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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: lbuf.c,v 1.2 1999/05/17 20:36:08 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 1.2 1999/05/17 20:36:08 mdw |
34 | * Make the magical constants for the buffer flags uppercase. |
35 | * |
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36 | * Revision 1.1 1999/05/14 21:01:14 mdw |
37 | * Integrated `select' handling bits from the background resolver project. |
38 | * |
39 | */ |
40 | |
41 | /*----- Header files ------------------------------------------------------*/ |
42 | |
43 | #include <stdio.h> |
44 | #include <stdlib.h> |
45 | #include <string.h> |
46 | |
47 | #include "lbuf.h" |
48 | |
49 | /*----- Main code ---------------------------------------------------------*/ |
50 | |
51 | /* --- @lbuf_flush@ --- * |
52 | * |
53 | * Arguments: @lbuf *b@ = pointer to buffer block |
54 | * @char *p@ = pointer to where to start searching |
55 | * @size_t len@ = length of new material added |
56 | * |
57 | * Returns: --- |
58 | * |
59 | * Use: Flushes any complete lines in a line buffer. New material |
60 | * is assumed to have been added starting at @p@. If @p@ is |
61 | * null, then the scan starts at the beginning of the buffer, |
62 | * and the size of data already in the buffer is used in place |
63 | * of @len@. |
64 | * |
65 | * It is assumed that the buffer is initially enabled. You |
66 | * shouldn't be contributing data to a disabled buffer anyway. |
67 | * However, the buffer handler may at some point disable itself, |
68 | * and @lbuf_flush@ can cope with this eventuality. Any pending |
69 | * data is left at the start of the buffer and can be flushed |
70 | * out by calling @lbuf_flush(b, 0, 0)@ if the buffer is ever |
71 | * re-enabled. |
72 | */ |
73 | |
74 | void lbuf_flush(lbuf *b, char *p, size_t len) |
75 | { |
76 | char *l; /* Limit of data in buffer */ |
77 | char *q; /* Roving pointer through string */ |
78 | char *base; /* Base address of current line */ |
79 | int cr; /* Carriage return state */ |
80 | |
81 | /* --- Initialize variables as necessary --- */ |
82 | |
83 | if (!p) { |
84 | p = b->buf; |
85 | cr = 0; |
86 | len = b->len; |
87 | } else |
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88 | cr = b->f & LBUF_CR; |
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89 | |
90 | l = p + len; |
91 | |
92 | /* --- Clear @base@ if I'm discarding an overlong line --- */ |
93 | |
94 | if (b->len == sizeof(b->buf)) |
95 | base = 0; |
96 | else |
97 | base = b->buf; |
98 | |
99 | /* --- Now I march through the string --- */ |
100 | |
101 | for (q = p; q < l; q++) { |
102 | |
103 | /* --- Quickly discard uninteresting characters --- */ |
104 | |
105 | if (*q != '\r' && *q != '\n') { |
106 | cr = 0; |
107 | continue; |
108 | } |
109 | if (*q == '\r') { |
110 | cr = 1; |
111 | continue; |
112 | } |
113 | |
114 | /* --- Two choices here --- * |
115 | * |
116 | * I can either be strict about CRLF line ends, or I can be shoddy |
117 | * and allow bare LFs. I'll do the latter, although I oughtn't, |
118 | * because it makes testing interactively and with Unix text files |
119 | * easier. |
120 | */ |
121 | |
122 | #ifdef STRICT_CRLF |
123 | if (!cr) |
124 | continue; |
125 | #endif |
126 | |
127 | /* --- I have a positive ID on a linefeed --- * |
128 | * |
129 | * If I'm interested in this string, report it to my owner. |
130 | */ |
131 | |
132 | if (base) { |
133 | if (cr) |
134 | q[-1] = 0; /* Exercise: why is this safe? */ |
135 | else |
136 | *q = 0; |
137 | b->func(base, b->p); |
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138 | if (!(b->f & LBUF_ENABLE)) { |
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139 | base = q + 1; |
140 | break; |
141 | } |
142 | } |
143 | base = q + 1; |
144 | cr = 0; |
145 | } |
146 | |
147 | /* --- Sift through the aftermath --- */ |
148 | |
149 | if (base) { |
150 | size_t len = l - base; |
151 | if (len == sizeof(b->buf)) { |
152 | b->buf[len - 1] = 0; |
153 | b->func(base, b->p); |
