root/ext/zip/lib/zip_source_crc.c

DEFINITIONS

1. zip_source_crc
2. crc_read

   1 /*
   2   zip_source_crc.c -- pass-through source that calculates CRC32 and size
   3   Copyright (C) 2009-2016 Dieter Baron and Thomas Klausner
   4 
   5   This file is part of libzip, a library to manipulate ZIP archives.
   6   The authors can be contacted at <libzip@nih.at>
   7 
   8   Redistribution and use in source and binary forms, with or without
   9   modification, are permitted provided that the following conditions
  10   are met:
  11   1. Redistributions of source code must retain the above copyright
  12      notice, this list of conditions and the following disclaimer.
  13   2. Redistributions in binary form must reproduce the above copyright
  14      notice, this list of conditions and the following disclaimer in
  15      the documentation and/or other materials provided with the
  16      distribution.
  17   3. The names of the authors may not be used to endorse or promote
  18      products derived from this software without specific prior
  19      written permission.
  20  
  21   THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS
  22   OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  23   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24   ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
  25   DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
  27   GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  28   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
  29   IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  30   OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
  31   IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32 */
  33 
  34 
  35 #include <stdlib.h>
  36 #include <string.h>
  37 #include <limits.h>
  38 
  39 #include "zipint.h"
  40 
  41 struct crc_context {
  42     int validate; /* whether to check CRC on EOF and return error on mismatch */
  43     int crc_complete; /* whether CRC was computed for complete file */
  44     zip_error_t error;
  45     zip_uint64_t size;
  46     zip_uint64_t position; /* current reading position */
  47     zip_uint64_t crc_position; /* how far we've computed the CRC */
  48     zip_uint32_t crc;
  49 };
  50 
  51 static zip_int64_t crc_read(zip_source_t *, void *, void *, zip_uint64_t, zip_source_cmd_t);
  52 
  53 
  54 zip_source_t *
  55 zip_source_crc(zip_t *za, zip_source_t *src, int validate)
  56 {
  57     struct crc_context *ctx;
  58 
  59     if (src == NULL) {
  60         zip_error_set(&za->error, ZIP_ER_INVAL, 0);
  61         return NULL;
  62     }
  63 
  64     if ((ctx=(struct crc_context *)malloc(sizeof(*ctx))) == NULL) {
  65         zip_error_set(&za->error, ZIP_ER_MEMORY, 0);
  66         return NULL;
  67     }
  68 
  69     zip_error_init(&ctx->error);
  70     ctx->validate = validate;
  71     ctx->crc_complete = 0;
  72     ctx->crc_position = 0;
  73     ctx->crc = (zip_uint32_t)crc32(0, NULL, 0);
  74     ctx->size = 0;
  75 
  76     return zip_source_layered(za, src, crc_read, ctx);
  77 }
  78 
  79 
  80 static zip_int64_t
  81 crc_read(zip_source_t *src, void *_ctx, void *data, zip_uint64_t len, zip_source_cmd_t cmd)
  82 {
  83     struct crc_context *ctx;
  84     zip_int64_t n;
  85 
  86     ctx = (struct crc_context *)_ctx;
  87 
  88     switch (cmd) {
  89         case ZIP_SOURCE_OPEN:
  90             ctx->position = 0;
  91             return 0;
  92             
  93         case ZIP_SOURCE_READ:
  94             if ((n = zip_source_read(src, data, len)) < 0) {
  95                 _zip_error_set_from_source(&ctx->error, src);
  96                 return -1;
  97             }
  98             
  99             if (n == 0) {
 100                 if (ctx->crc_position == ctx->position) {
 101                     ctx->crc_complete = 1;
 102                     ctx->size = ctx->position;
 103 
 104                     if (ctx->validate) {
