diff options
Diffstat (limited to 'libc/stdio/makebuf.c')
| -rw-r--r-- | libc/stdio/makebuf.c | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/libc/stdio/makebuf.c b/libc/stdio/makebuf.c new file mode 100644 index 0000000..d47e27c --- /dev/null +++ b/libc/stdio/makebuf.c @@ -0,0 +1,107 @@ +/* $OpenBSD: makebuf.c,v 1.8 2005/12/28 18:50:22 millert Exp $ */ +/*- + * Copyright (c) 1990, 1993 + * The Regents of the University of California. All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Chris Torek. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <sys/types.h> +#include <sys/stat.h> +#include <unistd.h> +#include <stdio.h> +#include <stdlib.h> +#include "local.h" + +/* + * Allocate a file buffer, or switch to unbuffered I/O. + * Per the ANSI C standard, ALL tty devices default to line buffered. + * + * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek + * optimisation) right after the fstat() that finds the buffer size. + */ +void +__smakebuf(FILE *fp) +{ + void *p; + int flags; + size_t size; + int couldbetty; + + if (fp->_flags & __SNBF) { + fp->_bf._base = fp->_p = fp->_nbuf; + fp->_bf._size = 1; + return; + } + flags = __swhatbuf(fp, &size, &couldbetty); + if ((p = malloc(size)) == NULL) { + fp->_flags |= __SNBF; + fp->_bf._base = fp->_p = fp->_nbuf; + fp->_bf._size = 1; + return; + } + __atexit_register_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(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 = S_ISCHR(st.st_mode); + 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); +} |