commit e28dd9f756fd7df72e39260e82a7569a3636d0af
author Michael Hoisie <hoisie@google.com> Tue Mar 12 18:15:14 2024 +0000
committer Michael Hoisie <hoisie@google.com> Sat Sep 28 05:49:44 2024 +0000
tree 33e1a587994d105c1ba9426844144143f95699b5
parent 35bb4587b0f6435dfcdb4b7937506239bbd2c4f6

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

libs/androidfw/CursorWindow.cpp

diff --git a/libs/androidfw/CursorWindow.cpp b/libs/androidfw/CursorWindow.cpp
index 5e645cc..cbb1e8f 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() {
     if (mAshmemFd != -1) {
-        ::munmap(mData, mSize);
+        mMappedFile.reset();
         ::close(mAshmemFd);
     } else {
         free(mData);
@@ -75,6 +76,7 @@
 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 @@
         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 @@
         mData = newData;
         mSize = mInflatedSize;
         mSlotsOffset = newSlotsOffset;
+        mMappedFile = std::move(mappedFile);
 
         updateSlotsData();
     }
@@ -130,7 +134,7 @@
 fail:
     LOG(ERROR) << "Failed maybeInflate";
 fail_silent:
-    ::munmap(newData, mInflatedSize);
+    mappedFile.reset();
     ::close(ashmemFd);
     return UNKNOWN_ERROR;
 }
@@ -167,11 +171,12 @@
             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;