
flag FS_TRANS_MUSTEXIST to robustly implement XATTR_REPLACE for translator.
3. This is not going to solve all your problems wrt archiving. As we
brought up before, there is the issue of examining translators with
O_NOTRANS lookups. The semantics of the existing libc calls are correct
as I've written them, and using O_NOTRANS for any of them would be
incorrect.
Enjoy,
Roland
Index: hurd/Makefile
===================================================================
RCS file: /cvs/glibc/libc/hurd/Makefile,v
retrieving revision 1.123
diff -b -p -u -r1.123 Makefile
--- hurd/Makefile 14 Oct 2002 01:03:09 -0000 1.123
+++ hurd/Makefile 22 Feb 2004 21:56:54 -0000
@@ -1,4 +1,4 @@
-# Copyright (C) 1991,92,93,94,95,96,97,98,99,2001,2002
+# Copyright (C) 1991,92,93,94,95,96,97,98,99,2001,2002,2004
# Free Software Foundation, Inc.
# This file is part of the GNU C Library.
@@ -60,7 +60,7 @@ routines = hurdstartup hurdinit \
vpprintf \
ports-get ports-set hurdports hurdmsg \
errno-loc \
- $(sig) $(dtable) $(inlines) port-cleanup report-wait
+ $(sig) $(dtable) $(inlines) port-cleanup report-wait xattr
sig = hurdsig hurdfault siginfo hurd-raise preempt-sig \
trampoline longjmp-ts catch-exc exc2signal hurdkill sigunwind \
thread-self thread-cancel intr-msg catch-signal
Index: hurd/xattr.c
===================================================================
RCS file: hurd/xattr.c
diff -N hurd/xattr.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ hurd/xattr.c 22 Feb 2004 21:56:54 -0000
@@ -0,0 +1,190 @@
+/* Support for *xattr interfaces on GNU/Hurd.
+ Copyright (C) 2004 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 <hurd.h>
+#include <hurd/xattr.h>
+#include <string.h>
+#include <sys/mman.h>
+
+/* Right now we support only a fixed set of xattr names for Hurd features.
+ There are no RPC interfaces for free-form xattr names and values.
+
+ Name Value encoding
+ ---- ----- --------
+ gnu.author empty if st_author==st_uid
+ uid_t giving st_author value
+ gnu.translator empty if no passive translator
+ translator and arguments: "/hurd/foo\0arg1\0arg2\0"
+*/
+
+error_t
+_hurd_xattr_get (io_t port, const char *name, void *value, size_t *size)
+{
+ if (strncmp (name, "gnu.", 4))
+ return EOPNOTSUPP;
+ name += 4;
+
+ if (!strcmp (name, "author"))
+ {
+ struct stat64 st;
+ error_t err = __io_stat (port, &st);
+ if (err)
+ return err;
+ if (st.st_author == st.st_uid)
+ *size = 0;
+ else if (value)
+ {
+ if (*size < sizeof st.st_author)
+ return ERANGE;
+ memcpy (value, &st.st_author, sizeof st.st_author);
+ }
+ *size = sizeof st.st_author;
+ return 0;
+ }
+
+ if (!strcmp (name, "translator"))
+ {
+ char *buf = value;
+ size_t bufsz = value ? *size : 0;
+ error_t err = __file_get_translator (port, &buf, &bufsz);
+ if (err)
+ return err;
+ if (*size > bufsz)
+ *size = bufsz;
+ if (buf != value && bufsz > 0)
+ {
+ if (value != NULL)
+ memcpy (value, buf, *size);
+ munmap (buf, bufsz);
+ }
+ return (value != NULL && *size < bufsz) ? ERANGE : 0;
+ }
+
+ return EOPNOTSUPP;
+}
+
+error_t
+_hurd_xattr_set (io_t port, const char *name, const void *value, size_t size,
+ int flags)
+{
+ if (strncmp (name, "gnu.", 4))
+ return EOPNOTSUPP;
+ name += 4;
+
+ if (!strcmp (name, "author"))
+ switch (size)
+ {
+ default:
+ return EINVAL;
+ case 0: /* "Clear" author by setting to st_uid. */
+ {
+ struct stat64 st;
+ error_t err = __io_stat (port, &st);
+ if (err)
+ return err;
+ if (st.st_author == st.st_uid)
+ {
+ /* Nothing to do. */
+ if (flags & XATTR_REPLACE)
+ return ENODATA;
+ return 0;
+ }
+ if (flags & XATTR_CREATE)
+ return EEXIST;
+ return __file_chauthor (port, st.st_uid);
