read bmp dimension

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <assert.h>
#define EXPECT_EXT "bmp"
#define WIDTH_OFFSET 0x12
#define HEIGHT_OFFSET 0x16

void checkArgs(int argc, char *argv[]) {
  if (argc == 1) {
    fprintf(stderr, "one more arg needed!\n");
    exit(-1);
  }
  char *ext = strrchr(argv[1], '.') + 1;
  if (strcmp(ext, EXPECT_EXT) != 0) {
      fprintf(stderr, "wrong extension, expected: %s, found: %s\n", EXPECT_EXT, ext);
      exit(-1);
  }
}

FILE *safeOpenFile(const char path[], const char mode[]) {
  FILE *file = NULL;
  if ((file = fopen(path, mode)) == NULL) {
    perror("");
    exit(EXIT_FAILURE);
  }
  return file;
}

void safeCloseFile(FILE *file) {
  if (fclose(file) == EOF) {
    perror("");
    exit(EXIT_FAILURE);
  }
}

uint32_t read(FILE *file, long offset) {
  fseek(file, offset, SEEK_SET);
  uint32_t data;
  assert(fread(&data, sizeof(uint32_t), 1, file) == 1);
  return data;
}

int main(int argc, char *argv[]) {
  checkArgs(argc, argv);
  FILE *file = safeOpenFile(argv[1], "rb");

  int width = read(file, WIDTH_OFFSET);
  int height = read(file, HEIGHT_OFFSET);
  printf("dimension: %u X %u\n", width, height);

  safeCloseFile(file);
  return 0;
}