Disallow calling Map on currently-mapped SharedMemory

This would leak the previous mapping of the memory.

BUG=

Review URL: https://codereview.chromium.org/195893022

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@257300 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 24 insertions, 2 deletions

diff --git a/base/memory/shared_memory.h b/base/memory/shared_memory.h
index 8e32e72..27c3747 100644
--- a/base/memory/shared_memory.h
+++ b/base/memory/shared_memory.h
@@ -154,7 +154,8 @@ class BASE_EXPORT SharedMemory {
   // Maps the shared memory into the caller's address space.
   // Returns true on success, false otherwise.  The memory address
   // is accessed via the memory() accessor.  The mapped address is guaranteed to
-  // have an alignment of at least MAP_MINIMUM_ALIGNMENT.
+  // have an alignment of at least MAP_MINIMUM_ALIGNMENT. This method will fail
+  // if this object is currently mapped.
   bool Map(size_t bytes) {
     return MapAt(0, bytes);
   }
diff --git a/base/memory/shared_memory_nacl.cc b/base/memory/shared_memory_nacl.cc
index 7647400..39625ee 100644
--- a/base/memory/shared_memory_nacl.cc
+++ b/base/memory/shared_memory_nacl.cc
@@ -91,6 +91,9 @@ bool SharedMemory::MapAt(off_t offset, size_t bytes) {
   if (bytes > static_cast<size_t>(std::numeric_limits<int>::max()))
     return false;
 
+  if (memory_)
+    return false;
+
   memory_ = mmap(NULL, bytes, PROT_READ | (read_only_ ? 0 : PROT_WRITE),
                  MAP_SHARED, mapped_file_, offset);
 
diff --git a/base/memory/shared_memory_posix.cc b/base/memory/shared_memory_posix.cc
index 1a90847..1756c29 100644
--- a/base/memory/shared_memory_posix.cc
+++ b/base/memory/shared_memory_posix.cc
@@ -279,6 +279,9 @@ bool SharedMemory::MapAt(off_t offset, size_t bytes) {
   if (bytes > static_cast<size_t>(std::numeric_limits<int>::max()))
     return false;
 
+  if (memory_)
+    return false;
+
 #if defined(OS_ANDROID)
   // On Android, Map can be called with a size and offset of zero to use the
   // ashmem-determined size.
diff --git a/base/memory/shared_memory_unittest.cc b/base/memory/shared_memory_unittest.cc
index b8999f6..f2a9e74 100644
--- a/base/memory/shared_memory_unittest.cc
+++ b/base/memory/shared_memory_unittest.cc
@@ -477,7 +477,6 @@ TEST(SharedMemoryTest, MapAt) {
 
   SharedMemory memory;
   ASSERT_TRUE(memory.CreateAndMapAnonymous(kDataSize));
-  ASSERT_TRUE(memory.Map(kDataSize));
   uint32* ptr = static_cast<uint32*>(memory.memory());
   ASSERT_NE(ptr, static_cast<void*>(NULL));
 
@@ -497,6 +496,19 @@ TEST(SharedMemoryTest, MapAt) {
   }
 }
 
+TEST(SharedMemoryTest, MapTwice) {
+  const uint32 kDataSize = 1024;
+  SharedMemory memory;
+  bool rv = memory.CreateAndMapAnonymous(kDataSize);
+  EXPECT_TRUE(rv);
+
+  void* old_address = memory.memory();
+
+  rv = memory.Map(kDataSize);
+  EXPECT_FALSE(rv);
+  EXPECT_EQ(old_address, memory.memory());
+}
+
 #if defined(OS_POSIX)
 // Create a shared memory object, mmap it, and mprotect it to PROT_EXEC.
 TEST(SharedMemoryTest, AnonymousExecutable) {
diff --git a/base/memory/shared_memory_win.cc b/base/memory/shared_memory_win.cc
index c9d603e..cc177ab 100644
--- a/base/memory/shared_memory_win.cc
+++ b/base/memory/shared_memory_win.cc
@@ -164,6 +164,9 @@ bool SharedMemory::MapAt(off_t offset, size_t bytes) {
   if (bytes > static_cast<size_t>(std::numeric_limits<int>::max()))
     return false;
 
+  if (memory_)
+    return false;
+
   memory_ = MapViewOfFile(mapped_file_,
                           read_only_ ? FILE_MAP_READ : FILE_MAP_READ |
                               FILE_MAP_WRITE,