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