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Re: 32bit UID support for glibc 2.1.3
>>>>> Ulrich Drepper writes:
Uli> Andreas Jaeger <aj@suse.de> writes:
>> The normal stat call only returns a 16bit uid. To get 32bit uids we
>> have to use stat64 and convert struct stat64 to struct stat with
>> checking for overflow (some entries in struct stat and struct stat64
>> have different sizes).
>>
>> Anybody with another idea how to solve the problem?
Uli> Look at the reality. I think that even though those fields have
Uli> larger types the values are not really larger and we can get along
Uli> with a simple assignment. The field type for stat64 are chosen after
Uli> the glibc version of stat64 not (only) because of changed kernel
Uli> requirements.
I'm appending a "clean" patch to implement my proposal. I check for
overflow in just two places: st_size and st_blocks. Both can be
larger than 32bit - in reality.
I'm just appending a patch for xstat for i386. If you agree that this
is the right solution, I'll do the rest. Please give me your feedback.
Thanks,
Andreas
2000-01-12 Andreas Jaeger <aj@suse.de>
* sysdeps/unix/sysv/linux/xstatconv.c (xstat32_conv): New
function; needed for 32bit uid support.
* sysdeps/unix/sysv/linux/i386/xstat.c: New file, handles 32bit
uids correctly.
============================================================
Index: sysdeps/unix/sysv/linux/xstatconv.c
--- sysdeps/unix/sysv/linux/xstatconv.c 1999/02/11 11:56:29 1.5
+++ sysdeps/unix/sysv/linux/xstatconv.c 2000/01/12 14:52:35
@@ -1,5 +1,5 @@
/* Convert between the kernel's `struct stat' format, and libc's.
- Copyright (C) 1991, 1995, 1996, 1997 Free Software Foundation, Inc.
+ Copyright (C) 1991, 1995, 1996, 1997, 2000 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
@@ -142,4 +142,72 @@
return 0;
#endif
+}
+
+static inline int
+xstat32_conv (int vers, struct stat64 *kbuf, struct stat *buf)
+{
+ switch (vers)
+ {
+ case _STAT_VER_LINUX:
+ {
+ /* Convert current kernel version of `struct stat64' to `struct stat'. */
+ buf->st_dev = kbuf->st_dev;
+#ifdef _HAVE___PAD1
+ buf->__pad1 = 0;
+#endif
+ buf->st_ino = kbuf->st_ino;
+ buf->st_mode = kbuf->st_mode;
+ buf->st_nlink = kbuf->st_nlink;
+ buf->st_uid = kbuf->st_uid;
+ buf->st_gid = kbuf->st_gid;
+ buf->st_rdev = kbuf->st_rdev;
+#ifdef _HAVE___PAD2
+ buf->__pad2 = 0;
+#endif
+ buf->st_size = kbuf->st_size;
+ /* Check for overflow. */
+ if (buf->st_size != kbuf->st_size)
+ {
+ __set_errno (EOVERFLOW);
+ return -1;
+ }
+ buf->st_blksize = kbuf->st_blksize;
+ buf->st_blocks = kbuf->st_blocks;
+ /* Check for overflow. */
+ if (buf->st_blocks != kbuf->st_blocks)
+ {
+ __set_errno (EOVERFLOW);
+ return -1;
+ }
+ buf->st_atime = kbuf->st_atime;
+#ifdef _HAVE___UNUSED1
+ buf->__unused1 = 0;
+#endif
+ buf->st_mtime = kbuf->st_mtime;
+#ifdef _HAVE___UNUSED2
+ buf->__unused2 = 0;
+#endif
+ buf->st_ctime = kbuf->st_ctime;
+#ifdef _HAVE___UNUSED3
+ buf->__unused3 = 0;
+#endif
+#ifdef _HAVE___UNUSED4
+ buf->__unused4 = 0;
+#endif
+#ifdef _HAVE___UNUSED5
+ buf->__unused5 = 0;
+#endif
+ }
+ break;
+
+ /* If struct stat64 is different from struct stat then
+ _STAT_VER_KERNEL does not make sense. */
+ case _STAT_VER_KERNEL:
+ default:
+ __set_errno (EINVAL);
+ return -1;
+ }
+
+ return 0;
}
============================================================
Index: sysdeps/unix/sysv/linux/i386/xstat.c
--- sysdeps/unix/sysv/linux/i386/xstat.c created
+++ sysdeps/unix/sysv/linux/i386/xstat.c Wed Jan 12 15:50:26 2000 1.1
@@ -0,0 +1,97 @@
+/* xstat using old-style Unix stat system call.
+ Copyright (C) 1991,95,96,97,98,2000 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 Library General Public License as
+ published by the Free Software Foundation; either version 2 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
+ Library General Public License for more details.
+
+ You should have received a copy of the GNU Library General Public
+ License along with the GNU C Library; see the file COPYING.LIB. If not,
+ write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+/* Ho hum, if xstat == xstat64 we must get rid of the prototype or gcc
+ will complain since they don't strictly match. */
+#define __xstat64 __xstat64_disable
+
+#include <errno.h>
+#include <stddef.h>
+#include <sys/stat.h>
+#include <kernel_stat.h>
+
+#include <sysdep.h>
+#include <sys/syscall.h>
+
+#include <xstatconv.c>
+
+extern int __syscall_stat (const char *, struct kernel_stat *);
+
+#ifdef __NR_stat64
+extern int __syscall_stat64 (const char *, struct stat64 *);
+# if __ASSUME_STAT64_SYSCALL == 0
+/* The variable is shared between all wrappers around *stat64 calls. */
+extern int __have_no_stat64;
+# endif
+#endif
+
+
+/* Get information about the file NAME in BUF. */
+int
+__xstat (int vers, const char *name, struct stat *buf)
+{
+#if __ASSUME_STAT64_SYSCALL > 0
+ struct kernel_stat kbuf;
+ int result;
+
+ result = INLINE_SYSCALL (stat64, 2, name, &buf64);
+ if (result == 0)
+ result = xstat32_conv (vers, &buf64, buf);
+ return result;
+#else
+ struct kernel_stat kbuf;
+ int result;
+
+ if (vers == _STAT_VER_KERNEL)
+ {
+ return INLINE_SYSCALL (stat, 2, name, (struct kernel_stat *) buf);
+ }
+# if defined __NR_stat64
+ /* To support 32 bit UIDs, we have to use stat64. The normal stat call only returns
+ 16 bit UIDs. */
+ if (! __have_no_stat64)
+ {
+ struct stat64 buf64;
+
+ int saved_errno = errno;
+ result = INLINE_SYSCALL (stat64, 2, name, &buf64);
+
+ if (result == 0)
+ result = xstat32_conv (vers, &buf64, buf);
+
+ if (result != -1 || errno != ENOSYS)
+ return result;
+
+ __set_errno (saved_errno);
+ __have_no_stat64 = 1;
+ }
+# endif
+ result = INLINE_SYSCALL (stat, 2, name, &kbuf);
+ if (result == 0)
+ result = xstat_conv (vers, &kbuf, buf);
+
+ return result;
+#endif /* __ASSUME_STAT64_SYSCALL */
+}
+
+weak_alias (__xstat, _xstat);
+#ifdef XSTAT_IS_XSTAT64
+#undef __xstat64
+strong_alias (__xstat, __xstat64);
+#endif
--
Andreas Jaeger
SuSE Labs aj@suse.de
private aj@arthur.rhein-neckar.de