3 * $Id: lbuf.c,v 1.5 2001/02/03 16:23:33 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 1.5 2001/02/03 16:23:33 mdw
34 * Bug fix: handle a disable during a close-induced flush without dumping
37 * Revision 1.4 2000/06/17 10:38:14 mdw
38 * Add support for variable buffer sizes.
40 * Revision 1.3 1999/05/22 13:38:50 mdw
41 * Fix bug which discarded initial portions of incomplete lines.
43 * Revision 1.2 1999/05/17 20:36:08 mdw
44 * Make the magical constants for the buffer flags uppercase.
46 * Revision 1.1 1999/05/14 21:01:14 mdw
47 * Integrated `select' handling bits from the background resolver project.
51 /*----- Header files ------------------------------------------------------*/
62 /*----- Main code ---------------------------------------------------------*/
64 /* --- @lbuf_flush@ --- *
66 * Arguments: @lbuf *b@ = pointer to buffer block
67 * @char *p@ = pointer to where to start searching
68 * @size_t len@ = length of new material added
72 * Use: Flushes any complete lines in a line buffer. New material
73 * is assumed to have been added starting at @p@. If @p@ is
74 * null, then the scan starts at the beginning of the buffer,
75 * and the size of data already in the buffer is used in place
78 * It is assumed that the buffer is initially enabled. You
79 * shouldn't be contributing data to a disabled buffer anyway.
80 * However, the buffer handler may at some point disable itself,
81 * and @lbuf_flush@ can cope with this eventuality. Any pending
82 * data is left at the start of the buffer and can be flushed
83 * out by calling @lbuf_flush(b, 0, 0)@ if the buffer is ever
87 void lbuf_flush(lbuf *b, char *p, size_t len)
89 char *l; /* Limit of data in buffer */
90 char *q; /* Roving pointer through string */
91 char *base; /* Base address of current line */
92 int cr; /* Carriage return state */
94 if (b->f & LBUF_CLOSE) {
99 /* --- Initialize variables as necessary --- */
110 /* --- Clear @base@ if I'm discarding an overlong line --- */
117 /* --- Now I march through the string --- */
119 for (q = p; q < l; q++) {
121 /* --- Quickly discard uninteresting characters --- */
123 if (*q != '\r' && *q != '\n') {
132 /* --- Two choices here --- *
134 * I can either be strict about CRLF line ends, or I can be shoddy
135 * and allow bare LFs. I'll do the latter, although I oughtn't,
136 * because it makes testing interactively and with Unix text files
145 /* --- I have a positive ID on a linefeed --- *
147 * If I'm interested in this string, report it to my owner.
152 q[-1] = 0; /* Exercise: why is this safe? */
156 if (!(b->f & LBUF_ENABLE)) {
165 /* --- Sift through the aftermath --- */
168 size_t len = l - base;
172 } else if (base != b->buf)
173 memmove(b->buf, base, len);
182 /* --- @lbuf_close@ --- *
184 * Arguments: @lbuf *b@ = pointer to buffer block
188 * Use: Empties the buffer of any data currently lurking in it, and
189 * informs the client that this has happened. It's assumed that
190 * the buffer is enabled: you shouldn't be reading close events
191 * on disabled buffers. The buffer, if allocated, is freed.
194 void lbuf_close(lbuf *b)
196 if (b->len && b->len != b->sz) {
198 b->func(b->buf, b->p);
201 x_free(b->a, b->buf);
205 if (b->f & LBUF_ENABLE)
209 /* --- @lbuf_free@ --- *
211 * Arguments: @lbuf *b@ = pointer to buffer block
212 * @char **p@ = output pointer to free space
214 * Returns: Free buffer size.
216 * Use: Returns the free portion of a line buffer. Data can then be
217 * written to this portion, and split out into lines by calling
218 * @lbuf_flush@. A buffer is allocated if none currently
222 size_t lbuf_free(lbuf *b, char **p)
224 /* --- There's a special case to consider --- *
226 * If a line from the file wouldn't fit in the buffer, I truncate it and
227 * return what would fit. The rest of the line ought to be discarded.
228 * This condition is signalled by @len = b->sz@, and means that the entire
229 * buffer is OK to be trashed. In other cases, @len@ is the amount of
230 * space currently occupied in the buffer. This special case is the reason
231 * this routine exists.
234 if (b->len != 0 && b->len != b->sz) {
235 *p = b->buf + b->len;
236 return (b->sz - b->len);
239 b->buf = x_alloc(b->a, b->sz);
245 /* --- @lbuf_snarf@ --- *
247 * Arguments: @lbuf *b@ = pointer to buffer block
248 * @const void *p@ = pointer to input data buffer
249 * @size_t sz@ = size of data in input buffer
253 * Use: Snarfs the data from the input buffer and spits it out as
254 * lines. This interface ignores the complexities of dealing
255 * with disablement: you should be using @lbuf_free@ to
256 * contribute data if you want to cope with that.
259 void lbuf_snarf(lbuf *b, const void *p, size_t sz)
262 while (sz && (b->f & LBUF_ENABLE)) {
266 bsz = lbuf_free(b, &bp);
270 lbuf_flush(b, bp, bsz);
276 /* --- @lbuf_setsize@ --- *
278 * Arguments: @lbuf *b@ = pointer to buffer block
279 * @size_t sz@ = requested maximum line size
283 * Use: Modifies the size of the buffer associated with the block.
284 * It is an error to resize a buffer while it contains data.
287 void lbuf_setsize(lbuf *b, size_t sz)
290 assert(((void)"Buffer in use in lbuf_setsize",
291 b->len == 0 || b->len == b->sz));
293 x_free(b->a, b->buf);
298 /* --- @lbuf_init@ --- *
300 * Arguments: @lbuf *b@ = pointer to buffer block
301 * @void (*func)(char *s, void *p)@ = handler function
302 * @void *p@ = argument pointer for @func@
306 * Use: Initializes a line buffer block. Any recognized lines are
307 * passed to @func@ for processing. No buffer is initially
308 * allocated; this is done when the buffer is actually required
309 * for the first time.
312 void lbuf_init(lbuf *b,
313 void (*func)(char */*s*/, void */*p*/),
322 lbuf_setsize(b, 256);
325 /* --- @lbuf_destroy@ --- *
327 * Arguments: @lbuf *b@ = pointer to buffer block
331 * Use: Deallocates a line buffer and frees any resources it owned.
334 void lbuf_destroy(lbuf *b)
337 x_free(b->a, b->buf);
342 /*----- That's all, folks -------------------------------------------------*/