xref: /freebsd/contrib/libcbor/examples/readfile.c (revision 3c4ba5f55438f7afd4f4b0b56f88f2bb505fd6a6)
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 "cbor.h"
10 
11 void usage(void) {
12   printf("Usage: readfile [input file]\n");
13   exit(1);
14 }
15 
16 /*
17  * Reads data from a file. Example usage:
18  * $ ./examples/readfile examples/data/nested_array.cbor
19  */
20 
21 int main(int argc, char* argv[]) {
22   if (argc != 2) usage();
23   FILE* f = fopen(argv[1], "rb");
24   if (f == NULL) usage();
25   fseek(f, 0, SEEK_END);
26   size_t length = (size_t)ftell(f);
27   fseek(f, 0, SEEK_SET);
28   unsigned char* buffer = malloc(length);
29   fread(buffer, length, 1, f);
30 
31   /* Assuming `buffer` contains `length` bytes of input data */
32   struct cbor_load_result result;
33   cbor_item_t* item = cbor_load(buffer, length, &result);
34   free(buffer);
35 
36   if (result.error.code != CBOR_ERR_NONE) {
37     printf(
38         "There was an error while reading the input near byte %zu (read %zu "
39         "bytes in total): ",
40         result.error.position, result.read);
41     switch (result.error.code) {
42       case CBOR_ERR_MALFORMATED: {
43         printf("Malformed data\n");
44         break;
45       }
46       case CBOR_ERR_MEMERROR: {
47         printf("Memory error -- perhaps the input is too large?\n");
48         break;
49       }
50       case CBOR_ERR_NODATA: {
51         printf("The input is empty\n");
52         break;
53       }
54       case CBOR_ERR_NOTENOUGHDATA: {
55         printf("Data seem to be missing -- is the input complete?\n");
56         break;
57       }
58       case CBOR_ERR_SYNTAXERROR: {
59         printf(
60             "Syntactically malformed data -- see "
61             "http://tools.ietf.org/html/rfc7049\n");
62         break;
63       }
64       case CBOR_ERR_NONE: {
65         // GCC's cheap dataflow analysis gag
66         break;
67       }
68     }
69     exit(1);
70   }
71 
72   /* Pretty-print the result */
73   cbor_describe(item, stdout);
74   fflush(stdout);
75   /* Deallocate the result */
76   cbor_decref(&item);
77 
78   fclose(f);
79 }
80