Return to ungetc.c CVS log

Up to [local] / prex-old / usr / lib / libc / stdio

Annotation of prex-old/usr/lib/libc/stdio/ungetc.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 <stdio.h>
        !            34: #include <stdlib.h>
        !            35: #include <string.h>
        !            36: #include "local.h"
        !            37:
        !            38: int
        !            39: ungetc(c, fp)
        !            40:        int c;
        !            41:        FILE *fp;
        !            42: {
        !            43:        if (c == EOF)
        !            44:                return (EOF);
        !            45:        if (!__sdidinit)
        !            46:                __sinit();
        !            47:        if ((fp->_flags & __SRD) == 0) {
        !            48:                /*
        !            49:                 * Not already reading: no good unless reading-and-writing.
        !            50:                 * Otherwise, flush any current write stuff.
        !            51:                 */
        !            52:                if ((fp->_flags & __SRW) == 0)
        !            53:                        return (EOF);
        !            54:                if (fp->_flags & __SWR) {
        !            55:                        if (__sflush(fp))
        !            56:                                return (EOF);
        !            57:                        fp->_flags &= ~__SWR;
        !            58:                        fp->_w = 0;
        !            59:                }
        !            60:                fp->_flags |= __SRD;
        !            61:        }
        !            62:        c = (unsigned char)c;
        !            63:
        !            64:        /*
        !            65:         * If we are in the middle of ungetc'ing, just continue.
        !            66:         */
        !            67:        if (HASUB(fp)) {
        !            68:                if (fp->_r >= fp->_ub._size)
        !            69:                        return (EOF);
        !            70:                *--fp->_p = c;
        !            71:                fp->_r++;
        !            72:                return (c);
        !            73:        }
        !            74:        fp->_flags &= ~__SEOF;
        !            75:
        !            76:        /*
        !            77:         * If we can handle this by simply backing up, do so,
        !            78:         * but never replace the original character.
        !            79:         * (This makes sscanf() work when scanning `const' data.)
        !            80:         */
        !            81:        if (fp->_bf._base != NULL && fp->_p > fp->_bf._base &&
        !            82:            fp->_p[-1] == c) {
        !            83:                fp->_p--;
        !            84:                fp->_r++;
        !            85:                return (c);
        !            86:        }
        !            87:
        !            88:        /*
        !            89:         * Create an ungetc buffer.
        !            90:         * we will use the `reserve' buffer.
        !            91:         */
        !            92:        fp->_ur = fp->_r;
        !            93:        fp->_up = fp->_p;
        !            94:        fp->_ub._base = fp->_ubuf;
        !            95:        fp->_ub._size = sizeof(fp->_ubuf);
        !            96:        fp->_ubuf[sizeof(fp->_ubuf) - 1] = c;
        !            97:        fp->_p = &fp->_ubuf[sizeof(fp->_ubuf) - 1];
        !            98:        fp->_r = 1;
        !            99:        return (c);
        !           100: }