3 * $Id: lbuf.c,v 1.4 2000/06/17 10:38:14 mdw Exp $
5 * Block-to-line buffering
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of the mLib utilities library.
14 * mLib is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
19 * mLib is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
24 * You should have received a copy of the GNU Library General Public
25 * License along with mLib; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.4 2000/06/17 10:38:14 mdw
34 * Add support for variable buffer sizes.
36 * Revision 1.3 1999/05/22 13:38:50 mdw
37 * Fix bug which discarded initial portions of incomplete lines.
39 * Revision 1.2 1999/05/17 20:36:08 mdw
40 * Make the magical constants for the buffer flags uppercase.
42 * Revision 1.1 1999/05/14 21:01:14 mdw
43 * Integrated `select' handling bits from the background resolver project.
47 /*----- Header files ------------------------------------------------------*/
58 /*----- Main code ---------------------------------------------------------*/
60 /* --- @lbuf_flush@ --- *
62 * Arguments: @lbuf *b@ = pointer to buffer block
63 * @char *p@ = pointer to where to start searching
64 * @size_t len@ = length of new material added
68 * Use: Flushes any complete lines in a line buffer. New material
69 * is assumed to have been added starting at @p@. If @p@ is
70 * null, then the scan starts at the beginning of the buffer,
71 * and the size of data already in the buffer is used in place
74 * It is assumed that the buffer is initially enabled. You
75 * shouldn't be contributing data to a disabled buffer anyway.
76 * However, the buffer handler may at some point disable itself,
77 * and @lbuf_flush@ can cope with this eventuality. Any pending
78 * data is left at the start of the buffer and can be flushed
79 * out by calling @lbuf_flush(b, 0, 0)@ if the buffer is ever
83 void lbuf_flush(lbuf
*b
, char *p
, size_t len
)
85 char *l
; /* Limit of data in buffer */
86 char *q
; /* Roving pointer through string */
87 char *base
; /* Base address of current line */
88 int cr
; /* Carriage return state */
90 /* --- Initialize variables as necessary --- */
101 /* --- Clear @base@ if I'm discarding an overlong line --- */
108 /* --- Now I march through the string --- */
110 for (q
= p
; q
< l
; q
++) {
112 /* --- Quickly discard uninteresting characters --- */
114 if (*q
!= '\r' && *q
!= '\n') {
123 /* --- Two choices here --- *
125 * I can either be strict about CRLF line ends, or I can be shoddy
126 * and allow bare LFs. I'll do the latter, although I oughtn't,
127 * because it makes testing interactively and with Unix text files
136 /* --- I have a positive ID on a linefeed --- *
138 * If I'm interested in this string, report it to my owner.
143 q
[-1] = 0; /* Exercise: why is this safe? */
147 if (!(b
->f
& LBUF_ENABLE
)) {
156 /* --- Sift through the aftermath --- */
159 size_t len
= l
- base
;
163 } else if (base
!= b
->buf
)
164 memmove(b
->buf
, base
, len
);
173 /* --- @lbuf_close@ --- *
175 * Arguments: @lbuf *b@ = pointer to buffer block
179 * Use: Empties the buffer of any data currently lurking in it, and
180 * informs the client that this has happened. It's assumed that
181 * the buffer is enabled: you shouldn't be reading close events
182 * on disabled buffers. The buffer, if allocated, is freed.
185 void lbuf_close(lbuf
*b
)
187 if (b
->len
&& b
->len
!= b
->sz
) {
189 b
->func(b
->buf
, b
->p
);
192 x_free(b
->a
, b
->buf
);
195 if (b
->f
& LBUF_ENABLE
)
199 /* --- @lbuf_free@ --- *
201 * Arguments: @lbuf *b@ = pointer to buffer block
202 * @char **p@ = output pointer to free space
204 * Returns: Free buffer size.
206 * Use: Returns the free portion of a line buffer. Data can then be
207 * written to this portion, and split out into lines by calling
208 * @lbuf_flush@. A buffer is allocated if none currently
212 size_t lbuf_free(lbuf
*b
, char **p
)
214 /* --- There's a special case to consider --- *
216 * If a line from the file wouldn't fit in the buffer, I truncate it and
217 * return what would fit. The rest of the line ought to be discarded.
218 * This condition is signalled by @len = b->sz@, and means that the entire
219 * buffer is OK to be trashed. In other cases, @len@ is the amount of
220 * space currently occupied in the buffer. This special case is the reason
221 * this routine exists.
224 if (b
->len
!= 0 && b
->len
!= b
->sz
) {
225 *p
= b
->buf
+ b
->len
;
226 return (b
->sz
- b
->len
);
229 b
->buf
= x_alloc(b
->a
, b
->sz
);
235 /* --- @lbuf_snarf@ --- *
237 * Arguments: @lbuf *b@ = pointer to buffer block
238 * @const void *p@ = pointer to input data buffer
239 * @size_t sz@ = size of data in input buffer
243 * Use: Snarfs the data from the input buffer and spits it out as
244 * lines. This interface ignores the complexities of dealing
245 * with disablement: you should be using @lbuf_free@ to
246 * contribute data if you want to cope with that.
249 void lbuf_snarf(lbuf
*b
, const void *p
, size_t sz
)
252 while (sz
&& (b
->f
& LBUF_ENABLE
)) {
256 bsz
= lbuf_free(b
, &bp
);
260 lbuf_flush(b
, bp
, bsz
);
266 /* --- @lbuf_setsize@ --- *
268 * Arguments: @lbuf *b@ = pointer to buffer block
269 * @size_t sz@ = requested maximum line size
273 * Use: Modifies the size of the buffer associated with the block.
274 * It is an error to resize a buffer while it contains data.
277 void lbuf_setsize(lbuf
*b
, size_t sz
)
280 assert(((void)"Buffer in use in lbuf_setsize",
281 b
->len
== 0 || b
->len
== b
->sz
));
283 x_free(b
->a
, b
->buf
);
288 /* --- @lbuf_init@ --- *
290 * Arguments: @lbuf *b@ = pointer to buffer block
291 * @void (*func)(char *s, void *p)@ = handler function
292 * @void *p@ = argument pointer for @func@
296 * Use: Initializes a line buffer block. Any recognized lines are
297 * passed to @func@ for processing. No buffer is initially
298 * allocated; this is done when the buffer is actually required
299 * for the first time.
302 void lbuf_init(lbuf
*b
,
303 void (*func
)(char */
*s*/
, void */
*p*/
),
312 lbuf_setsize(b
, 256);
315 /* --- @lbuf_destroy@ --- *
317 * Arguments: @lbuf *b@ = pointer to buffer block
321 * Use: Deallocates a line buffer and frees any resources it owned.
324 void lbuf_destroy(lbuf
*b
)
327 x_free(b
->a
, b
->buf
);
332 /*----- That's all, folks -------------------------------------------------*/