/*- * 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. */ #if defined(LIBC_SCCS) && !defined(lint) static char sccsid[] = "@(#)ungetc.c 8.1 (Berkeley) 6/4/93"; #endif /* LIBC_SCCS and not lint */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include "local.h" /* * Expand the ungetc buffer `in place'. That is, adjust fp->_p when * the buffer moves, so that it points the same distance from the end, * and move the bytes in the buffer around as necessary so that they * are all at the end (stack-style). */ static __submore(fp) register FILE *fp; { register int i; register unsigned char *p; if (fp->_ub._base == fp->_ubuf) { /* * Get a new buffer (rather than expanding the old one). */ if ((p = malloc((size_t)BUFSIZ)) == NULL) return (EOF); fp->_ub._base = p; fp->_ub._size = BUFSIZ; p += BUFSIZ - sizeof(fp->_ubuf); for (i = sizeof(fp->_ubuf); --i >= 0;) p[i] = fp->_ubuf[i]; fp->_p = p; return (0); } i = fp->_ub._size; p = realloc(fp->_ub._base, i << 1); if (p == NULL) return (EOF); /* no overlap (hence can use memcpy) because we doubled the size */ (void)memcpy((void *)(p + i), (void *)p, (size_t)i); fp->_p = p + i; fp->_ub._base = p; fp->_ub._size = i << 1; return (0); } ungetc(c, fp) int c; register FILE *fp; { if (c == EOF) return (EOF); if (!__sdidinit) __sinit(); if ((fp->_flags & __SRD) == 0) { /* * Not already reading: no good unless reading-and-writing. * Otherwise, flush any current write stuff. */ if ((fp->_flags & __SRW) == 0) return (EOF); if (fp->_flags & __SWR) { if (__sflush(fp)) return (EOF); fp->_flags &= ~__SWR; fp->_w = 0; fp->_lbfsize = 0; } fp->_flags |= __SRD; } c = (unsigned char)c; /* * If we are in the middle of ungetc'ing, just continue. * This may require expanding the current ungetc buffer. */ if (HASUB(fp)) { if (fp->_r >= fp->_ub._size && __submore(fp)) return (EOF); *--fp->_p = c; fp->_r++; return (c); } /* * If we can handle this by simply backing up, do so, * but never replace the original character. * (This makes sscanf() work when scanning `const' data.) */ if (fp->_bf._base != NULL && fp->_p > fp->_bf._base && fp->_p[-1] == c) { fp->_p--; fp->_r++; return (c); } /* * Create an ungetc buffer. * Initially, we will use the `reserve' buffer. */ fp->_ur = fp->_r; fp->_up = fp->_p; fp->_ub._base = fp->_ubuf; fp->_ub._size = sizeof(fp->_ubuf); fp->_ubuf[sizeof(fp->_ubuf) - 1] = c; fp->_p = &fp->_ubuf[sizeof(fp->_ubuf) - 1]; fp->_r = 1; return (c); }