github.com/afumu/libc@v0.0.6/musl/src/stdio/__uflow.c (about)

     1  #include "stdio_impl.h"
     2  
     3  /* This function assumes it will never be called if there is already
     4   * data buffered for reading. */
     5  
     6  int __uflow(FILE *f)
     7  {
     8  	unsigned char c;
     9  	if (!__toread(f) && f->read(f, &c, 1)==1) return c;
    10  	return EOF;
    11  }