206 lines
5.4 KiB
C
206 lines
5.4 KiB
C
/*
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* Copyright (c) 2014 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* env.c
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* Set the environment for command invocation.
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*/
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#include <errno.h>
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#include <error.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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void clean_environment(void)
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{
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while ( environ[0] )
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{
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size_t equal_pos = strcspn(environ[0], "=");
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if ( environ[0][equal_pos] != '=' )
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error(125, 0, "Bad Environment");
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char* key = strndup(environ[0], equal_pos);
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if ( !key )
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error(125, errno, "strndup");
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if ( unsetenv(key) != 0 )
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error(125, errno, "cannot unset `%s'", key);
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free(key);
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}
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}
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static void compact_arguments(int* argc, char*** argv)
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{
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for ( int i = 0; i < *argc; i++ )
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{
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while ( i < *argc && !(*argv)[i] )
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{
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for ( int n = i; n < *argc; n++ )
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(*argv)[n] = (*argv)[n+1];
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(*argc)--;
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}
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}
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}
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static void help(FILE* fp, const char* argv0)
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{
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fprintf(fp, "Usage: %s [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]\n", argv0);
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fprintf(fp, "Set each NAME to VALUE in the environment and run COMMAND.\n");
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fprintf(fp, "\n");
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fprintf(fp, " -i, --ignore-environment start with an empty environment\n");
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fprintf(fp, " -0, --null end each output line with 0 byte rather than newline\n");
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fprintf(fp, " -u, --unset=NAME remove variable from the environment\n");
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fprintf(fp, " --help display this help and exit\n");
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fprintf(fp, " --version output version information and exit\n");
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fprintf(fp, "\n");
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fprintf(fp, "A mere - implies -i. If no COMMAND, print the resulting environment.\n");
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}
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static void version(FILE* fp, const char* argv0)
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{
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fprintf(fp, "%s (Sortix) %s\n", argv0, VERSIONSTR);
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}
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int main(int argc, char* argv[])
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{
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bool ignore_environment = false;
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bool null_terminate = false;
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const char* argv0 = argv[0];
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for ( int i = 1; i < argc; i++ )
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{
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const char* arg = argv[i];
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if ( arg[0] != '-' )
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break; // Intentionally not continue.
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if ( arg[0] == '-' && !arg[1] )
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{
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ignore_environment = true;
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break;
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}
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argv[i] = NULL;
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if ( !strcmp(arg, "--") )
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break;
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if ( arg[1] != '-' )
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{
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char c;
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while ( (c = *++arg) ) switch ( c )
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{
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case 'i': ignore_environment = true; break;
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case 'u':
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if ( !arg[1] )
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{
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if ( i + 1 == argc )
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{
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error(0, 0, "option requires an argument -- 'u'");
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fprintf(stderr, "Try `%s --help' for more information.\n", argv[0]);
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exit(125);
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}
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const char* key = argv[i+1];
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argv[++i] = NULL;
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if ( unsetenv(key) != 0 )
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error(125, errno, "cannot unset `%s'", key);
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}
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else
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{
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const char* key = arg + 1;
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if ( unsetenv(key) != 0 )
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error(125, errno, "cannot unset `%s'", key);
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}
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arg = "u";
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break;
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case '0': null_terminate = true; break;
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default:
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fprintf(stderr, "%s: unknown option -- '%c'\n", argv0, c);
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help(stderr, argv0);
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exit(1);
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}
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}
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else if ( !strcmp(arg, "--help") )
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help(stdout, argv0), exit(0);
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else if ( !strcmp(arg, "--version") )
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version(stdout, argv0), exit(0);
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else if ( !strcmp(arg, "--ignore-environment") )
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ignore_environment = true;
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else if ( !strcmp(arg, "--null") )
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null_terminate = true;
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else if ( !strncmp(arg, "--unset=", strlen("--unset=")) )
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{
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const char* key = arg + strlen("--unset=");
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if ( unsetenv(key) != 0 )
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error(125, errno, "cannot unset `%s'", key);
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}
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else if ( !strcmp(arg, "--unset") )
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{
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if ( i + 1 == argc )
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{
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error(0, 0, "option '--unset' requires an argument");
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fprintf(stderr, "Try `%s --help' for more information.\n", argv[0]);
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exit(125);
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}
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const char* key = argv[i+1];
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argv[++i] = NULL;
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if ( unsetenv(key) != 0 )
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error(125, errno, "cannot unset `%s'", key);
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}
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else
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{
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fprintf(stderr, "%s: unknown option: %s\n", argv0, arg);
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help(stderr, argv0);
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exit(1);
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}
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}
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if ( ignore_environment )
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clean_environment();
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compact_arguments(&argc, &argv);
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for ( int i = 1; i < argc; i++ )
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{
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char* arg = argv[i];
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size_t equal_pos = strcspn(arg, "=");
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if ( arg[equal_pos] != '=' )
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break;
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argv[i] = NULL;
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arg[equal_pos] = '\0';
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const char* key = arg;
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const char* value = arg + equal_pos + 1;
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if ( setenv(key, value, 1) != 0 )
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error(125, errno, "setenv(\"%s\", \"%s\")", key, value);
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}
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compact_arguments(&argc, &argv);
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if ( argc == 1 )
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{
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for ( size_t i = 0; environ[i]; i++ )
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{
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fputs(environ[i], stdout);
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fputc(null_terminate ? '\0' : '\n', stdout);
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}
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return 0;
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}
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if ( null_terminate )
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{
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error(0, 0, "cannot specify --null (-0) with command");
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fprintf(stderr, "Try `%s --help' for more information.\n", argv[0]);
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exit(125);
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}
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execvp(argv[1], argv + 1);
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error(errno == ENOENT ? 127 : 126, errno, "%s", argv[1]);
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}
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