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| // 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"));
fprintf(stderr, "DONE\n");
}
// CHECK-NOT: WARNING: ThreadSanitizer: data race
// CHECK: DONE
|