file_io.c

#include <assert.h> // assert
#include <stdio.h> // fprintf, FILE, fopen, fseek, SEEK_END, ftell, rewind, fread, fclose
#include <stdlib.h> // exit, malloc
#include "file_io.h"

// return 0 is success
#define GUARD(expr) assert(!(expr))

void err (const char* const msg) {
  fprintf(stderr, "%s\n", msg);
  exit(1);
}

char* read_file (const char* const filename) {
  if (filename == NULL) {
    return NULL;
  }

  FILE* fp = fopen(filename, "r");
  if (fp == NULL) {
    return NULL;
  }

  GUARD(fseek(fp, 0, SEEK_END));
  long file_size = ftell(fp);
  rewind(fp);
  size_t code_size = sizeof(char) * file_size;
  char* code = malloc(code_size);
  if (code == NULL) {
    return NULL;
  }
  fread(code, 1, file_size, fp);
  GUARD(fclose(fp));
  return code;
}