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Annotation of prex-old/usr/lib/libc/stdio/makebuf.c, Revision 1.1.1.1

1.1       nbrk        1: /*-
                      2:  * Copyright (c) 1990, 1993
                      3:  *     The Regents of the University of California.  All rights reserved.
                      4:  *
                      5:  * This code is derived from software contributed to Berkeley by
                      6:  * Chris Torek.
                      7:  *
                      8:  * Redistribution and use in source and binary forms, with or without
                      9:  * modification, are permitted provided that the following conditions
                     10:  * are met:
                     11:  * 1. Redistributions of source code must retain the above copyright
                     12:  *    notice, this list of conditions and the following disclaimer.
                     13:  * 2. Redistributions in binary form must reproduce the above copyright
                     14:  *    notice, this list of conditions and the following disclaimer in the
                     15:  *    documentation and/or other materials provided with the distribution.
                     16:  * 3. Neither the name of the University nor the names of its contributors
                     17:  *    may be used to endorse or promote products derived from this software
                     18:  *    without specific prior written permission.
                     19:  *
                     20:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     21:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     22:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     23:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     24:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     25:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     26:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     27:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     28:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     29:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     30:  * SUCH DAMAGE.
                     31:  */
                     32:
                     33: #include <sys/types.h>
                     34: #include <sys/stat.h>
                     35: #include <unistd.h>
                     36: #include <stdio.h>
                     37: #include <stdlib.h>
                     38: #include "local.h"
                     39:
                     40: /*
                     41:  * Internal routine to determine `proper' buffering for a file.
                     42:  */
                     43: static int
                     44: __swhatbuf(FILE *fp, size_t *bufsize, int *couldbetty)
                     45: {
                     46:        struct stat st;
                     47:
                     48:        *bufsize = BUFSIZ;
                     49:        *couldbetty = 0;
                     50:        if (fp->_file < 0 || fstat(fp->_file, &st) < 0)
                     51:                return 0;
                     52:
                     53:        /* could be a tty iff it is a character device */
                     54:        *couldbetty = S_ISCHR(st.st_mode);
                     55:        return 0;
                     56: }
                     57:
                     58: /*
                     59:  * Allocate a file buffer, or switch to unbuffered I/O.
                     60:  * Per the ANSI C standard, ALL tty devices default to line buffered.
                     61:  *
                     62:  * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
                     63:  * optimisation) right after the fstat() that finds the buffer size.
                     64:  */
                     65: void
                     66: __smakebuf(fp)
                     67:        FILE *fp;
                     68: {
                     69:        void *p;
                     70:        int flags;
                     71:        size_t size;
                     72:        int couldbetty;
                     73:
                     74:        if (fp->_flags & __SNBF) {
                     75:                fp->_bf._base = fp->_p = fp->_nbuf;
                     76:                fp->_bf._size = 1;
                     77:                return;
                     78:        }
                     79:        flags = __swhatbuf(fp, &size, &couldbetty);
                     80:        if ((p = malloc(size)) == NULL) {
                     81:                fp->_flags |= __SNBF;
                     82:                fp->_bf._base = fp->_p = fp->_nbuf;
                     83:                fp->_bf._size = 1;
                     84:                return;
                     85:        }
                     86:        __cleanup = _cleanup;
                     87:        flags |= __SMBF;
                     88:        fp->_bf._base = fp->_p = p;
                     89:        fp->_bf._size = size;
                     90:        if (couldbetty && isatty(fp->_file))
                     91:                flags |= __SLBF;
                     92:
                     93:        fp->_flags |= flags;
                     94: }