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      1 /*-
      2  * Copyright (c) 2017 The NetBSD Foundation, Inc.
      3  * All rights reserved.
      4  *
      5  * This code is derived from software contributed to The NetBSD Foundation
      6  * by Christos Zoulas.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     18  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     19  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     20  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     21  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     22  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     23  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     24  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     25  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     26  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     27  * POSSIBILITY OF SUCH DAMAGE.
     28  */
     29 
     30 #include <stdio.h>
     31 #include <stdlib.h>
     32 #include <err.h>
     33 #include <sys/sysctl.h>
     34 
     35 static int
     36 getprocpath(char *path, size_t len, pid_t pid)
     37 {
     38 	const int name[] = {
     39 	    CTL_KERN, KERN_PROC_ARGS, pid, KERN_PROC_PATHNAME,
     40 	};
     41      	return sysctl(name, __arraycount(name), path, &len, NULL, 0);
     42 }
     43 
     44 int
     45 main(int argc, char *argv[])
     46 {
     47 	if (argc != 2) {
     48 		fprintf(stderr, "Usage: %s <pid>\n", getprogname());
     49 		return EXIT_FAILURE;
     50 	}
     51 
     52 	char buf[MAXPATHLEN];
     53 	pid_t pid = atoi(argv[1]);
     54 
     55 	if (getprocpath(buf, sizeof(buf), pid) == -1)
     56 		err(EXIT_FAILURE, "sysctl: %d", pid);
     57 	printf("%s\n", buf);
     58 	return EXIT_SUCCESS;
     59 }
     60