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/*
* Copyright (c) 2017, The Linux Foundation. All rights reserved.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* 3. Neither the name of the copyright holder nor the names of its contributors
* may be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <limits.h>
#include "AEEBufBound.h"
#include "AEEstd.h"
/* Note on bounds-checking logic and saturation:
Simple pointer comparisons are not adequate for bounds checking. pcBuf
and pcEnd are assumed to be valid pointers in the address space. But
pcWrite is not ... it is a theoretical value that can exceed pcEnd, and
may in fact wrap around the end of the address space. In that case the
test for (pcWrite < pcEnd) will yield TRUE, although pcWrite is outside
the buffer. Use (pcEnd-pcWrite) > 0 to be accurate.
In order to ensure this works in all cases, we need to avoid integer
overflows. We do this by restricting pcWrite to the range
[pcBuf..pcBuf+INT_MAX]. The ensures that pcWrite-pcBuf and pcWrite-pcBuf
will always be valid integers. It also allows us to ensure that
BufBound_Wrote() will not return wildly misleading results.
PCSAT
pcBuf pcEnd pcBuf+MAXINT
|-------------------| . . . . . . . . . |
^ ^
pcWrite: (a) (b) */
#define PCSAT(me) ((me)->pcBuf + INT_MAX)
/* Advance me->pcWrite, saturating.
On entry:
*pnLen = number of bytes to be written (non-negative)
On exit:
return value = where to write (pointer into the buffer)
*pnLen = number of bytes to write */
static char *BufBound_ValidateWrite(BufBound *me, int *pnLen)
{
int nLen = *pnLen;
char *pcWrite = me->pcWrite;
int nMaxCopy = me->pcEnd - pcWrite; /* could be negative! */
if (nMaxCopy < nLen)
{
/* Must check PCSAT to validate advance */
int nMaxAdvance = PCSAT(me) - pcWrite; /* max amount to advance */
if (nLen > nMaxAdvance)
{
nLen = nMaxAdvance;
}
if (nMaxCopy < 0)
{
nMaxCopy = 0;
}
}
else
{
/* Simple case: all fits in the buffer */
nMaxCopy = nLen;
}
*pnLen = nMaxCopy;
me->pcWrite = pcWrite + nLen;
return pcWrite;
}
void BufBound_Write(BufBound *me, const char *pc, int nLen)
{
if (nLen > 0)
{
char *pcDest = BufBound_ValidateWrite(me, &nLen);
while (--nLen >= 0)
{
pcDest[nLen] = pc[nLen];
}
}
}
void BufBound_Putnc(BufBound *me, char c, int nLen)
{
if (nLen > 0)
{
char *pcDest = BufBound_ValidateWrite(me, &nLen);
while (--nLen >= 0)
{
pcDest[nLen] = c;
}
}
}
void BufBound_Advance(BufBound *me, int nLen)
{
uint32 uOffset = (uint32)((me->pcWrite - me->pcBuf) + nLen);
if (uOffset > INT_MAX)
{
uOffset = INT_MAX;
if (nLen < 0)
{
uOffset = 0;
}
}
me->pcWrite = me->pcBuf + uOffset;
}
void BufBound_Init(BufBound *me, char *pBuf, int nLen)
{
if (nLen < 0)
{
nLen = 0;
}
me->pcWrite = me->pcBuf = pBuf;
me->pcEnd = pBuf + nLen;
}
void BufBound_Putc(BufBound *me, char c)
{
if ((me->pcEnd - me->pcWrite) > 0)
{
*me->pcWrite++ = c;
}
else if (me->pcWrite != PCSAT(me))
{
++me->pcWrite;
}
}
void BufBound_ForceNullTerm(BufBound *me)
{
if ((me->pcEnd - me->pcWrite) > 0)
{
*me->pcWrite++ = '\0';
}
else
{
if (me->pcWrite != PCSAT(me))
{
++me->pcWrite;
}
/* Ensure null termination if non-empty buffer */
if (me->pcEnd != me->pcBuf)
{
me->pcEnd[-1] = '\0';
}
}
}
void BufBound_Puts(BufBound *me, const char *cpsz)
{
BufBound_Write(me, cpsz, std_strlen(cpsz));
}
int BufBound_BufSize(BufBound *me)
{
return me->pcEnd - me->pcBuf;
}
int BufBound_Left(BufBound *me)
{
return (me->pcEnd - me->pcWrite);
}
int BufBound_ReallyWrote(BufBound *me)
{
return STD_MIN(me->pcEnd - me->pcBuf, me->pcWrite - me->pcBuf);
}
int BufBound_Wrote(BufBound *me)
{
return (me->pcWrite - me->pcBuf);
}
void BufBound_WriteLE(BufBound *me,
const void *pvSrc, int nSrcSize,
const char *pszFields)
{
if (nSrcSize > 0)
{
int nLen = nSrcSize;
char *pcDest = BufBound_ValidateWrite(me, &nLen);
(void)std_CopyLE(pcDest, nLen, pvSrc, nSrcSize, pszFields);
}
}
void BufBound_WriteBE(BufBound *me,
const void *pvSrc, int nSrcSize,
const char *pszFields)
{
if (nSrcSize > 0)
{
int nLen = nSrcSize;
char *pcDest = BufBound_ValidateWrite(me, &nLen);
(void)std_CopyBE(pcDest, nLen, pvSrc, nSrcSize, pszFields);
}
}
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