1 files changed, 80 insertions, 0 deletions
diff --git a/mozglue/baseprofiler/lul/AutoObjectMapper.cpp b/mozglue/baseprofiler/lul/AutoObjectMapper.cpp
new file mode 100644
index 0000000000..0037c943aa
--- /dev/null
+++ b/mozglue/baseprofiler/lul/AutoObjectMapper.cpp
@@ -0,0 +1,80 @@
+/* -*- 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 <sys/mman.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Sprintf.h"
+
+#include "BaseProfiler.h"
+#include "PlatformMacros.h"
+#include "AutoObjectMapper.h"
+
+// A helper function for creating failure error messages in
+// AutoObjectMapper*::Map.
+static void failedToMessage(void (*aLog)(const char*), const char* aHowFailed,
+                            std::string aFileName) {
+  char buf[300];
+  SprintfLiteral(buf, "AutoObjectMapper::Map: Failed to %s \'%s\'", aHowFailed,
+                 aFileName.c_str());
+  buf[sizeof(buf) - 1] = 0;
+  aLog(buf);
+}
+
+AutoObjectMapperPOSIX::AutoObjectMapperPOSIX(void (*aLog)(const char*))
+    : mImage(nullptr), mSize(0), mLog(aLog), mIsMapped(false) {}
+
+AutoObjectMapperPOSIX::~AutoObjectMapperPOSIX() {
+  if (!mIsMapped) {
+    // There's nothing to do.
+    MOZ_ASSERT(!mImage);
+    MOZ_ASSERT(mSize == 0);
+    return;
+  }
+  MOZ_ASSERT(mSize > 0);
+  // The following assertion doesn't necessarily have to be true,
+  // but we assume (reasonably enough) that no mmap facility would
+  // be crazy enough to map anything at page zero.
+  MOZ_ASSERT(mImage);
+  munmap(mImage, mSize);
+}
+
+bool AutoObjectMapperPOSIX::Map(/*OUT*/ void** start, /*OUT*/ size_t* length,
+                                std::string fileName) {
+  MOZ_ASSERT(!mIsMapped);
+
+  int fd = open(fileName.c_str(), O_RDONLY);
+  if (fd == -1) {
+    failedToMessage(mLog, "open", fileName);
+    return false;
+  }
+
+  struct stat st;
+  int err = fstat(fd, &st);
+  size_t sz = (err == 0) ? st.st_size : 0;
+  if (err != 0 || sz == 0) {
+    failedToMessage(mLog, "fstat", fileName);
+    close(fd);
+    return false;
+  }
+
+  void* image = mmap(nullptr, sz, PROT_READ, MAP_SHARED, fd, 0);
+  if (image == MAP_FAILED) {
+    failedToMessage(mLog, "mmap", fileName);
+    close(fd);
+    return false;
+  }
+
+  close(fd);
+  mIsMapped = true;
+  mImage = *start = image;
+  mSize = *length = sz;
+  return true;
+}