/*	$OpenBSD: buf.c,v 1.30 2023/09/04 11:35:11 espie Exp $	*/
/*	$NetBSD: buf.c,v 1.9 1996/12/31 17:53:21 christos Exp $ */

/*
 * Copyright (c) 1999 Marc Espie.
 *
 * Extensive code changes for the OpenBSD project.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE OPENBSD PROJECT 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 OPENBSD
 * PROJECT 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.
 */
/*
 * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
 * Copyright (c) 1988, 1989 by Adam de Boor
 * Copyright (c) 1989 by Berkeley Softworks
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * 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. 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.
 */

/*-
 * buf.c --
 *	Functions for automatically expanded buffers.
 */

#include <assert.h>
#include <ctype.h>
#include <limits.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <stdarg.h>
#include "defines.h"
#include "buf.h"
#include "stats.h"
#include "memory.h"

#ifdef STATS_BUF
#define DO_STAT_BUF(bp, nb)					\
	STAT_BUFS_EXPANSION++;			\
	if ((bp)->endPtr - (bp)->buffer == 1)			\
		STAT_WEIRD_INEFFICIENT++;
#else
#define DO_STAT_BUF(a, b)
#endif

static void
fatal_overflow()
{
	fprintf(stderr, "buffer size overflow\n");
	exit(2);
}

#define BUF_DEF_SIZE	256U	/* Default buffer size */
#define BUF_MARGIN	256U	/* Make sure we are comfortable */

/* BufExpand(bp, nb)
 *	Expand buffer bp to hold up to nb additional
 *	chars.	Makes sure there's always room for an extra '\0' char 
 *	at the end of the buffer for Buf_Retrieve. */
void
BufExpand(Buffer bp, size_t nb)
{
	size_t   occupied = bp->inPtr - bp->buffer;
	size_t   size = bp->endPtr - bp->buffer;
	DO_STAT_BUF(bp, nb);

	do {
		if (size <= SIZE_MAX/2) {
			size *= 2 ;
		} else {
			fatal_overflow();
		}
		assert(size >= occupied);
	} while (size - occupied < nb+1+BUF_MARGIN);
	bp->buffer = erealloc(bp->buffer, size);
	bp->inPtr = bp->buffer +occupied;
	bp->endPtr = bp->buffer + size;
}

void
Buf_AddChars(Buffer bp, size_t numBytes, const char *bytesPtr)
{
	assert(bp->endPtr >= bp->inPtr);
	if ((size_t)(bp->endPtr - bp->inPtr) < numBytes+1)
		BufExpand(bp, numBytes);

	memcpy(bp->inPtr, bytesPtr, numBytes);
	bp->inPtr += numBytes;
}

void
Buf_printf(Buffer bp, const char *fmt, ...)
{
	va_list va;
	int n;
	va_start(va, fmt);
	n = vsnprintf(bp->inPtr, bp->endPtr - bp->inPtr, fmt, va);
	va_end(va);
	if (n+1 > bp->endPtr - bp->inPtr) {
		va_list vb;
		BufExpand(bp, n);
		va_start(vb, fmt);
		(void)vsnprintf(bp->inPtr, bp->endPtr - bp->inPtr, fmt, vb);
		va_end(vb);
	}
	bp->inPtr += n;
}

void
Buf_Reinit(Buffer bp, size_t size)
{
	if (bp->buffer == NULL)
		Buf_Init(bp, size);
	else
		Buf_Reset(bp);
}

void
Buf_Init(Buffer bp, size_t size)
{
#ifdef STATS_BUF
	STAT_TOTAL_BUFS++;
	if (size == 0)
		STAT_DEFAULT_BUFS++;
	if (size == 1)
		STAT_WEIRD_BUFS++;
#endif
	if (size == 0)
		size = BUF_DEF_SIZE;
	bp->inPtr = bp->endPtr = bp->buffer = emalloc(size);
	bp->endPtr += size;
}