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sortix--sortix/utils/env.cpp
2015-12-12 19:28:07 +01:00

209 lines
5.7 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2014.
This program is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your option)
any later version.
This program 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 General Public License for
more details.
You should have received a copy of the GNU General Public License along with
this program. If not, see <http://www.gnu.org/licenses/>.
env.cpp
Set the environment for command invocation.
*******************************************************************************/
#include <errno.h>
#include <error.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
void clean_environment()
{
while ( environ[0] )
{
size_t equal_pos = strcspn(environ[0], "=");
if ( environ[0][equal_pos] != '=' )
error(125, 0, "Bad Environment");
char* key = strndup(environ[0], equal_pos);
if ( !key )
error(125, errno, "strndup");
if ( unsetenv(key) != 0 )
error(125, errno, "cannot unset `%s'", key);
free(key);
}
}
static void compact_arguments(int* argc, char*** argv)
{
for ( int i = 0; i < *argc; i++ )
{
while ( i < *argc && !(*argv)[i] )
{
for ( int n = i; n < *argc; n++ )
(*argv)[n] = (*argv)[n+1];
(*argc)--;
}
}
}
static void help(FILE* fp, const char* argv0)
{
fprintf(fp, "Usage: %s [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]\n", argv0);
fprintf(fp, "Set each NAME to VALUE in the environment and run COMMAND.\n");
fprintf(fp, "\n");
fprintf(fp, " -i, --ignore-environment start with an empty environment\n");
fprintf(fp, " -0, --null end each output line with 0 byte rather than newline\n");
fprintf(fp, " -u, --unset=NAME remove variable from the environment\n");
fprintf(fp, " --help display this help and exit\n");
fprintf(fp, " --version output version information and exit\n");
fprintf(fp, "\n");
fprintf(fp, "A mere - implies -i. If no COMMAND, print the resulting environment.\n");
}
static void version(FILE* fp, const char* argv0)
{
fprintf(fp, "%s (Sortix) %s\n", argv0, VERSIONSTR);
fprintf(fp, "License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.\n");
fprintf(fp, "This is free software: you are free to change and redistribute it.\n");
fprintf(fp, "There is NO WARRANTY, to the extent permitted by law.\n");
}
int main(int argc, char* argv[])
{
bool ignore_environment = false;
bool null_terminate = false;
const char* argv0 = argv[0];
for ( int i = 1; i < argc; i++ )
{
const char* arg = argv[i];
if ( arg[0] != '-' )
break; // Intentionally not continue.
if ( arg[0] == '-' && !arg[1] )
{
ignore_environment = true;
break;
}
argv[i] = NULL;
if ( !strcmp(arg, "--") )
break;
if ( arg[1] != '-' )
{
while ( char c = *++arg ) switch ( c )
{
case 'i': ignore_environment = true; break;
case 'u':
if ( !arg[1] )
{
if ( i + 1 == argc )
{
error(0, 0, "option requires an argument -- 'u'");
fprintf(stderr, "Try `%s --help' for more information.\n", argv[0]);
exit(125);
}
const char* key = argv[i+1];
argv[++i] = NULL;
if ( unsetenv(key) != 0 )
error(125, errno, "cannot unset `%s'", key);
}
else
{
const char* key = arg + 1;
if ( unsetenv(key) != 0 )
error(125, errno, "cannot unset `%s'", key);
}
arg = "u";
break;
case '0': null_terminate = true; break;
default:
fprintf(stderr, "%s: unknown option -- '%c'\n", argv0, c);
help(stderr, argv0);
exit(1);
}
}
else if ( !strcmp(arg, "--help") )
help(stdout, argv0), exit(0);
else if ( !strcmp(arg, "--version") )
version(stdout, argv0), exit(0);
else if ( !strcmp(arg, "--ignore-environment") )
ignore_environment = true;
else if ( !strcmp(arg, "--null") )
null_terminate = true;
else if ( !strncmp(arg, "--unset=", strlen("--unset=")) )
{
const char* key = arg + strlen("--unset=");
if ( unsetenv(key) != 0 )
error(125, errno, "cannot unset `%s'", key);
}
else if ( !strcmp(arg, "--unset") )
{
if ( i + 1 == argc )
{
error(0, 0, "option '--unset' requires an argument");
fprintf(stderr, "Try `%s --help' for more information.\n", argv[0]);
exit(125);
}
const char* key = argv[i+1];
argv[++i] = NULL;
if ( unsetenv(key) != 0 )
error(125, errno, "cannot unset `%s'", key);
}
else
{
fprintf(stderr, "%s: unknown option: %s\n", argv0, arg);
help(stderr, argv0);
exit(1);
}
}
if ( ignore_environment )
clean_environment();
compact_arguments(&argc, &argv);
for ( int i = 1; i < argc; i++ )
{
char* arg = argv[i];
size_t equal_pos = strcspn(arg, "=");
if ( arg[equal_pos] != '=' )
break;
argv[i] = NULL;
arg[equal_pos] = '\0';
const char* key = arg;
const char* value = arg + equal_pos + 1;
if ( setenv(key, value, 1) != 0 )
error(125, errno, "setenv(\"%s\", \"%s\")", key, value);
}
compact_arguments(&argc, &argv);
if ( argc == 1 )
{
for ( size_t i = 0; environ[i]; i++ )
{
fputs(environ[i], stdout);
fputc(null_terminate ? '\0' : '\n', stdout);
}
return 0;
}
if ( null_terminate )
{
error(0, 0, "cannot specify --null (-0) with command");
fprintf(stderr, "Try `%s --help' for more information.\n", argv[0]);
exit(125);
}
execvp(argv[1], argv + 1);
error(errno == ENOENT ? 127 : 126, errno, "%s", argv[1]);
}