executor: use /proc/thread-self/fail-nth instead of /proc/self/task/%…

…d/fail-nth

Makes code slightly simpler.

executor/common_linux.h

@@ -921,15 +921,14 @@ static void remove_dir(const char* dir)
 static int inject_fault(int nth)
 {
 	int fd;
-	char buf[128];
+	char buf[16];
 
-	sprintf(buf, "/proc/self/task/%d/fail-nth", (int)syscall(SYS_gettid));
-	fd = open(buf, O_RDWR);
+	fd = open("/proc/thread-self/fail-nth", O_RDWR);
 	if (fd == -1)
-		fail("failed to open /proc/self/task/tid/fail-nth");
+		fail("failed to open /proc/thread-self/fail-nth");
 	sprintf(buf, "%d", nth + 1);
 	if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
-		fail("failed to write /proc/self/task/tid/fail-nth");
+		fail("failed to write /proc/thread-self/fail-nth");
 	return fd;
 }
 #endif
@@ -940,11 +939,11 @@ static int fault_injected(int fail_fd)
 	char buf[16];
 	int n = read(fail_fd, buf, sizeof(buf) - 1);
 	if (n <= 0)
-		fail("failed to read /proc/self/task/tid/fail-nth");
+		fail("failed to read /proc/thread-self/fail-nth");
 	int res = n == 2 && buf[0] == '0' && buf[1] == '\n';
 	buf[0] = '0';
 	if (write(fail_fd, buf, 1) != 1)
-		fail("failed to write /proc/self/task/tid/fail-nth");
+		fail("failed to write /proc/thread-self/fail-nth");
 	close(fail_fd);
 	return res;
 }