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