+ __cleanup = _cleanup;
+ flags |= __SMBF;
+ fp->_bf._base = fp->_p = p;
+ fp->_bf._size = size;
+ if (couldbetty && isatty(fp->_file))
+ flags |= __SLBF;
+ fp->_flags |= flags;
+}
+
+/*
+ * Internal routine to determine `proper' buffering for a file.
+ */
+int
+__swhatbuf(fp, bufsize, couldbetty)
+ register FILE *fp;
+ size_t *bufsize;
+ int *couldbetty;
+{
+ struct stat st;
+
+ if (fp->_file < 0 || fstat(fp->_file, &st) < 0) {
+ *couldbetty = 0;
+ *bufsize = BUFSIZ;
+ return (__SNPT);
+ }
+
+ /* could be a tty iff it is a character device */
+ *couldbetty = (st.st_mode & S_IFMT) == S_IFCHR;
+ if (st.st_blksize <= 0) {
+ *bufsize = BUFSIZ;
+ return (__SNPT);
+ }
+
+ /*
+ * Optimise fseek() only if it is a regular file. (The test for
+ * __sseek is mainly paranoia.) It is safe to set _blksize
+ * unconditionally; it will only be used if __SOPT is also set.
+ */
+ *bufsize = st.st_blksize;
+ fp->_blksize = st.st_blksize;
+ return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ?
+ __SOPT : __SNPT);