chiark / gitweb /
Main template expander and some built-in expansions. All untested.
[disorder] / lib / macros-builtin.c
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RK
1/*
2 * This file is part of DisOrder
3 * Copyright (C) 2008 Richard Kettlewell
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
18 * USA
19 */
20
21/** @file lib/macros-builtin.c
22 * @brief Built-in expansions
23 *
24 * This is a grab-bag of non-domain-specific expansions. Note that
25 * documentation will be generated from the comments at the head of
26 * each function.
27 */
28
29#include <config.h>
30#include "types.h"
31
32#include <stdio.h>
33#include <string.h>
34#include <errno.h>
35#include <assert.h>
36#include <unistd.h>
37
38#include "macros.h"
39#include "sink.h"
40#include "syscalls.h"
41#include "log.h"
42#include "wstat.h"
43#include "kvp.h"
44
45/** @brief Return 1 if @p s is 'true' else 0 */
46int mx_str2bool(const char *s) {
47 return !strcmp(s, "true");
48}
49
50/** @brief Return "true" if @p n is nonzero else "false" */
51const char *mx_bool2str(int n) {
52 return n ? "true" : "false";
53}
54
55/* @include{TEMPLATE}@
56 *
57 * Includes TEMPLATE as if its text were substituted for the @include
58 * expansion. TODO
59 */
60static int exp_include(int attribute((unused)) nargs,
61 char attribute((unused)) **args,
62 struct sink attribute((unused)) *output,
63 void attribute((unused)) *u) {
64 assert(!"TODO implement search path");
65}
66
67/* @include{COMMAND}
68 *
69 * Executes COMMAND via the shell (using "sh -c") and copies its
70 * standard output to the template output. The shell command output
71 * is not expanded or modified in any other way.
72 *
73 * The shell command's standard error is copied to the error log.
74 *
75 * If the shell exits nonzero then this is reported to the error log
76 * but otherwise no special action is taken.
77 */
78static int exp_shell(int attribute((unused)) nargs,
79 char **args,
80 struct sink *output,
81 void attribute((unused)) *u) {
82 int w, p[2], n;
83 char buffer[4096];
84 pid_t pid;
85
86 xpipe(p);
87 if(!(pid = xfork())) {
88 exitfn = _exit;
89 xclose(p[0]);
90 xdup2(p[1], 1);
91 xclose(p[1]);
92 execlp("sh", "sh", "-c", args[0], (char *)0);
93 fatal(errno, "error executing sh");
94 }
95 xclose(p[1]);
96 while((n = read(p[0], buffer, sizeof buffer))) {
97 if(n < 0) {
98 if(errno == EINTR)
99 continue;
100 else
101 fatal(errno, "error reading from pipe");
102 }
103 if(output->write(output, buffer, n) < 0)
104 return -1;
105 }
106 xclose(p[0]);
107 while((n = waitpid(pid, &w, 0)) < 0 && errno == EINTR)
108 ;
109 if(n < 0)
110 fatal(errno, "error calling waitpid");
111 if(w)
112 error(0, "shell command '%s' %s", args[0], wstat(w));
113 return 0;
114}
115
116/* @if{CONDITION}{IF-TRUE}{IF-FALSE}
117 *
118 * If CONDITION is "true" then evaluates to IF-TRUE. Otherwise
119 * evaluates to IF-FALSE. The IF-FALSE part is optional.
120 */
121static int exp_if(int nargs,
122 const struct mx_node **args,
123 struct sink *output,
124 void *u) {
125 char *s;
126 int rc;
127
128 if((rc = mx_expandstr(args[0], &s, u)))
129 return rc;
130 if(mx_str2bool(s))
131 return mx_expand(args[1], output, u);
132 else if(nargs > 2)
133 return mx_expand(args[2], output, u);
134 else
135 return 0;
136}
137
138/* @and{BRANCH}{BRANCH}...
139 *
140 * Expands to "true" if all the branches are "true" otherwise to "false". If
141 * there are no brances then the result is "true". Only as many branches as
142 * necessary to compute the answer are evaluated (starting from the first one),
143 * so if later branches have side effects they may not take place.
144 */
145static int exp_and(int nargs,
146 const struct mx_node **args,
147 struct sink *output,
148 void *u) {
149 int n, result = 1, rc;
150 char *s;
151
152 for(n = 0; n < nargs; ++n) {
153 if((rc = mx_expandstr(args[n], &s, u)))
154 return rc;
155 if(!mx_str2bool(s)) {
156 result = 0;
157 break;
158 }
159 }
160 if(sink_writes(output, mx_bool2str(result)) < 0)
161 return -1;
162 else
163 return 0;
164}
165
166/* @or{BRANCH}{BRANCH}...
167 *
168 * Expands to "true" if any of the branches are "true" otherwise to "false".
169 * If there are no brances then the result is "false". Only as many branches
170 * as necessary to compute the answer are evaluated (starting from the first
171 * one), so if later branches have side effects they may not take place.
172 */
173static int exp_or(int nargs,
174 const struct mx_node **args,
175 struct sink *output,
176 void *u) {
177 int n, result = 0, rc;
178 char *s;
179
180 for(n = 0; n < nargs; ++n) {
181 if((rc = mx_expandstr(args[n], &s, u)))
182 return rc;
183 if(mx_str2bool(s)) {
184 result = 1;
185 break;
186 }
187 }
188 if(sink_writes(output, mx_bool2str(result)) < 0)
189 return -1;
190 else
191 return 0;
192}
193
194/* @not{CONDITION}
195 *
196 * Expands to "true" unless CONDITION is "true" in which case "false".
197 */
198static int exp_not(int attribute((unused)) nargs,
199 char **args,
200 struct sink *output,
201 void attribute((unused)) *u) {
202 if(sink_writes(output, mx_bool2str(!mx_str2bool(args[0]))) < 0)
203 return -1;
204 else
205 return 0;
206}
207
208/* @#{...}
209 *
210 * Expands to nothing. The argument(s) are not fully evaluated, and no side
211 * effects occur.
212 */
213static int exp_comment(int attribute((unused)) nargs,
214 const struct mx_node attribute((unused)) **args,
215 struct sink attribute((unused)) *output,
216 void attribute((unused)) *u) {
217 return 0;
218}
219
220/* @urlquote{STRING}
221 *
222 * URL-quotes a string, i.e. replaces any characters not safe to use unquoted
223 * in a URL with %-encoded form.
224 */
225static int exp_urlquote(int attribute((unused)) nargs,
226 char **args,
227 struct sink *output,
228 void attribute((unused)) *u) {
229 if(sink_writes(output, urlencodestring(args[0])) < 0)
230 return -1;
231 else
232 return 0;
233}
234
235void mx_register_builtin(void) {
236 mx_register("include", 1, 1, exp_include);
237 mx_register("shell", 1, 1, exp_shell);
238 mx_magic_register("if", 2, 3, exp_if);
239 mx_magic_register("and", 0, INT_MAX, exp_and);
240 mx_magic_register("or", 0, INT_MAX, exp_or);
241 mx_register("not", 1, 1, exp_not);
242 mx_magic_register("#", 0, INT_MAX, exp_comment);
243 mx_register("urlquote", 1, 1, exp_urlquote);
244 /* TODO: eq */
245 /* TODO: ne */
246 /* TODO: define */
247 /* TODO: discard */
248}
249
250/*
251Local Variables:
252c-basic-offset:2
253comment-column:40
254fill-column:79
255indent-tabs-mode:nil
256End:
257*/