--- makebuf.c.bsdnew 2009-11-11 13:33:12.000000000 -0800 +++ makebuf.c 2009-11-11 13:33:13.000000000 -0800 @@ -47,6 +47,9 @@ __FBSDID("$FreeBSD: src/lib/libc/stdio/m #include "libc_private.h" #include "local.h" +#define MAXBUFSIZE (1 << 16) +#define TTYBUFSIZE 4096 + /* * Allocate a file buffer, or switch to unbuffered I/O. * Per the ANSI C standard, ALL tty devices default to line buffered. @@ -69,6 +72,12 @@ __smakebuf(fp) return; } flags = __swhatbuf(fp, &size, &couldbetty); + if (couldbetty && isatty(fp->_file)) { + flags |= __SLBF; + /* st_blksize for ttys is 128K, so make it more reasonable */ + if (size > TTYBUFSIZE) + fp->_blksize = size = TTYBUFSIZE; + } if ((p = malloc(size)) == NULL) { fp->_flags |= __SNBF; fp->_bf._base = fp->_p = fp->_nbuf; @@ -79,8 +88,6 @@ __smakebuf(fp) flags |= __SMBF; fp->_bf._base = fp->_p = p; fp->_bf._size = size; - if (couldbetty && isatty(fp->_file)) - flags |= __SLBF; fp->_flags |= flags; } @@ -113,8 +120,7 @@ __swhatbuf(fp, bufsize, couldbetty) * __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; + fp->_blksize = *bufsize = st.st_blksize > MAXBUFSIZE ? MAXBUFSIZE : st.st_blksize; return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ? __SOPT : __SNPT); }