uncompr.c

/* uncompr.c -- decompress a memory buffer
 * Copyright (C) 1995-2026 Jean-loup Gailly, Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

/* @(#) $Id$ */

#define ZLIB_INTERNAL
#include "zlib.h"

/* ===========================================================================
     Decompresses the source buffer into the destination buffer.  *sourceLen is
   the byte length of the source buffer. Upon entry, *destLen is the total size
   of the destination buffer, which must be large enough to hold the entire
   uncompressed data. (The size of the uncompressed data must have been saved
   previously by the compressor and transmitted to the decompressor by some
   mechanism outside the scope of this compression library.) Upon exit,
   *destLen is the size of the decompressed data and *sourceLen is the number
   of source bytes consumed. Upon return, source + *sourceLen points to the
   first unused input byte.

     uncompress returns Z_OK if success, Z_MEM_ERROR if there was not enough
   memory, Z_BUF_ERROR if there was not enough room in the output buffer, or
   Z_DATA_ERROR if the input data was corrupted, including if the input data is
   an incomplete zlib stream.

     The _z versions of the functions take size_t length arguments.
*/
int ZEXPORT uncompress2_z(Bytef *dest, z_size_t *destLen, const Bytef *source,
                          z_size_t *sourceLen) {
    z_stream stream;
    int err;
    const uInt max = (uInt)-1;
    z_size_t len, left;

    if (sourceLen == NULL || (*sourceLen > 0 && source == NULL) ||
        destLen == NULL || (*destLen > 0 && dest == NULL))
        return Z_STREAM_ERROR;

    len = *sourceLen;
    left = *destLen;
    if (left == 0 && dest == Z_NULL)
        dest = (Bytef *)&stream.reserved;       /* next_out cannot be NULL */

    stream.next_in = (z_const Bytef *)source;
    stream.avail_in = 0;
    stream.zalloc = (alloc_func)0;
    stream.zfree = (free_func)0;
    stream.opaque = (voidpf)0;

    err = inflateInit(&stream);
    if (err != Z_OK) return err;

    stream.next_out = dest;
    stream.avail_out = 0;

    do {
        if (stream.avail_out == 0) {
            stream.avail_out = left > (z_size_t)max ? max : (uInt)left;
            left -= stream.avail_out;
        }
        if (stream.avail_in == 0) {
            stream.avail_in = len > (z_size_t)max ? max : (uInt)len;
            len -= stream.avail_in;
        }
        err = inflate(&stream, Z_NO_FLUSH);
    } while (err == Z_OK);

    /* Set len and left to the unused input data and unused output space. Set
       *sourceLen to the amount of input consumed. Set *destLen to the amount
       of data produced. */
    len += stream.avail_in;
    left += stream.avail_out;
    *sourceLen -= len;
    *destLen -= left;

    inflateEnd(&stream);
    return err == Z_STREAM_END ? Z_OK :
           err == Z_NEED_DICT ? Z_DATA_ERROR  :
           err == Z_BUF_ERROR && len == 0 ? Z_DATA_ERROR :
           err;
}
int ZEXPORT uncompress2(Bytef *dest, uLongf *destLen, const Bytef *source,
                        uLong *sourceLen) {
    int ret;
    z_size_t got = *destLen, used = *sourceLen;
    ret = uncompress2_z(dest, &got, source, &used);
    *sourceLen = (uLong)used;
    *destLen = (uLong)got;
    return ret;
}
int ZEXPORT uncompress_z(Bytef *dest, z_size_t *destLen, const Bytef *source,
                         z_size_t sourceLen) {
    z_size_t used = sourceLen;
    return uncompress2_z(dest, destLen, source, &used);
}
int ZEXPORT uncompress(Bytef *dest, uLongf *destLen, const Bytef *source,
                       uLong sourceLen) {
    uLong used = sourceLen;
    return uncompress2(dest, destLen, source, &used);
}