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1 | /* -*-c-*- |
2 | * |
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3 | * Configuration parsing |
4 | * |
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5 | * (c) 1999 Straylight/Edgeware |
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6 | */ |
7 | |
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8 | /*----- Licensing notice --------------------------------------------------* |
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9 | * |
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10 | * This file is part of the `fwd' port forwarder. |
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11 | * |
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12 | * `fwd' is free software; you can redistribute it and/or modify |
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13 | * it under the terms of the GNU General Public License as published by |
14 | * the Free Software Foundation; either version 2 of the License, or |
15 | * (at your option) any later version. |
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16 | * |
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17 | * `fwd' is distributed in the hope that it will be useful, |
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18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
20 | * GNU General Public License for more details. |
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21 | * |
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22 | * You should have received a copy of the GNU General Public License |
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23 | * along with `fwd'; if not, write to the Free Software Foundation, |
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24 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
25 | */ |
26 | |
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27 | #ifndef CONF_H |
28 | #define CONF_H |
29 | |
30 | #ifdef __cplusplus |
31 | extern "C" { |
32 | #endif |
33 | |
34 | /*----- Header files ------------------------------------------------------*/ |
35 | |
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36 | #include <mLib/dstr.h> |
37 | |
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38 | #ifndef SCAN_H |
39 | # include "scan.h" |
40 | #endif |
41 | |
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42 | /*----- Magic numbers -----------------------------------------------------*/ |
43 | |
44 | #define CTOK_EOF (-1) |
45 | #define CTOK_WORD 256 |
46 | |
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47 | /*----- Functions provided ------------------------------------------------*/ |
48 | |
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49 | /* --- @conf_undelim@ --- * |
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50 | * |
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51 | * Arguments: @scanner *sc@ = pointer to scanner definition |
52 | * @const char *d, *dd@ = pointer to characters to escape |
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53 | * |
54 | * Returns: --- |
55 | * |
56 | * Use: Modifies the tokenizer. Characters in the first list will |
57 | * always be considered to begin a word. Characters in the |
58 | * second list will always be allowed to continue a word. |
59 | */ |
60 | |
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61 | extern void conf_undelim(scanner */*sc*/, |
62 | const char */*d*/, const char */*dd*/); |
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63 | |
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64 | /* --- @token@ --- * |
65 | * |
66 | * Arguments: @scanner *sc@ = pointer to scanner definition |
67 | * |
68 | * Returns: Type of token scanned. |
69 | * |
70 | * Use: Reads the next token from the character scanner. |
71 | */ |
72 | |
73 | extern int token(scanner */*sc*/); |
74 | |
75 | /* --- @error@ --- * |
76 | * |
77 | * Arguments: @scanner *sc@ = pointer to scanner definition |
78 | * @const char *msg@ = message skeleton string |
79 | * @...@ = extra arguments for the skeleton |
80 | * |
81 | * Returns: Doesn't |
82 | * |
83 | * Use: Reports an error at the current scanner location. |
84 | */ |
85 | |
86 | extern void error(scanner */*sc*/, const char */*msg*/, ...); |
87 | |
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88 | /* --- @pushback@ --- * |
89 | * |
90 | * Arguments: @scanner *sc@ = pointer to scanner definition |
91 | * |
92 | * Returns: --- |
93 | * |
94 | * Use: Pushes the current token back. This is normally a precursor |
95 | * to pushing a new scanner source. |
96 | */ |
97 | |
98 | extern void pushback(scanner */*sc*/); |
99 | |
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100 | /* --- @conf_enum@ --- * |
101 | * |
102 | * Arguments: @scanner *sc@ = pointer to a scanner object |
103 | * @const char *list@ = comma-separated things to allow |
104 | * @unsigned @f = flags for the search |
105 | * @const char *err@ = error message if not found |
106 | * |
107 | * Returns: Index into list, zero-based, or @-1@. |
108 | * |
109 | * Use: Checks whether the current token is a string which matches |
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110 | * one of the comma-separated items given. The return value is |
111 | * the index (zero-based) of the matched string in the list. |
112 | * |
113 | * The flags control the behaviour if no exact match is found. |
114 | * If @ENUM_ABBREV@ is set, and the current token is a left |
115 | * substring of exactly one of the possibilities, then that one |
116 | * is chosen. If @ENUM_NONE@ is set, the value @-1@ is |
117 | * returned; otherwise an error is reported and the program is |
118 | * terminated. |
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119 | */ |
120 | |
121 | #define ENUM_ABBREV 1u |
122 | #define ENUM_NONE 2u |
123 | |
124 | extern int conf_enum(scanner */*sc*/, const char */*list*/, |
125 | unsigned /*flags*/, const char */*err*/); |
126 | |
127 | /* --- @conf_prefix@ --- * |
128 | * |
129 | * Arguments: @scanner *sc@ = pointer to a scanner object |
130 | * @const char *p@ = pointer to prefix string to check |
131 | * |
132 | * Returns: Nonzero if the prefix matches. |
133 | * |
134 | * Use: If the current token is a word matching the given prefix |
