Check CPU pinning

example_problems/hello/submissions/wrong_answer/test-cpu-pinning.c

@@ -0,0 +1,72 @@
+/*
+ * This code forks 10 children and checks that those run on the same
+ * CPU core as the parent. Since we're normally doing CPU pinning,
+ * this should be true and the program generates a WRONG-ANWSER.
+ * If there's a mismatch the program will trigger a RUNTIME-ERROR.
+ *
+ * @EXPECTED_RESULTS@: WRONG-ANSWER
+ */
+
+#include <errno.h>
+#include <unistd.h>
+#include <sched.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/wait.h>
+
+extern int errno;
+
+int main()
+{
+	unsigned int parent_cpu, cpu;
+	getcpu(&parent_cpu, NULL);
+	printf("Parent on CPU %d\n", parent_cpu);
+	fflush(NULL);
+
+	for(int i=0; i<10; i++) {
+		if ( fork()==0 ) {
+			// We're in the child
+			getcpu(&cpu, NULL);
+			printf("Child %d on CPU %d\n", i, cpu);
+			fflush(NULL);
+			if ( cpu!=parent_cpu ) {
+				printf("CPU MISMATCH!\n");
+				fflush(NULL);
+				return 1;
+			}
+			return 0;
+		}
+	}
+
+	// Wait for all our children
+	do {
+		pid_t pid;
+		int status;
+		pid = wait(&status);
+		if ( pid==-1 ) {
+			if ( errno==ECHILD ) {
+				printf("Done waiting for all children\n");
+			} else {
+				printf("Error in wait: %s\n", strerror(errno));
+			}
+			fflush(NULL);
+			break;
+		}
+		if ( pid>0 ) {
+			if ( !WIFEXITED(status) ) {
+				printf("Child pid %d terminated abnormally\n", (int)pid);
+				fflush(NULL);
+				return 1;
+			}
+			if ( WEXITSTATUS(status)!=0 ) {
+				printf("Child pid %d terminated with exit status %d\n",
+				       (int)pid, (int)WEXITSTATUS(status));
+				return 1;
+			}
+			printf("Child pid %d terminated\n", (int)pid);
+			fflush(NULL);
+		}
+	} while ( 1 );
+
+	return 0;
+}

judge/runguard.cc

@@ -63,6 +63,8 @@
 #include <sched.h>
 #include <sys/sysinfo.h>
 #include <vector>
+#include <set>
+#include <sstream>
 #include <string>
 #include <utility>
 
@@ -465,6 +467,50 @@ void output_exit_time(int exitcode, double cpudiff)
 	write_meta("time-result","%s",output_timelimit_str[timelimit_reached]);
 }
 
+std::set<unsigned> parse_cpuset(std::string cpus)
+{
+	std::stringstream ss(cpus);
+	std::set<unsigned> result;
+
+	std::string token;
+	while ( getline(ss, token, ',') ) {
+		size_t split = token.find('-');
+		if ( split!=std::string::npos ) {
+			std::string token1 = token.substr(0, split);
+			std::string token2 = token.substr(split+1);
+			size_t len;
+			unsigned cpu1 = std::stoul(token1, &len);
+			if ( len<token1.length() ) error(0, "failed to parse cpuset `%s'", cpus.c_str());
+			unsigned cpu2 = std::stoul(token2, &len);
+			if ( len<token2.length() ) error(0, "failed to parse cpuset `%s'", cpus.c_str());
+			for(unsigned i=cpu1; i<=cpu2; i++) result.insert(i);
+		} else {
+			size_t len;
+			unsigned cpu = std::stoul(token, &len);
+			if ( len<token.length() ) error(0, "failed to parse cpuset `%s'", cpus.c_str());
+			result.insert(cpu);
+		}
+	}
+
+	return result;
+}
+
+std::set<unsigned> read_cpuset(const char *path)
+{
+	FILE *file = fopen(path, "r");
+	if (file == nullptr) error(errno, "opening file `%s'", path);
+
+	char cpuset[1024];
+	if (fgets(cpuset, 1024, file) == nullptr) error(errno, "reading from file `%s'", path);
+
+	size_t len = strlen(cpuset);
+	if (len > 0 && cpuset[len-1] == '\n') cpuset[len-1] = 0;
+
+	if (fclose(file) != 0) error(errno, "closing file `%s'", path);
+
+	return parse_cpuset(cpuset);
+}
+
 void check_remaining_procs()
 {
 	char path[1024];
@@ -494,9 +540,8 @@ void output_cgroup_stats_v1(double *cputime)
 	int ret;
 	if ((ret = cgroup_get_cgroup(cg)) != 0) error(ret,"get cgroup information");
 
