source: lib/iow-zlib.c @ 15e9390

#include <zlib.h>
#include "wandio.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>

enum err_t {
        ERR_OK  = 1,
        ERR_EOF = 0,
        ERR_ERROR = -1
};

struct zlibw_t {
        z_stream strm;
        Bytef outbuff[1024*1024];
        iow_t *child;
        enum err_t err;
        int inoffset;
};


extern iow_source_t zlib_wsource; 

#define DATA(iow) ((struct zlibw_t *)((iow)->data))
#define min(a,b) ((a)<(b) ? (a) : (b))

iow_t *zlib_wopen(iow_t *child, int compress_level)
{
        iow_t *iow;
        if (!child)
                return NULL;
        iow = malloc(sizeof(iow_t));
        iow->source = &zlib_wsource;
        iow->data = malloc(sizeof(struct zlibw_t));

        DATA(iow)->child = child;

        DATA(iow)->strm.next_in = NULL;
        DATA(iow)->strm.avail_in = 0;
        DATA(iow)->strm.next_out = DATA(iow)->outbuff;
        DATA(iow)->strm.avail_out = sizeof(DATA(iow)->outbuff);
        DATA(iow)->strm.zalloc = Z_NULL;
        DATA(iow)->strm.zfree = Z_NULL;
        DATA(iow)->strm.opaque = NULL;
        DATA(iow)->err = ERR_OK;

        deflateInit2(&DATA(iow)->strm, 
                        compress_level, /* Level */
                        Z_DEFLATED,     /* Method */
                        15 | 16,        /* 15 bits of windowsize, 16 == use gzip header */
                        9,              /* Use maximum (fastest) amount of memory usage */
                        Z_DEFAULT_STRATEGY
                );

        return iow;
}


static off_t zlib_wwrite(iow_t *iow, const char *buffer, off_t len)
{
        if (DATA(iow)->err == ERR_EOF) {
                return 0; /* EOF */
        }
        if (DATA(iow)->err == ERR_ERROR) {
                return -1; /* ERROR! */
        }

        DATA(iow)->strm.next_in = (Bytef*)buffer; /* This casts away const, but it's really const 
                                                   * anyway 
                                                   */
        DATA(iow)->strm.avail_in = len;

        while (DATA(iow)->err == ERR_OK && DATA(iow)->strm.avail_in > 0) {
                while (DATA(iow)->strm.avail_out <= 0) {
                        int bytes_written = wandio_wwrite(DATA(iow)->child, 
                                (char *)DATA(iow)->outbuff,
                                sizeof(DATA(iow)->outbuff));
                        if (bytes_written <= 0) { /* Error */
                                DATA(iow)->err = ERR_ERROR;
                                /* Return how much data we managed to write ok */
                                if (DATA(iow)->strm.avail_in != len) {
                                        return len-DATA(iow)->strm.avail_in;
                                }
                                /* Now return error */
                                return -1;
                        }
                        DATA(iow)->strm.next_out = DATA(iow)->outbuff;
                        DATA(iow)->strm.avail_out = sizeof(DATA(iow)->outbuff);
                }
                /* Decompress some data into the output buffer */
                int err=deflate(&DATA(iow)->strm, 0);
                switch(err) {
                        case Z_OK:
                                DATA(iow)->err = ERR_OK;
                                break;
                        default:
                                DATA(iow)->err = ERR_ERROR;
                }
        }
        /* Return the number of bytes decompressed */
        return len-DATA(iow)->strm.avail_in;
}

static void zlib_wclose(iow_t *iow)
{
        while (deflate(&DATA(iow)->strm, Z_FINISH) == Z_OK) {
                /* Need to flush the output buffer */
                wandio_wwrite(DATA(iow)->child, 
                                (char*)DATA(iow)->outbuff,
                                sizeof(DATA(iow)->outbuff)-DATA(iow)->strm.avail_out);
                DATA(iow)->strm.next_out = DATA(iow)->outbuff;
                DATA(iow)->strm.avail_out = sizeof(DATA(iow)->outbuff);
        }
        deflateEnd(&DATA(iow)->strm);
        wandio_wwrite(DATA(iow)->child, 
                        (char *)DATA(iow)->outbuff,
                        sizeof(DATA(iow)->outbuff)-DATA(iow)->strm.avail_out);
        wandio_wdestroy(DATA(iow)->child);
        free(iow->data);
        free(iow);
}

iow_source_t zlib_wsource = {
        "zlibw",
        zlib_wwrite,
        zlib_wclose
};