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Diffstat (limited to 'test/tsan/fd_dup_norace2.cc')
-rw-r--r-- | test/tsan/fd_dup_norace2.cc | 60 |
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 |