97f65b00 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: lbuf.c,v 1.1 1999/05/14 21:01:14 mdw Exp $ |
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 $ |
33 | * Revision 1.1 1999/05/14 21:01:14 mdw |
34 | * Integrated `select' handling bits from the background resolver project. |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include <stdio.h> |
41 | #include <stdlib.h> |
42 | #include <string.h> |
43 | |
44 | #include "lbuf.h" |
45 | |
46 | /*----- Main code ---------------------------------------------------------*/ |
47 | |
48 | /* --- @lbuf_flush@ --- * |
49 | * |
50 | * Arguments: @lbuf *b@ = pointer to buffer block |
51 | * @char *p@ = pointer to where to start searching |
52 | * @size_t len@ = length of new material added |
53 | * |
54 | * Returns: --- |
55 | * |
56 | * Use: Flushes any complete lines in a line buffer. New material |
57 | * is assumed to have been added starting at @p@. If @p@ is |
58 | * null, then the scan starts at the beginning of the buffer, |
59 | * and the size of data already in the buffer is used in place |
60 | * of @len@. |
61 | * |
62 | * It is assumed that the buffer is initially enabled. You |
63 | * shouldn't be contributing data to a disabled buffer anyway. |
64 | * However, the buffer handler may at some point disable itself, |
65 | * and @lbuf_flush@ can cope with this eventuality. Any pending |
66 | * data is left at the start of the buffer and can be flushed |
67 | * out by calling @lbuf_flush(b, 0, 0)@ if the buffer is ever |
68 | * re-enabled. |
69 | */ |
70 | |
71 | void lbuf_flush(lbuf *b, char *p, size_t len) |
72 | { |
73 | char *l; /* Limit of data in buffer */ |
74 | char *q; /* Roving pointer through string */ |
75 | char *base; /* Base address of current line */ |
76 | int cr; /* Carriage return state */ |
77 | |
78 | /* --- Initialize variables as necessary --- */ |
79 | |
80 | if (!p) { |
81 | p = b->buf; |
82 | cr = 0; |
83 | len = b->len; |
84 | } else |
85 | cr = b->f & lbuf_cr; |
86 | |
87 | l = p + len; |
88 | |
89 | /* --- Clear @base@ if I'm discarding an overlong line --- */ |
90 | |
91 | if (b->len == sizeof(b->buf)) |
92 | base = 0; |
93 | else |
94 | base = b->buf; |
95 | |
96 | /* --- Now I march through the string --- */ |
97 | |
98 | for (q = p; q < l; q++) { |
99 | |
100 | /* --- Quickly discard uninteresting characters --- */ |
101 | |
102 | if (*q != '\r' && *q != '\n') { |
103 | cr = 0; |
104 | continue; |
105 | } |
106 | if (*q == '\r') { |
107 | cr = 1; |
108 | continue; |
109 | } |
110 | |
111 | /* --- Two choices here --- * |
112 | * |
113 | * I can either be strict about CRLF line ends, or I can be shoddy |
114 | * and allow bare LFs. I'll do the latter, although I oughtn't, |
115 | * because it makes testing interactively and with Unix text files |
116 | * easier. |
117 | */ |
118 | |
119 | #ifdef STRICT_CRLF |
120 | if (!cr) |
121 | continue; |
122 | #endif |
123 | |
124 | /* --- I have a positive ID on a linefeed --- * |
125 | * |
126 | * If I'm interested in this string, report it to my owner. |
127 | */ |
128 | |
129 | if (base) { |
130 | if (cr) |
131 | q[-1] = 0; /* Exercise: why is this safe? */ |
132 | else |
133 | *q = 0; |
134 | b->func(base, b->p); |
135 | if (!(b->f & lbuf_enable)) { |
136 | base = q + 1; |
137 | break; |
138 | } |
139 | } |
140 | base = q + 1; |
141 | cr = 0; |
142 | } |
143 | |
144 | /* --- Sift through the aftermath --- */ |
145 | |
146 | if (base) { |
147 | size_t len = l - base; |
148 | if (len == sizeof(b->buf)) { |
149 | b->buf[len - 1] = 0; |
150 | b->func(base, b->p); |
151 | } else if (base != b->buf) |
