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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, Fifth Floor, 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);
}
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