1 /*
2  * Copyright (c) 2014-2020 Pavel Kalvoda <me@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