fdsel.cpp   [plain text]

/*
 * Copyright (c) 2000-2001 Apple Computer, Inc. All Rights Reserved.
 * 
 * The contents of this file constitute Original Code as defined in and are
 * subject to the Apple Public Source License Version 1.2 (the 'License').
 * You may not use this file except in compliance with the License. Please obtain
 * a copy of the License at http://www.apple.com/publicsource and read it before
 * using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
 * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
 * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
 * specific language governing rights and limitations under the License.
 */


//
// fdsel - select-style file descriptor set management
//
#include "fdsel.h"


namespace Security {
namespace UnixPlusPlus {


//
// Throw the bitvectors away on destruction
// 
FDSet::~FDSet()
{
    delete mBits;
    delete mUseBits;
}


//
// Given the old and desired new sizes (in fd_mask words), grow
// the bitvectors. New storage is zero filled. Note that we preserve
// the mUseBits vector, so this is safe to do during a post-select scan.
// This function cannot shrink the bitmaps.
//
void FDSet::grow(int oldWords, int newWords)
{
    assert(oldWords < newWords);
    grow(mBits, oldWords, newWords);
    grow(mUseBits, oldWords, newWords);
}

void FDSet::grow(fd_mask * &bits, int oldWords, int newWords)
{
    fd_mask *newBits = new fd_mask[newWords];
    memcpy(newBits, bits, oldWords * sizeof(fd_mask));
    memset(newBits + oldWords, 0, (newWords - oldWords) * sizeof(fd_mask));
    delete [] bits;
    bits = newBits;
}


//
// Set or clear a single bit in the map.
// No check for overflow is perfomed.
//
void FDSet::set(int fd, bool on)
{
    if (on) {
        FD_SET(fd, (fd_set *)mBits);
    } else {
        FD_CLR(fd, (fd_set *)mBits);
        FD_CLR(fd, (fd_set *)mUseBits);
    }
}


//
// Copy only the first words fd_mask words from mBits to mUseBits
// and return that for select(2) use.
//
fd_set *FDSet::make(int words)
{
    //@@@ if empty -> return NULL (but check caller for [] use)
    memcpy(mUseBits, mBits, words * sizeof(fd_mask));
    return (fd_set *)mUseBits;
}


}	// end namespace IPPlusPlus
}	// end namespace Security