+/* -*-c-*-
+ *
+ * $Id: env.c,v 1.1 1999/07/26 23:15:57 mdw Exp $
+ *
+ * Fiddling with environment variables
+ *
+ * (c) 1999 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of the mLib utilities library.
+ *
+ * mLib is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * mLib is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with mLib; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/*----- Revision history --------------------------------------------------*
+ *
+ * $Log: env.c,v $
+ * Revision 1.1 1999/07/26 23:15:57 mdw
+ * Fiddling with environment variables.
+ *
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "alloc.h"
+#include "sym.h"
+
+/*----- Data structures ---------------------------------------------------*/
+
+typedef struct var {
+ sym_base _base;
+ char *v;
+} var;
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @env_get@ --- *
+ *
+ * Arguments: @sym_table *t@ = pointer to a symbol table
+ * @const char *name@ = pointer to variable name to look up
+ *
+ * Returns: Pointer to corresponding value string, or null.
+ *
+ * Use: Looks up an environment variable in the table and returns its
+ * value. If the variable can't be found, a null pointer is
+ * returned.
+ */
+
+char *env_get(sym_table *t, const char *name)
+{
+ var *e = sym_find(t, name, -1, 0, 0);
+ return (e ? e->v : 0);
+}
+
+/* --- @env_put@ --- *
+ *
+ * Arguments: @sym_table *t@ = pointer to a symbol table
+ * @const char *name@ = pointer to variable name to set
+ * @const char *value@ = pointer to value string to assign
+ *
+ * Returns: ---
+ *
+ * Use: Assigns a value to a variable. If the @name@ contains an
+ * equals character, then it's assumed to be of the form
+ * `VAR=VALUE' and @value@ argument is ignored. Otherwise, if
+ * @value@ is null, the variable is deleted. Finally, the
+ * normal case: @name@ is a plain name, and @value@ is a normal
+ * string causes the variable to be assigned the value in the
+ * way you'd expect.
+ */
+
+void env_put(sym_table *t, const char *name, const char *value)
+{
+ char *q = 0;
+
+ /* --- Sort out the mess with `NAME=VALUE' forms --- */
+
+ {
+ size_t eq = strcspn(name, "=");
+ if (name[eq] == '=') {
+ q = xmalloc(eq + 1);
+ memcpy(q, name, eq);
+ q[eq] = 0;
+ value = name + eq + 1;
+ name = q;
+ }
+ }
+
+ /* --- Read the current value --- */
+
+ if (!value) {
+ var *v;
+ if ((v = sym_find(t, name, -1, 0, 0)) != 0) {
+ free(v->v);
+ sym_remove(t, v);
+ }
+ } else {
+ unsigned found;
+ var *v = sym_find(t, name, -1, sizeof(*v), &found);
+ if (found)
+ free(v->v);
+ v->v = xstrdup(value);
+ }
+
+ /* --- Tidying --- */
+
+ if (q)
+ free(q);
+}
+
+/* --- @env_import@ --- *
+ *
+ * Arguments: @sym_table *t@ = pointer to a symbol table
+ * @char **env@ = pointer to an environment list
+ *
+ * Returns: ---
+ *
+ * Use: Inserts all of the environment variables listed into a symbol
+ * table for rapid access. Equivalent to a lot of calls to
+ * @env_put@.
+ */
+
+void env_import(sym_table *t, char **env)
+{
+ while (*env) {
+ env_put(t, *env, 0);
+ env++;
+ }
+}
+
+/* --- @env_export@ --- *
+ *
+ * Arguments: @sym_table *t@ = pointer to a symbol table
+ *
+ * Returns: A big environment list.
+ *
+ * Use: Extracts an environment table from a symbol table
+ * representation of an environment. The table and all of the
+ * strings are in one big block allocated from the heap.
+ */
+
+char **env_export(sym_table *t)
+{
+ size_t n = 1;
+ size_t sz = 0;
+ sym_iter i;
+ var *v;
+ char **env;
+ char *p, **pp;
+
+ /* --- Work out sizes for everything --- */
+
+ for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; ) {
+ n++;
+ sz += strlen(SYM_NAME(v)) + strlen(v->v) + 2;
+ }
+
+ /* --- Allocate the big chunk of memory --- */
+
+ env = pp = xmalloc(n * sizeof(char *) + sz);
+ p = (char *)(env + n);
+
+ /* --- Dump the output in the big chunk of memory --- */
+
+ for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; ) {
+ const char *name = SYM_NAME(v);
+ size_t nlen = strlen(name), vlen = strlen(v->v);
+ *pp++ = p;
+ memcpy(p, name, nlen); p += nlen;
+ *p++ = '=';
+ memcpy(p, v->v, vlen); p += vlen;
+ *p++ = 0;
+ }
+ *pp++ = 0;
+ return (env);
+}
+
+/* --- @env_destroy@ --- *
+ *
+ * Arguments: @sym_table *t@ = pointer to symbol table
+ *
+ * Returns: ---
+ *
+ * Use: Destroys all the variables in the symbol table.
+ */
+
+void env_destroy(sym_table *t)
+{
+ sym_iter i;
+ var *v;
+
+ for (sym_mkiter(&i, t); (v = sym_next(&i)) != 0; )
+ free(v->v);
+ sym_destroy(t);
+}
+
+/*----- That's all, folks -------------------------------------------------*/
~mdw / mLib / commitdiff