source: smplayer/vendor/0.8.6/zlib/gzwrite.c@ 177

/* gzwrite.c -- zlib functions for writing gzip files
 * Copyright (C) 2004, 2005, 2010, 2011, 2012 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

#include "gzguts.h"

/* Local functions */
local int gz_init OF((gz_statep));
local int gz_comp OF((gz_statep, int));
local int gz_zero OF((gz_statep, z_off64_t));

/* Initialize state for writing a gzip file.  Mark initialization by setting
   state->size to non-zero.  Return -1 on failure or 0 on success. */
local int gz_init(state)
    gz_statep state;
{
    int ret;
    z_streamp strm = &(state->strm);

    /* allocate input buffer */
    state->in = malloc(state->want);
    if (state->in == NULL) {
        gz_error(state, Z_MEM_ERROR, "out of memory");
        return -1;
    }

    /* only need output buffer and deflate state if compressing */
    if (!state->direct) {
        /* allocate output buffer */
        state->out = malloc(state->want);
        if (state->out == NULL) {
            free(state->in);
            gz_error(state, Z_MEM_ERROR, "out of memory");
            return -1;
        }

        /* allocate deflate memory, set up for gzip compression */
        strm->zalloc = Z_NULL;
        strm->zfree = Z_NULL;
        strm->opaque = Z_NULL;
        ret = deflateInit2(strm, state->level, Z_DEFLATED,
                           MAX_WBITS + 16, DEF_MEM_LEVEL, state->strategy);
        if (ret != Z_OK) {
            free(state->out);
            free(state->in);
            gz_error(state, Z_MEM_ERROR, "out of memory");
            return -1;
        }
    }

    /* mark state as initialized */
    state->size = state->want;

    /* initialize write buffer if compressing */
    if (!state->direct) {
        strm->avail_out = state->size;
        strm->next_out = state->out;
        state->x.next = strm->next_out;
    }
    return 0;
}

/* Compress whatever is at avail_in and next_in and write to the output file.
   Return -1 if there is an error writing to the output file, otherwise 0.
   flush is assumed to be a valid deflate() flush value.  If flush is Z_FINISH,
   then the deflate() state is reset to start a new gzip stream.  If gz->direct
   is true, then simply write to the output file without compressing, and
   ignore flush. */
local int gz_comp(state, flush)
    gz_statep state;
    int flush;
{
    int ret, got;
    unsigned have;
    z_streamp strm = &(state->strm);

    /* allocate memory if this is the first time through */
    if (state->size == 0 && gz_init(state) == -1)
        return -1;

    /* write directly if requested */
    if (state->direct) {
        got = write(state->fd, strm->next_in, strm->avail_in);
        if (got < 0 || (unsigned)got != strm->avail_in) {
            gz_error(state, Z_ERRNO, zstrerror());
            return -1;
        }
        strm->avail_in = 0;
        return 0;
    }

    /* run deflate() on provided input until it produces no more output */
    ret = Z_OK;
    do {
        /* write out current buffer contents if full, or if flushing, but if
           doing Z_FINISH then don't write until we get to Z_STREAM_END */
        if (strm->avail_out == 0 || (flush != Z_NO_FLUSH &&
            (flush != Z_FINISH || ret == Z_STREAM_END))) {
            have = (unsigned)(strm->next_out - state->x.next);
            if (have && ((got = write(state->fd, state->x.next, have)) < 0 ||
                         (unsigned)got != have)) {
                gz_error(state, Z_ERRNO, zstrerror());
                return -1;
            }
            if (strm->avail_out == 0) {
                strm->avail_out = state->size;
                strm->next_out = state->out;
            }
            state->x.next = strm->next_out;
        }

        /* compress */
        have = strm->avail_out;
        ret = deflate(strm, flush);
        if (ret == Z_STREAM_ERROR) {
            gz_error(state, Z_STREAM_ERROR,
                      "internal error: deflate stream corrupt");
            return -1;
        }
        have -= strm->avail_out;
    } while (have);

    /* if that completed a deflate stream, allow another to start */
    if (flush == Z_FINISH)
        deflateReset(strm);

    /* all done, no errors */
    return 0;
}

/* Compress len zeros to output.  Return -1 on error, 0 on success. */
local int gz_zero(state, len)
    gz_statep state;
    z_off64_t len;
{
    int first;
    unsigned n;
    z_streamp strm = &(state->strm);

    /* consume whatever's left in the input buffer */
    if (strm->avail_in && gz_comp(state, Z_NO_FLUSH) == -1)
        return -1;

    /* compress len zeros (len guaranteed > 0) */
    first = 1;
    while (len) {
        n = GT_OFF(state->size) || (z_off64_t)state->size > len ?
            (unsigned)len : state->size;
        if (first) {
            memset(state->in, 0, n);
            first = 0;
        }
        strm->avail_in = n;
        strm->next_in = state->in;
        state->x.pos += n;
        if (gz_comp(state, Z_NO_FLUSH) == -1)
            return -1;
        len -= n;
    }
    return 0;
}

/* -- see zlib.h -- */
int ZEXPORT gzwrite(file, buf, len)
    gzFile file;
    voidpc buf;
    unsigned len;
{
    unsigned put = len;
    unsigned n;
    gz_statep state;
    z_streamp strm;

    /* get internal structure */
    if (file == NULL)
        return 0;
    state = (gz_statep)file;
    strm = &(state->strm);

    /* check that we're writing and that there's no error */
    if (state->mode != GZ_WRITE || state->err != Z_OK)
        return 0;

    /* since an int is returned, make sure len fits in one, otherwise return
       with an error (this avoids the flaw in the interface) */
    if ((int)len < 0) {
        gz_error(state, Z_DATA_ERROR, "requested length does not fit in int");
        return 0;
    }

    /* if len is zero, avoid unnecessary operations */
    if (len == 0)