Adding a build id check to blob cache.
Add a build id field to the header structure in blob cache. Add build
id support with reading and writing the cache. When the cache gets
written it writes the build id at the end of the header. When read it
checks to see if there is a match between the current version and the
version in the cache. If not, it invalidates the cache which would
typically only occur during an ota update. Also remove blob cache
from the host build.
bug: 18262905
Change-Id: I753b1de1986703a4c1c8691b9d2bb533b2546143
diff --git a/include/utils/BlobCache.h b/include/utils/BlobCache.h
index 7d621e4..65dca9f 100644
--- a/include/utils/BlobCache.h
+++ b/include/utils/BlobCache.h
@@ -185,6 +185,12 @@
// mNumEntries is number of cache entries following the header in the
// data.
size_t mNumEntries;
+
+ // mBuildId is the build id of the device when the cache was created.
+ // When an update to the build happens (via an OTA or other update) this
+ // is used to invalidate the cache.
+ int mBuildIdLength;
+ char mBuildId[];
};
// An EntryHeader is the header for a serialized cache entry. No need to
diff --git a/libutils/Android.mk b/libutils/Android.mk
index f675a94..40cd31e 100644
--- a/libutils/Android.mk
+++ b/libutils/Android.mk
@@ -16,7 +16,6 @@
commonSources:= \
BasicHashtable.cpp \
- BlobCache.cpp \
CallStack.cpp \
FileMap.cpp \
JenkinsHash.cpp \
@@ -74,6 +73,7 @@
# we have the common sources, plus some device-specific stuff
LOCAL_SRC_FILES:= \
$(commonSources) \
+ BlobCache.cpp \
Looper.cpp \
Trace.cpp
@@ -83,7 +83,8 @@
LOCAL_CFLAGS += -Werror
LOCAL_STATIC_LIBRARIES := \
- libcutils
+ libcutils \
+ libc
LOCAL_SHARED_LIBRARIES := \
libbacktrace \
diff --git a/libutils/BlobCache.cpp b/libutils/BlobCache.cpp
index 0ea09cf..126995b 100644
--- a/libutils/BlobCache.cpp
+++ b/libutils/BlobCache.cpp
@@ -25,13 +25,15 @@
#include <utils/Errors.h>
#include <utils/Log.h>
+#include <cutils/properties.h>
+
namespace android {
// BlobCache::Header::mMagicNumber value
static const uint32_t blobCacheMagic = ('_' << 24) + ('B' << 16) + ('b' << 8) + '$';
// BlobCache::Header::mBlobCacheVersion value
-static const uint32_t blobCacheVersion = 2;
+static const uint32_t blobCacheVersion = 3;
// BlobCache::Header::mDeviceVersion value
static const uint32_t blobCacheDeviceVersion = 1;
@@ -165,7 +167,7 @@
}
size_t BlobCache::getFlattenedSize() const {
- size_t size = align4(sizeof(Header));
+ size_t size = align4(sizeof(Header) + PROPERTY_VALUE_MAX);
for (size_t i = 0; i < mCacheEntries.size(); i++) {
const CacheEntry& e(mCacheEntries[i]);
sp<Blob> keyBlob = e.getKey();
@@ -187,10 +189,13 @@
header->mBlobCacheVersion = blobCacheVersion;
header->mDeviceVersion = blobCacheDeviceVersion;
header->mNumEntries = mCacheEntries.size();
+ char buildId[PROPERTY_VALUE_MAX];
+ header->mBuildIdLength = property_get("ro.build.id", buildId, "");
+ memcpy(header->mBuildId, buildId, header->mBuildIdLength);
// Write cache entries
uint8_t* byteBuffer = reinterpret_cast<uint8_t*>(buffer);
- off_t byteOffset = align4(sizeof(Header));
+ off_t byteOffset = align4(sizeof(Header) + header->mBuildIdLength);
for (size_t i = 0; i < mCacheEntries.size(); i++) {
const CacheEntry& e(mCacheEntries[i]);
sp<Blob> keyBlob = e.getKey();
@@ -239,15 +244,19 @@
ALOGE("unflatten: bad magic number: %" PRIu32, header->mMagicNumber);
return BAD_VALUE;
}
+ char buildId[PROPERTY_VALUE_MAX];
+ int len = property_get("ro.build.id", buildId, "");
if (header->mBlobCacheVersion != blobCacheVersion ||
- header->mDeviceVersion != blobCacheDeviceVersion) {
+ header->mDeviceVersion != blobCacheDeviceVersion ||
+ len != header->mBuildIdLength ||
+ strncmp(buildId, header->mBuildId, len)) {
// We treat version mismatches as an empty cache.
return OK;
}
// Read cache entries
const uint8_t* byteBuffer = reinterpret_cast<const uint8_t*>(buffer);
- off_t byteOffset = align4(sizeof(Header));
+ off_t byteOffset = align4(sizeof(Header) + header->mBuildIdLength);
size_t numEntries = header->mNumEntries;
for (size_t i = 0; i < numEntries; i++) {
if (byteOffset + sizeof(EntryHeader) > size) {