github.com/grailbio/base@v0.0.11/compress/libdeflate/gzip_decompress.c (about)

     1  /*
     2   * gzip_decompress.c - decompress with a gzip 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 "gzip_constants.h"
    31  #include "unaligned.h"
    32  
    33  #include "libdeflate.h"
    34  
    35  LIBDEFLATEAPI enum libdeflate_result
    36  libdeflate_gzip_decompress_ex(struct libdeflate_decompressor *d,
    37  			      const void *in, size_t in_nbytes,
    38  			      void *out, size_t out_nbytes_avail,
    39  			      size_t *actual_in_nbytes_ret,
    40  			      size_t *actual_out_nbytes_ret)
    41  {
    42  	const u8 *in_next = in;
    43  	const u8 * const in_end = in_next + in_nbytes;
    44  	u8 flg;
    45  	size_t actual_in_nbytes;
    46  	size_t actual_out_nbytes;
    47  	enum libdeflate_result result;
    48  
    49  	if (in_nbytes < GZIP_MIN_OVERHEAD)
    50  		return LIBDEFLATE_BAD_DATA;
    51  
    52  	/* ID1 */
    53  	if (*in_next++ != GZIP_ID1)
    54  		return LIBDEFLATE_BAD_DATA;
    55  	/* ID2 */
    56  	if (*in_next++ != GZIP_ID2)
    57  		return LIBDEFLATE_BAD_DATA;
    58  	/* CM */
    59  	if (*in_next++ != GZIP_CM_DEFLATE)
    60  		return LIBDEFLATE_BAD_DATA;
    61  	flg = *in_next++;
    62  	/* MTIME */
    63  	in_next += 4;
    64  	/* XFL */
    65  	in_next += 1;
    66  	/* OS */
    67  	in_next += 1;
    68  
    69  	if (flg & GZIP_FRESERVED)
    70  		return LIBDEFLATE_BAD_DATA;
    71  
    72  	/* Extra field */
    73  	if (flg & GZIP_FEXTRA) {
    74  		u16 xlen = get_unaligned_le16(in_next);
    75  		in_next += 2;
    76  
    77  		if (in_end - in_next < (u32)xlen + GZIP_FOOTER_SIZE)
    78  			return LIBDEFLATE_BAD_DATA;
    79  
    80  		in_next += xlen;
    81  	}
    82  
    83  	/* Original file name (zero terminated) */
    84  	if (flg & GZIP_FNAME) {
    85  		while (*in_next++ != 0 && in_next != in_end)
    86  			;
    87  		if (in_end - in_next < GZIP_FOOTER_SIZE)
    88  			return LIBDEFLATE_BAD_DATA;
    89  	}
    90  
    91  	/* File comment (zero terminated) */
    92  	if (flg & GZIP_FCOMMENT) {
    93  		while (*in_next++ != 0 && in_next != in_end)
    94  			;
    95  		if (in_end - in_next < GZIP_FOOTER_SIZE)
    96  			return LIBDEFLATE_BAD_DATA;
    97  	}
    98  
    99  	/* CRC16 for gzip header */
   100  	if (flg & GZIP_FHCRC) {
   101  		in_next += 2;
   102  		if (in_end - in_next < GZIP_FOOTER_SIZE)
   103  			return LIBDEFLATE_BAD_DATA;
   104  	}
   105  
   106  	/* Compressed data  */
   107  	result = libdeflate_deflate_decompress_ex(d, in_next,
   108  					in_end - GZIP_FOOTER_SIZE - in_next,
   109  					out, out_nbytes_avail,
   110  					&actual_in_nbytes,
   111  					actual_out_nbytes_ret);
   112  	if (result != LIBDEFLATE_SUCCESS)
   113  		return result;
   114  
   115  	if (actual_out_nbytes_ret)
   116  		actual_out_nbytes = *actual_out_nbytes_ret;
   117  	else
   118  		actual_out_nbytes = out_nbytes_avail;
   119  
   120  	in_next += actual_in_nbytes;
   121  
   122  	/* CRC32 */
   123  	if (libdeflate_crc32(0, out, actual_out_nbytes) !=
   124  	    get_unaligned_le32(in_next))
   125  		return LIBDEFLATE_BAD_DATA;
   126  	in_next += 4;
   127  
   128  	/* ISIZE */
   129  	if ((u32)actual_out_nbytes != get_unaligned_le32(in_next))
   130  		return LIBDEFLATE_BAD_DATA;
   131  	in_next += 4;
   132  
   133  	if (actual_in_nbytes_ret)
   134  		*actual_in_nbytes_ret = in_next - (u8 *)in;
   135  
   136  	return LIBDEFLATE_SUCCESS;
   137  }
   138  
   139  LIBDEFLATEAPI enum libdeflate_result
   140  libdeflate_gzip_decompress(struct libdeflate_decompressor *d,
   141  			   const void *in, size_t in_nbytes,
   142  			   void *out, size_t out_nbytes_avail,
   143  			   size_t *actual_out_nbytes_ret)
   144  {
   145  	return libdeflate_gzip_decompress_ex(d, in, in_nbytes,
   146  					     out, out_nbytes_avail,
   147  					     NULL, actual_out_nbytes_ret);
   148  }