lib/membuff.c - u-boot - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Copyright (c) 2015 Google, Inc
  * Written by Simon Glass <sjg@chromium.org>
  *
  * Copyright (c) 1992 Simon Glass
  */

 #include <errno.h>
 #include <log.h>
 #include <malloc.h>
 #include "membuff.h"

 void membuff_purge(struct membuff *mb)
 {
 	/* set mb->head and mb->tail so the buffers look empty */
 	mb->head = mb->start;
 	mb->tail = mb->start;
 }

 static int membuff_putrawflex(struct membuff *mb, int maxlen, bool update,
 			      char ***data, int *offsetp)
 {
 	int len;

 	/* always write to 'mb->head' */
 	assert(data && offsetp);
 	*data = &mb->start;
 	*offsetp = mb->head - mb->start;

 	/* if there is no buffer, we can do nothing */
 	if (!mb->start)
 		return 0;

 	/*
 	 * if head is ahead of tail, we can write from head until the end of
 	 * the buffer
 	 */
 	if (mb->head >= mb->tail) {
 		/* work out how many bytes can fit here */
 		len = mb->end - mb->head - 1;
 		if (maxlen >= 0 && len > maxlen)
 			len = maxlen;

 		/* update the head pointer to mark these bytes as written */
 		if (update)
 			mb->head += len;

 		/*
 		 * if the tail isn't at start of the buffer, then we can
 		 * write one more byte right at the end
 		 */
 		if ((maxlen < 0 || len < maxlen) && mb->tail != mb->start) {
 			len++;
 			if (update)
 				mb->head = mb->start;
 		}

 	/* otherwise now we can write until head almost reaches tail */
 	} else {
 		/* work out how many bytes can fit here */
 		len = mb->tail - mb->head - 1;
 		if (maxlen >= 0 && len > maxlen)
 			len = maxlen;

 		/* update the head pointer to mark these bytes as written */
 		if (update)
 			mb->head += len;
 	}

 	/* return the number of bytes which can be/must be written */
 	return len;
 }

 int membuff_putraw(struct membuff *mb, int maxlen, bool update, char **data)
 {
 	char **datap;
 	int offset;
 	int size;

 	size = membuff_putrawflex(mb, maxlen, update, &datap, &offset);
 	*data = *datap + offset;

 	return size;
 }

 bool membuff_putbyte(struct membuff *mb, int ch)
 {
 	char *data;

 	if (membuff_putraw(mb, 1, true, &data) != 1)
 		return false;
 	*data = ch;

 	return true;
 }

 int membuff_getraw(struct membuff *mb, int maxlen, bool update, char **data)
 {
 	int len;

 	/* assume for now there is no data to get */
 	len = 0;

 	/*
 	 * in this case head is ahead of tail, so we must return data between
 	 *'tail' and 'head'
 	 */
 	if (mb->head > mb->tail) {
 		/* work out the amount of data */
 		*data = mb->tail;
 		len = mb->head - mb->tail;

 		/* check it isn't too much */
 		if (maxlen >= 0 && len > maxlen)
 			len = maxlen;

 		/* & mark it as read from the buffer */
 		if (update)
 			mb->tail += len;
 	}

 	/*
 	 * if head is before tail, then we have data between 'tail' and 'end'
 	 * and some more data between 'start' and 'head'(which we can't
 	 * return this time
 	 */
 	else if (mb->head < mb->tail) {
 		/* work out the amount of data */
 		*data = mb->tail;
 		len = mb->end - mb->tail;
 		if (maxlen >= 0 && len > maxlen)
 			len = maxlen;
 		if (update) {
 			mb->tail += len;
 			if (mb->tail == mb->end)
 				mb->tail = mb->start;
 		}
 	}

 	debug("getraw: maxlen=%d, update=%d, head=%d, tail=%d, data=%d, len=%d",
 	      maxlen, update, (int)(mb->head - mb->start),
 	      (int)(mb->tail - mb->start), (int)(*data - mb->start), len);

