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