97f65b00 |
1 | /* -*-c-*- |
2 | * |
83c63e03 |
3 | * $Id: lbuf.h,v 1.7 2002/01/13 13:32:52 mdw Exp $ |
97f65b00 |
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.h,v $ |
83c63e03 |
33 | * Revision 1.7 2002/01/13 13:32:52 mdw |
34 | * Pass line length to line handler function. Provide a @typedef@ for |
35 | * handler functions. Allow run-time configuration of line delimiters. |
36 | * |
3fd896a4 |
37 | * Revision 1.6 2001/02/03 16:23:33 mdw |
38 | * Bug fix: handle a disable during a close-induced flush without dumping |
39 | * core. |
40 | * |
393cf1d9 |
41 | * Revision 1.5 2001/01/20 12:06:01 mdw |
42 | * Define flags with macros, to ensure unsignedness. |
43 | * |
e03be5f4 |
44 | * Revision 1.4 2000/06/17 10:38:14 mdw |
45 | * Add support for variable buffer sizes. |
46 | * |
c6e0eaf0 |
47 | * Revision 1.3 1999/12/10 23:42:04 mdw |
48 | * Change header file guard names. |
49 | * |
1ef7279c |
50 | * Revision 1.2 1999/05/17 20:36:08 mdw |
51 | * Make the magical constants for the buffer flags uppercase. |
52 | * |
97f65b00 |
53 | * Revision 1.1 1999/05/14 21:01:14 mdw |
54 | * Integrated `select' handling bits from the background resolver project. |
55 | * |
56 | */ |
57 | |
c6e0eaf0 |
58 | #ifndef MLIB_LBUF_H |
59 | #define MLIB_LBUF_H |
97f65b00 |
60 | |
61 | #ifdef __cplusplus |
62 | extern "C" { |
63 | #endif |
64 | |
65 | /*----- Line buffering ----------------------------------------------------* |
66 | * |
67 | * The line buffer accepts as input arbitrary-sized lumps of data and |
68 | * converts them, by passing them to a client-supplied function, into a |
69 | * sequence of lines. It's particularly useful when performing multiplexed |
70 | * network I/O. It's not normally acceptable to block while waiting for the |
71 | * rest of a text line to arrive, for example. The line buffer stores the |
72 | * start of the line until the rest of it arrives later. |
73 | * |
74 | * A line is a piece of text terminated by either a linefeed or a carriage- |
75 | * return/linefeed pair. (The former is there to cope with Unix; the latter |
76 | * copes with Internet-format line ends.) |
77 | * |
78 | * There's a limit to the size of lines that the buffer can cope with. It's |
79 | * not hard to remove this limit, but it's probably a bad idea in a lot of |
80 | * cases, because it'd allow a remote user to gobble arbitrary amounts of |
81 | * your memory. If a line exceeds the limit, it is truncated: the initial |
82 | * portion of the line is processed normally, and the remaining portion is |
83 | * simply discarded. |
84 | * |
85 | * Lines extracted from the input data are passed, one at a time, to a |
86 | * `handler function', along with a caller-supplied pointer argument to |
87 | * provide the handler with some context. The line read is null-terminated |
88 | * and does not include the trailing newline characters. It is legal for a |
89 | * handler function to modify the string it is passed. However, writing |
90 | * beyond the terminating null byte is not allowed. An end-of-file condition |
91 | * is signalled to the handler by passing it a null pointer rather than the |
92 | * address of a string. |
93 | * |
94 | * A complexity arises because of the concept of a `disabled' buffer. |
95 | * Disablement is really a higher-level concept, but it turns out to be |
96 | * important to implement it here. It's useful for a line handler function |
97 | * to `disable' itself, so that it doesn't get called any more. For example, |
98 | * this might happen if it encouters an error, or when it finishes reading |
99 | * everything it wanted to read. The line buffer needs to be `in the loop' |
100 | * so that it stops attempting to flush any further lines stored in its |
101 | * buffer towards a handler function which isn't ready to accept them. |
102 | * Buffers are initially enabled, although higher- level buffering systems |
103 | * might well disable them immediately for their own purposes. |
104 | */ |
105 | |
106 | /*----- Header files ------------------------------------------------------*/ |
107 | |
108 | #include <stddef.h> |
109 | |
e03be5f4 |
110 | #ifndef MLIB_ARENA_H |
111 | # include "arena.h" |
112 | #endif |
113 | |
97f65b00 |
114 | /*----- Data structures ---------------------------------------------------*/ |
115 | |
116 | /* --- The buffer structure --- * |
117 | * |
118 | * The only thing that's safe to fiddle with in here is the @lbuf_enable@ |
119 | * flag. Only higher-level buffering systems should be playing with even |
120 | * that. |
121 | */ |
122 | |
83c63e03 |
123 | struct lbuf; |
124 | |
125 | typedef void lbuf_func(char */*s*/, size_t /*len*/, void */*p*/); |
126 | |
97f65b00 |
127 | typedef struct lbuf { |
83c63e03 |
128 | lbuf_func *func; /* Handler function */ |
97f65b00 |
129 | void *p; /* Argument for handler */ |
