Libc-262.tar.gz

[apple/libc.git] / stdio / makebuf.c

diff --git a/stdio/makebuf.c b/stdio/makebuf.c
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+/*
+ * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * The contents of this file constitute Original Code as defined in and
+ * are subject to the Apple Public Source License Version 1.1 (the
+ * "License").  You may not use this file except in compliance with the
+ * License.  Please obtain a copy of the License at
+ * http://www.apple.com/publicsource and read it before using this file.
+ * 
+ * This Original Code and all software distributed under the License are
+ * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
+ * License for the specific language governing rights and limitations
+ * under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+/*
+ * 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. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *     This product includes software developed by the University of
+ *     California, Berkeley and its contributors.
+ * 4. 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(fp)
+       register FILE *fp;
+{
+       register void *p;
+       register 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;
+       }
+       __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);
+}