 	/* return the number of bytes we found */
 	return len;
 }

 int membuff_getbyte(struct membuff *mb)
 {
 	char *data = 0;

 	return membuff_getraw(mb, 1, true, &data) != 1 ? -1 : *(uint8_t *)data;
 }

 int membuff_peekbyte(struct membuff *mb)
 {
 	char *data = 0;

 	return membuff_getraw(mb, 1, false, &data) != 1 ? -1 : *(uint8_t *)data;
 }

 int membuff_get(struct membuff *mb, char *buff, int maxlen)
 {
 	char *data = 0, *buffptr = buff;
 	int len = 1, i;

 	/*
 	 * do this in up to two lots(see GetRaw for why) stopping when there
 	 * is no more data
 	 */
 	for (i = 0; len && i < 2; i++) {
 		/* get a pointer to the data available */
 		len = membuff_getraw(mb, maxlen, true, &data);

 		/* copy it into the buffer */
 		memcpy(buffptr, data, len);
 		buffptr += len;
 		maxlen -= len;
 	}

 	/* return the number of bytes read */
 	return buffptr - buff;
 }

 int membuff_put(struct membuff *mb, const char *buff, int length)
 {
 	char *data;
 	int towrite, i, written;

 	for (i = written = 0; i < 2; i++) {
 		/* ask where some data can be written */
 		towrite = membuff_putraw(mb, length, true, &data);

 		/* and write it, updating the bytes length */
 		memcpy(data, buff, towrite);
 		written += towrite;
 		buff += towrite;
 		length -= towrite;
 	}

 	/* return the number of bytes written */
 	return written;
 }

 bool membuff_isempty(struct membuff *mb)
 {
 	return mb->head == mb->tail;
 }

 int membuff_avail(struct membuff *mb)
 {
 	struct membuff copy;
 	int i, avail;
 	char *data = 0;

 	/* make a copy of this buffer's control data */
 	copy = *mb;

 	/* now read everything out of the copied buffer */
 	for (i = avail = 0; i < 2; i++)
 		avail += membuff_getraw(&copy, -1, true, &data);

 	/* and return how much we read */
 	return avail;
 }

 int membuff_size(struct membuff *mb)
 {
 	return mb->end - mb->start;
 }

 bool membuff_makecontig(struct membuff *mb)
 {
 	int topsize, botsize;

 	debug("makecontig: head=%d, tail=%d, size=%d",
 	      (int)(mb->head - mb->start), (int)(mb->tail - mb->start),
 	      (int)(mb->end - mb->start));

 	/*
 	 * first we move anything at the start of the buffer into the correct
 	 * place some way along
 	 */
 	if (mb->tail > mb->head) {
 		/*
 		 * the data is split into two parts, from 0 to ->head and
 		 * from ->tail to ->end. We move the stuff from 0 to ->head
 		 * up to make space for the other data before it
 		 */
 		topsize = mb->end - mb->tail;
 		botsize = mb->head - mb->start;

 		/*
 		 * must move data at bottom up by 'topsize' bytes - check if
 		 * there's room
 		 */
 		if (mb->head + topsize >= mb->tail)
 			return false;
 		memmove(mb->start + topsize, mb->start, botsize);
 		debug("	- memmove(%d, %d, %d)", topsize, 0, botsize);

 	/* nothing at the start, so skip that step */
 	} else {
 		topsize = mb->head - mb->tail;
 		botsize = 0;
 	}

 	/* now move data at top down to the bottom */
 	memcpy(mb->start, mb->tail, topsize);
 	debug("	- memcpy(%d, %d, %d)", 0, (int)(mb->tail - mb->start), topsize);

 	/* adjust pointers */
 	mb->tail = mb->start;
 	mb->head = mb->start + topsize + botsize;

 	debug("	- head=%d, tail=%d", (int)(mb->head - mb->start),
 	      (int)(mb->tail - mb->start));

 	/* all ok */
 	return true;
 }

 int membuff_free(struct membuff *mb)
 {
 	return mb->end == mb->start ? 0 :
 			(mb->end - mb->start) - 1 - membuff_avail(mb);
 }

 int membuff_readline(struct membuff *mb, char *str, int maxlen, int minch, bool must_fit)
 {
 	int len;  /* number of bytes read (!= string length) */
 	char *s, *end;
 	bool ok = false;
 	char *orig = str;

 	end = mb->head >= mb->tail ? mb->head : mb->end;
 	for (len = 0, s = mb->tail; s < end && len < maxlen - 1; str++) {
 		*str = *s++;
 		len++;
 		if (*str == '\n' || *str < minch) {
 			ok = true;
 			break;
 		}
 		if (s == end && mb->tail > mb->head) {
 			s = mb->start;
 			end = mb->head;
 		}
 	}

