3 * $Id: env.c,v 1.5 2004/04/08 01:36:11 mdw Exp $
5 * Fiddling with environment variables
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of the mLib utilities library.
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.
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.
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,
30 /*----- Header files ------------------------------------------------------*/
39 /*----- Data structures ---------------------------------------------------*/
46 /*----- Main code ---------------------------------------------------------*/
48 /* --- @env_get@ --- *
50 * Arguments: @sym_table *t@ = pointer to a symbol table
51 * @const char *name@ = pointer to variable name to look up
53 * Returns: Pointer to corresponding value string, or null.
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
60 char *env_get(sym_table *t, const char *name)
62 var *e = sym_find(t, name, -1, 0, 0);
63 return (e ? e->v : 0);
66 /* --- @env_put@ --- *
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
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
83 void env_put(sym_table *t, const char *name, const char *value)
87 /* --- Sort out the mess with `NAME=VALUE' forms --- */
90 size_t eq = strcspn(name, "=");
91 if (name[eq] == '=') {
92 q = x_alloc(t->t.a, eq + 1);
95 value = name + eq + 1;
100 /* --- Read the current value --- */
104 if ((v = sym_find(t, name, -1, 0, 0)) != 0) {
105 x_free(t->t.a, v->v);
110 var *v = sym_find(t, name, -1, sizeof(*v), &found);
112 x_free(t->t.a, v->v);
113 v->v = x_strdup(t->t.a, value);
116 /* --- Tidying --- */
122 /* --- @env_import@ --- *
124 * Arguments: @sym_table *t@ = pointer to a symbol table
125 * @char **env@ = pointer to an environment list
129 * Use: Inserts all of the environment variables listed into a symbol
130 * table for rapid access. Equivalent to a lot of calls to
134 void env_import(sym_table *t, char **env)
142 /* --- @env_export@ --- *
144 * Arguments: @sym_table *t@ = pointer to a symbol table
146 * Returns: A big environment list.
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.
153 char **env_export(sym_table *t)
162 /* --- Work out sizes for everything --- */
164 for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; ) {
166 sz += SYM_LEN(v) + strlen(v->v) + 2;
169 /* --- Allocate the big chunk of memory --- */
171 env = pp = xmalloc(n * sizeof(char *) + sz);
172 p = (char *)(env + n);
174 /* --- Dump the output in the big chunk of memory --- */
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);
180 memcpy(p, name, nlen); p += nlen;
182 memcpy(p, v->v, vlen); p += vlen;
189 /* --- @env_destroy@ --- *
191 * Arguments: @sym_table *t@ = pointer to symbol table
195 * Use: Destroys all the variables in the symbol table.
198 void env_destroy(sym_table *t)
203 for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; )
204 x_free(t->t.a, v->v);
208 /*----- That's all, folks -------------------------------------------------*/