usr.bin/make/buf.c

/*
 * Copyright (c) 1988, 1989, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 * 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. 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.
 *
 * @(#)buf.c	8.1 (Berkeley) 6/6/93
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: head/usr.bin/make/buf.c 138342 2004-12-03 12:02:14Z harti $");

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

#include "sprite.h"
#include "make.h"
#include "buf.h"

#ifndef max
#define	max(a,b)  ((a) > (b) ? (a) : (b))
#endif

/*
 * BufExpand --
 * 	Expand the given buffer to hold the given number of additional
 *	bytes.
 *	Makes sure there's room for an extra NULL byte at the end of the
 *	buffer in case it holds a string.
 */
#define	BufExpand(bp, nb) do {						\
 	if ((bp)->left < (nb) + 1) {					\
		int newSize = (bp)->size + max((nb) + 1, BUF_ADD_INC);	\
		Byte  *newBuf = erealloc((bp)->buffer, newSize);	\
									\
		(bp)->inPtr = newBuf + ((bp)->inPtr - (bp)->buffer);	\
		(bp)->outPtr = newBuf + ((bp)->outPtr - (bp)->buffer);	\
		(bp)->buffer = newBuf;					\
		(bp)->size = newSize;					\
		(bp)->left = newSize - ((bp)->inPtr - (bp)->buffer);	\
	}								\
    } while (0)

#define	BUF_DEF_SIZE	256 	/* Default buffer size */
#define	BUF_ADD_INC	256 	/* Expansion increment when Adding */
#define	BUF_UNGET_INC	16  	/* Expansion increment when Ungetting */

/*-
 *-----------------------------------------------------------------------
 * Buf_OvAddByte --
 *	Add a single byte to the buffer.  left is zero or negative.
 *
 * Results:
 *	None.
 *
 * Side Effects:
 *	The buffer may be expanded.
 *
 *-----------------------------------------------------------------------
 */
void
Buf_OvAddByte(Buffer bp, Byte byte)
{

	bp->left = 0;
	BufExpand(bp, 1);

	*bp->inPtr++ = byte;
	bp->left--;

	/*
	 * Null-terminate
	 */
	*bp->inPtr = 0;
}

/*-
 *-----------------------------------------------------------------------
 * Buf_AddBytes --
 *	Add a number of bytes to the buffer.
 *
 * Results:
 *	None.
 *
 * Side Effects:
 *	Guess what?
 *
 *-----------------------------------------------------------------------
 */
void
Buf_AddBytes(Buffer bp, size_t numBytes, const Byte *bytesPtr)
{

	BufExpand(bp, numBytes);

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

	/*
	 * Null-terminate
	 */
	*bp->inPtr = 0;
}

/*-
 *-----------------------------------------------------------------------
 * Buf_UngetByte --
 *	Place the byte back at the beginning of the buffer.
 *
 * Results:
 *	SUCCESS if the byte was added ok. FAILURE if not.
 *
 * Side Effects:
 *	The byte is stuffed in the buffer and outPtr is decremented.
 *
 *-----------------------------------------------------------------------
 */
void
Buf_UngetByte(Buffer bp, Byte byte)
{

	if (bp->outPtr != bp->buffer) {
		bp->outPtr--;
		*bp->outPtr = byte;

	} else if (bp->outPtr == bp->inPtr) {
		*bp->inPtr = byte;
		bp->inPtr++;
		bp->left--;
		*bp->inPtr = 0;

	} else {
		/*
		 * Yech. have to expand the buffer to stuff this thing in.
		 * We use a different expansion constant because people don't
		 * usually push back many bytes when they're doing it a byte at
		 * a time...
		 */
		size_t numBytes = bp->inPtr - bp->outPtr;
		Byte *newBuf;

		newBuf = emalloc(bp->size + BUF_UNGET_INC);
		memcpy(newBuf + BUF_UNGET_INC, bp->outPtr, numBytes + 1);
		bp->outPtr = newBuf + BUF_UNGET_INC;
		bp->inPtr = bp->outPtr + numBytes;
		free(bp->buffer);
		bp->buffer = newBuf;
		bp->size += BUF_UNGET_INC;
		bp->left = bp->size - (bp->inPtr - bp->buffer);
		bp->outPtr -= 1;
		*bp->outPtr = byte;
	}
}

/*-
 *-----------------------------------------------------------------------
 * Buf_UngetBytes --
 *	Push back a series of bytes at the beginning of the buffer.
 *
 * Results:
 *	None.
 *
 * Side Effects:
 *	outPtr is decremented and the bytes copied into the buffer.
 *
 *-----------------------------------------------------------------------
 */
void
Buf_UngetBytes(Buffer bp, size_t numBytes, Byte *bytesPtr)
{

	if ((size_t)(bp->outPtr - bp->buffer) >= numBytes) {
		bp->outPtr -= numBytes;
		memcpy(bp->outPtr, bytesPtr, numBytes);
	} else if (bp->outPtr == bp->inPtr) {
		Buf_AddBytes(bp, numBytes, bytesPtr);
	} else {
		size_t curNumBytes = bp->inPtr - bp->outPtr;
		Byte *newBuf;
		size_t newBytes = max(numBytes, BUF_UNGET_INC);

		newBuf = emalloc(bp->size + newBytes);
		memcpy(newBuf + newBytes, bp->outPtr, curNumBytes + 1);
		bp->outPtr = newBuf + newBytes;
		bp->inPtr = bp->outPtr + curNumBytes;
		free(bp->buffer);
		bp->buffer = newBuf;
		bp->size += newBytes;
		bp->left = bp->size - (bp->inPtr - bp->buffer);
		bp->outPtr -= numBytes;
		memcpy(bp->outPtr, bytesPtr, numBytes);
	}
}

