github.com/Schaudge/grailbase@v0.0.0-20240223061707-44c758a471c0/compress/libdeflate/zlib_decompress.c (about)

     1  /*
     2   * zlib_decompress.c - decompress with a zlib wrapper
     3   *
     4   * Originally public domain; changes after 2016-09-07 are copyrighted.
     5   *
     6   * Copyright 2016 Eric Biggers
     7   *
     8   * Permission is hereby granted, free of charge, to any person
     9   * obtaining a copy of this software and associated documentation
    10   * files (the "Software"), to deal in the Software without
    11   * restriction, including without limitation the rights to use,
    12   * copy, modify, merge, publish, distribute, sublicense, and/or sell
    13   * copies of the Software, and to permit persons to whom the
    14   * Software is furnished to do so, subject to the following
    15   * conditions:
    16   *
    17   * The above copyright notice and this permission notice shall be
    18   * included in all copies or substantial portions of the Software.
    19   *
    20   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    21   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
    22   * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
    23   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    24   * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
    25   * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    26   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
    27   * OTHER DEALINGS IN THE SOFTWARE.
    28   */
    29  
    30  #include "unaligned.h"
    31  #include "zlib_constants.h"
    32  
    33  #include "libdeflate.h"
    34  
    35  LIBDEFLATEAPI enum libdeflate_result
    36  libdeflate_zlib_decompress(struct libdeflate_decompressor *d,
    37  			   const void *in, size_t in_nbytes,
    38  			   void *out, size_t out_nbytes_avail,
    39  			   size_t *actual_out_nbytes_ret)
    40  {
    41  	const u8 *in_next = in;
    42  	const u8 * const in_end = in_next + in_nbytes;
    43  	u16 hdr;
    44  	size_t actual_out_nbytes;
    45  	enum libdeflate_result result;
    46  
    47  	if (in_nbytes < ZLIB_MIN_OVERHEAD)
    48  		return LIBDEFLATE_BAD_DATA;
    49  
    50  	/* 2 byte header: CMF and FLG  */
    51  	hdr = get_unaligned_be16(in_next);
    52  	in_next += 2;
    53  
    54  	/* FCHECK */
    55  	if ((hdr % 31) != 0)
    56  		return LIBDEFLATE_BAD_DATA;
    57  
    58  	/* CM */
    59  	if (((hdr >> 8) & 0xF) != ZLIB_CM_DEFLATE)
    60  		return LIBDEFLATE_BAD_DATA;
    61  
    62  	/* CINFO */
    63  	if ((hdr >> 12) > ZLIB_CINFO_32K_WINDOW)
    64  		return LIBDEFLATE_BAD_DATA;
    65  
    66  	/* FDICT */
    67  	if ((hdr >> 5) & 1)
    68  		return LIBDEFLATE_BAD_DATA;
    69  
    70  	/* Compressed data  */
    71  	result = libdeflate_deflate_decompress(d, in_next,
    72  					in_end - ZLIB_FOOTER_SIZE - in_next,
    73  					out, out_nbytes_avail,
    74  					actual_out_nbytes_ret);
    75  	if (result != LIBDEFLATE_SUCCESS)
    76  		return result;
    77  
    78  	if (actual_out_nbytes_ret)
    79  		actual_out_nbytes = *actual_out_nbytes_ret;
    80  	else
    81  		actual_out_nbytes = out_nbytes_avail;
    82  
    83  	in_next = in_end - ZLIB_FOOTER_SIZE;
    84  
    85  	/* ADLER32  */
    86  	if (libdeflate_adler32(1, out, actual_out_nbytes) !=
    87  	    get_unaligned_be32(in_next))
    88  		return LIBDEFLATE_BAD_DATA;
    89  
    90  	return LIBDEFLATE_SUCCESS;
    91  }