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-rw-r--r--src/util/clean_env.c128
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diff --git a/src/util/clean_env.c b/src/util/clean_env.c
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+/*++
+/* 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);
+}