busybox/coreutils/env.c
James Byrne 6937487be7 libbb: reduce the overhead of single parameter bb_error_msg() calls
Back in 2007, commit 0c97c9d437 ("'simple' error message functions by
Loic Grenie") introduced bb_simple_perror_msg() to allow for a lower
overhead call to bb_perror_msg() when only a string was being printed
with no parameters. This saves space for some CPU architectures because
it avoids the overhead of a call to a variadic function. However there
has never been a simple version of bb_error_msg(), and since 2007 many
new calls to bb_perror_msg() have been added that only take a single
parameter and so could have been using bb_simple_perror_message().

This changeset introduces 'simple' versions of bb_info_msg(),
bb_error_msg(), bb_error_msg_and_die(), bb_herror_msg() and
bb_herror_msg_and_die(), and replaces all calls that only take a
single parameter, or use something like ("%s", arg), with calls to the
corresponding 'simple' version.

Since it is likely that single parameter calls to the variadic functions
may be accidentally reintroduced in the future a new debugging config
option WARN_SIMPLE_MSG has been introduced. This uses some macro magic
which will cause any such calls to generate a warning, but this is
turned off by default to avoid use of the unpleasant macros in normal
circumstances.

This is a large changeset due to the number of calls that have been
replaced. The only files that contain changes other than simple
substitution of function calls are libbb.h, libbb/herror_msg.c,
libbb/verror_msg.c and libbb/xfuncs_printf.c. In miscutils/devfsd.c,
networking/udhcp/common.h and util-linux/mdev.c additonal macros have
been added for logging so that single parameter and multiple parameter
logging variants exist.

The amount of space saved varies considerably by architecture, and was
found to be as follows (for 'defconfig' using GCC 7.4):

Arm:     -92 bytes
MIPS:    -52 bytes
PPC:   -1836 bytes
x86_64: -938 bytes

Note that for the MIPS architecture only an exception had to be made
disabling the 'simple' calls for 'udhcp' (in networking/udhcp/common.h)
because it made these files larger on MIPS.

Signed-off-by: James Byrne <james.byrne@origamienergy.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2019-07-02 11:35:03 +02:00

133 lines
4.3 KiB
C

/* vi: set sw=4 ts=4: */
/*
* env implementation for busybox
*
* Copyright (c) 1988, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*
* Original copyright notice is retained at the end of this file.
*
* Modified for BusyBox by Erik Andersen <andersen@codepoet.org>
*/
/* Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org)
*
* Fixed bug involving exit return codes if execvp fails. Also added
* output error checking.
*/
/*
* Modified by Vladimir Oleynik <dzo@simtreas.ru> (C) 2003
* - correct "-" option usage
* - multiple "-u unsetenv" support
* - GNU long option support
* - use xfunc_error_retval
*/
//config:config ENV
//config: bool "env (4 kb)"
//config: default y
//config: help
//config: env is used to set an environment variable and run
//config: a command; without options it displays the current
//config: environment.
//applet:IF_ENV(APPLET_NOEXEC(env, env, BB_DIR_USR_BIN, BB_SUID_DROP, env))
//kbuild:lib-$(CONFIG_ENV) += env.o
/* BB_AUDIT SUSv3 compliant */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/env.html */
//usage:#define env_trivial_usage
//usage: "[-iu] [-] [name=value]... [PROG ARGS]"
//usage:#define env_full_usage "\n\n"
//usage: "Print the current environment or run PROG after setting up\n"
//usage: "the specified environment\n"
//usage: "\n -, -i Start with an empty environment"
//usage: "\n -u Remove variable from the environment"
#include "libbb.h"
int env_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int env_main(int argc UNUSED_PARAM, char **argv)
{
unsigned opts;
llist_t *unset_env = NULL;
opts = getopt32long(argv, "+iu:*",
"ignore-environment\0" No_argument "i"
"unset\0" Required_argument "u"
, &unset_env
);
argv += optind;
if (argv[0] && LONE_DASH(argv[0])) {
opts |= 1;
++argv;
}
if (opts & 1) {
clearenv();
}
while (unset_env) {
char *var = llist_pop(&unset_env);
/* This does not handle -uVAR=VAL
* (coreutils _sets_ the variable in that case): */
/*unsetenv(var);*/
/* This does, but uses somewhan undocumented feature that
* putenv("name_without_equal_sign") unsets the variable: */
putenv(var);
}
while (*argv && (strchr(*argv, '=') != NULL)) {
if (putenv(*argv) < 0) {
bb_simple_perror_msg_and_die("putenv");
}
++argv;
}
if (argv[0]) {
BB_EXECVP_or_die(argv);
}
if (environ) { /* clearenv() may set environ == NULL! */
char **ep;
for (ep = environ; *ep; ep++) {
puts(*ep);
}
}
fflush_stdout_and_exit(EXIT_SUCCESS);
}
/*
* Copyright (c) 1988, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. BSD Advertising Clause omitted per the July 22, 1999 licensing change
* ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change
*
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ''AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/