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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: env.c,v 1.5 2004/04/08 01:36:11 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 | |
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30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include <stdio.h> |
33 | #include <stdlib.h> |
34 | #include <string.h> |
35 | |
36 | #include "alloc.h" |
37 | #include "sym.h" |
38 | |
39 | /*----- Data structures ---------------------------------------------------*/ |
40 | |
41 | typedef struct var { |
42 | sym_base _base; |
43 | char *v; |
44 | } var; |
45 | |
46 | /*----- Main code ---------------------------------------------------------*/ |
47 | |
48 | /* --- @env_get@ --- * |
49 | * |
50 | * Arguments: @sym_table *t@ = pointer to a symbol table |
51 | * @const char *name@ = pointer to variable name to look up |
52 | * |
53 | * Returns: Pointer to corresponding value string, or null. |
54 | * |
55 | * Use: Looks up an environment variable in the table and returns its |
56 | * value. If the variable can't be found, a null pointer is |
57 | * returned. |
58 | */ |
59 | |
60 | char *env_get(sym_table *t, const char *name) |
61 | { |
62 | var *e = sym_find(t, name, -1, 0, 0); |
63 | return (e ? e->v : 0); |
64 | } |
65 | |
66 | /* --- @env_put@ --- * |
67 | * |
68 | * Arguments: @sym_table *t@ = pointer to a symbol table |
69 | * @const char *name@ = pointer to variable name to set |
70 | * @const char *value@ = pointer to value string to assign |
71 | * |
72 | * Returns: --- |
73 | * |
74 | * Use: Assigns a value to a variable. If the @name@ contains an |
75 | * equals character, then it's assumed to be of the form |
76 | * `VAR=VALUE' and @value@ argument is ignored. Otherwise, if |
77 | * @value@ is null, the variable is deleted. Finally, the |
78 | * normal case: @name@ is a plain name, and @value@ is a normal |
79 | * string causes the variable to be assigned the value in the |
80 | * way you'd expect. |
81 | */ |
82 | |
83 | void env_put(sym_table *t, const char *name, const char *value) |
84 | { |
85 | char *q = 0; |
86 | |
87 | /* --- Sort out the mess with `NAME=VALUE' forms --- */ |
88 | |
89 | { |
90 | size_t eq = strcspn(name, "="); |
91 | if (name[eq] == '=') { |
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92 | q = x_alloc(t->t.a, eq + 1); |
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93 | memcpy(q, name, eq); |
94 | q[eq] = 0; |
95 | value = name + eq + 1; |
96 | name = q; |
97 | } |
98 | } |
99 | |
100 | /* --- Read the current value --- */ |
101 | |
102 | if (!value) { |
103 | var *v; |
104 | if ((v = sym_find(t, name, -1, 0, 0)) != 0) { |
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105 | x_free(t->t.a, v->v); |
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106 | sym_remove(t, v); |
107 | } |
108 | } else { |
109 | unsigned found; |
110 | var *v = sym_find(t, name, -1, sizeof(*v), &found); |
111 | if (found) |
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112 | x_free(t->t.a, v->v); |
113 | v->v = x_strdup(t->t.a, value); |
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114 | } |
115 | |
116 | /* --- Tidying --- */ |
117 | |
118 | if (q) |
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119 | xfree(q); |
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120 | } |
121 | |
122 | /* --- @env_import@ --- * |
123 | * |
124 | * Arguments: @sym_table *t@ = pointer to a symbol table |
125 | * @char **env@ = pointer to an environment list |
126 | * |
127 | * Returns: --- |
128 | * |
129 | * Use: Inserts all of the environment variables listed into a symbol |
130 | * table for rapid access. Equivalent to a lot of calls to |
131 | * @env_put@. |
132 | */ |
133 | |
134 | void env_import(sym_table *t, char **env) |
135 | { |
136 | while (*env) { |
137 | env_put(t, *env, 0); |
138 | env++; |
139 | } |
140 | } |
141 | |
142 | /* --- @env_export@ --- * |
143 | * |
144 | * Arguments: @sym_table *t@ = pointer to a symbol table |
145 | * |
146 | * Returns: A big environment list. |
147 | * |
148 | * Use: Extracts an environment table from a symbol table |
149 | * representation of an environment. The table and all of the |
150 | * strings are in one big block allocated from the heap. |
151 | */ |
152 | |
153 | char **env_export(sym_table *t) |
154 | { |
155 | size_t n = 1; |
156 | size_t sz = 0; |
157 | sym_iter i; |
158 | var *v; |
159 | char **env; |
160 | char *p, **pp; |
161 | |
162 | /* --- Work out sizes for everything --- */ |
163 | |
164 | for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; ) { |
165 | n++; |
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166 | sz += SYM_LEN(v) + strlen(v->v) + 2; |
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167 | } |
168 | |
169 | /* --- Allocate the big chunk of memory --- */ |
170 | |
171 | env = pp = xmalloc(n * sizeof(char *) + sz); |
172 | p = (char *)(env + n); |
173 | |
174 | /* --- Dump the output in the big chunk of memory --- */ |
175 | |
176 | for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; ) { |
177 | const char *name = SYM_NAME(v); |
178 | size_t nlen = strlen(name), vlen = strlen(v->v); |
179 | *pp++ = p; |
180 | memcpy(p, name, nlen); p += nlen; |
181 | *p++ = '='; |
182 | memcpy(p, v->v, vlen); p += vlen; |
183 | *p++ = 0; |
184 | } |
185 | *pp++ = 0; |
186 | return (env); |
187 | } |
188 | |
189 | /* --- @env_destroy@ --- * |
190 | * |
191 | * Arguments: @sym_table *t@ = pointer to symbol table |
192 | * |
193 | * Returns: --- |
194 | * |
195 | * Use: Destroys all the variables in the symbol table. |
196 | */ |
197 | |
198 | void env_destroy(sym_table *t) |
199 | { |
200 | sym_iter i; |
201 | var *v; |
202 | |
203 | for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; ) |
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204 | x_free(t->t.a, v->v); |
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205 | sym_destroy(t); |
206 | } |
207 | |
208 | /*----- That's all, folks -------------------------------------------------*/ |