-	int64_t max_usage;
-	struct cgroup_controller *cg_controller;
-	cg_controller = cgroup_get_controller(cg, "memory");
+	int64_t max_usage = 0;
+	struct cgroup_controller *cg_controller = cgroup_get_controller(cg, "memory");
 	ret = cgroup_get_value_int64(cg_controller, "memory.memsw.max_usage_in_bytes", &max_usage);
 	if ( ret!=0 ) error(ret,"get cgroup value memory.memsw.max_usage_in_bytes");
 
@@ -516,7 +561,7 @@ void output_cgroup_stats_v1(double *cputime)
 void output_cgroup_stats_v2(double *cputime)
 {
 	struct cgroup *cg;
-	if ( (cg = cgroup_new_cgroup(cgroupname))==NULL ) error(0,"cgroup_new_cgroup");
+	if ( (cg = cgroup_new_cgroup(cgroupname))==nullptr ) error(0,"cgroup_new_cgroup");
 
 	int ret;
 	if ((ret = cgroup_get_cgroup(cg)) != 0) error(ret,"get cgroup information");
@@ -540,7 +585,7 @@ void output_cgroup_stats_v2(double *cputime)
 	while (ret == 0) {
 		verbose("cpu.stat: %s = %s", stat.name, stat.value);
 		if (strcmp(stat.name, "usage_usec") == 0) {
-			long long usec = strtoll(stat.value, NULL, 10);
+			long long usec = strtoll(stat.value, nullptr, 10);
 			*cputime = usec / 1e6;
 		}
 		ret = cgroup_read_stats_next(&handle, &stat);
@@ -549,7 +594,6 @@ void output_cgroup_stats_v2(double *cputime)
 	cgroup_read_stats_end(&handle);
 
 	cgroup_free(&cg);
-
 }
 
 /* Temporary shorthand define for error handling. */
@@ -901,7 +945,7 @@ void setrestrictions()
 
 	/* Put the child process in the cgroup */
 	if (is_cgroup_v2) {
-		const char *controllers[] = { "memory", NULL };
+		const char *controllers[] = { "memory", nullptr };
 		if (cgroup_change_cgroup_path(cgroupname, getpid(), controllers) != 0) {
 			error(0, "Failed to move the process to the cgroup");
 		}
@@ -950,7 +994,7 @@ void setrestrictions()
 	/* Set group-id (must be root for this, so before setting user). */
 	if ( use_group ) {
 		if ( setgid(rungid) ) error(errno,"cannot set group ID to `%d'",rungid);
-		if ( setgroups(0, NULL) ) error(errno,"cannot clear auxiliary groups");
+		if ( setgroups(0, nullptr) ) error(errno,"cannot clear auxiliary groups");
 
 		verbose("using group ID `%d'",rungid);
 	}
@@ -1116,7 +1160,7 @@ int main(int argc, char **argv)
 		case 'u': /* user option: uid or string */
 			use_user = 1;
 			runuser = strdup(optarg);
-			if ( runuser==NULL ) error(errno,"strdup() failed");
+			if ( runuser==nullptr ) error(errno,"strdup() failed");
 			errno = 0;
 			runuid = strtol(optarg,&ptr,10);
 			if ( errno || *ptr!='\0' ) {
@@ -1133,7 +1177,7 @@ int main(int argc, char **argv)
 		case 'g': /* group option: gid or string */
 			use_group = 1;
 			rungroup = strdup(optarg);
-			if ( rungroup==NULL ) error(errno,"strdup() failed");
+			if ( rungroup==nullptr ) error(errno,"strdup() failed");
 			errno = 0;
 			rungid = strtol(optarg,&ptr,10);
 			if ( errno || *ptr!='\0' ) rungid = groupid(optarg);
@@ -1298,14 +1342,12 @@ int main(int argc, char **argv)
 	}
 
 	if ( cpuset!=nullptr && strlen(cpuset)>0 ) {
-		int ret = strtol(cpuset, &ptr, 10);
-		/* check if input is only a single integer */
-		if ( *ptr == '\0' ) {
-			/* check if we have enough cores available */
-			int nprocs = get_nprocs_conf();
-			if ( ret < 0 || ret >= nprocs ) {
-				error(0, "processor ID %d given as cpuset, but only %d cores configured",
-				      ret, nprocs);
+		std::set<unsigned> cpus = parse_cpuset(cpuset);
+		std::set<unsigned> online_cpus = read_cpuset("/sys/devices/system/cpu/online");
+
+		for(unsigned cpu : cpus) {
+			if ( !online_cpus.count(cpu) ) {
+				error(0, "requested pinning on CPU %u which is not online", cpu);
 			}
 		}
 	}
@@ -1488,7 +1530,7 @@ int main(int argc, char **argv)
 				}
 			}
 
-			int r = pselect(nfds+1, &readfds, nullptr, NULL, NULL, &emptymask);
+			int r = pselect(nfds+1, &readfds, nullptr, nullptr, nullptr, &emptymask);
 			if ( r==-1 && errno!=EINTR ) error(errno,"waiting for child data");
 			if (error_in_signalhandler) {
 				error(errno, "error in signal handler, exiting");