[msan] Re-submit test for process_vm_readv.

Includes a workaround for glibc < 2.15, which does not provide the
function under test.

llvm-svn: 251079

compiler-rt/test/msan/Linux/process_vm_readv.cc

@@ -0,0 +1,66 @@
+// RUN: %clangxx_msan -std=c++11 -O0 %s -o %t && %run %t
+// RUN: %clangxx_msan -std=c++11 -O0 %s -o %t -DPOSITIVE && not %run %t |& FileCheck %s
+
+#include <assert.h>
+#include <dlfcn.h>
+#include <sanitizer/msan_interface.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <unistd.h>
+
+typedef ssize_t (*process_vm_readwritev_fn)(pid_t, const iovec *, unsigned long,
+                                            const iovec *, unsigned long,
+                                            unsigned long);
+
+int main(void) {
+  // This requires glibc 2.15.
+  process_vm_readwritev_fn process_vm_readv =
+      (process_vm_readwritev_fn)dlsym(RTLD_DEFAULT, "process_vm_readv");
+  process_vm_readwritev_fn process_vm_writev =
+      (process_vm_readwritev_fn)dlsym(RTLD_DEFAULT, "process_vm_writev");
+  if (!process_vm_readv) {
+    assert(!process_vm_writev);
+// Exit with success, emulating the expected output.
+#ifdef POSITIVE
+    printf("process_vm_readv not found!\n");
+    printf(
+        "WARNING: MemorySanitizer: use-of-uninitialized-value (not really)\n");
+    return 1;
+#else
+    return 0;
+#endif
+  }
+  assert(process_vm_readv && process_vm_writev);
+
+  char a[100];
+  memset(a, 0xab, 100);
+
+  char b[100];
+  iovec iov_a[] = {{(void *)a, 20}, (void *)(a + 50), 10};
+  iovec iov_b[] = {{(void *)(b + 10), 10}, (void *)(b + 30), 20};
+
+  __msan_poison(&b, sizeof(b));
+  ssize_t res = process_vm_readv(getpid(), iov_b, 2, iov_a, 2, 0);
+  assert(res == 30);
+  __msan_check_mem_is_initialized(b + 10, 10);
+  __msan_check_mem_is_initialized(b + 30, 20);
+  assert(__msan_test_shadow(b + 9, 1) == 0);
+  assert(__msan_test_shadow(b + 20, 1) == 0);
+  assert(__msan_test_shadow(b + 29, 1) == 0);
+  assert(__msan_test_shadow(b + 50, 1) == 0);
+
+#ifdef POSITIVE
+  __msan_unpoison(&b, sizeof(b));
+  __msan_poison(b + 32, 1);
+  res = process_vm_writev(getpid(), iov_b, 2, iov_a, 2, 0);
+// CHECK: WARNING: MemorySanitizer: use-of-uninitialized-value
+#else
+  __msan_unpoison(&b, sizeof(b));
+  res = process_vm_writev(getpid(), iov_b, 2, iov_a, 2, 0);
+  assert(res == 30);
+#endif
+
+  return 0;
+}