WebSVN - shark - Blame - Rev 2 - /shark/branches/pj/libc/stdio/fgetln.c

Rev	Author	Line No.	Line
2	pj	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. All advertising materials mentioning features or use of this software
		17	* must display the following acknowledgement:
		18	* This product includes software developed by the University of
		19	* California, Berkeley and its contributors.
		20	* 4. Neither the name of the University nor the names of its contributors
		21	* may be used to endorse or promote products derived from this software
		22	* without specific prior written permission.
		23	*
		24	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
		25	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
		26	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
		27	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
		28	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
		29	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
		30	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
		31	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
		32	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
		33	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
		34	* SUCH DAMAGE.
		35	*/
		36
		37	#if defined(LIBC_SCCS) && !defined(lint)
		38	#if 0
		39	static char sccsid[] = "@(#)fgetln.c 8.2 (Berkeley) 1/2/94";
		40	#endif
		41	static const char rcsid[] =
		42	"$\Id: fgetln.c,v 1.3 1996/06/22 10:33:08 jraynard Exp $";
		43	#endif /* LIBC_SCCS and not lint */
		44
		45	#include <stdio.h>
		46	#include <stdlib.h>
		47	#include <string.h>
		48	#include "local.h"
		49
		50	/*
		51	* Expand the line buffer. Return -1 on error.
		52	#ifdef notdef
		53	* The `new size' does not account for a terminating '\0',
		54	* so we add 1 here.
		55	#endif
		56	*/
		57	int
		58	__slbexpand(fp, newsize)
		59	FILE *fp;
		60	size_t newsize;
		61	{
		62	void *p;
		63
		64	#ifdef notdef
		65	++newsize;
		66	#endif
		67	if (fp->_lb._size >= newsize)
		68	return (0);
		69	if ((p = realloc(fp->_lb._base, newsize)) == NULL)
		70	return (-1);
		71	fp->_lb._base = p;
		72	fp->_lb._size = newsize;
		73	return (0);
		74	}
		75
		76	/*
		77	* Get an input line. The returned pointer often (but not always)
		78	* points into a stdio buffer. Fgetln does not alter the text of
		79	* the returned line (which is thus not a C string because it will
		80	* not necessarily end with '\0'), but does allow callers to modify
		81	* it if they wish. Thus, we set __SMOD in case the caller does.
		82	*/
		83	char *
		84	fgetln(fp, lenp)
		85	register FILE *fp;
		86	size_t *lenp;
		87	{
		88	register unsigned char *p;
		89	register size_t len;
		90	size_t off;
		91
		92	/* make sure there is input */
		93	if (fp->_r <= 0 && __srefill(fp)) {
		94	*lenp = 0;
		95	return (NULL);
		96	}
		97
		98	/* look for a newline in the input */
		99	if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) != NULL) {
		100	register char *ret;
		101
		102	/*
		103	* Found one. Flag buffer as modified to keep fseek from
		104	* `optimising' a backward seek, in case the user stomps on
		105	* the text.
		106	*/
		107	p++; /* advance over it */
		108	ret = (char *)fp->_p;
		109	*lenp = len = p - fp->_p;
		110	fp->_flags \|= __SMOD;
		111	fp->_r -= len;
		112	fp->_p = p;
		113	return (ret);
		114	}
		115
		116	/*
		117	* We have to copy the current buffered data to the line buffer.
		118	* As a bonus, though, we can leave off the __SMOD.
		119	*
		120	* OPTIMISTIC is length that we (optimistically) expect will
		121	* accomodate the `rest' of the string, on each trip through the
		122	* loop below.
		123	*/
		124	#define OPTIMISTIC 80
		125
		126	for (len = fp->_r, off = 0;; len += fp->_r) {
		127	register size_t diff;
		128
		129	/*
		130	* Make sure there is room for more bytes. Copy data from
		131	* file buffer to line buffer, refill file and look for
		132	* newline. The loop stops only when we find a newline.
		133	*/
		134	if (__slbexpand(fp, len + OPTIMISTIC))
		135	goto error;
		136	(void)memcpy((void )(fp->_lb._base + off), (void )fp->_p,
		137	len - off);
		138	off = len;
		139	if (__srefill(fp))
		140	break; /* EOF or error: return partial line */
		141	if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) == NULL)
		142	continue;
		143
		144	/* got it: finish up the line (like code above) */
		145	p++;
		146	diff = p - fp->_p;
		147	len += diff;
		148	if (__slbexpand(fp, len))
		149	goto error;
		150	(void)memcpy((void )(fp->_lb._base + off), (void )fp->_p,
		151	diff);
		152	fp->_r -= diff;
		153	fp->_p = p;
		154	break;
		155	}
		156	*lenp = len;
		157	#ifdef notdef
		158	fp->_lb._base[len] = 0;
		159	#endif
		160	return ((char *)fp->_lb._base);
		161
		162	error:
		163	lenp = 0; / ??? */
		164	return (NULL); /* ??? */
		165	}

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