 	/* couldn't get the whole string */
 	if (!ok && must_fit) {
 		if (maxlen)
 			*orig = '\0';
 		return 0;
 	}

 	/* terminate the string, update the membuff and return success */
 	*str = '\0';
 	mb->tail = s == mb->end ? mb->start : s;

 	return len;
 }

 int membuff_extend_by(struct membuff *mb, int by, int max)
 {
 	int oldhead, oldtail;
 	int size, orig;
 	char *ptr;

 	/* double the buffer size until it is big enough */
 	assert(by >= 0);
 	for (orig = mb->end - mb->start, size = orig; size < orig + by;)
 		size *= 2;
 	if (max != -1)
 		size = min(size, max);
 	by = size - orig;

 	/* if we're already at maximum, give up */
 	if (by <= 0)
 		return -E2BIG;

 	oldhead = mb->head - mb->start;
 	oldtail = mb->tail - mb->start;
 	ptr = realloc(mb->start, size);
 	if (!ptr)
 		return -ENOMEM;
 	mb->start = ptr;
 	mb->head = mb->start + oldhead;
 	mb->tail = mb->start + oldtail;

 	if (mb->head < mb->tail) {
 		memmove(mb->tail + by, mb->tail, orig - oldtail);
 		mb->tail += by;
 	}
 	mb->end = mb->start + size;

 	return 0;
 }

 void membuff_init(struct membuff *mb, char *buff, int size)
 {
 	mb->start = buff;
 	mb->end = mb->start + size;
 	membuff_purge(mb);
 }

 int membuff_new(struct membuff *mb, int size)
 {
 	mb->start = malloc(size);
 	if (!mb->start)
 		return -ENOMEM;

 	membuff_init(mb, mb->start, size);
 	return 0;
 }

 void membuff_uninit(struct membuff *mb)
 {
 	mb->end = NULL;
 	mb->start = NULL;
 	membuff_purge(mb);
 }

 void membuff_dispose(struct membuff *mb)
 {
 	free(&mb->start);
 	membuff_uninit(mb);
 }
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Copyright (c) 2015 Google, Inc
	* Written by Simon Glass <sjg@chromium.org>
	*
	* Copyright (c) 1992 Simon Glass
	*/

	#include <errno.h>
	#include <log.h>
	#include <malloc.h>
	#include "membuff.h"

	void membuff_purge(struct membuff *mb)
	{
	/* set mb->head and mb->tail so the buffers look empty */
	mb->head = mb->start;
	mb->tail = mb->start;
	}

	static int membuff_putrawflex(struct membuff *mb, int maxlen, bool update,
	char **data, int offsetp)
	{
	int len;

	/* always write to 'mb->head' */
	assert(data && offsetp);
	*data = &mb->start;
	*offsetp = mb->head - mb->start;

	/* if there is no buffer, we can do nothing */
	if (!mb->start)
	return 0;

	/*
	* if head is ahead of tail, we can write from head until the end of
	* the buffer
	*/
	if (mb->head >= mb->tail) {
	/* work out how many bytes can fit here */
	len = mb->end - mb->head - 1;
	if (maxlen >= 0 && len > maxlen)
	len = maxlen;

	/* update the head pointer to mark these bytes as written */
	if (update)
	mb->head += len;

	/*
	* if the tail isn't at start of the buffer, then we can
	* write one more byte right at the end
	*/
	if ((maxlen < 0 \|\| len < maxlen) && mb->tail != mb->start) {
	len++;
	if (update)
	mb->head = mb->start;
	}

	/* otherwise now we can write until head almost reaches tail */
	} else {
	/* work out how many bytes can fit here */
	len = mb->tail - mb->head - 1;
	if (maxlen >= 0 && len > maxlen)
	len = maxlen;

