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      1 /*
      2  *  This program is free software; you can redistribute it and/or modify
      3  *  it under the terms of the GNU General Public License version 2.
      4  *
      5  *  This program is distributed in the hope that it will be useful,
      6  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
      7  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      8  *  GNU General Public License for more details.
      9  *
     10  *
     11  * Test that sched_setscheduler() sets errno == EPERM when the requesting
     12  * process  does not have permission to set the scheduling parameters for the
     13  * specified process, or does not have the appropriate privilege to invoke
     14  * sched_setscheduler().
     15  *
     16  * Atempt to change the policy of the process whose ID is 1 which is generally
     17  * belongs to root. This test can not be run by root.
     18  */
     19 
     20 #define _XOPEN_SOURCE 600
     21 #include <stdio.h>
     22 #include <sched.h>
     23 #include <errno.h>
     24 #include <unistd.h>
     25 #include <sys/types.h>
     26 #include <pwd.h>
     27 #include <string.h>
     28 #include "posixtest.h"
     29 
     30 /** Set the euid of this process to a non-root uid */
     31 int set_nonroot()
     32 {
     33 	struct passwd *pw;
     34 	setpwent();
     35 	/* search for the first user which is non root */
     36 	while ((pw = getpwent()) != NULL)
     37 		if (strcmp(pw->pw_name, "root"))
     38 			break;
     39 	endpwent();
     40 	if (pw == NULL) {
     41 		printf("There is no other user than current and root.\n");
     42 		return 1;
     43 	}
     44 
     45 	if (setuid(pw->pw_uid) != 0) {
     46 		if (errno == EPERM) {
     47 			printf
     48 			    ("You don't have permission to change your UID.\n");
     49 			return 1;
     50 		}
     51 		perror("An error occurs when calling seteuid()");
     52 		return 1;
     53 	}
     54 
     55 	printf("Testing with user '%s' (euid: %d)(uid: %d)\n",
     56 	       pw->pw_name, (int)geteuid(), (int)getuid());
     57 	return 0;
     58 }
     59 
     60 int main(void)
     61 {
     62 	int result;
     63 	struct sched_param param;
     64 
     65 	/* We assume process Number 1 is created by root */
     66 	/* and can only be accessed by root */
     67 	/* This test should be run under standard user permissions */
     68 	if (getuid() == 0) {
     69 		if (set_nonroot() != 0) {
     70 			printf("Cannot run this test as non-root user\n");
     71 			return PTS_UNTESTED;
     72 		}
     73 	}
     74 
     75 	param.sched_priority = sched_get_priority_max(SCHED_FIFO);
     76 
     77 	result = sched_setscheduler(1, SCHED_FIFO, &param);
     78 
     79 	if (result == -1 && errno == EPERM) {
     80 		printf("Test PASSED\n");
     81 		return PTS_PASS;
     82 	} else if (errno != EPERM) {
     83 		perror("errno is not EPERM");
     84 		return PTS_FAIL;
     85 	} else {
     86 		printf("The returned code is not -1.\n");
     87 		return PTS_FAIL;
     88 	}
     89 }
     90