GzipHeader.cpp
/*
* Copyright (C) 2010 Regents of the University of Michigan
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "GzipHeader.h"
#include <iostream>
#include <cstring>
// Constructor to initialize member data to 0.
GzipHeader::GzipHeader()
{
// clear the union via memset:
memset(headerBuffer, 0, sizeof(headerBuffer));
}
// Desctructor - nothing to do.
GzipHeader::~GzipHeader()
{
}
// Method to read the gzip header from a file.
// Returns true if the file is a gzip file, false, otherwise.
bool GzipHeader::readHeader(FILE* filePtr)
{
bool isGzip = false;
// If the file is not already open, return false.
if (filePtr == NULL)
{
// File is not open, so return false - not a gzip file.
return(false);
}
// Try to read a header from the file.
// if(144 == fread(buffer, 1, 144, filePtr))
if (GZIP_HEADER_SIZE == fread(buffer, 1, GZIP_HEADER_SIZE, filePtr))
{
memcpy(headerBuffer, buffer, GZIP_HEADER_SIZE);
// Successfully read enough bytes, so check to see if it is a GzipFile.
if (isGzipFile())
{
// It is a gzip file.
isGzip = true;
}
}
return isGzip;
}
// Method to read the gzip header from a file.
// Returns true if the file is a gzip file, false, otherwise.
bool GzipHeader::readHeader(UncompressedFileType& file)
{
bool isGzip = false;
// If the file is not already open, return false.
if (!file.isOpen())
{
// File is not open, so return false - not a gzip file.
return(false);
}
// Try to read a header from the file.
// if(144 == file.read(buffer, 1, 144, filePtr))
if ((int)GZIP_HEADER_SIZE == file.read(buffer, GZIP_HEADER_SIZE))
{
memcpy(headerBuffer, buffer, GZIP_HEADER_SIZE);
// Successfully read enough bytes, so check to see if it is a GzipFile.
if (isGzipFile())
{
// It is a gzip file.
isGzip = true;
}
}
return isGzip;
}
// Determine if the file is a gzip file.
bool GzipHeader::isGzipFile()
{
if ((id1 == 31) && (id2 == 139))
{
return true;
}
return false;
}
// Determine if the file is a BGZF compressed file.
bool GzipHeader::isBgzfFile()
{
if (isGzipFile() && (si1 == 66) && (si2 == 67))
{
return true;
}
return false;
}
UncompressedFileType
Definition: UncompressedFileType.h:27