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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);
}
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