6563dfe551
Add forward compatibility so that new binaries can run on old
kernels. If the new system call from ino64 isn't available on your
system, then the old one will be used and the results translated. The
stat and statfs families of functions are fully emulated. While not
required by policy, in this case it is helpful to our users to provide
this compatibility. In this case, it allows rollback of the kernel
after installing a new userland should a problem be discovered. It
also prevents foot-shooting if a user does an install before rebooting
with the new kernel. Finally, it allows the use case where one needs
to run new binaries on an old kernel as part of an upgrade process.
The getdirentries family uses tricks that may not work on remote
filesystems. Specifically, it uses a buffer 1/4 the size requested to
get the data from he old syscall.
The code carefully uses direct syscalls for old system calls to avoid
referencing freebsd11_* symbols, which contaminate ld-elf.so.1's
export table due to its use of stat functions, which causes errno to
be incorrect in client programs due to the wrong *stat* function being
resolved in some cases.
This code should removed sometime after 12 is branched.
Tested on: 12-current binaries on a 10.3-beta kernel run and return
consistent results. 12-current kernel and userland with
packages from before ino64 was committed also work.
Differential Revision: https://reviews.freebsd.org/D11185
Reviewed by: kib@, emaste@
118 lines
3.9 KiB
C
118 lines
3.9 KiB
C
/*-
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* Copyright (c) 2017 M. Warner Losh <imp@FreeBSD.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#define _WANT_FREEBSD11_DIRENT
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#include "namespace.h"
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#include <sys/param.h>
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#include <sys/syscall.h>
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#include "compat-ino64.h"
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#include <dirent.h>
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#include <errno.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include "libc_private.h"
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static ssize_t
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__cvt_dirents_from11(const char *de11, ssize_t len11, char *de, ssize_t len)
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{
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struct dirent *dst;
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const struct freebsd11_dirent *src;
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const char *edst, *esrc;
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ssize_t rlen;
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src = (const struct freebsd11_dirent *)de11;
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dst = (struct dirent *)de;
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esrc = de11 + len11;
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edst = de + len;
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while ((const char *)src < esrc && (const char *)dst < edst) {
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rlen = roundup(offsetof(struct dirent, d_name) + src->d_namlen + 1, 8);
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if ((const char *)dst + rlen >= edst)
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break;
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dst->d_fileno = src->d_fileno;
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dst->d_off = 0; /* nothing uses it yet, so safe for now */
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dst->d_reclen = rlen;
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dst->d_type = src->d_type;
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dst->d_pad0 = 0;
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dst->d_namlen = src->d_namlen;
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dst->d_pad1 = 0;
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memset(dst->d_name, 0, roundup(src->d_namlen + 1, 8));
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memcpy(dst->d_name, src->d_name, src->d_namlen);
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dst = (struct dirent *)((char *)dst + rlen);
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src = (const struct freebsd11_dirent *)((const char *)src + src->d_reclen);
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}
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return ((char *)dst - de);
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}
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#undef getdirentries
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__weak_reference(_getdirentries, getdirentries);
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#pragma weak _getdirentries
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ssize_t
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_getdirentries(int fd, char *buf, size_t nbytes, off_t *basep)
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{
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char *oldbuf;
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size_t len;
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ssize_t rv;
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if (__getosreldate() >= INO64_FIRST)
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return (__sys_getdirentries(fd, buf, nbytes, basep));
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/*
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* Because the old system call returns entries that are smaller than the
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* new, we could wind up in a situation where we have too many to fit in
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* the buffer with the new encoding. So sacrifice a small bit of
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* efficiency to ensure that never happens. We pick 1/4 the size round
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* up to the next DIRBLKSIZ. This will guarnatee enough room exists in
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* the dst buffer due to changes in efficiency in packing dirent
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* entries. We don't check against minimum block size to avoid a lot of
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* stat calls, we'll see if that's wise or not.
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* TBD: Will this difference matter to lseek?
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*/
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len = roundup(nbytes / 4, DIRBLKSIZ);
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oldbuf = malloc(len);
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if (oldbuf == NULL) {
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errno = EINVAL; /* ENOMEM not in possible list */
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return (-1);
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}
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rv = syscall(SYS_freebsd11_getdirentries, fd, oldbuf, len, basep);
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if (rv == -1) {
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free(oldbuf);
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return (rv);
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}
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if (rv > 0)
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rv = __cvt_dirents_from11(oldbuf, rv, buf, nbytes);
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free(oldbuf);
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return (rv);
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}
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