1 files changed, 128 insertions, 0 deletions
diff --git a/src/util/clean_env.c b/src/util/clean_env.c
new file mode 100644
index 0000000..c6daffa
--- /dev/null
+++ b/src/util/clean_env.c
@@ -0,0 +1,128 @@
+/*++
+/* NAME
+/*	clean_env 3
+/* SUMMARY
+/*	clean up the environment
+/* SYNOPSIS
+/*	#include <clean_env.h>
+/*
+/*	void	clean_env(preserve_list)
+/*	const char **preserve_list;
+/*
+/*	void	update_env(preserve_list)
+/*	const char **preserve_list;
+/* DESCRIPTION
+/*	clean_env() reduces the process environment to the bare minimum.
+/*	The function takes a null-terminated list of arguments.
+/*	Each argument specifies the name of an environment variable
+/*	that should be preserved, or specifies a name=value that should
+/*	be entered into the new environment.
+/*
+/*	update_env() applies name=value settings, but otherwise does not
+/*	change the process environment.
+/* DIAGNOSTICS
+/*	Fatal error: out of memory.
+/* SEE ALSO
+/*	safe_getenv(3), guarded getenv()
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Wietse Venema
+/*	Google, Inc.
+/*	111 8th Avenue
+/*	New York, NY 10011, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <argv.h>
+#include <safe.h>
+#include <clean_env.h>
+
+/* clean_env - clean up the environment */
+
+void    clean_env(char **preserve_list)
+{
+    extern char **environ;
+    ARGV   *save_list;
+    char   *value;
+    char  **cpp;
+    char   *eq;
+
+    /*
+     * Preserve or specify selected environment variables.
+     */
+#define STRING_AND_LENGTH(x, y) (x), (ssize_t) (y)
+
+    save_list = argv_alloc(10);
+    for (cpp = preserve_list; *cpp; cpp++)
+	if ((eq = strchr(*cpp, '=')) != 0)
+	    argv_addn(save_list, STRING_AND_LENGTH(*cpp, eq - *cpp),
+		      STRING_AND_LENGTH(eq + 1, strlen(eq + 1)), (char *) 0);
+	else if ((value = safe_getenv(*cpp)) != 0)
+	    argv_add(save_list, *cpp, value, (char *) 0);
+
+    /*
+     * Truncate the process environment, if available. On some systems
+     * (Ultrix!), environ can be a null pointer.
+     */
+    if (environ)
+	environ[0] = 0;
+
+    /*
+     * Restore preserved environment variables.
+     */
+    for (cpp = save_list->argv; *cpp; cpp += 2)
+	if (setenv(cpp[0], cpp[1], 1))
+	    msg_fatal("setenv(%s, %s): %m", cpp[0], cpp[1]);
+
+    /*
+     * Cleanup.
+     */
+    argv_free(save_list);
+}
+
+/* update_env - apply name=value settings only */
+
+void    update_env(char **preserve_list)
+{
+    char  **cpp;
+    ARGV   *save_list;
+    char   *eq;
+
+    /*
+     * Extract name=value settings.
+     */
+    save_list = argv_alloc(10);
+    for (cpp = preserve_list; *cpp; cpp++)
+	if ((eq = strchr(*cpp, '=')) != 0)
+	    argv_addn(save_list, STRING_AND_LENGTH(*cpp, eq - *cpp),
+		      STRING_AND_LENGTH(eq + 1, strlen(eq + 1)), (char *) 0);
+
+    /*
+     * Apply name=value settings.
+     */
+    for (cpp = save_list->argv; *cpp; cpp += 2)
+	if (setenv(cpp[0], cpp[1], 1))
+	    msg_fatal("setenv(%s, %s): %m", cpp[0], cpp[1]);
+
+    /*
+     * Cleanup.
+     */
+    argv_free(save_list);
+}