154 | } else if (base != b->buf) |
155 | memmove(b->buf, base, len); |
156 | b->len = len; |
157 | if (cr) |
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158 | b->f |= LBUF_CR; |
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159 | else |
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160 | b->f &= ~LBUF_CR; |
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161 | } |
162 | } |
163 | |
164 | /* --- @lbuf_close@ --- * |
165 | * |
166 | * Arguments: @lbuf *b@ = pointer to buffer block |
167 | * |
168 | * Returns: --- |
169 | * |
170 | * Use: Empties the buffer of any data currently lurking in it, and |
171 | * informs the client that this has happened. It's assumed that |
172 | * the buffer is enabled: you shouldn't be reading close events |
173 | * on disabled buffers. |
174 | */ |
175 | |
176 | void lbuf_close(lbuf *b) |
177 | { |
178 | if (b->len && b->len != sizeof(b->buf)) { |
179 | b->buf[b->len] = 0; |
180 | b->func(b->buf, b->p); |
181 | } |
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182 | if (b->f & LBUF_ENABLE) |
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183 | b->func(0, b->p); |
184 | } |
185 | |
186 | /* --- @lbuf_free@ --- * |
187 | * |
188 | * Arguments: @lbuf *b@ = pointer to buffer block |
189 | * @char **p@ = output pointer to free space |
190 | * |
191 | * Returns: Free buffer size. |
192 | * |
193 | * Use: Returns the free portion of a line buffer. Data can then be |
194 | * written to this portion, and split out into lines by calling |
195 | * @lbuf_flush@. |
196 | */ |
197 | |
198 | size_t lbuf_free(lbuf *b, char **p) |
199 | { |
200 | /* --- There's a special case to consider --- * |
201 | * |
202 | * If a line from the file wouldn't fit in the buffer, I truncate it and |
203 | * return what would fit. The rest of the line ought to be discarded. |
204 | * This condition is signalled by @len = sizeof(buf)@, and means that the |
205 | * entire buffer is OK to be trashed. In other cases, @len@ is the amount |
206 | * of space currently occupied in the buffer. This special case is the |
207 | * reason this routine exists. |
208 | */ |
209 | |
210 | if (b->len == 0 || b->len == sizeof(b->buf)) { |
211 | *p = b->buf + b->len; |
212 | return (sizeof(b->buf) - b->len); |
213 | } else { |
214 | *p = b->buf; |
215 | return (sizeof(b->buf)); |
216 | } |
217 | } |
218 | |
219 | /* --- @lbuf_snarf@ --- * |
220 | * |
221 | * Arguments: @lbuf *b@ = pointer to buffer block |
222 | * @const void *p@ = pointer to input data buffer |
223 | * @size_t sz@ = size of data in input buffer |
224 | * |
225 | * Returns: --- |
226 | * |
227 | * Use: Snarfs the data from the input buffer and spits it out as |
228 | * lines. This interface ignores the complexities of dealing |
229 | * with disablement: you should be using @lbuf_free@ to |
230 | * contribute data if you want to cope with that. |
231 | */ |
232 | |
233 | void lbuf_snarf(lbuf *b, const void *p, size_t sz) |
234 | { |
235 | const char *pp = p; |
236 | while (sz) { |
237 | size_t bsz; |
238 | char *bp; |
239 | |
240 | bsz = lbuf_free(b, &bp); |
241 | if (bsz > sz) |
242 | bsz = sz; |
243 | memcpy(bp, pp, bsz); |
244 | lbuf_flush(b, bp, bsz); |
245 | pp += bsz; |
246 | sz -= bsz; |
247 | } |
248 | } |
249 | |
250 | /* --- @lbuf_init@ --- * |
251 | * |
252 | * Arguments: @lbuf *b@ = pointer to buffer block |
253 | * @void (*func)(char *s, void *p)@ = handler function |
254 | * @void *p@ = argument pointer for @func@ |
255 | * |
256 | * Returns: --- |
257 | * |
258 | * Use: Initializes a line buffer block. Any recognized lines are |
259 | * passed to @func@ for processing. |
260 | */ |
261 | |
262 | void lbuf_init(lbuf *b, |
263 | void (*func)(char */*s*/, void */*p*/), |
264 | void *p) |
265 | { |
266 | b->func = func; |
267 | b->p = p; |
268 | b->len = 0; |
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269 | b->f = LBUF_ENABLE; |
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270 | } |
271 | |
272 | /*----- That's all, folks -------------------------------------------------*/ |