zoneminder/src/zm_buffer.cpp

94 lines
2.8 KiB
C++

/*
* ZoneMinder flexible memory class implementation, $Date$, $Revision$
* Copyright (C) 2001-2008 Philip Coombes
*
* 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; either version 2
* of the License, or (at your option) any later version.
*
* 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 02110-1301 USA.
*/
#include "zm_buffer.h"
#include <unistd.h>
unsigned int Buffer::assign(const unsigned char *pStorage, unsigned int pSize) {
if ( mAllocation < pSize ) {
delete[] mStorage;
mAllocation = pSize;
mHead = mStorage = new unsigned char[pSize];
}
mSize = pSize;
memcpy(mStorage, pStorage, mSize);
mHead = mStorage;
mTail = mHead + mSize;
return mSize;
}
unsigned int Buffer::expand(unsigned int count) {
int spare = mAllocation - mSize;
int headSpace = mHead - mStorage;
int tailSpace = spare - headSpace;
int width = mTail - mHead;
if ( spare >= static_cast<int>(count) ) {
// There is enough space in the allocation might need to shift everything over though
//
if ( tailSpace < static_cast<int>(count) ) {
// if there is extra space at the head, shift everything over
memmove(mStorage, mHead, mSize);
mHead = mStorage;
mTail = mHead + width;
}
} else {
mAllocation += count;
unsigned char *newStorage = new unsigned char[mAllocation];
if ( mStorage ) {
memcpy(newStorage, mHead, mSize);
delete[] mStorage;
}
mStorage = newStorage;
mHead = mStorage;
mTail = mHead + width;
}
return mSize;
}
int Buffer::read_into(int sd, unsigned int bytes) {
// Make sure there is enough space
this->expand(bytes);
Debug(3, "Reading %u bytes", bytes);
int bytes_read = ::read(sd, mTail, bytes);
if (bytes_read > 0) {
mTail += bytes_read;
mSize += bytes_read;
}
return bytes_read;
}
int Buffer::read_into(int sd, unsigned int bytes, Microseconds timeout) {
fd_set set;
FD_ZERO(&set); /* clear the set */
FD_SET(sd, &set); /* add our file descriptor to the set */
timeval timeout_tv = zm::chrono::duration_cast<timeval>(timeout);
int rv = select(sd + 1, &set, nullptr, nullptr, &timeout_tv);
if (rv == -1) {
Error("Error %d %s from select", errno, strerror(errno));
return rv;
} else if (rv == 0) {
Debug(1, "timeout"); /* a timeout occured */
return 0;
}
return read_into(sd, bytes);
}