Merge pull request #318 from mrunalp/subreaper

Use the child subreaper option only when available

namespaces/nsenter/nsenter.c

@@ -15,10 +15,6 @@
 #include <unistd.h>
 #include <getopt.h>
 
-#ifndef PR_SET_CHILD_SUBREAPER
-#define PR_SET_CHILD_SUBREAPER 36
-#endif
-
 static const kBufSize = 256;
 static const char *kNsEnter = "nsenter";
 
@@ -93,11 +89,13 @@ void nsenter()
 		return;
 	}
 
+	#ifdef PR_SET_CHILD_SUBREAPER
 	if (prctl(PR_SET_CHILD_SUBREAPER, 1, 0, 0, 0) == -1) {
 		fprintf(stderr, "nsenter: failed to set child subreaper: %s",
 			strerror(errno));
 		exit(1);
 	}
+	#endif
 
 	static const struct option longopts[] = {
 		{"nspid", required_argument, NULL, 'n'},