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      1 /*
      2  * Copyright (c) 2014-2019 Pavel Kalvoda <me (at) pavelkalvoda.com>
      3  *
      4  * libcbor is free software; you can redistribute it and/or modify
      5  * it under the terms of the MIT license. See LICENSE for details.
      6  */
      7 
      8 #include <stdio.h>
      9 #include <string.h>
     10 #include "cbor.h"
     11 
     12 void usage() {
     13   printf("Usage: streaming_parser [input file]\n");
     14   exit(1);
     15 }
     16 
     17 /*
     18  * Illustrates how one might skim through a map (which is assumed to have
     19  * string keys and values only), looking for the value of a specific key
     20  *
     21  * Use the examples/data/map.cbor input to test this.
     22  */
     23 
     24 const char* key = "a secret key";
     25 bool key_found = false;
     26 
     27 void find_string(void* _ctx, cbor_data buffer, size_t len) {
     28   if (key_found) {
     29     printf("Found the value: %.*s\n", (int)len, buffer);
     30     key_found = false;
     31   } else if (len == strlen(key)) {
     32     key_found = (memcmp(key, buffer, len) == 0);
     33   }
     34 }
     35 
     36 int main(int argc, char* argv[]) {
     37   if (argc != 2) usage();
     38   FILE* f = fopen(argv[1], "rb");
     39   if (f == NULL) usage();
     40   fseek(f, 0, SEEK_END);
     41   size_t length = (size_t)ftell(f);
     42   fseek(f, 0, SEEK_SET);
     43   unsigned char* buffer = malloc(length);
     44   fread(buffer, length, 1, f);
     45 
     46   struct cbor_callbacks callbacks = cbor_empty_callbacks;
     47   struct cbor_decoder_result decode_result;
     48   size_t bytes_read = 0;
     49   callbacks.string = find_string;
     50   while (bytes_read < length) {
     51     decode_result = cbor_stream_decode(buffer + bytes_read, length - bytes_read,
     52                                        &callbacks, NULL);
     53     bytes_read += decode_result.read;
     54   }
     55 
     56   free(buffer);
     57   fclose(f);
     58 }
     59