githubmirror/libcbor

examples/readfile.c
83 строки2 KB
Pavel Kalvoda
Fix bugs and improve robustness in example code (#407)
16 фев 2026, 03:02
16 фев 2026, 03:02d638af0
/*
 * Copyright (c) 2014-2020 Pavel Kalvoda <me@pavelkalvoda.com>
 *
 * libcbor is free software; you can redistribute it and/or modify
 * it under the terms of the MIT license. See LICENSE for details.
 */

#include <stdio.h>
#include <stdlib.h>
#include "cbor.h"

void usage(void) {
  printf("Usage: readfile [input file]\n");
  exit(1);
}

/*
 * Reads data from a file. Example usage:
 * $ ./examples/readfile examples/data/nested_array.cbor
 */

int main(int argc, char* argv[]) {
  if (argc != 2) usage();
  FILE* f = fopen(argv[1], "rb");
  if (f == NULL) usage();
  fseek(f, 0, SEEK_END);
  size_t length = (size_t)ftell(f);
  fseek(f, 0, SEEK_SET);
  unsigned char* buffer = malloc(length);
  if (fread(buffer, length, 1, f) != 1) {
    fprintf(stderr, "Failed to read input\n");
    exit(1);
  }

  /* Assuming `buffer` contains `length` bytes of input data */
  struct cbor_load_result result;
  cbor_item_t* item = cbor_load(buffer, length, &result);
  free(buffer);

  if (result.error.code != CBOR_ERR_NONE) {
    printf(
        "There was an error while reading the input near byte %zu (read %zu "
        "bytes in total): ",
        result.error.position, result.read);
    switch (result.error.code) {
      case CBOR_ERR_MALFORMATED: {
        printf("Malformed data\n");
        break;
      }
      case CBOR_ERR_MEMERROR: {
        printf("Memory error -- perhaps the input is too large?\n");
        break;
      }
      case CBOR_ERR_NODATA: {
        printf("The input is empty\n");
        break;
      }
      case CBOR_ERR_NOTENOUGHDATA: {
        printf("Data seem to be missing -- is the input complete?\n");
        break;
      }
      case CBOR_ERR_SYNTAXERROR: {
        printf(
            "Syntactically malformed data -- see "
            "https://www.rfc-editor.org/info/std94\n");
        break;
      }
      case CBOR_ERR_NONE: {
        // GCC's cheap dataflow analysis gag
        break;
      }
    }
    exit(1);
  }

  /* Pretty-print the result */
  cbor_describe(item, stdout);
  fflush(stdout);
  /* Deallocate the result */
  cbor_decref(&item);

  fclose(f);
}