	/* update the head pointer to mark these bytes as written */
	if (update)
	mb->head += len;
	}

	/* return the number of bytes which can be/must be written */
	return len;
	}

	int membuff_putraw(struct membuff mb, int maxlen, bool update, char *data)
	{
	char **datap;
	int offset;
	int size;

	size = membuff_putrawflex(mb, maxlen, update, &datap, &offset);
	data = datap + offset;

	return size;
	}

	bool membuff_putbyte(struct membuff *mb, int ch)
	{
	char *data;

	if (membuff_putraw(mb, 1, true, &data) != 1)
	return false;
	*data = ch;

	return true;
	}

	int membuff_getraw(struct membuff mb, int maxlen, bool update, char *data)
	{
	int len;

	/* assume for now there is no data to get */
	len = 0;

	/*
	* in this case head is ahead of tail, so we must return data between
	*'tail' and 'head'
	*/
	if (mb->head > mb->tail) {
	/* work out the amount of data */
	*data = mb->tail;
	len = mb->head - mb->tail;

	/* check it isn't too much */
	if (maxlen >= 0 && len > maxlen)
	len = maxlen;

	/* & mark it as read from the buffer */
	if (update)
	mb->tail += len;
	}

	/*
	* if head is before tail, then we have data between 'tail' and 'end'
	* and some more data between 'start' and 'head'(which we can't
	* return this time
	*/
	else if (mb->head < mb->tail) {
	/* work out the amount of data */
	*data = mb->tail;
	len = mb->end - mb->tail;
	if (maxlen >= 0 && len > maxlen)
	len = maxlen;
	if (update) {
	mb->tail += len;
	if (mb->tail == mb->end)
	mb->tail = mb->start;
	}
	}

	debug("getraw: maxlen=%d, update=%d, head=%d, tail=%d, data=%d, len=%d",
	maxlen, update, (int)(mb->head - mb->start),
	(int)(mb->tail - mb->start), (int)(*data - mb->start), len);

	/* return the number of bytes we found */
	return len;
	}

	int membuff_getbyte(struct membuff *mb)
	{
	char *data = 0;

	return membuff_getraw(mb, 1, true, &data) != 1 ? -1 : (uint8_t )data;
	}

	int membuff_peekbyte(struct membuff *mb)
	{
	char *data = 0;

	return membuff_getraw(mb, 1, false, &data) != 1 ? -1 : (uint8_t )data;
	}

	int membuff_get(struct membuff mb, char buff, int maxlen)
	{
	char data = 0, buffptr = buff;
	int len = 1, i;

	/*
	* do this in up to two lots(see GetRaw for why) stopping when there
	* is no more data
	*/
	for (i = 0; len && i < 2; i++) {
	/* get a pointer to the data available */
	len = membuff_getraw(mb, maxlen, true, &data);

	/* copy it into the buffer */
	memcpy(buffptr, data, len);
	buffptr += len;
	maxlen -= len;
	}

	/* return the number of bytes read */
	return buffptr - buff;
	}

	int membuff_put(struct membuff mb, const char buff, int length)
	{
	char *data;
	int towrite, i, written;

	for (i = written = 0; i < 2; i++) {
	/* ask where some data can be written */
	towrite = membuff_putraw(mb, length, true, &data);

	/* and write it, updating the bytes length */
	memcpy(data, buff, towrite);
	written += towrite;
	buff += towrite;
	length -= towrite;
	}

	/* return the number of bytes written */
	return written;
	}

	bool membuff_isempty(struct membuff *mb)
	{
	return mb->head == mb->tail;
	}

	int membuff_avail(struct membuff *mb)
	{
	struct membuff copy;
	int i, avail;
	char *data = 0;

	/* make a copy of this buffer's control data */
	copy = *mb;

	/* now read everything out of the copied buffer */
	for (i = avail = 0; i < 2; i++)
	avail += membuff_getraw(&copy, -1, true, &data);

	/* and return how much we read */
	return avail;
	}

	int membuff_size(struct membuff *mb)
	{
	return mb->end - mb->start;
	}

	bool membuff_makecontig(struct membuff *mb)
	{
	int topsize, botsize;

	debug("makecontig: head=%d, tail=%d, size=%d",
	(int)(mb->head - mb->start), (int)(mb->tail - mb->start),
	(int)(mb->end - mb->start));