130 | size_t len; /* Length of data in buffer */ |
e03be5f4 |
131 | size_t sz; /* Buffer size */ |
83c63e03 |
132 | unsigned delim; /* Delimiter to look for */ |
97f65b00 |
133 | unsigned f; /* Various useful state flags */ |
e03be5f4 |
134 | arena *a; /* Memory allocation arena */ |
135 | char *buf; /* The actual buffer */ |
97f65b00 |
136 | } lbuf; |
137 | |
393cf1d9 |
138 | #define LBUF_CR 1u /* Read a carriage return */ |
139 | #define LBUF_ENABLE 2u /* Buffer is currently enabled */ |
3fd896a4 |
140 | #define LBUF_CLOSE 4u /* Buffer is now closed */ |
97f65b00 |
141 | |
83c63e03 |
142 | enum { |
143 | LBUF_CRLF = 256, |
144 | LBUF_STRICTCRLF = 257 |
145 | }; |
146 | |
97f65b00 |
147 | /*----- Functions provided ------------------------------------------------*/ |
148 | |
149 | /* --- @lbuf_flush@ --- * |
150 | * |
151 | * Arguments: @lbuf *b@ = pointer to buffer block |
152 | * @char *p@ = pointer to where to start searching |
153 | * @size_t len@ = length of new material added |
154 | * |
155 | * Returns: --- |
156 | * |
157 | * Use: Flushes any complete lines in a line buffer. New material |
158 | * is assumed to have been added starting at @p@. If @p@ is |
159 | * null, then the scan starts at the beginning of the buffer, |
160 | * and the size of data already in the buffer is used in place |
161 | * of @len@. |
162 | * |
163 | * It is assumed that the buffer is initially enabled. You |
164 | * shouldn't be contributing data to a disabled buffer anyway. |
165 | * However, the buffer handler may at some point disable itself, |
166 | * and @lbuf_flush@ can cope with this eventuality. Any pending |
167 | * data is left at the start of the buffer and can be flushed |
168 | * out by calling @lbuf_flush(b, 0, 0)@ if the buffer is ever |
169 | * re-enabled. |
170 | */ |
171 | |
172 | extern void lbuf_flush(lbuf */*b*/, char */*p*/, size_t /*len*/); |
173 | |
174 | /* --- @lbuf_close@ --- * |
175 | * |
176 | * Arguments: @lbuf *b@ = pointer to buffer block |
177 | * |
178 | * Returns: --- |
179 | * |
180 | * Use: Empties the buffer of any data currently lurking in it, and |
181 | * informs the client that this has happened. It's assumed that |
182 | * the buffer is enabled: you shouldn't be reading close events |
183 | * on disabled buffers. |
184 | */ |
185 | |
186 | extern void lbuf_close(lbuf */*b*/); |
187 | |
188 | /* --- @lbuf_free@ --- * |
189 | * |
190 | * Arguments: @lbuf *b@ = pointer to buffer block |
191 | * @char **p@ = output pointer to free space |
192 | * |
193 | * Returns: Free buffer size. |
194 | * |
195 | * Use: Returns the free portion of a line buffer. Data can then be |
196 | * written to this portion, and split out into lines by calling |
197 | * @lbuf_flush@. |
198 | */ |
199 | |
200 | extern size_t lbuf_free(lbuf */*b*/, char **/*p*/); |
201 | |
202 | /* --- @lbuf_snarf@ --- * |
203 | * |
204 | * Arguments: @lbuf *b@ = pointer to buffer block |
205 | * @const void *p@ = pointer to input data buffer |
206 | * @size_t sz@ = size of data in input buffer |
207 | * |
208 | * Returns: --- |
209 | * |
210 | * Use: Snarfs the data from the input buffer and spits it out as |
211 | * lines. This interface ignores the complexities of dealing |
212 | * with disablement: you should be using @lbuf_free@ to |
213 | * contribute data if you want to cope with that. |
214 | */ |
215 | |
216 | extern void lbuf_snarf(lbuf */*b*/, const void */*p*/, size_t /*sz*/); |
217 | |
e03be5f4 |
218 | /* --- @lbuf_setsize@ --- * |
219 | * |
220 | * Arguments: @lbuf *b@ = pointer to buffer block |
221 | * @size_t sz@ = requested maximum line size |
222 | * |
223 | * Returns: --- |
224 | * |
225 | * Use: Allocates a buffer of the requested size reading lines. |
226 | */ |
227 | |
228 | extern void lbuf_setsize(lbuf */*b*/, size_t /*sz*/); |
229 | |
97f65b00 |
230 | /* --- @lbuf_init@ --- * |
231 | * |
232 | * Arguments: @lbuf *b@ = pointer to buffer block |
83c63e03 |
233 | * @lbuf_func *func@ = handler function |
97f65b00 |
234 | * @void *p@ = argument pointer for @func@ |
235 | * |
236 | * Returns: --- |
237 | * |
238 | * Use: Initializes a line buffer block. Any recognized lines are |
239 | * passed to @func@ for processing. |
240 | */ |
241 | |
83c63e03 |
242 | extern void lbuf_init(lbuf */*b*/, lbuf_func */*func*/, void */*p*/); |
97f65b00 |
243 | |
e03be5f4 |
244 | /* --- @lbuf_destroy@ --- * |
245 | * |
246 | * Arguments: @lbuf *b@ = pointer to buffer block |
247 | * |
248 | * Returns: --- |
249 | * |
250 | * Use: Deallocates a line buffer and frees any resources it owned. |
251 | */ |
252 | |
253 | extern void lbuf_destroy(lbuf */*b*/); |
254 | |
97f65b00 |
255 | /*----- That's all, folks -------------------------------------------------*/ |
256 | |
257 | #ifdef __cplusplus |
258 | } |
259 | #endif |
260 | |
261 | #endif |