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/*
** Copyright (c) 2011 D. Richard Hipp
**
** This program is free software; you can redistribute it and/or
** modify it under the terms of the Simplified BSD License (also
** known as the "2-Clause License" or "FreeBSD 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.
**
** Author contact information:
** drh@hwaci.com
** http://www.hwaci.com/drh/
**
*******************************************************************************
**
** This file contains code used to incrementally generate a GZIP compressed
** file. The GZIP format is described in RFC-1952.
**
** State information is stored in static variables, so this implementation
** can only be building up a single GZIP file at a time.
*/
#include "config.h"
#include <assert.h>
#include <zlib.h>
#include "gzip.h"
/*
** State information for the GZIP file under construction.
*/
struct gzip_state {
int eState; /* 0: idle 1: header 2: compressing */
unsigned long iCRC; /* The checksum */
z_stream stream; /* The working compressor */
Blob out; /* Results stored here */
} gzip;
/*
** Write a 32-bit integer as little-endian into the given buffer.
*/
static void put32(char *z, int v){
z[0] = v & 0xff;
z[1] = (v>>8) & 0xff;
z[2] = (v>>16) & 0xff;
z[3] = (v>>24) & 0xff;
}
/*
** Begin constructing a gzip file.
*/
void gzip_begin(sqlite3_int64 now){
char aHdr[10];
assert( gzip.eState==0 );
blob_zero(&gzip.out);
aHdr[0] = 0x1f;
aHdr[1] = 0x8b;
aHdr[2] = 8;
aHdr[3] = 0;
if( now==-1 ){
now = db_int64(0, "SELECT (julianday('now') - 2440587.5)*86400.0");
}
put32(&aHdr[4], now&0xffffffff);
aHdr[8] = 2;
aHdr[9] = -1;
blob_append(&gzip.out, aHdr, 10);
gzip.iCRC = 0;
gzip.eState = 1;
}
/*
** Add nIn bytes of content from pIn to the gzip file.
*/
#define GZIP_BUFSZ 100000
void gzip_step(const char *pIn, int nIn){
char *zOutBuf;
int nOut;
nOut = nIn + nIn/10 + 100;
if( nOut<100000 ) nOut = 100000;
zOutBuf = fossil_malloc(nOut);
gzip.stream.avail_in = nIn;
gzip.stream.next_in = (unsigned char*)pIn;
gzip.stream.avail_out = nOut;
gzip.stream.next_out = (unsigned char*)zOutBuf;
if( gzip.eState==1 ){
gzip.stream.zalloc = (alloc_func)0;
gzip.stream.zfree = (free_func)0;
gzip.stream.opaque = 0;
deflateInit2(&gzip.stream, 9, Z_DEFLATED, -MAX_WBITS,8,Z_DEFAULT_STRATEGY);
gzip.eState = 2;
}
gzip.iCRC = crc32(gzip.iCRC, gzip.stream.next_in, gzip.stream.avail_in);
do{
deflate(&gzip.stream, nIn==0 ? Z_FINISH : 0);
blob_append(&gzip.out, zOutBuf, nOut - gzip.stream.avail_out);
gzip.stream.avail_out = nOut;
gzip.stream.next_out = (unsigned char*)zOutBuf;
}while( gzip.stream.avail_in>0 );
fossil_free(zOutBuf);
}
/*
** Finish the gzip file and put the content in *pOut
*/
void gzip_finish(Blob *pOut){
char aTrailer[8];
assert( gzip.eState>0 );
gzip_step("", 0);
deflateEnd(&gzip.stream);
put32(aTrailer, gzip.iCRC);
put32(&aTrailer[4], gzip.stream.total_in);
blob_append(&gzip.out, aTrailer, 8);
*pOut = gzip.out;
blob_zero(&gzip.out);
gzip.eState = 0;
}
/*
** COMMAND: test-gzip
**
** Usage: %fossil test-gzip FILENAME
**
** Compress a file using gzip.
*/
void test_gzip_cmd(void){
Blob b;
char *zOut;
if( g.argc!=3 ) usage("FILENAME");
sqlite3_open(":memory:", &g.db);
gzip_begin(-1);
blob_read_from_file(&b, g.argv[2], ExtFILE);
zOut = mprintf("%s.gz", g.argv[2]);
gzip_step(blob_buffer(&b), blob_size(&b));
blob_reset(&b);
gzip_finish(&b);
blob_write_to_file(&b, zOut);
blob_reset(&b);
fossil_free(zOut);
}
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