mirror of
https://github.com/MariaDB/server.git
synced 2025-01-21 22:34:18 +01:00
8923f6b741
Prevent GCC from moving a mach_read_from_4() before we have checked that we have 4 bytes to read. The pointer may only point to a 1, 2 or 3 bytes in which case the code should not read 4 bytes. This is a workaround to a GCC bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77673 Patch submitted by: Laurynas Biveinis <laurynas.biveinis@gmail.com> RB: 14135 Reviewed by: Pawel Olchawa <pawel.olchawa@oracle.com>
129 lines
3.3 KiB
C++
129 lines
3.3 KiB
C++
/*****************************************************************************
|
|
|
|
Copyright (c) 1995, 2016, Oracle and/or its affiliates. All Rights Reserved.
|
|
|
|
This program is free software; you can redistribute it and/or modify it under
|
|
the terms of the GNU General Public License as published by the Free Software
|
|
Foundation; version 2 of the License.
|
|
|
|
This program 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 General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License along with
|
|
this program; if not, write to the Free Software Foundation, Inc.,
|
|
51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
|
|
|
|
*****************************************************************************/
|
|
|
|
/******************************************************************//**
|
|
@file mach/mach0data.cc
|
|
Utilities for converting data from the database file
|
|
to the machine format.
|
|
|
|
Created 11/28/1995 Heikki Tuuri
|
|
***********************************************************************/
|
|
|
|
#include "mach0data.h"
|
|
|
|
/** Read a 32-bit integer in a compressed form.
|
|
@param[in,out] ptr pointer to memory where to read;
|
|
advanced by the number of bytes consumed, or set NULL if out of space
|
|
@param[in] end_ptr end of the buffer
|
|
@return unsigned value */
|
|
ib_uint32_t
|
|
mach_parse_compressed(
|
|
const byte** ptr,
|
|
const byte* end_ptr)
|
|
{
|
|
ulint val;
|
|
|
|
if (*ptr >= end_ptr) {
|
|
*ptr = NULL;
|
|
return(0);
|
|
}
|
|
|
|
val = mach_read_from_1(*ptr);
|
|
|
|
if (val < 0x80) {
|
|
/* 0nnnnnnn (7 bits) */
|
|
++*ptr;
|
|
return(static_cast<ib_uint32_t>(val));
|
|
}
|
|
|
|
/* Workaround GCC bug
|
|
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77673:
|
|
the compiler moves mach_read_from_4 right to the beginning of the
|
|
function, causing and out-of-bounds read if we are reading a short
|
|
integer close to the end of buffer. */
|
|
#if defined(__GNUC__) && (__GNUC__ >= 5) && !defined(__clang__)
|
|
#define DEPLOY_FENCE
|
|
#endif
|
|
|
|
#ifdef DEPLOY_FENCE
|
|
__atomic_thread_fence(__ATOMIC_ACQUIRE);
|
|
#endif
|
|
|
|
if (val < 0xC0) {
|
|
/* 10nnnnnn nnnnnnnn (14 bits) */
|
|
if (end_ptr >= *ptr + 2) {
|
|
val = mach_read_from_2(*ptr) & 0x3FFF;
|
|
ut_ad(val > 0x7F);
|
|
*ptr += 2;
|
|
return(static_cast<ib_uint32_t>(val));
|
|
}
|
|
*ptr = NULL;
|
|
return(0);
|
|
}
|
|
|
|
#ifdef DEPLOY_FENCE
|
|
__atomic_thread_fence(__ATOMIC_ACQUIRE);
|
|
#endif
|
|
|
|
if (val < 0xE0) {
|
|
/* 110nnnnn nnnnnnnn nnnnnnnn (21 bits) */
|
|
if (end_ptr >= *ptr + 3) {
|
|
val = mach_read_from_3(*ptr) & 0x1FFFFF;
|
|
ut_ad(val > 0x3FFF);
|
|
*ptr += 3;
|
|
return(static_cast<ib_uint32_t>(val));
|
|
}
|
|
*ptr = NULL;
|
|
return(0);
|
|
}
|
|
|
|
#ifdef DEPLOY_FENCE
|
|
__atomic_thread_fence(__ATOMIC_ACQUIRE);
|
|
#endif
|
|
|
|
if (val < 0xF0) {
|
|
/* 1110nnnn nnnnnnnn nnnnnnnn nnnnnnnn (28 bits) */
|
|
if (end_ptr >= *ptr + 4) {
|
|
val = mach_read_from_4(*ptr) & 0xFFFFFFF;
|
|
ut_ad(val > 0x1FFFFF);
|
|
*ptr += 4;
|
|
return(static_cast<ib_uint32_t>(val));
|
|
}
|
|
*ptr = NULL;
|
|
return(0);
|
|
}
|
|
|
|
#ifdef DEPLOY_FENCE
|
|
__atomic_thread_fence(__ATOMIC_ACQUIRE);
|
|
#endif
|
|
|
|
#undef DEPLOY_FENCE
|
|
|
|
ut_ad(val == 0xF0);
|
|
|
|
/* 11110000 nnnnnnnn nnnnnnnn nnnnnnnn nnnnnnnn (32 bits) */
|
|
if (end_ptr >= *ptr + 5) {
|
|
val = mach_read_from_4(*ptr + 1);
|
|
ut_ad(val > 0xFFFFFFF);
|
|
*ptr += 5;
|
|
return(static_cast<ib_uint32_t>(val));
|
|
}
|
|
|
|
*ptr = NULL;
|
|
return(0);
|
|
}
|