152 | memmove(b->buf, base, len); |
153 | b->len = len; |
154 | if (cr) |
155 | b->f |= lbuf_cr; |
156 | else |
157 | b->f &= ~lbuf_cr; |
158 | } |
159 | } |
160 | |
161 | /* --- @lbuf_close@ --- * |
162 | * |
163 | * Arguments: @lbuf *b@ = pointer to buffer block |
164 | * |
165 | * Returns: --- |
166 | * |
167 | * Use: Empties the buffer of any data currently lurking in it, and |
168 | * informs the client that this has happened. It's assumed that |
169 | * the buffer is enabled: you shouldn't be reading close events |
170 | * on disabled buffers. |
171 | */ |
172 | |
173 | void lbuf_close(lbuf *b) |
174 | { |
175 | if (b->len && b->len != sizeof(b->buf)) { |
176 | b->buf[b->len] = 0; |
177 | b->func(b->buf, b->p); |
178 | } |
179 | if (b->f & lbuf_enable) |
180 | b->func(0, b->p); |
181 | } |
182 | |
183 | /* --- @lbuf_free@ --- * |
184 | * |
185 | * Arguments: @lbuf *b@ = pointer to buffer block |
186 | * @char **p@ = output pointer to free space |
187 | * |
188 | * Returns: Free buffer size. |
189 | * |
190 | * Use: Returns the free portion of a line buffer. Data can then be |
191 | * written to this portion, and split out into lines by calling |
192 | * @lbuf_flush@. |
193 | */ |
194 | |
195 | size_t lbuf_free(lbuf *b, char **p) |
196 | { |
197 | /* --- There's a special case to consider --- * |
198 | * |
199 | * If a line from the file wouldn't fit in the buffer, I truncate it and |
200 | * return what would fit. The rest of the line ought to be discarded. |
201 | * This condition is signalled by @len = sizeof(buf)@, and means that the |
202 | * entire buffer is OK to be trashed. In other cases, @len@ is the amount |
203 | * of space currently occupied in the buffer. This special case is the |
204 | * reason this routine exists. |
205 | */ |
206 | |
207 | if (b->len == 0 || b->len == sizeof(b->buf)) { |
208 | *p = b->buf + b->len; |
209 | return (sizeof(b->buf) - b->len); |
210 | } else { |
211 | *p = b->buf; |
212 | return (sizeof(b->buf)); |
213 | } |
214 | } |
215 | |
216 | /* --- @lbuf_snarf@ --- * |
217 | * |
218 | * Arguments: @lbuf *b@ = pointer to buffer block |
219 | * @const void *p@ = pointer to input data buffer |
220 | * @size_t sz@ = size of data in input buffer |
221 | * |
222 | * Returns: --- |
223 | * |
224 | * Use: Snarfs the data from the input buffer and spits it out as |
225 | * lines. This interface ignores the complexities of dealing |
226 | * with disablement: you should be using @lbuf_free@ to |
227 | * contribute data if you want to cope with that. |
228 | */ |
229 | |
230 | void lbuf_snarf(lbuf *b, const void *p, size_t sz) |
231 | { |
232 | const char *pp = p; |
233 | while (sz) { |
234 | size_t bsz; |
235 | char *bp; |
236 | |
237 | bsz = lbuf_free(b, &bp); |
238 | if (bsz > sz) |
239 | bsz = sz; |
240 | memcpy(bp, pp, bsz); |
241 | lbuf_flush(b, bp, bsz); |
242 | pp += bsz; |
243 | sz -= bsz; |
244 | } |
245 | } |
246 | |
247 | /* --- @lbuf_init@ --- * |
248 | * |
249 | * Arguments: @lbuf *b@ = pointer to buffer block |
250 | * @void (*func)(char *s, void *p)@ = handler function |
251 | * @void *p@ = argument pointer for @func@ |
252 | * |
253 | * Returns: --- |
254 | * |
255 | * Use: Initializes a line buffer block. Any recognized lines are |
256 | * passed to @func@ for processing. |
257 | */ |
258 | |
259 | void lbuf_init(lbuf *b, |
260 | void (*func)(char */*s*/, void */*p*/), |
261 | void *p) |
262 | { |
263 | b->func = func; |
264 | b->p = p; |
265 | b->len = 0; |
266 | b->f = lbuf_enable; |
267 | } |
268 | |
269 | /*----- That's all, folks -------------------------------------------------*/ |