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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: lbuf.c,v 1.5 2001/02/03 16:23:33 mdw Exp $ |
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4 | * |
5 | * Block-to-line buffering |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of the mLib utilities library. |
13 | * |
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. |
18 | * |
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. |
23 | * |
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, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: lbuf.c,v $ |
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33 | * Revision 1.5 2001/02/03 16:23:33 mdw |
34 | * Bug fix: handle a disable during a close-induced flush without dumping |
35 | * core. |
36 | * |
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37 | * Revision 1.4 2000/06/17 10:38:14 mdw |
38 | * Add support for variable buffer sizes. |
39 | * |
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40 | * Revision 1.3 1999/05/22 13:38:50 mdw |
41 | * Fix bug which discarded initial portions of incomplete lines. |
42 | * |
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43 | * Revision 1.2 1999/05/17 20:36:08 mdw |
44 | * Make the magical constants for the buffer flags uppercase. |
45 | * |
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46 | * Revision 1.1 1999/05/14 21:01:14 mdw |
47 | * Integrated `select' handling bits from the background resolver project. |
48 | * |
49 | */ |
50 | |
51 | /*----- Header files ------------------------------------------------------*/ |
52 | |
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53 | #include <assert.h> |
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54 | #include <stdio.h> |
55 | #include <stdlib.h> |
56 | #include <string.h> |
57 | |
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58 | #include "alloc.h" |
59 | #include "arena.h" |
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60 | #include "lbuf.h" |
61 | |
62 | /*----- Main code ---------------------------------------------------------*/ |
63 | |
64 | /* --- @lbuf_flush@ --- * |
65 | * |
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 |
69 | * |
70 | * Returns: --- |
71 | * |
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 |
76 | * of @len@. |
77 | * |
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 |
84 | * re-enabled. |
85 | */ |
86 | |
87 | void lbuf_flush(lbuf *b, char *p, size_t len) |
88 | { |
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 */ |
93 | |
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94 | if (b->f & LBUF_CLOSE) { |
95 | b->func(0, b->p); |
96 | return; |
97 | } |
98 | |
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99 | /* --- Initialize variables as necessary --- */ |
100 | |
101 | if (!p) { |
102 | p = b->buf; |
103 | cr = 0; |
104 | len = b->len; |
105 | } else |
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106 | cr = b->f & LBUF_CR; |
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107 | |
108 | l = p + len; |
109 | |
110 | /* --- Clear @base@ if I'm discarding an overlong line --- */ |
111 | |
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112 | if (b->len == b->sz) |
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113 | base = 0; |
114 | else |
115 | base = b->buf; |
116 | |
117 | /* --- Now I march through the string --- */ |
118 | |
119 | for (q = p; q < l; q++) { |
120 | |
121 | /* --- Quickly discard uninteresting characters --- */ |
122 | |
123 | if (*q != '\r' && *q != '\n') { |
124 | cr = 0; |
125 | continue; |
126 | } |
127 | if (*q == '\r') { |
128 | cr = 1; |
129 | continue; |
130 | } |
131 | |
132 | /* --- Two choices here --- * |
133 | * |
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 |
137 | * easier. |
138 | */ |
139 | |
140 | #ifdef STRICT_CRLF |
141 | if (!cr) |
142 | continue; |
143 | #endif |
144 | |
145 | /* --- I have a positive ID on a linefeed --- * |
146 | * |
147 | * If I'm interested in this string, report it to my owner. |
148 | */ |
149 | |
150 | if (base) { |
151 | if (cr) |
152 | q[-1] = 0; /* Exercise: why is this safe? */ |
153 | else |
154 | *q = 0; |
155 | b->func(base, b->p); |
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156 | if (!(b->f & LBUF_ENABLE)) { |
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157 | base = q + 1; |
158 | break; |
159 | } |
160 | } |
161 | base = q + 1; |
162 | cr = 0; |
163 | } |
164 | |
165 | /* --- Sift through the aftermath --- */ |
166 | |
167 | if (base) { |
168 | size_t len = l - base; |
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169 | if (len == b->sz) { |
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170 | b->buf[len - 1] = 0; |
171 | b->func(base, b->p); |
172 | } else if (base != b->buf) |
173 | memmove(b->buf, base, len); |
174 | b->len = len; |
175 | if (cr) |
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176 | b->f |= LBUF_CR; |
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177 | else |
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178 | b->f &= ~LBUF_CR; |
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179 | } |
180 | } |
181 | |
182 | /* --- @lbuf_close@ --- * |
183 | * |
184 | * Arguments: @lbuf *b@ = pointer to buffer block |