+ }
+ case sizeof (uid_t): /* Set the author. */
+ {
+ uid_t id;
+ memcpy (&id, value, sizeof id);
+ if (flags & (XATTR_CREATE|XATTR_REPLACE))
+ {
+ struct stat64 st;
+ error_t err = __io_stat (port, &st);
+ if (err)
+ return err;
+ if (st.st_author == st.st_uid)
+ {
+ if (flags & XATTR_REPLACE)
+ return ENODATA;
+ }
+ else if (flags & XATTR_CREATE)
+ return EEXIST;
+ if (st.st_author == id)
+ /* Nothing to do. */
+ return 0;
+ }
+ return __file_chauthor (port, id);
+ }
+ }
+
+ if (!strcmp (name, "translator"))
+ {
+ if (flags & XATTR_REPLACE)
+ {
+ /* Must make sure it's already there. */
+ char *buf = NULL;
+ size_t bufsz = 0;
+ error_t err = __file_get_translator (port, &buf, &bufsz);
+ if (err)
+ return err;
+ if (bufsz > 0)
+ {
+ munmap (buf, bufsz);
+ return ENODATA;
+ }
+ }
+ return __file_set_translator (port,
+ FS_TRANS_SET | ((flags & XATTR_CREATE)
+ ? FS_TRANS_EXCL : 0), 0, 0,
+ value, size,
+ MACH_PORT_NULL, MACH_MSG_TYPE_COPY_SEND);
+ }
+
+ return EOPNOTSUPP;
+}
+
+error_t
+_hurd_xattr_list (io_t port, void *buffer, size_t *size)
+{
+ size_t total = 0;
+ char *bufp = buffer;
+ inline void add (const char *name, size_t len)
+ {
+ total += len;
+ if (bufp != NULL && total <= *size)
+ bufp = __mempcpy (bufp, name, len);
+ }
+#define add(s) add (s, sizeof s)
+
+ struct stat64 st;
+ error_t err = __io_stat (port, &st);
+ if (err)
+ return err;
+
+ if (st.st_author != st.st_uid)
+ add ("gnu.author");
+ if (st.st_mode & S_IPTRANS)
+ add ("gnu.translator");
+
+ if (buffer != NULL && total > *size)
+ return ERANGE;
+ *size = total;
+ return 0;
+}
Index: hurd/hurd/xattr.h
===================================================================
RCS file: hurd/hurd/xattr.h
diff -N hurd/hurd/xattr.h
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ hurd/hurd/xattr.h 22 Feb 2004 21:56:54 -0000
@@ -0,0 +1,34 @@
+/* Access to extended attributes on files for GNU/Hurd.
+ Copyright (C) 2004 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. */
+
+#ifndef _HURD_XATTR_H
+#define _HURD_XATTR_H 1
+
+#include <sys/xattr.h> /* This defines the XATTR_* flags. */
+
+/* These are the internal versions of getxattr/setxattr/listxattr. */
+extern error_t _hurd_xattr_get (io_t port, const char *name,
+ void *value, size_t *size);
+extern error_t _hurd_xattr_set (io_t port, const char *name,
+ const void *value, size_t size, int flags);
+extern error_t _hurd_xattr_list (io_t port, void *buffer, size_t *size);
+
+
+
+#endif /* hurd/xattr.h */
Index: sysdeps/mach/hurd/fgetxattr.c
===================================================================
RCS file: sysdeps/mach/hurd/fgetxattr.c
diff -N sysdeps/mach/hurd/fgetxattr.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ sysdeps/mach/hurd/fgetxattr.c 22 Feb 2004 21:56:54 -0000
@@ -0,0 +1,34 @@
+/* Access to extended attributes on files. Hurd version.
+ Copyright (C) 2004 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 <sys/xattr.h>
+#include <hurd.h>
+#include <hurd/xattr.h>
+#include <hurd/fd.h>
+
+ssize_t
+fgetxattr (int fd, const char *name, void *value, size_t size)
+{
+ error_t err;
+
+ err = HURD_DPORT_USE (fd, _hurd_xattr_get (port, name, value, &size));
+
+ return err ? __hurd_dfail (fd, err) : size;
+}
Index: sysdeps/mach/hurd/fsetxattr.c
===================================================================
RCS file: sysdeps/mach/hurd/fsetxattr.c
diff -N sysdeps/mach/hurd/fsetxattr.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ sysdeps/mach/hurd/fsetxattr.c 22 Feb 2004 21:56:54 -0000
@@ -0,0 +1,34 @@
+/* Access to extended attributes on files. Hurd version.
