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