Incompatible functions - fopen

My solution: wrap FILE* and all functions which use FILE*

  typedef struct __darwin_sFILE {
    unsigned char *_p;      /* current position in (some) buffer */
    int     _r;             /* read space left for getc() */
    int     _w;             /* write space left for putc() */
    // TODO(hamaji): we need to modify this value with ferror and feof...
    short   _flags;         /* flags, below; this FILE is free if 0 */
    short   _file;          /* fileno, if Unix descriptor, else -1 */
  
    FILE* linux_fp;
  }
  
  int __darwin_fputs(const char* s, __darwin_FILE* fp) {
    return fputs(s, fp->linux_fp);
  }

My emulation layer doesn't handle _flags field properly
feof and ferror should be broken