185 | * |
186 | * Returns: --- |
187 | * |
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 |
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191 | * on disabled buffers. The buffer, if allocated, is freed. |
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192 | */ |
193 | |
194 | void lbuf_close(lbuf *b) |
195 | { |
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196 | if (b->len && b->len != b->sz) { |
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197 | b->buf[b->len] = 0; |
198 | b->func(b->buf, b->p); |
199 | } |
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200 | if (b->buf) { |
201 | x_free(b->a, b->buf); |
202 | b->buf = 0; |
203 | } |
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204 | b->f |= LBUF_CLOSE; |
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205 | if (b->f & LBUF_ENABLE) |
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206 | b->func(0, b->p); |
207 | } |
208 | |
209 | /* --- @lbuf_free@ --- * |
210 | * |
211 | * Arguments: @lbuf *b@ = pointer to buffer block |
212 | * @char **p@ = output pointer to free space |
213 | * |
214 | * Returns: Free buffer size. |
215 | * |
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 |
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218 | * @lbuf_flush@. A buffer is allocated if none currently |
219 | * exists. |
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220 | */ |
221 | |
222 | size_t lbuf_free(lbuf *b, char **p) |
223 | { |
224 | /* --- There's a special case to consider --- * |
225 | * |
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. |
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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. |
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232 | */ |
233 | |
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234 | if (b->len != 0 && b->len != b->sz) { |
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235 | *p = b->buf + b->len; |
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236 | return (b->sz - b->len); |
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237 | } else { |
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238 | if (!b->buf) |
239 | b->buf = x_alloc(b->a, b->sz); |
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240 | *p = b->buf; |
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241 | return (b->sz); |
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242 | } |
243 | } |
244 | |
245 | /* --- @lbuf_snarf@ --- * |
246 | * |
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 |
250 | * |
251 | * Returns: --- |
252 | * |
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. |
257 | */ |
258 | |
259 | void lbuf_snarf(lbuf *b, const void *p, size_t sz) |
260 | { |
261 | const char *pp = p; |
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262 | while (sz && (b->f & LBUF_ENABLE)) { |
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263 | size_t bsz; |
264 | char *bp; |
265 | |
266 | bsz = lbuf_free(b, &bp); |
267 | if (bsz > sz) |
268 | bsz = sz; |
269 | memcpy(bp, pp, bsz); |
270 | lbuf_flush(b, bp, bsz); |
271 | pp += bsz; |
272 | sz -= bsz; |
273 | } |
274 | } |
275 | |
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276 | /* --- @lbuf_setsize@ --- * |
277 | * |
278 | * Arguments: @lbuf *b@ = pointer to buffer block |
279 | * @size_t sz@ = requested maximum line size |
280 | * |
281 | * Returns: --- |
282 | * |
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. |
285 | */ |
286 | |
287 | void lbuf_setsize(lbuf *b, size_t sz) |
288 | { |
289 | if (b->buf) |
290 | assert(((void)"Buffer in use in lbuf_setsize", |
291 | b->len == 0 || b->len == b->sz)); |
292 | if (b->buf) |
293 | x_free(b->a, b->buf); |
294 | b->sz = sz; |
295 | b->buf = 0; |
296 | } |
297 | |
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298 | /* --- @lbuf_init@ --- * |
299 | * |
300 | * Arguments: @lbuf *b@ = pointer to buffer block |
301 | * @void (*func)(char *s, void *p)@ = handler function |
302 | * @void *p@ = argument pointer for @func@ |
303 | * |
304 | * Returns: --- |
305 | * |
306 | * Use: Initializes a line buffer block. Any recognized lines are |
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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. |
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310 | */ |
311 | |
312 | void lbuf_init(lbuf *b, |
313 | void (*func)(char */*s*/, void */*p*/), |
314 | void *p) |
315 | { |
316 | b->func = func; |
317 | b->p = p; |
318 | b->len = 0; |
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319 | b->f = LBUF_ENABLE; |
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320 | b->buf = 0; |
321 | b->a = arena_global; |
322 | lbuf_setsize(b, 256); |
323 | } |
324 | |
325 | /* --- @lbuf_destroy@ --- * |
326 | * |
327 | * Arguments: @lbuf *b@ = pointer to buffer block |
328 | * |
329 | * Returns: --- |
330 | * |
331 | * Use: Deallocates a line buffer and frees any resources it owned. |
332 | */ |
333 | |
334 | void lbuf_destroy(lbuf *b) |
335 | { |
336 | if (b->buf) { |
337 | x_free(b->a, b->buf); |
338 | b->buf = 0; |
339 | } |
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340 | } |
341 | |
342 | /*----- That's all, folks -------------------------------------------------*/ |