Use MappedFile for mmap-related operations in CursorWindow

MappedFile from libbase can encapsulate all mmap and munmap operations.
The advantage to MappedFile is that it is supported on all host
platforms, including Windows. This change is a no-op in terms of
functionality.

Test: Roboelctric SQLiteDatabaseTest
Bug: 317884162
Change-Id: I77b6b5481b64a930ecd2bd5ddf3692e54be60751

2 files changed, 17 insertions, 8 deletions

diff --git a/libs/androidfw/CursorWindow.cpp b/libs/androidfw/CursorWindow.cpp
index 5e645cceea2d..cbb1e8f82838 100644
--- a/libs/androidfw/CursorWindow.cpp
+++ b/libs/androidfw/CursorWindow.cpp
@@ -18,11 +18,12 @@
 
 #include <androidfw/CursorWindow.h>
 
-#include <sys/mman.h>
-
 #include "android-base/logging.h"
+#include "android-base/mapped_file.h"
 #include "cutils/ashmem.h"
 
+using android::base::MappedFile;
+
 namespace android {
 
 /**
@@ -39,7 +40,7 @@ CursorWindow::CursorWindow() {
 
 CursorWindow::~CursorWindow() {
     if (mAshmemFd != -1) {
-        ::munmap(mData, mSize);
+        mMappedFile.reset();
         ::close(mAshmemFd);
     } else {
         free(mData);
@@ -75,6 +76,7 @@ fail_silent:
 status_t CursorWindow::maybeInflate() {
     int ashmemFd = 0;
     void* newData = nullptr;
+    std::unique_ptr<MappedFile> mappedFile;
 
     // Bail early when we can't expand any further
     if (mReadOnly || mSize == mInflatedSize) {
@@ -95,11 +97,12 @@ status_t CursorWindow::maybeInflate() {
         goto fail_silent;
     }
 
-    newData = ::mmap(nullptr, mInflatedSize, PROT_READ | PROT_WRITE, MAP_SHARED, ashmemFd, 0);
-    if (newData == MAP_FAILED) {
+    mappedFile = MappedFile::FromFd(ashmemFd, 0, mInflatedSize, PROT_READ | PROT_WRITE);
+    if (mappedFile == nullptr) {
         PLOG(ERROR) << "Failed mmap";
         goto fail_silent;
     }
+    newData = mappedFile->data();
 
     if (ashmem_set_prot_region(ashmemFd, PROT_READ) < 0) {
         PLOG(ERROR) << "Failed ashmem_set_prot_region";
@@ -120,6 +123,7 @@ status_t CursorWindow::maybeInflate() {
         mData = newData;
         mSize = mInflatedSize;
         mSlotsOffset = newSlotsOffset;
+        mMappedFile = std::move(mappedFile);
 
         updateSlotsData();
     }
@@ -130,7 +134,7 @@ status_t CursorWindow::maybeInflate() {
 fail:
     LOG(ERROR) << "Failed maybeInflate";
 fail_silent:
-    ::munmap(newData, mInflatedSize);
+    mappedFile.reset();
     ::close(ashmemFd);
     return UNKNOWN_ERROR;
 }
@@ -167,11 +171,12 @@ status_t CursorWindow::createFromParcel(Parcel* parcel, CursorWindow** outWindow
             goto fail_silent;
         }
 
-        window->mData = ::mmap(nullptr, window->mSize, PROT_READ, MAP_SHARED, window->mAshmemFd, 0);
-        if (window->mData == MAP_FAILED) {
+        window->mMappedFile = MappedFile::FromFd(window->mAshmemFd, 0, window->mSize, PROT_READ);
+        if (window->mMappedFile == nullptr) {
             PLOG(ERROR) << "Failed mmap";
             goto fail_silent;
         }
+        window->mData = window->mMappedFile->data();
     } else {
         window->mAshmemFd = -1;
 
diff --git a/libs/androidfw/include/androidfw/CursorWindow.h b/libs/androidfw/include/androidfw/CursorWindow.h
index 9ec026a19c4c..c2eac12eb77d 100644
--- a/libs/androidfw/include/androidfw/CursorWindow.h
+++ b/libs/androidfw/include/androidfw/CursorWindow.h
@@ -26,6 +26,8 @@
 #include "binder/Parcel.h"
 #include "utils/String8.h"
 
+#include "android-base/mapped_file.h"
+
 #define LOG_WINDOW(...)
 
 namespace android {
@@ -149,6 +151,8 @@ private:
     String8 mName;
     int mAshmemFd = -1;
     void* mData = nullptr;
+    std::unique_ptr<android::base::MappedFile> mMappedFile;
+
     /**
      * Pointer to the first FieldSlot, used to optimize the extremely
      * hot code path of getFieldSlot().