chiark / gitweb /
New array adjustment macros for unsigned arguments.
[mLib] / env.c
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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
49typedef 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
68char *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
91void 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
142void 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
161char **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
206void 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 -------------------------------------------------*/