135 | * string, then it and an optional `.' character are removed and |
136 | * a nonzero result is returned. Otherwise the current token is |
137 | * left as it is, and zero is returned. |
138 | * |
139 | * Typical options parsing code would remove an expected prefix, |
140 | * scan an option anyway (since qualifying prefixes are |
141 | * optional) and if a match is found, claim the option. If no |
142 | * match is found, and a prefix was stripped, then an error |
143 | * should be reported. |
144 | */ |
145 | |
146 | extern int conf_prefix(scanner */*sc*/, const char */*p*/); |
147 | |
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148 | /* --- @CONF_BEGIN@, @CONF_END@ --- * |
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149 | * |
150 | * Arguments: @sc@ = scanner to read from |
151 | * @prefix@ = prefix to scan for |
152 | * @desc@ = description of what we're parsing |
153 | * |
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154 | * Use: Bracket an options parsing routine. The current token is |
155 | * checked to see whether it matches the prefix. If so, it is |
156 | * removed and the following token examined. If that's a `.' |
157 | * then it's removed. If it's a `{' then the enclosed |
158 | * option-parsing code is executed in a loop until a matching |
159 | * '}' is found. If the options parser doesn't accept an |
160 | * option, the behaviour is dependent on whether a prefix was |
161 | * seen: if so, an error is reported; otherwse a zero return is |
162 | * made. |
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163 | */ |
164 | |
165 | #define CS_PLAIN 0 |
166 | #define CS_PREFIX 1 |
167 | #define CS_BRACE 2 |
168 | #define CS_UNKNOWN 3 |
169 | |
170 | #define CONF_BEGIN(sc, prefix, desc) do { \ |
171 | scanner *_conf_sc = (sc); \ |
172 | const char *_conf_desc = (desc); \ |
173 | int _conf_state = CS_PLAIN; \ |
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174 | \ |
175 | /* --- Read the initial prefix --- */ \ |
176 | \ |
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177 | if (_conf_sc->t == CTOK_WORD && \ |
178 | strcmp(_conf_sc->d.buf, (prefix)) == 0) { \ |
179 | token(_conf_sc); \ |
180 | _conf_state = CS_PREFIX; \ |
181 | if (_conf_sc->t == '.') \ |
182 | token(_conf_sc); \ |
183 | else if (_conf_sc->t == '{') { \ |
184 | token(_conf_sc); \ |
185 | _conf_state = CS_BRACE; \ |
186 | } \ |
187 | } \ |
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188 | \ |
189 | /* --- Ensure the next token is a word --- */ \ |
190 | \ |
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191 | if (_conf_sc->t != CTOK_WORD) \ |
192 | error(_conf_sc, "parse error, expected option keyword"); \ |
193 | do { |
194 | |
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195 | #define CONF_END \ |
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196 | \ |
197 | /* --- Reject an option --- * \ |
198 | * \ |
199 | * We could get here as a result of an explicit @CONF_REJECT@ or \ |
200 | * because the option wasn't accepted. \ |
201 | */ \ |
202 | \ |
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203 | goto _conf_reject; \ |
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204 | _conf_reject: \ |
205 | if (_conf_state == CS_PLAIN) \ |
206 | _conf_state = CS_UNKNOWN; \ |
207 | else { \ |
208 | error(_conf_sc, "unknown %s option `%s'", \ |
209 | _conf_desc, _conf_sc->d.buf); \ |
210 | } \ |
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211 | \ |
212 | /* --- Accept an option --- * \ |
213 | * \ |
214 | * It's safe to drop through from above. Either an error will have \ |
215 | * been reported, or the state is not @CS_BRACE@. \ |
216 | */ \ |
217 | \ |
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218 | _conf_accept: \ |
219 | if (_conf_state == CS_BRACE && _conf_sc->t == ';') \ |
220 | token(_conf_sc); \ |
221 | } while (_conf_state == CS_BRACE && _conf_sc->t == CTOK_WORD); \ |
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222 | \ |
223 | /* --- Check for a closing brace --- */ \ |
224 | \ |
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225 | if (_conf_state == CS_BRACE) { \ |
226 | if (_conf_sc->t == '}') \ |
227 | token(_conf_sc); \ |
228 | else \ |
229 | error(_conf_sc, "parse error, expected `}'"); \ |
230 | } \ |
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231 | \ |
232 | /* --- Return an appropriate value --- */ \ |
233 | \ |
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234 | return (_conf_state != CS_UNKNOWN); \ |
235 | } while (0) |
236 | |
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237 | /* --- @CONF_ACCEPT@, @CONF_REJECT@ --- * |
238 | * |
239 | * Arguments: --- |
240 | * |
241 | * Use: Within an options parser (between @CONF_BEGIN@ and |
242 | * @CONF_END@), accept or reject an option. |
243 | */ |
244 | |
245 | #define CONF_ACCEPT goto _conf_accept |
246 | #define CONF_REJECT goto _conf_reject |
247 | |
248 | /* --- @CONF_QUAL@ --- * |
249 | * |
250 | * Arguments: --- |
251 | * |
252 | * Use: Evaluates to a nonzero value if the current option is |
253 | * qualified. This can be used to decide whether abbreviations |
254 | * for options should be accepted. |
255 | */ |
256 | |
257 | #define CONF_QUAL (_conf_state != CS_PLAIN) |
258 | |
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259 | /* --- @conf_name@ --- * |
260 | * |
261 | * Arguments: @scanner *sc@ = pointer to scanner |
262 | * @char delim@ = delimiter character to look for |
263 | * @dstr *d@ = pointer to dynamic string for output |
264 | * |
265 | * Returns: --- |
266 | * |
267 | * Use: Reads in a compound name consisting of words separated by |
268 | * delimiters. Leading and trailing delimiters are permitted, |
269 | * although they'll probably cause confusion if used. The name |
270 | * may be enclosed in square brackets if that helps at all. |
271 | * |
272 | * Examples of compound names are filenames (delimited by `/') |
273 | * and IP addresses (delimited by `.'). |
274 | */ |
275 | |
276 | extern void conf_name(scanner */*sc*/, char /*delim*/, dstr */*d*/); |
277 | |
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278 | /*----- That's all, folks -------------------------------------------------*/ |
279 | |
280 | #ifdef __cplusplus |
281 | } |
282 | #endif |
283 | |
284 | #endif |