1 files changed, 81 insertions, 0 deletions
diff --git a/libartbase/base/safe_copy.cc b/libartbase/base/safe_copy.cc
new file mode 100644
index 0000000000..7ba5cbd3e6
--- /dev/null
+++ b/libartbase/base/safe_copy.cc
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "safe_copy.h"
+
+#include <sys/uio.h>
+#include <sys/user.h>
+#include <unistd.h>
+
+#include <algorithm>
+
+#include <android-base/macros.h>
+
+#include "base/bit_utils.h"
+
+namespace art {
+
+ssize_t SafeCopy(void *dst, const void *src, size_t len) {
+#if defined(__linux__)
+  struct iovec dst_iov = {
+    .iov_base = dst,
+    .iov_len = len,
+  };
+
+  // Split up the remote read across page boundaries.
+  // From the manpage:
+  //   A partial read/write may result if one of the remote_iov elements points to an invalid
+  //   memory region in the remote process.
+  //
+  //   Partial transfers apply at the granularity of iovec elements.  These system calls won't
+  //   perform a partial transfer that splits a single iovec element.
+  constexpr size_t kMaxIovecs = 64;
+  struct iovec src_iovs[kMaxIovecs];
+  size_t iovecs_used = 0;
+
+  const char* cur = static_cast<const char*>(src);
+  while (len > 0) {
+    if (iovecs_used == kMaxIovecs) {
+      errno = EINVAL;
+      return -1;
+    }
+
+    src_iovs[iovecs_used].iov_base = const_cast<char*>(cur);
+    if (!IsAlignedParam(cur, PAGE_SIZE)) {
+      src_iovs[iovecs_used].iov_len = AlignUp(cur, PAGE_SIZE) - cur;
+    } else {
+      src_iovs[iovecs_used].iov_len = PAGE_SIZE;
+    }
+
+    src_iovs[iovecs_used].iov_len = std::min(src_iovs[iovecs_used].iov_len, len);
+
+    len -= src_iovs[iovecs_used].iov_len;
+    cur += src_iovs[iovecs_used].iov_len;
+    ++iovecs_used;
+  }
+
+  ssize_t rc = process_vm_readv(getpid(), &dst_iov, 1, src_iovs, iovecs_used, 0);
+  if (rc == -1) {
+    return 0;
+  }
+  return rc;
+#else
+  UNUSED(dst, src, len);
+  return -1;
+#endif
+}
+
+}  // namespace art