/*-
 *-----------------------------------------------------------------------
 * Buf_GetByte --
 *	Return the next byte from the buffer. Actually returns an integer.
 *
 * Results:
 *	Returns BUF_ERROR if there's no byte in the buffer, or the byte
 *	itself if there is one.
 *
 * Side Effects:
 *	outPtr is incremented and both outPtr and inPtr will be reset if
 *	the buffer is emptied.
 *
 *-----------------------------------------------------------------------
 */
int
Buf_GetByte(Buffer bp)
{
	int res;

	if (bp->inPtr == bp->outPtr)
		return (BUF_ERROR);

	res = (int)*bp->outPtr;
	bp->outPtr += 1;
	if (bp->outPtr == bp->inPtr) {
		bp->outPtr = bp->inPtr = bp->buffer;
		bp->left = bp->size;
		*bp->inPtr = 0;
	}
	return (res);
}

/*-
 *-----------------------------------------------------------------------
 * Buf_GetBytes --
 *	Extract a number of bytes from the buffer.
 *
 * Results:
 *	The number of bytes gotten.
 *
 * Side Effects:
 *	The passed array is overwritten.
 *
 *-----------------------------------------------------------------------
 */
int
Buf_GetBytes(Buffer bp, size_t numBytes, Byte *bytesPtr)
{

	if ((size_t)(bp->inPtr - bp->outPtr) < numBytes)
		numBytes = bp->inPtr - bp->outPtr;

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

	if (bp->outPtr == bp->inPtr) {
		bp->outPtr = bp->inPtr = bp->buffer;
		bp->left = bp->size;
		*bp->inPtr = 0;
	}
	return (numBytes);
}

/*-
 *-----------------------------------------------------------------------
 * Buf_GetAll --
 *	Get all the available data at once.
 *
 * Results:
 *	A pointer to the data and the number of bytes available.
 *
 * Side Effects:
 *	None.
 *
 *-----------------------------------------------------------------------
 */
Byte *
Buf_GetAll(Buffer bp, size_t *numBytesPtr)
{

	if (numBytesPtr != NULL)
		*numBytesPtr = bp->inPtr - bp->outPtr;

	return (bp->outPtr);
}

/*-
 *-----------------------------------------------------------------------
 * Buf_Discard --
 *	Throw away bytes in a buffer.
 *
 * Results:
 *	None.
 *
 * Side Effects:
 *	The bytes are discarded.
 *
 *-----------------------------------------------------------------------
 */
void
Buf_Discard(Buffer bp, size_t numBytes)
{

	if ((size_t)(bp->inPtr - bp->outPtr) <= numBytes) {
		bp->inPtr = bp->outPtr = bp->buffer;
		bp->left = bp->size;
		*bp->inPtr = 0;
	} else
		bp->outPtr += numBytes;
}

/*-
 *-----------------------------------------------------------------------
 * Buf_Size --
 *	Returns the number of bytes in the given buffer. Doesn't include
 *	the null-terminating byte.
 *
 * Results:
 *	The number of bytes.
 *
 * Side Effects:
 *	None.
 *
 *-----------------------------------------------------------------------
 */
size_t
Buf_Size(Buffer buf)
{

	return (buf->inPtr - buf->outPtr);
}

/*-
 *-----------------------------------------------------------------------
 * Buf_Init --
 *	Initialize a buffer. If no initial size is given, a reasonable
 *	default is used.
 *
 * Results:
 *	A buffer to be given to other functions in this library.
 *
 * Side Effects:
 *	The buffer is created, the space allocated and pointers
 *	initialized.
 *
 *-----------------------------------------------------------------------
 */
Buffer
Buf_Init(size_t size)
{
	Buffer bp;	  	/* New Buffer */

	bp = emalloc(sizeof(*bp));

	if (size <= 0)
		size = BUF_DEF_SIZE;

	bp->left = bp->size = size;
	bp->buffer = emalloc(size);
	bp->inPtr = bp->outPtr = bp->buffer;
	*bp->inPtr = 0;

	return (bp);
}

/*-
 *-----------------------------------------------------------------------
 * Buf_Destroy --
 *	Destroy a buffer, and optionally free its data, too.
 *
 * Results:
 *	None.
 *
 * Side Effects:
 *	The buffer is freed.
 *
 *-----------------------------------------------------------------------
 */
void
Buf_Destroy(Buffer buf, Boolean freeData)
{

	if (freeData)
		free(buf->buffer);
	free(buf);
}

/*-
 *-----------------------------------------------------------------------
 * Buf_ReplaceLastByte --
 *     Replace the last byte in a buffer.
 *
 * Results:
 *     None.
 *
 * Side Effects:
 *     If the buffer was empty intially, then a new byte will be added.
 *     Otherwise, the last byte is overwritten.
 *
 *-----------------------------------------------------------------------
 */
void
Buf_ReplaceLastByte(Buffer buf, Byte byte)
{
	if (buf->inPtr == buf->outPtr)
		Buf_AddByte(buf, byte);
	else
		*(buf->inPtr - 1) = byte;
}