src/buffers.c

/*
 * Buffer management functions.
 *
 * Copyright 2000-2007 Willy Tarreau <w@1wt.eu>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 */

#include <stdarg.h>
#include <stdio.h>
#include <string.h>

#include <common/config.h>
#include <common/memory.h>
#include <proto/buffers.h>
#include <types/global.h>

struct pool_head *pool2_buffer;


/* perform minimal intializations, report 0 in case of error, 1 if OK. */
int init_buffer()
{
	pool2_buffer = create_pool("buffer", sizeof(struct buffer) + global.tune.bufsize, MEM_F_SHARED);
	return pool2_buffer != NULL;
}


/* writes <len> bytes from message <msg> to buffer <buf>. Returns -1 in case of
 * success, -2 if the message is larger than the buffer size, or the number of
 * bytes available otherwise. The send limit is automatically adjusted with the
 * amount of data written. FIXME-20060521: handle unaligned data.
 */
int buffer_write(struct buffer *buf, const char *msg, int len)
{
	int max;

	if (len == 0)
		return -1;

	if (len > buf->size) {
		/* we can't write this chunk and will never be able to, because
		 * it is larger than the buffer. This must be reported as an
		 * error. Then we return -2 so that writers that don't care can
		 * ignore it and go on, and others can check for this value.
		 */
		return -2;
	}

	max = buffer_realign(buf);

	if (len > max)
		return max;

	memcpy(buf->r, msg, len);
	buf->l += len;
	buf->send_max += len;
	buf->r += len;
	buf->total += len;
	if (buf->r == buf->data + buf->size)
		buf->r = buf->data;

	buf->flags &= ~(BF_OUT_EMPTY|BF_FULL);
	if (buf->l >= buf->max_len)
		buf->flags |= BF_FULL;

	return -1;
}

/* Try to write string <str> into buffer <buf> after length controls. This
 * is the equivalent of buffer_write() except that to_forward and send_max
 * are updated and that max_len is respected. Returns -1 in case of success,
 * -2 if it is larger than the buffer size, or the number of bytes available
 * otherwise. The send limit is automatically adjusted with the amount of data
 * written.
 */
int buffer_feed(struct buffer *buf, const char *str, int len)
{
	int max;

	if (len == 0)
		return -1;

	if (len > buf->max_len) {
		/* we can't write this chunk and will never be able to, because
		 * it is larger than the buffer's current max size.
		 */
		return -2;
	}

	max = buffer_contig_space(buf);

	if (len > max)
		return max;

	memcpy(buf->r, str, len);
	buf->l += len;
	buf->r += len;
	buf->total += len;
	if (buf->to_forward > 0) {
		int fwd = MIN(buf->to_forward, len);
		buf->send_max   += fwd;
		buf->to_forward -= fwd;
		buf->flags &= ~BF_OUT_EMPTY;
	}

	if (buf->r == buf->data + buf->size)
		buf->r = buf->data;

	buf->flags &= ~BF_FULL;
	if (buf->l >= buf->max_len)
		buf->flags |= BF_FULL;

	return -1;
}

/* Get one text line out of a buffer from a stream interface.
 * Return values :
 *   >0 : number of bytes read. Includes the \n if present before len or end.
 *   =0 : no '\n' before end found. <buf> is undefined.
 *   <0 : no more bytes readable + shutdown set.
 * The buffer status is not changed. The caller must call buffer_skip() to
 * update it. The '\n' is waited for as long as neither the buffer nor the
 * output are full. If either of them is full, the string may be returned
 * as is, without the '\n'.
 */
int buffer_si_peekline(struct buffer *buf, char *str, int len)
{
	int ret, max;
	char *p;

	ret = 0;
	max = len;
	if (!buf->send_max) {
		if (buf->flags & (BF_SHUTW|BF_SHUTW_NOW))
			ret = -1;
		goto out;
	}

	p = buf->w;

	if (max > buf->send_max) {
		max = buf->send_max;
		str[max] = 0;
	}
	while (max) {
		*str++ = *p;
		ret++;
		max--;

		if (*p == '\n')
			break;
		p++;
		if (p == buf->data + buf->size)
			p = buf->data;
	}
	if (*p != '\n' && ret < len && ret < buf->max_len &&
	   !(buf->flags & (BF_SHUTW|BF_SHUTW_NOW)))
		ret = 0;
 out:
	if (max)
		*str = 0;
	return ret;
}

/*
 * this function writes the string <str> at position <pos> which must be in buffer <b>,
 * and moves <end> just after the end of <str>.
 * <b>'s parameters (l, r, w, h, lr) are recomputed to be valid after the shift.
 * the shift value (positive or negative) is returned.
 * If there's no space left, the move is not done.
 * The function does not adjust ->send_max nor BF_OUT_EMPTY because it does not
 * make sense to use it on data scheduled to be sent.
 *
 */
int buffer_replace(struct buffer *b, char *pos, char *end, const char *str)
{
	int delta;
	int len;

	len = strlen(str);
	delta = len - (end - pos);

	if (delta + b->r >= b->data + b->size)
		return 0;  /* no space left */

	/* first, protect the end of the buffer */
	memmove(end + delta, end, b->data + b->l - end);

