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Code Block
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int opener(FILE* file, int *width, int *height, int *data_offset) {
  int file_w;
  int file_h;
  int file_o;
  intfpos_t offset;

  if (file = 0;
= NULL) { return -1; }
  if (fgetpos(file, &offset) !== NULL0) { return -1; }
  if (fscanf(file, "%i %i %i", &file_w, &file_h, &file_o)  != 3) { return -1; }
  if (fsetpos(file, &offset) != 0) { return -1; }

  *width = file_w;
  *height = file_h;
  *data_offset = file_o;

  return 0; 
}

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Code Block
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errno_t opener(FILE* file, int *width, int *height, int *data_offset) {
  int file_w;
  int file_h;
  int file_o;
  int rc;
  fpos_t offset;

  if (file == NULL) { return EINVAL; }
  if ((rc = fgetpos(file, &offset);
  if (rc) != 0 ) { return (errno_t)rc; }
  if (fscanf(file, "%i %i %i", &file_w, &file_h, &file_o)  != 3) { return EIO; }
  if ((rc = fsetpos(file, &offset));
  if (rc != 0 ) { return -1rc; }
 
  *width = file_w;
  *height = file_h;
  *data_offset = file_o;

  return 0; 
}

NOTE: Neither EINVAL nor EIO are defined in C99 but are defined in most implementations.

Risk Assessment

Failing to test for error conditions can lead to vulnerabilities of varying severity. Declaring functions that return an errno with a return type of errno_t will not eliminate this problem, but will help mitigate in its mitigation.

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