1 files changed, 60 insertions, 0 deletions
diff --git a/security/sandbox/linux/SandboxLogging.cpp b/security/sandbox/linux/SandboxLogging.cpp
new file mode 100644
index 000000000..19196a75a
--- /dev/null
+++ b/security/sandbox/linux/SandboxLogging.cpp
@@ -0,0 +1,60 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SandboxLogging.h"
+
+#ifdef ANDROID
+#include <android/log.h>
+#endif
+#include <algorithm>
+#include <stdio.h>
+#include <string.h>
+#include <sys/uio.h>
+#include <unistd.h>
+
+#include "base/posix/eintr_wrapper.h"
+
+namespace mozilla {
+
+// Alters an iovec array to remove the first `toDrop` bytes.  This
+// complexity is necessary because writev can return a short write
+// (e.g., if stderr is a pipe and the buffer is almost full).
+static void
+IOVecDrop(struct iovec* iov, int iovcnt, size_t toDrop)
+{
+  while (toDrop > 0 && iovcnt > 0) {
+    size_t toDropHere = std::min(toDrop, iov->iov_len);
+    iov->iov_base = static_cast<char*>(iov->iov_base) + toDropHere;
+    iov->iov_len -= toDropHere;
+    toDrop -= toDropHere;
+    ++iov;
+    --iovcnt;
+  }
+}
+
+void
+SandboxLogError(const char* message)
+{
+#ifdef ANDROID
+  // This uses writev internally and appears to be async signal safe.
+  __android_log_write(ANDROID_LOG_ERROR, "Sandbox", message);
+#endif
+  static const char logPrefix[] = "Sandbox: ", logSuffix[] = "\n";
+  struct iovec iovs[3] = {
+    { const_cast<char*>(logPrefix), sizeof(logPrefix) - 1 },
+    { const_cast<char*>(message), strlen(message) },
+    { const_cast<char*>(logSuffix), sizeof(logSuffix) - 1 },
+  };
+  while (iovs[2].iov_len > 0) {
+    ssize_t written = HANDLE_EINTR(writev(STDERR_FILENO, iovs, 3));
+    if (written <= 0) {
+      break;
+    }
+    IOVecDrop(iovs, 3, static_cast<size_t>(written));
+  }
+}
+
+}