3 * Fiddling with environment variables
5 * (c) 1999 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of the mLib utilities library.
12 * mLib is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Library General Public License as
14 * published by the Free Software Foundation; either version 2 of the
15 * License, or (at your option) any later version.
17 * mLib is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU Library General Public License for more details.
22 * You should have received a copy of the GNU Library General Public
23 * License along with mLib; if not, write to the Free
24 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
28 /*----- Header files ------------------------------------------------------*/
37 /*----- Data structures ---------------------------------------------------*/
44 /*----- Main code ---------------------------------------------------------*/
46 /* --- @env_get@ --- *
48 * Arguments: @sym_table *t@ = pointer to a symbol table
49 * @const char *name@ = pointer to variable name to look up
51 * Returns: Pointer to corresponding value string, or null.
53 * Use: Looks up an environment variable in the table and returns its
54 * value. If the variable can't be found, a null pointer is
58 char *env_get(sym_table *t, const char *name)
60 var *e = sym_find(t, name, -1, 0, 0);
61 return (e ? e->v : 0);
64 /* --- @env_put@ --- *
66 * Arguments: @sym_table *t@ = pointer to a symbol table
67 * @const char *name@ = pointer to variable name to set
68 * @const char *value@ = pointer to value string to assign
72 * Use: Assigns a value to a variable. If the @name@ contains an
73 * equals character, then it's assumed to be of the form
74 * `VAR=VALUE' and @value@ argument is ignored. Otherwise, if
75 * @value@ is null, the variable is deleted. Finally, the
76 * normal case: @name@ is a plain name, and @value@ is a normal
77 * string causes the variable to be assigned the value in the
81 void env_put(sym_table *t, const char *name, const char *value)
85 /* --- Sort out the mess with `NAME=VALUE' forms --- */
88 size_t eq = strcspn(name, "=");
89 if (name[eq] == '=') {
90 q = x_alloc(t->t.a, eq + 1);
93 value = name + eq + 1;
98 /* --- Read the current value --- */
102 if ((v = sym_find(t, name, -1, 0, 0)) != 0) {
103 x_free(t->t.a, v->v);
108 var *v = sym_find(t, name, -1, sizeof(*v), &found);
110 x_free(t->t.a, v->v);
111 v->v = x_strdup(t->t.a, value);
114 /* --- Tidying --- */
120 /* --- @env_import@ --- *
122 * Arguments: @sym_table *t@ = pointer to a symbol table
123 * @char **env@ = pointer to an environment list
127 * Use: Inserts all of the environment variables listed into a symbol
128 * table for rapid access. Equivalent to a lot of calls to
132 void env_import(sym_table *t, char **env)
140 /* --- @env_export@ --- *
142 * Arguments: @sym_table *t@ = pointer to a symbol table
144 * Returns: A big environment list.
146 * Use: Extracts an environment table from a symbol table
147 * representation of an environment. The table and all of the
148 * strings are in one big block allocated from the heap.
151 char **env_export(sym_table *t)
160 /* --- Work out sizes for everything --- */
162 for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; ) {
164 sz += SYM_LEN(v) + strlen(v->v) + 2;
167 /* --- Allocate the big chunk of memory --- */
169 env = pp = xmalloc(n * sizeof(char *) + sz);
170 p = (char *)(env + n);
172 /* --- Dump the output in the big chunk of memory --- */
174 for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; ) {
175 const char *name = SYM_NAME(v);
176 size_t nlen = strlen(name), vlen = strlen(v->v);
178 memcpy(p, name, nlen); p += nlen;
180 memcpy(p, v->v, vlen); p += vlen;
187 /* --- @env_destroy@ --- *
189 * Arguments: @sym_table *t@ = pointer to symbol table
193 * Use: Destroys all the variables in the symbol table.
196 void env_destroy(sym_table *t)
201 for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; )
202 x_free(t->t.a, v->v);
206 /*----- That's all, folks -------------------------------------------------*/