e19206c2 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: env.c,v 1.1 1999/07/26 23:15:57 mdw Exp $ |
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 $ |
33 | * Revision 1.1 1999/07/26 23:15:57 mdw |
34 | * Fiddling with environment variables. |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include <stdio.h> |
41 | #include <stdlib.h> |
42 | #include <string.h> |
43 | |
44 | #include "alloc.h" |
45 | #include "sym.h" |
46 | |
47 | /*----- Data structures ---------------------------------------------------*/ |
48 | |
49 | typedef struct var { |
50 | sym_base _base; |
51 | char *v; |
52 | } var; |
53 | |
54 | /*----- Main code ---------------------------------------------------------*/ |
55 | |
56 | /* --- @env_get@ --- * |
57 | * |
58 | * Arguments: @sym_table *t@ = pointer to a symbol table |
59 | * @const char *name@ = pointer to variable name to look up |
60 | * |
61 | * Returns: Pointer to corresponding value string, or null. |
62 | * |
63 | * Use: Looks up an environment variable in the table and returns its |
64 | * value. If the variable can't be found, a null pointer is |
65 | * returned. |
66 | */ |
67 | |
68 | char *env_get(sym_table *t, const char *name) |
69 | { |
70 | var *e = sym_find(t, name, -1, 0, 0); |
71 | return (e ? e->v : 0); |
72 | } |
73 | |
74 | /* --- @env_put@ --- * |
75 | * |
76 | * Arguments: @sym_table *t@ = pointer to a symbol table |
77 | * @const char *name@ = pointer to variable name to set |
78 | * @const char *value@ = pointer to value string to assign |
79 | * |
80 | * Returns: --- |
81 | * |
82 | * Use: Assigns a value to a variable. If the @name@ contains an |
83 | * equals character, then it's assumed to be of the form |
84 | * `VAR=VALUE' and @value@ argument is ignored. Otherwise, if |
85 | * @value@ is null, the variable is deleted. Finally, the |
86 | * normal case: @name@ is a plain name, and @value@ is a normal |
87 | * string causes the variable to be assigned the value in the |
88 | * way you'd expect. |
89 | */ |
90 | |
91 | void env_put(sym_table *t, const char *name, const char *value) |
92 | { |
93 | char *q = 0; |
94 | |
95 | /* --- Sort out the mess with `NAME=VALUE' forms --- */ |
96 | |
97 | { |
98 | size_t eq = strcspn(name, "="); |
99 | if (name[eq] == '=') { |
100 | q = xmalloc(eq + 1); |
101 | memcpy(q, name, eq); |
102 | q[eq] = 0; |
103 | value = name + eq + 1; |
104 | name = q; |
105 | } |
106 | } |
107 | |
108 | /* --- Read the current value --- */ |
109 | |
110 | if (!value) { |
111 | var *v; |
112 | if ((v = sym_find(t, name, -1, 0, 0)) != 0) { |
113 | free(v->v); |
114 | sym_remove(t, v); |
115 | } |
116 | } else { |
117 | unsigned found; |
118 | var *v = sym_find(t, name, -1, sizeof(*v), &found); |
119 | if (found) |
120 | free(v->v); |
121 | v->v = xstrdup(value); |
122 | } |
123 | |
124 | /* --- Tidying --- */ |
125 | |
126 | if (q) |
127 | free(q); |
128 | } |
129 | |
130 | /* --- @env_import@ --- * |
131 | * |
132 | * Arguments: @sym_table *t@ = pointer to a symbol table |
133 | * @char **env@ = pointer to an environment list |
134 | * |
135 | * Returns: --- |
136 | * |
137 | * Use: Inserts all of the environment variables listed into a symbol |
138 | * table for rapid access. Equivalent to a lot of calls to |
139 | * @env_put@. |
140 | */ |
141 | |
142 | void env_import(sym_table *t, char **env) |
143 | { |
144 | while (*env) { |
145 | env_put(t, *env, 0); |
146 | env++; |
147 | } |
148 | } |
149 | |
150 | /* --- @env_export@ --- * |
151 | * |
152 | * Arguments: @sym_table *t@ = pointer to a symbol table |
153 | * |
154 | * Returns: A big environment list. |
155 | * |
156 | * Use: Extracts an environment table from a symbol table |
157 | * representation of an environment. The table and all of the |
158 | * strings are in one big block allocated from the heap. |
159 | */ |
160 | |
161 | char **env_export(sym_table *t) |
162 | { |
163 | size_t n = 1; |
164 | size_t sz = 0; |
165 | sym_iter i; |
166 | var *v; |
167 | char **env; |
168 | char *p, **pp; |
169 | |
170 | /* --- Work out sizes for everything --- */ |
171 | |
172 | for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; ) { |
173 | n++; |
174 | sz += strlen(SYM_NAME(v)) + strlen(v->v) + 2; |
175 | } |
176 | |
177 | /* --- Allocate the big chunk of memory --- */ |
178 | |
179 | env = pp = xmalloc(n * sizeof(char *) + sz); |
180 | p = (char *)(env + n); |
181 | |
182 | /* --- Dump the output in the big chunk of memory --- */ |
183 | |
184 | for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; ) { |
185 | const char *name = SYM_NAME(v); |
186 | size_t nlen = strlen(name), vlen = strlen(v->v); |
187 | *pp++ = p; |
188 | memcpy(p, name, nlen); p += nlen; |
189 | *p++ = '='; |
190 | memcpy(p, v->v, vlen); p += vlen; |
191 | *p++ = 0; |
192 | } |
193 | *pp++ = 0; |
194 | return (env); |
195 | } |
196 | |
197 | /* --- @env_destroy@ --- * |
198 | * |
199 | * Arguments: @sym_table *t@ = pointer to symbol table |
200 | * |
201 | * Returns: --- |
202 | * |
203 | * Use: Destroys all the variables in the symbol table. |
204 | */ |
205 | |
206 | void env_destroy(sym_table *t) |
207 | { |
208 | sym_iter i; |
209 | var *v; |
210 | |
211 | for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; ) |
212 | free(v->v); |
213 | sym_destroy(t); |
214 | } |
215 | |
216 | /*----- That's all, folks -------------------------------------------------*/ |