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-rw-r--r--test/tsan/fd_dup_norace2.cc60
1 files changed, 60 insertions, 0 deletions
diff --git a/test/tsan/fd_dup_norace2.cc b/test/tsan/fd_dup_norace2.cc
new file mode 100644
index 000000000000..662c686f33a8
--- /dev/null
+++ b/test/tsan/fd_dup_norace2.cc
@@ -0,0 +1,60 @@
+// RUN: %clangxx_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
+#include "test.h"
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+
+// dup2(oldfd, newfd) races with read(newfd).
+// This is not reported as race because:
+// 1. Some software dups a closed pipe in place of a socket before closing
+// the socket (to prevent races actually).
+// 2. Some daemons dup /dev/null in place of stdin/stdout.
+
+int fd;
+
+void *Thread(void *x) {
+ char buf;
+ int n = read(fd, &buf, 1);
+ if (n != 1) {
+ // This read can "legitimately" fail regadless of the fact that glibc claims
+ // that "there is no instant in the middle of calling dup2 at which new is
+ // closed and not yet a duplicate of old". Strace of the failing runs
+ // looks as follows:
+ //
+ // [pid 122196] open("/dev/urandom", O_RDONLY) = 3
+ // [pid 122196] open("/dev/urandom", O_RDONLY) = 4
+ // Process 122382 attached
+ // [pid 122382] read(3, <unfinished ...>
+ // [pid 122196] dup2(4, 3 <unfinished ...>
+ // [pid 122382] <... read resumed> 0x7fcd139960b7, 1) = -1 EBADF (Bad file descriptor)
+ // [pid 122196] <... dup2 resumed> ) = 3
+ // read failed: n=-1 errno=9
+ //
+ // The failing read does not interfere with what this test tests,
+ // so we just ignore the failure.
+ //
+ // exit(printf("read failed: n=%d errno=%d\n", n, errno));
+ }
+ return 0;
+}
+
+int main() {
+ fd = open("/dev/urandom", O_RDONLY);
+ int fd2 = open("/dev/urandom", O_RDONLY);
+ if (fd == -1 || fd2 == -1)
+ exit(printf("open failed\n"));
+ pthread_t th;
+ pthread_create(&th, 0, Thread, 0);
+ if (dup2(fd2, fd) == -1)
+ exit(printf("dup2 failed\n"));
+ pthread_join(th, 0);
+ if (close(fd) == -1)
+ exit(printf("close failed\n"));
+ if (close(fd2) == -1)
+ exit(printf("close failed\n"));
+ printf("DONE\n");
+}
+
+// CHECK-NOT: WARNING: ThreadSanitizer: data race
+// CHECK: DONE