 105                         struct zip_stat st;
 106                     
 107                         if (zip_source_stat(src, &st) < 0) {
 108                             _zip_error_set_from_source(&ctx->error, src);
 109                             return -1;
 110                         }
 111                     
 112                         if ((st.valid & ZIP_STAT_CRC) && st.crc != ctx->crc) {
 113                             zip_error_set(&ctx->error, ZIP_ER_CRC, 0);
 114                             return -1;
 115                         }
 116                         if ((st.valid & ZIP_STAT_SIZE) && st.size != ctx->size) {
 117                             zip_error_set(&ctx->error, ZIP_ER_INCONS, 0);
 118                             return -1;
 119                         }
 120                     }
 121                 }
 122             }
 123             else if (!ctx->crc_complete && ctx->position <= ctx->crc_position) {
 124                 zip_uint64_t i, nn;
 125 
 126                 for (i = ctx->crc_position - ctx->position; i < (zip_uint64_t)n; i += nn) {
 127                     nn = ZIP_MIN(UINT_MAX, (zip_uint64_t)n-i);
 128 
 129                     ctx->crc = (zip_uint32_t)crc32(ctx->crc, (const Bytef *)data+i, (uInt)nn);
 130                     ctx->crc_position += nn;
 131                 }
 132             }
 133             ctx->position += (zip_uint64_t)n;
 134             return n;
 135 
 136         case ZIP_SOURCE_CLOSE:
 137             return 0;
 138 
 139         case ZIP_SOURCE_STAT:
 140         {
 141             zip_stat_t *st;
 142 
 143             st = (zip_stat_t *)data;
 144 
 145             if (ctx->crc_complete) {
 146                 /* TODO: Set comp_size, comp_method, encryption_method?
 147                         After all, this only works for uncompressed data. */
 148                 st->size = ctx->size;
 149                 st->crc = ctx->crc;
 150                 st->comp_size = ctx->size;
 151                 st->comp_method = ZIP_CM_STORE;
 152                 st->encryption_method = ZIP_EM_NONE;
 153                 st->valid |= ZIP_STAT_SIZE|ZIP_STAT_CRC|ZIP_STAT_COMP_SIZE|ZIP_STAT_COMP_METHOD|ZIP_STAT_ENCRYPTION_METHOD;;
 154             }
 155             return 0;
 156         }
 157             
 158         case ZIP_SOURCE_ERROR:
 159             return zip_error_to_data(&ctx->error, data, len);
 160 
 161         case ZIP_SOURCE_FREE:
 162             free(ctx);
 163             return 0;
 164             
 165         case ZIP_SOURCE_SUPPORTS:
 166         {
 167             zip_int64_t mask = zip_source_supports(src);
 168 
 169             if (mask < 0) {
 170                 _zip_error_set_from_source(&ctx->error, src);
 171                 return -1;
 172             }
 173 
 174             return mask & ~zip_source_make_command_bitmap(ZIP_SOURCE_BEGIN_WRITE, ZIP_SOURCE_COMMIT_WRITE, ZIP_SOURCE_ROLLBACK_WRITE, ZIP_SOURCE_SEEK_WRITE, ZIP_SOURCE_TELL_WRITE, ZIP_SOURCE_REMOVE, -1);
 175         }
 176 
 177         case ZIP_SOURCE_SEEK:
 178         {
 179             zip_int64_t new_position;
 180             zip_source_args_seek_t *args = ZIP_SOURCE_GET_ARGS(zip_source_args_seek_t, data, len, &ctx->error);
 181 
 182             if (args == NULL) {
 183                 return -1;
 184             }
 185             if (zip_source_seek(src, args->offset, args->whence) < 0 || (new_position = zip_source_tell(src)) < 0) {
 186                 _zip_error_set_from_source(&ctx->error, src);
 187                 return -1;
 188             }
 189 
 190             ctx->position = (zip_uint64_t)new_position;
 191 
 192             return 0;
 193         }
 194 
 195         case ZIP_SOURCE_TELL:
 196             return (zip_int64_t)ctx->position;
 197             
 198         default:
 199             zip_error_set(&ctx->error, ZIP_ER_OPNOTSUPP, 0);
 200             return -1;
 201     }
 202 }