compctl: Print 'Unexpected hangup' if no reply is received

compctl.c

@@ -63,7 +63,7 @@ run(int argc, char *argv[])
 	fgets(line, sizeof(line), f);
 	fclose(f);
 	if (line[0] != '1') {
-		fputs(line, stderr);
+		fputs(*line ? line : "unexpected hangup\n", stderr);
 		return EXIT_FAILURE;
 	}
 
@@ -96,7 +96,7 @@ stop(pid_t pid)
 	fgets(line, sizeof(line), f);
 	fclose(f);
 	if (line[0] != '1') {
-		fputs(line, stderr);
+		fputs(*line ? line : "unexpected hangup\n", stderr);
 		exit(EXIT_FAILURE);
 	}
 }
@@ -110,7 +110,7 @@ stop_all(void)
 	fgets(line, sizeof(line), f);
 	fclose(f);
 	if (line[0] != '1') {
-		fputs(line, stderr);
+		fputs(*line ? line : "unexpected hangup\n", stderr);
 		exit(EXIT_FAILURE);
 	}
 	fputs(line + 2, stdout);
@@ -126,7 +126,7 @@ limit_mem(size_t limit)
 	fclose(f);
 	if (line[0] != '1') {
 		/* TODO: Error message postprocessing. */
-		fputs(line, stderr);
+		fputs(*line ? line : "unexpected hangup\n", stderr);
 		exit(EXIT_FAILURE);
 	}
 }