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/* $Cambridge: hermes/src/prayer/shared/gzip.c,v 1.3 2008/09/16 09:59:58 dpc22 Exp $ */
/************************************************
* Prayer - a Webmail Interface *
************************************************/
/* Copyright (c) University of Cambridge 2000 - 2008 */
/* See the file NOTICE for conditions of use and distribution. */
/* Code stolen from zlib: gzio.c and gzutil.c */
#include "shared.h"
#ifndef GZIP_ENABLE
struct buffer *gzip(struct buffer *input)
{
log_fatal("gzip() called without gzip support enabled");
return (NIL);
}
#else
#include <zlib.h>
#define DEF_MEM_LEVEL 8
#define Z_BUFSIZE 16384
#define OS_CODE 0x03 /* assume Unix */
#define ALLOC(size) malloc(size)
#define TRYFREE(p) {if (p) free(p);}
#define F_OPEN(name, mode) fopen((name), (mode))
static int gz_magic[2] = { 0x1f, 0x8b }; /* gzip magic header */
typedef struct gz_stream {
z_stream stream;
int z_err; /* error code for last stream operation */
int z_eof; /* set if end of input file */
Byte *inbuf; /* input buffer */
Byte *outbuf; /* output buffer */
uLong crc; /* crc32 of uncompressed data */
char *msg; /* error message */
int transparent; /* 1 if input file is not a .gz file */
struct buffer *output;
} gz_stream;
/* ====================================================================== */
/* Utility functions */
static void putLong(struct buffer *b, uLong x)
{
int n;
for (n = 0; n < 4; n++) {
bputc(b, (int) (x & 0xff));
x >>= 8;
}
}
static void bwrite(struct buffer *b, unsigned char *x, unsigned long len)
{
while (len > 0) {
bputc(b, *x++);
len--;
}
}
static int do_flush(gzFile file, int flush)
{
uInt len;
int done = 0;
gz_stream *s = (gz_stream *) file;
s->stream.avail_in = 0; /* should be zero already anyway */
for (;;) {
len = Z_BUFSIZE - s->stream.avail_out;
if (len != 0) {
bwrite(s->output, s->outbuf, len);
s->stream.next_out = s->outbuf;
s->stream.avail_out = Z_BUFSIZE;
}
if (done)
break;
s->z_err = deflate(&(s->stream), flush);
/* Ignore the second of two consecutive flushes: */
if (len == 0 && s->z_err == Z_BUF_ERROR)
s->z_err = Z_OK;
/* deflate has finished flushing only when it hasn't used up
* all the available space in the output buffer:
*/
done = (s->stream.avail_out != 0 || s->z_err == Z_STREAM_END);
if (s->z_err != Z_OK && s->z_err != Z_STREAM_END)
break;
}
return s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
}
static int destroy(gz_stream * s)
{
int err = Z_OK;
if (!s)
return Z_STREAM_ERROR;
TRYFREE(s->msg);
if (s->stream.state != NULL)
err = deflateEnd(&(s->stream));
if (s->z_err < 0)
err = s->z_err;
TRYFREE(s->inbuf);
TRYFREE(s->outbuf);
TRYFREE(s);
return (err);
}
/* ====================================================================== */
static gzFile my_gzopen(struct buffer *output)
{
int err;
int level = Z_DEFAULT_COMPRESSION; /* compression level */
int strategy = Z_DEFAULT_STRATEGY; /* compression strategy */
gz_stream *s;
s = (gz_stream *) ALLOC(sizeof(gz_stream));
if (!s)
return Z_NULL;
s->stream.zalloc = (alloc_func) 0;
s->stream.zfree = (free_func) 0;
s->stream.opaque = (voidpf) 0;
s->stream.next_in = s->inbuf = Z_NULL;
s->stream.next_out = s->outbuf = Z_NULL;
s->stream.avail_in = s->stream.avail_out = 0;
s->z_err = Z_OK;
s->z_eof = 0;
s->crc = crc32(0L, Z_NULL, 0);
s->msg = NULL;
s->transparent = 0;
s->output = output;
err = deflateInit2(&(s->stream), level,
Z_DEFLATED, -MAX_WBITS, DEF_MEM_LEVEL, strategy);
/* windowBits is passed < 0 to suppress zlib header */
s->stream.next_out = s->outbuf = (Byte *) ALLOC(Z_BUFSIZE);
if (err != Z_OK || s->outbuf == Z_NULL)
return destroy(s), (gzFile) Z_NULL;
s->stream.avail_out = Z_BUFSIZE;
errno = 0;
/* Write a very simple .gz header:
*/
bprintf(s->output, "%c%c%c%c%c%c%c%c%c%c", gz_magic[0], gz_magic[1],
Z_DEFLATED, 0 /*flags */ , 0, 0, 0, 0 /*time */ ,
0 /*xflags */ ,
OS_CODE);
return (gzFile) s;
}
static int my_gzwrite(gzFile file, const voidp buf, unsigned len)
{
gz_stream *s = (gz_stream *) file;
s->stream.next_in = (Bytef *) buf;
s->stream.avail_in = len;
while (s->stream.avail_in != 0) {
if (s->stream.avail_out == 0) {
s->stream.next_out = s->outbuf;
bwrite(s->output, s->outbuf, Z_BUFSIZE);
s->stream.avail_out = Z_BUFSIZE;
}
s->z_err = deflate(&(s->stream), Z_NO_FLUSH);
if (s->z_err != Z_OK)
break;
}
s->crc = crc32(s->crc, (const Bytef *) buf, len);
return (int) (len - s->stream.avail_in);
}
static int my_gzclose(gzFile file)
{
int err;
gz_stream *s = (gz_stream *) file;
if (s == NULL)
return Z_STREAM_ERROR;
err = do_flush(file, Z_FINISH);
if (err != Z_OK)
return destroy((gz_stream *) file);
putLong(s->output, s->crc);
putLong(s->output, s->stream.total_in);
return destroy((gz_stream *) file);
}
/* ====================================================================== */
struct buffer *gzip(struct buffer *input)
{
struct pool *pool = input->pool;
struct buffer *output = buffer_create(pool, 0);
gz_stream *stream = my_gzopen(output);
unsigned char *src;
unsigned long srcl;
buffer_rewind(input);
while (buffer_fetch_block(input, &src, &srcl))
my_gzwrite(stream, src, srcl);
my_gzclose(stream);
return (output);
}
#endif
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