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/*****************************************************************************
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"
#ifdef UNIV_NONINL
#include "mach0data.ic"
#endif
/*********************************************************//**
Reads a ulint in a compressed form if the log record fully contains it.
@return pointer to end of the stored field, NULL if not complete */
UNIV_INTERN
byte*
mach_parse_compressed(
/*==================*/
byte* ptr, /*!< in: pointer to buffer from where to read */
byte* end_ptr,/*!< in: pointer to end of the buffer */
ulint* val) /*!< out: read value (< 2^32) */
{
ulint flag;
ut_ad(ptr && end_ptr && val);
if (ptr >= end_ptr) {
return(NULL);
}
flag = mach_read_from_1(ptr);
if (flag < 0x80UL) {
*val = flag;
return(ptr + 1);
}
/* 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 (flag < 0xC0UL) {
if (end_ptr < ptr + 2) {
return(NULL);
}
*val = mach_read_from_2(ptr) & 0x7FFFUL;
return(ptr + 2);
}
#ifdef DEPLOY_FENCE
__atomic_thread_fence(__ATOMIC_ACQUIRE);
#endif
if (flag < 0xE0UL) {
if (end_ptr < ptr + 3) {
return(NULL);
}
*val = mach_read_from_3(ptr) & 0x3FFFFFUL;
return(ptr + 3);
}
#ifdef DEPLOY_FENCE
__atomic_thread_fence(__ATOMIC_ACQUIRE);
#endif
if (flag < 0xF0UL) {
if (end_ptr < ptr + 4) {
return(NULL);
}
*val = mach_read_from_4(ptr) & 0x1FFFFFFFUL;
return(ptr + 4);
}
#ifdef DEPLOY_FENCE
__atomic_thread_fence(__ATOMIC_ACQUIRE);
#endif
#undef DEPLOY_FENCE
ut_ad(flag == 0xF0UL);
if (end_ptr < ptr + 5) {
return(NULL);
}
*val = mach_read_from_4(ptr + 1);
return(ptr + 5);
}
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