tsan: add a simple syscall test

[dvyukov]

Summary

Add a simple test that uses syscall annotations.
Just to ensure at least basic functionality works.
Also factor out annotated syscall wrappers into a separate
header file as they may be useful for future tests.

compiler-rt/test/tsan/Linux/fork_syscall.cpp

 // RUN: %clangxx_tsan -O1 %s -o %t && %env_tsan_opts=atexit_sleep_ms=50 %run %t 2>&1 | FileCheck %s
 #include "../test.h"
+#include "syscall.h"
 #include <errno.h>
-#include <sanitizer/linux_syscall_hooks.h>
-#include <sys/syscall.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 
 int counter;
 
 static void *incrementer(void *p) {
   for (;;)
     __sync_fetch_and_add(&counter, 1);
   return 0;
 }
 
-int myfork() {
-  __sanitizer_syscall_pre_fork();
-#ifdef SYS_fork
-  int res = syscall(SYS_fork);
-#else
-  int res = syscall(SYS_clone, SIGCHLD, 0);
-#endif
-  __sanitizer_syscall_post_fork(res);
-  return res;
-}
-
 int main() {
-  barrier_init(&barrier, 2);
   pthread_t th1;
   pthread_create(&th1, 0, incrementer, 0);
   for (int i = 0; i < 10; i++) {
     switch (myfork()) {
     default: // parent
       while (wait(0) < 0) {
       }
       fprintf(stderr, ".");

compiler-rt/test/tsan/Linux/syscall.h

+#include <sanitizer/linux_syscall_hooks.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+int myfork() {
+  __sanitizer_syscall_pre_fork();
+#ifdef SYS_fork
+  int res = syscall(SYS_fork);
+#else
+  int res = syscall(SYS_clone, SIGCHLD, 0);
+#endif
+  __sanitizer_syscall_post_fork(res);
+  return res;
+}
+
+int mypipe(int pipefd[2]) {
+  __sanitizer_syscall_pre_pipe(pipefd);
+  int res = syscall(SYS_pipe, pipefd);
+  __sanitizer_syscall_post_pipe(res, pipefd);
+  return res;
+}
+
+int myclose(int fd) {
+  __sanitizer_syscall_pre_close(fd);
+  int res = syscall(SYS_close, fd);
+  __sanitizer_syscall_post_close(res, fd);
+  return res;
+}
+
+ssize_t myread(int fd, void *buf, size_t count) {
+  __sanitizer_syscall_pre_read(fd, buf, count);
+  ssize_t res = syscall(SYS_read, fd, buf, count);
+  __sanitizer_syscall_post_read(res, fd, buf, count);
+  return res;
+}
+
+ssize_t mywrite(int fd, const void *buf, size_t count) {
+  __sanitizer_syscall_pre_write(fd, buf, count);
+  ssize_t res = syscall(SYS_write, fd, buf, count);
+  __sanitizer_syscall_post_write(res, fd, buf, count);
+  return res;
+}

compiler-rt/test/tsan/Linux/syscall.cpp

+// RUN: %clangxx_tsan -O1 %s -o %t && %deflake %run %t 2>&1 | FileCheck %s
+#include "syscall.h"
+#include "../test.h"
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+int pipefd[2];
+char buf[10];
+
+static void *thr(void *p) {
+  barrier_wait(&barrier);
+  mywrite(pipefd[1], buf, sizeof(buf));
+  return 0;
+}
+
+int main() {
+  barrier_init(&barrier, 2);
+  if (mypipe(pipefd))
+    exit((perror("pipe"), 1));
+  mywrite(pipefd[1], buf, sizeof(buf));
+  pthread_t th;
+  pthread_create(&th, 0, thr, 0);
+  myread(pipefd[0], buf, sizeof(buf));
+  barrier_wait(&barrier);
+  pthread_join(th, 0);
+  fprintf(stderr, "DONE\n");
+}
+
+// CHECK: WARNING: ThreadSanitizer: data race
+// CHECK:   Read of size 8
+// CHECK:     #0 mywrite
+// CHECK:     #1 thr
+// CHECK:   Previous write of size 8
+// CHECK:     #0 myread
+// CHECK:     #1 main
+// CHECK: DONE