3 * $Id: lbuf.c,v 1.3 1999/05/22 13:38:50 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 1.3 1999/05/22 13:38:50 mdw
34 * Fix bug which discarded initial portions of incomplete lines.
36 * Revision 1.2 1999/05/17 20:36:08 mdw
37 * Make the magical constants for the buffer flags uppercase.
39 * Revision 1.1 1999/05/14 21:01:14 mdw
40 * Integrated `select' handling bits from the background resolver project.
44 /*----- Header files ------------------------------------------------------*/
52 /*----- Main code ---------------------------------------------------------*/
54 /* --- @lbuf_flush@ --- *
56 * Arguments: @lbuf *b@ = pointer to buffer block
57 * @char *p@ = pointer to where to start searching
58 * @size_t len@ = length of new material added
62 * Use: Flushes any complete lines in a line buffer. New material
63 * is assumed to have been added starting at @p@. If @p@ is
64 * null, then the scan starts at the beginning of the buffer,
65 * and the size of data already in the buffer is used in place
68 * It is assumed that the buffer is initially enabled. You
69 * shouldn't be contributing data to a disabled buffer anyway.
70 * However, the buffer handler may at some point disable itself,
71 * and @lbuf_flush@ can cope with this eventuality. Any pending
72 * data is left at the start of the buffer and can be flushed
73 * out by calling @lbuf_flush(b, 0, 0)@ if the buffer is ever
77 void lbuf_flush(lbuf
*b
, char *p
, size_t len
)
79 char *l
; /* Limit of data in buffer */
80 char *q
; /* Roving pointer through string */
81 char *base
; /* Base address of current line */
82 int cr
; /* Carriage return state */
84 /* --- Initialize variables as necessary --- */
95 /* --- Clear @base@ if I'm discarding an overlong line --- */
97 if (b
->len
== sizeof(b
->buf
))
102 /* --- Now I march through the string --- */
104 for (q
= p
; q
< l
; q
++) {
106 /* --- Quickly discard uninteresting characters --- */
108 if (*q
!= '\r' && *q
!= '\n') {
117 /* --- Two choices here --- *
119 * I can either be strict about CRLF line ends, or I can be shoddy
120 * and allow bare LFs. I'll do the latter, although I oughtn't,
121 * because it makes testing interactively and with Unix text files
130 /* --- I have a positive ID on a linefeed --- *
132 * If I'm interested in this string, report it to my owner.
137 q
[-1] = 0; /* Exercise: why is this safe? */
141 if (!(b
->f
& LBUF_ENABLE
)) {
150 /* --- Sift through the aftermath --- */
153 size_t len
= l
- base
;
154 if (len
== sizeof(b
->buf
)) {
157 } else if (base
!= b
->buf
)
158 memmove(b
->buf
, base
, len
);
167 /* --- @lbuf_close@ --- *
169 * Arguments: @lbuf *b@ = pointer to buffer block
173 * Use: Empties the buffer of any data currently lurking in it, and
174 * informs the client that this has happened. It's assumed that
175 * the buffer is enabled: you shouldn't be reading close events
176 * on disabled buffers.
179 void lbuf_close(lbuf
*b
)
181 if (b
->len
&& b
->len
!= sizeof(b
->buf
)) {
183 b
->func(b
->buf
, b
->p
);
185 if (b
->f
& LBUF_ENABLE
)
189 /* --- @lbuf_free@ --- *
191 * Arguments: @lbuf *b@ = pointer to buffer block
192 * @char **p@ = output pointer to free space
194 * Returns: Free buffer size.
196 * Use: Returns the free portion of a line buffer. Data can then be
197 * written to this portion, and split out into lines by calling
201 size_t lbuf_free(lbuf
*b
, char **p
)
203 /* --- There's a special case to consider --- *
205 * If a line from the file wouldn't fit in the buffer, I truncate it and
206 * return what would fit. The rest of the line ought to be discarded.
207 * This condition is signalled by @len = sizeof(buf)@, and means that the
208 * entire buffer is OK to be trashed. In other cases, @len@ is the amount
209 * of space currently occupied in the buffer. This special case is the
210 * reason this routine exists.
213 if (b
->len
!= 0 && b
->len
!= sizeof(b
->buf
)) {
214 *p
= b
->buf
+ b
->len
;
215 return (sizeof(b
->buf
) - b
->len
);
218 return (sizeof(b
->buf
));
222 /* --- @lbuf_snarf@ --- *
224 * Arguments: @lbuf *b@ = pointer to buffer block
225 * @const void *p@ = pointer to input data buffer
226 * @size_t sz@ = size of data in input buffer
230 * Use: Snarfs the data from the input buffer and spits it out as
231 * lines. This interface ignores the complexities of dealing
232 * with disablement: you should be using @lbuf_free@ to
233 * contribute data if you want to cope with that.
236 void lbuf_snarf(lbuf
*b
, const void *p
, size_t sz
)
243 bsz
= lbuf_free(b
, &bp
);
247 lbuf_flush(b
, bp
, bsz
);
253 /* --- @lbuf_init@ --- *
255 * Arguments: @lbuf *b@ = pointer to buffer block
256 * @void (*func)(char *s, void *p)@ = handler function
257 * @void *p@ = argument pointer for @func@
261 * Use: Initializes a line buffer block. Any recognized lines are
262 * passed to @func@ for processing.
265 void lbuf_init(lbuf
*b
,
266 void (*func
)(char */
*s*/
, void */
*p*/
),
275 /*----- That's all, folks -------------------------------------------------*/