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/* $OpenBSD: ringbuf.c,v 1.10 2016/10/16 22:12:50 bluhm Exp $ */
/*
* Copyright (c) 2004 Damien Miller
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* Simple ringbuffer for lines of text.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "syslogd.h"
#define MINIMUM(a, b) (((a) < (b)) ? (a) : (b))
/* Initialise a ring buffer */
struct ringbuf *
ringbuf_init(size_t len)
{
struct ringbuf *ret;
if (len == 0 || (ret = malloc(sizeof(*ret))) == NULL)
return (NULL);
if ((ret->buf = malloc(len)) == NULL) {
free(ret);
return (NULL);
}
ret->len = len;
ret->start = ret->end = 0;
return (ret);
}
/* Free a ring buffer */
void
ringbuf_free(struct ringbuf *rb)
{
free(rb->buf);
free(rb);
}
/* Clear a ring buffer */
void
ringbuf_clear(struct ringbuf *rb)
{
rb->start = rb->end = 0;
}
/* Return the number of bytes used in a ringbuffer */
size_t
ringbuf_used(struct ringbuf *rb)
{
return ((rb->len + rb->end - rb->start) % rb->len);
}
/*
* Append a line to a ring buffer, will delete lines from start
* of buffer as necessary
*/
int
ringbuf_append_line(struct ringbuf *rb, char *line)
{
size_t llen, used, copy_len;
int overflow = 0;
if (rb == NULL || line == NULL)
return (-1);
llen = strlen(line);
if (llen == 0)
return (-1);
if (line[llen - 1] != '\n')
llen++; /* one extra for appended '\n' */
if (llen >= rb->len)
return (-1);
/*
* If necessary, advance start pointer to make room for appended
* string. Ensure that start pointer is at the beginning of a line
* once we are done (i.e move to after '\n').
*/
used = ringbuf_used(rb);
if (used + llen >= rb->len) {
rb->start = (rb->start + used + llen - rb->len) % rb->len;
/* Find next '\n' */
while (rb->buf[rb->start] != '\n')
rb->start = (rb->start + 1) % rb->len;
/* Skip it */
rb->start = (rb->start + 1) % rb->len;
overflow = 1;
}
/*
* Now append string, starting from last pointer and wrapping if
* necessary
*/
if (rb->end + llen > rb->len) {
copy_len = rb->len - rb->end;
memcpy(rb->buf + rb->end, line, copy_len);
memcpy(rb->buf, line + copy_len, llen - copy_len - 1);
rb->buf[llen - copy_len - 1] = '\n';
} else {
memcpy(rb->buf + rb->end, line, llen - 1);
rb->buf[rb->end + llen - 1] = '\n';
}
rb->end = (rb->end + llen) % rb->len;
return (overflow);
}
/*
* Copy and nul-terminate a ringbuffer to a string.
*/
ssize_t
ringbuf_to_string(char *buf, size_t len, struct ringbuf *rb)
{
size_t copy_len, n;
if (buf == NULL || rb == NULL || len == 0)
return (-1);
copy_len = MINIMUM(len - 1, ringbuf_used(rb));
if (copy_len == 0)
return (copy_len);
if (rb->start < rb->end)
memcpy(buf, rb->buf + rb->start, copy_len);
else {
/* If the buffer is wrapped, copy each hunk separately */
n = rb->len - rb->start;
memcpy(buf, rb->buf + rb->start, MINIMUM(n, copy_len));
if (copy_len > n)
memcpy(buf + n, rb->buf,
MINIMUM(rb->end, copy_len - n));
}
buf[copy_len] = '\0';
return (ringbuf_used(rb));
}
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