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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: env.c,v 1.4 2001/01/25 21:14:26 mdw Exp $ |
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4 | * |
5 | * Fiddling with environment variables |
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: env.c,v $ |
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33 | * Revision 1.4 2001/01/25 21:14:26 mdw |
34 | * Nowadays, @SYM_LEN@ doesn't include the terminating null, so revise the |
35 | * buffer-usage calculation. |
36 | * |
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37 | * Revision 1.3 2001/01/20 11:48:10 mdw |
38 | * Use new @SYM_LEN@ macro for name lengths. |
39 | * |
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40 | * Revision 1.2 2000/06/17 10:39:00 mdw |
41 | * Add support for arena management. |
42 | * |
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43 | * Revision 1.1 1999/07/26 23:15:57 mdw |
44 | * Fiddling with environment variables. |
45 | * |
46 | */ |
47 | |
48 | /*----- Header files ------------------------------------------------------*/ |
49 | |
50 | #include <stdio.h> |
51 | #include <stdlib.h> |
52 | #include <string.h> |
53 | |
54 | #include "alloc.h" |
55 | #include "sym.h" |
56 | |
57 | /*----- Data structures ---------------------------------------------------*/ |
58 | |
59 | typedef struct var { |
60 | sym_base _base; |
61 | char *v; |
62 | } var; |
63 | |
64 | /*----- Main code ---------------------------------------------------------*/ |
65 | |
66 | /* --- @env_get@ --- * |
67 | * |
68 | * Arguments: @sym_table *t@ = pointer to a symbol table |
69 | * @const char *name@ = pointer to variable name to look up |
70 | * |
71 | * Returns: Pointer to corresponding value string, or null. |
72 | * |
73 | * Use: Looks up an environment variable in the table and returns its |
74 | * value. If the variable can't be found, a null pointer is |
75 | * returned. |
76 | */ |
77 | |
78 | char *env_get(sym_table *t, const char *name) |
79 | { |
80 | var *e = sym_find(t, name, -1, 0, 0); |
81 | return (e ? e->v : 0); |
82 | } |
83 | |
84 | /* --- @env_put@ --- * |
85 | * |
86 | * Arguments: @sym_table *t@ = pointer to a symbol table |
87 | * @const char *name@ = pointer to variable name to set |
88 | * @const char *value@ = pointer to value string to assign |
89 | * |
90 | * Returns: --- |
91 | * |
92 | * Use: Assigns a value to a variable. If the @name@ contains an |
93 | * equals character, then it's assumed to be of the form |
94 | * `VAR=VALUE' and @value@ argument is ignored. Otherwise, if |
95 | * @value@ is null, the variable is deleted. Finally, the |
96 | * normal case: @name@ is a plain name, and @value@ is a normal |
97 | * string causes the variable to be assigned the value in the |
98 | * way you'd expect. |
99 | */ |
100 | |
101 | void env_put(sym_table *t, const char *name, const char *value) |
102 | { |
103 | char *q = 0; |
104 | |
105 | /* --- Sort out the mess with `NAME=VALUE' forms --- */ |
106 | |
107 | { |
108 | size_t eq = strcspn(name, "="); |
109 | if (name[eq] == '=') { |
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110 | q = x_alloc(t->t.a, eq + 1); |
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111 | memcpy(q, name, eq); |
112 | q[eq] = 0; |
113 | value = name + eq + 1; |
114 | name = q; |
115 | } |
116 | } |
117 | |
118 | /* --- Read the current value --- */ |
119 | |
120 | if (!value) { |
121 | var *v; |
122 | if ((v = sym_find(t, name, -1, 0, 0)) != 0) { |
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123 | x_free(t->t.a, v->v); |
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124 | sym_remove(t, v); |
125 | } |
126 | } else { |
127 | unsigned found; |
128 | var *v = sym_find(t, name, -1, sizeof(*v), &found); |
129 | if (found) |
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130 | x_free(t->t.a, v->v); |
131 | v->v = x_strdup(t->t.a, value); |
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132 | } |
133 | |
134 | /* --- Tidying --- */ |
135 | |
136 | if (q) |
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137 | xfree(q); |
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138 | } |
139 | |
140 | /* --- @env_import@ --- * |
141 | * |
142 | * Arguments: @sym_table *t@ = pointer to a symbol table |
143 | * @char **env@ = pointer to an environment list |
144 | * |
145 | * Returns: --- |
146 | * |
147 | * Use: Inserts all of the environment variables listed into a symbol |
148 | * table for rapid access. Equivalent to a lot of calls to |
149 | * @env_put@. |
150 | */ |
151 | |
152 | void env_import(sym_table *t, char **env) |
153 | { |
154 | while (*env) { |
155 | env_put(t, *env, 0); |
156 | env++; |
157 | } |
158 | } |
159 | |
160 | /* --- @env_export@ --- * |
161 | * |
162 | * Arguments: @sym_table *t@ = pointer to a symbol table |
163 | * |
164 | * Returns: A big environment list. |
165 | * |
166 | * Use: Extracts an environment table from a symbol table |
167 | * representation of an environment. The table and all of the |
168 | * strings are in one big block allocated from the heap. |
169 | */ |
170 | |
171 | char **env_export(sym_table *t) |
172 | { |
173 | size_t n = 1; |
174 | size_t sz = 0; |
175 | sym_iter i; |
176 | var *v; |
177 | char **env; |
178 | char *p, **pp; |
179 | |
180 | /* --- Work out sizes for everything --- */ |
181 | |
182 | for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; ) { |
183 | n++; |
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184 | sz += SYM_LEN(v) + strlen(v->v) + 2; |
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185 | } |
186 | |
187 | /* --- Allocate the big chunk of memory --- */ |
188 | |
189 | env = pp = xmalloc(n * sizeof(char *) + sz); |
190 | p = (char *)(env + n); |
191 | |
192 | /* --- Dump the output in the big chunk of memory --- */ |
193 | |
194 | for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; ) { |
195 | const char *name = SYM_NAME(v); |
196 | size_t nlen = strlen(name), vlen = strlen(v->v); |
197 | *pp++ = p; |
198 | memcpy(p, name, nlen); p += nlen; |
199 | *p++ = '='; |
200 | memcpy(p, v->v, vlen); p += vlen; |
201 | *p++ = 0; |
202 | } |
203 | *pp++ = 0; |
204 | return (env); |
205 | } |
206 | |
207 | /* --- @env_destroy@ --- * |
208 | * |
209 | * Arguments: @sym_table *t@ = pointer to symbol table |
210 | * |
211 | * Returns: --- |
212 | * |
213 | * Use: Destroys all the variables in the symbol table. |
214 | */ |
215 | |
216 | void env_destroy(sym_table *t) |
217 | { |
218 | sym_iter i; |
219 | var *v; |
220 | |
221 | for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; ) |
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222 | x_free(t->t.a, v->v); |
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223 | sym_destroy(t); |
224 | } |
225 | |
226 | /*----- That's all, folks -------------------------------------------------*/ |