	/*
	* first we move anything at the start of the buffer into the correct
	* place some way along
	*/
	if (mb->tail > mb->head) {
	/*
	* the data is split into two parts, from 0 to ->head and
	* from ->tail to ->end. We move the stuff from 0 to ->head
	* up to make space for the other data before it
	*/
	topsize = mb->end - mb->tail;
	botsize = mb->head - mb->start;

	/*
	* must move data at bottom up by 'topsize' bytes - check if
	* there's room
	*/
	if (mb->head + topsize >= mb->tail)
	return false;
	memmove(mb->start + topsize, mb->start, botsize);
	debug(" - memmove(%d, %d, %d)", topsize, 0, botsize);

	/* nothing at the start, so skip that step */
	} else {
	topsize = mb->head - mb->tail;
	botsize = 0;
	}

	/* now move data at top down to the bottom */
	memcpy(mb->start, mb->tail, topsize);
	debug(" - memcpy(%d, %d, %d)", 0, (int)(mb->tail - mb->start), topsize);

	/* adjust pointers */
	mb->tail = mb->start;
	mb->head = mb->start + topsize + botsize;

	debug(" - head=%d, tail=%d", (int)(mb->head - mb->start),
	(int)(mb->tail - mb->start));

	/* all ok */
	return true;
	}

	int membuff_free(struct membuff *mb)
	{
	return mb->end == mb->start ? 0 :
	(mb->end - mb->start) - 1 - membuff_avail(mb);
	}

	int membuff_readline(struct membuff mb, char str, int maxlen, int minch, bool must_fit)
	{
	int len; /* number of bytes read (!= string length) */
	char s, end;
	bool ok = false;
	char *orig = str;

	end = mb->head >= mb->tail ? mb->head : mb->end;
	for (len = 0, s = mb->tail; s < end && len < maxlen - 1; str++) {
	str = s++;
	len++;
	if (str == '\n' \|\| str < minch) {
	ok = true;
	break;
	}
	if (s == end && mb->tail > mb->head) {
	s = mb->start;
	end = mb->head;
	}
	}

	/* couldn't get the whole string */
	if (!ok && must_fit) {
	if (maxlen)
	*orig = '\0';
	return 0;
	}

	/* terminate the string, update the membuff and return success */
	*str = '\0';
	mb->tail = s == mb->end ? mb->start : s;

	return len;
	}

	int membuff_extend_by(struct membuff *mb, int by, int max)
	{
	int oldhead, oldtail;
	int size, orig;
	char *ptr;

	/* double the buffer size until it is big enough */
	assert(by >= 0);
	for (orig = mb->end - mb->start, size = orig; size < orig + by;)
	size *= 2;
	if (max != -1)
	size = min(size, max);
	by = size - orig;

	/* if we're already at maximum, give up */
	if (by <= 0)
	return -E2BIG;

	oldhead = mb->head - mb->start;
	oldtail = mb->tail - mb->start;
	ptr = realloc(mb->start, size);
	if (!ptr)
	return -ENOMEM;
	mb->start = ptr;
	mb->head = mb->start + oldhead;
	mb->tail = mb->start + oldtail;

	if (mb->head < mb->tail) {
	memmove(mb->tail + by, mb->tail, orig - oldtail);
	mb->tail += by;
	}
	mb->end = mb->start + size;

	return 0;
	}

	void membuff_init(struct membuff mb, char buff, int size)
	{
	mb->start = buff;
	mb->end = mb->start + size;
	membuff_purge(mb);
	}

	int membuff_new(struct membuff *mb, int size)
	{
	mb->start = malloc(size);
	if (!mb->start)
	return -ENOMEM;

	membuff_init(mb, mb->start, size);
	return 0;
	}

	void membuff_uninit(struct membuff *mb)
	{
	mb->end = NULL;
	mb->start = NULL;
	membuff_purge(mb);
	}

	void membuff_dispose(struct membuff *mb)
	{
	free(&mb->start);
	membuff_uninit(mb);
	}