+ Copyright (C) 2004 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 <sys/xattr.h>
+#include <hurd.h>
+#include <hurd/xattr.h>
+#include <hurd/fd.h>
+
+ssize_t
+fsetxattr (int fd, const char *name, const void *value, size_t size, int flags)
+{
+ error_t err;
+
+ err = HURD_DPORT_USE (fd, _hurd_xattr_set (port, name, value, size, flags));
+
+ return err ? __hurd_dfail (fd, err) : size;
+}
Index: sysdeps/mach/hurd/getxattr.c
===================================================================
RCS file: sysdeps/mach/hurd/getxattr.c
diff -N sysdeps/mach/hurd/getxattr.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ sysdeps/mach/hurd/getxattr.c 22 Feb 2004 21:56:54 -0000
@@ -0,0 +1,35 @@
+/* Access to extended attributes on files. Hurd version.
+ Copyright (C) 2004 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 <sys/xattr.h>
+#include <hurd.h>
+#include <hurd/xattr.h>
+
+ssize_t
+getxattr (const char *path, const char *name, void *value, size_t size)
+{
+ error_t err;
+ file_t port = __file_name_lookup (path, 0, 0);
+ if (port == MACH_PORT_NULL)
+ return -1;
+ err = _hurd_xattr_get (port, name, value, &size);
+ __mach_port_deallocate (__mach_task_self (), port);
+ return err ? __hurd_fail (err) : size;
+}
Index: sysdeps/mach/hurd/lgetxattr.c
===================================================================
RCS file: sysdeps/mach/hurd/lgetxattr.c
diff -N sysdeps/mach/hurd/lgetxattr.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ sysdeps/mach/hurd/lgetxattr.c 22 Feb 2004 21:56:54 -0000
@@ -0,0 +1,36 @@
+/* Access to extended attributes on files. Hurd version.
+ Copyright (C) 2004 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 <sys/xattr.h>
+#include <hurd.h>
+#include <hurd/xattr.h>
+#include <fcntl.h>
+
+ssize_t
+lgetxattr (const char *path, const char *name, void *value, size_t size)
+{
+ error_t err;
+ file_t port = __file_name_lookup (path, O_NOLINK, 0);
+ if (port == MACH_PORT_NULL)
+ return -1;
+ err = _hurd_xattr_get (port, name, value, &size);
+ __mach_port_deallocate (__mach_task_self (), port);
+ return err ? __hurd_fail (err) : size;
+}
Index: sysdeps/mach/hurd/lsetxattr.c
===================================================================
RCS file: sysdeps/mach/hurd/lsetxattr.c
diff -N sysdeps/mach/hurd/lsetxattr.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ sysdeps/mach/hurd/lsetxattr.c 22 Feb 2004 21:56:54 -0000
@@ -0,0 +1,37 @@
+/* Access to extended attributes on files. Hurd version.
+ Copyright (C) 2004 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 <sys/xattr.h>
+#include <hurd.h>
+#include <hurd/xattr.h>
+#include <fcntl.h>
+
+ssize_t
+lsetxattr (const char *path, const char *name, const void *value, size_t size,
+ int flags)
+{
+ error_t err;
+ file_t port = __file_name_lookup (path, O_NOLINK, 0);
+ if (port == MACH_PORT_NULL)
+ return -1;
+ err = _hurd_xattr_set (port, name, value, size, flags);
+ __mach_port_deallocate (__mach_task_self (), port);
+ return err ? __hurd_fail (err) : size;
+}
Index: sysdeps/mach/hurd/setxattr.c
===================================================================
RCS file: sysdeps/mach/hurd/setxattr.c
diff -N sysdeps/mach/hurd/setxattr.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ sysdeps/mach/hurd/setxattr.c 22 Feb 2004 21:56:54 -0000
@@ -0,0 +1,36 @@
+/* Access to extended attributes on files. Hurd version.
+ Copyright (C) 2004 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 <sys/xattr.h>
+#include <hurd.h>
+#include <hurd/xattr.h>
+
+ssize_t
+setxattr (const char *path, const char *name, const void *value, size_t size,
+ int flags)
+{
+ error_t err;
+ file_t port = __file_name_lookup (path, 0, 0);
+ if (port == MACH_PORT_NULL)
+ return -1;
+ err = _hurd_xattr_set (port, name, value, size, flags);
+ __mach_port_deallocate (__mach_task_self (), port);
+ return err ? __hurd_fail (err) : size;
+}
| [Prev in Thread] |
Current Thread |
[Next in Thread] |
- Hurd libc implementations of *xattr calls,
Roland McGrath <=