	/* now, copy str over pos */
	memcpy(pos, str,len);

	/* we only move data after the displaced zone */
	if (b->r  > pos) b->r  += delta;
	if (b->w  > pos) b->w  += delta;
	if (b->lr > pos) b->lr += delta;
	b->l += delta;

	b->flags &= ~BF_FULL;
	if (b->l == 0)
		b->r = b->w = b->lr = b->data;
	if (b->l >= b->max_len)
		b->flags |= BF_FULL;

	return delta;
}

/*
 * same except that the string length is given, which allows str to be NULL if
 * len is 0. The send limit is *not* adjusted.
 */
int buffer_replace2(struct buffer *b, char *pos, char *end, const char *str, int len)
{
	int delta;

	delta = len - (end - pos);

	if (delta + b->r >= b->data + b->size)
		return 0;  /* no space left */

	if (b->data + b->l < end) {
		/* The data has been stolen, we could have crashed.
		 * Maybe we should abort() ? */
		return 0;
	}

	/* first, protect the end of the buffer */
	memmove(end + delta, end, b->data + b->l - end);

	/* now, copy str over pos */
	if (len)
		memcpy(pos, str, len);

	/* we only move data after the displaced zone */
	if (b->r  > pos) b->r  += delta;
	if (b->w  > pos) b->w  += delta;
	if (b->lr > pos) b->lr += delta;
	b->l += delta;

	b->flags &= ~BF_FULL;
	if (b->l == 0)
		b->r = b->w = b->lr = b->data;
	if (b->l >= b->max_len)
		b->flags |= BF_FULL;

	return delta;
}


/*
 * Inserts <str> followed by "\r\n" at position <pos> in buffer <b>. The <len>
 * argument informs about the length of string <str> so that we don't have to
 * measure it. It does not include the "\r\n". If <str> is NULL, then the buffer
 * is only opened for len+2 bytes but nothing is copied in. It may be useful in
 * some circumstances. The send limit is *not* adjusted.
 *
 * The number of bytes added is returned on success. 0 is returned on failure.
 */
int buffer_insert_line2(struct buffer *b, char *pos, const char *str, int len)
{
	int delta;

	delta = len + 2;

	if (delta + b->r >= b->data + b->size)
		return 0;  /* no space left */

	/* first, protect the end of the buffer */
	memmove(pos + delta, pos, b->data + b->l - pos);

	/* now, copy str over pos */
	if (len && str) {
		memcpy(pos, str, len);
		pos[len] = '\r';
		pos[len + 1] = '\n';
	}

	/* we only move data after the displaced zone */
	if (b->r  > pos) b->r  += delta;
	if (b->w  > pos) b->w  += delta;
	if (b->lr > pos) b->lr += delta;
	b->l += delta;

	b->flags &= ~BF_FULL;
	if (b->l >= b->max_len)
		b->flags |= BF_FULL;

	return delta;
}


/*
 * Does an snprintf() at the end of chunk <chk>, respecting the limit of
 * at most <size> chars. If the size is over, nothing is added. Returns
 * the new chunk size.
 */
int chunk_printf(struct chunk *chk, int size, const char *fmt, ...)
{
	va_list argp;
	int ret;

	va_start(argp, fmt);
	ret = vsnprintf(chk->str + chk->len, size - chk->len, fmt, argp);
	if (ret >= size - chk->len)
		/* do not copy anything in case of truncation */
		chk->str[chk->len] = 0;
	else
		chk->len += ret;
	va_end(argp);
	return chk->len;
}

/*
 * Dumps part or all of a buffer.
 */
void buffer_dump(FILE *o, struct buffer *b, int from, int to)
{
	fprintf(o, "Dumping buffer %p\n", b);
	fprintf(o, "  data=%p l=%d r=%p w=%p lr=%p\n",
		b->data, b->l, b->r, b->w, b->lr);

	if (!to || to > b->l)
		to = b->l;

	fprintf(o, "Dumping contents from byte %d to byte %d\n", from, to);
	for (; from < to; from++) {
		if ((from & 15) == 0)
			fprintf(o, "  %04x: ", from);
		fprintf(o, "%02x ", b->data[from]);
		if ((from & 15) == 7)
			fprintf(o, "- ");
		else if (((from & 15) == 15) && (from != to-1))
			fprintf(o, "\n");
	}
	fprintf(o, "\n--\n");
}


/*
 * Local variables:
 *  c-indent-level: 8
 *  c-basic-offset: 8
 * End:
 */