Move some of the logic from egl_cache_t into FileBlobCache

HWUI is using BlobCache to implement SkSL shader cache very
similar to egl_cache_t. Create a new class FileBlobCache,
that is used by both egl_cache_t and HWUI. FileBlobCache adds
the logic to save and load the BlobCache from a memory mapped
file.

Test: Built and ran Android. Verified that EGL cache still works
Test: for gmail and calc apps.
Bug: 66740665
Change-Id: Ia4d194963d039a60244f3bc76108844418adc99d
diff --git a/opengl/libs/EGL/egl_cache.cpp b/opengl/libs/EGL/egl_cache.cpp
index 579e422..ec548f3 100644
--- a/opengl/libs/EGL/egl_cache.cpp
+++ b/opengl/libs/EGL/egl_cache.cpp
@@ -20,12 +20,8 @@
 
 #include "egl_display.h"
 
-
 #include <private/EGL/cache.h>
 
-#include <inttypes.h>
-#include <sys/mman.h>
-#include <sys/stat.h>
 #include <unistd.h>
 
 #include <thread>
@@ -37,10 +33,6 @@
 static const size_t maxValueSize = 64 * 1024;
 static const size_t maxTotalSize = 2 * 1024 * 1024;
 
-// Cache file header
-static const char* cacheFileMagic = "EGL$";
-static const size_t cacheFileHeaderSize = 8;
-
 // The time in seconds to wait before saving newly inserted cache entries.
 static const unsigned int deferredSaveDelay = 4;
 
@@ -124,7 +116,9 @@
 
 void egl_cache_t::terminate() {
     std::lock_guard<std::mutex> lock(mMutex);
-    saveBlobCacheLocked();
+    if (mBlobCache) {
+        mBlobCache->writeToFile();
+    }
     mBlobCache = NULL;
 }
 
@@ -146,8 +140,8 @@
             std::thread deferredSaveThread([this]() {
                 sleep(deferredSaveDelay);
                 std::lock_guard<std::mutex> lock(mMutex);
-                if (mInitialized) {
-                    saveBlobCacheLocked();
+                if (mInitialized && mBlobCache) {
+                    mBlobCache->writeToFile();
                 }
                 mSavePending = false;
             });
@@ -179,163 +173,11 @@
 
 BlobCache* egl_cache_t::getBlobCacheLocked() {
     if (mBlobCache == nullptr) {
-        mBlobCache.reset(new BlobCache(maxKeySize, maxValueSize, maxTotalSize));
-        loadBlobCacheLocked();
+        mBlobCache.reset(new FileBlobCache(maxKeySize, maxValueSize, maxTotalSize, mFilename));
     }
     return mBlobCache.get();
 }
 
-static uint32_t crc32c(const uint8_t* buf, size_t len) {
-    const uint32_t polyBits = 0x82F63B78;
-    uint32_t r = 0;
-    for (size_t i = 0; i < len; i++) {
-        r ^= buf[i];
-        for (int j = 0; j < 8; j++) {
-            if (r & 1) {
-                r = (r >> 1) ^ polyBits;
-            } else {
-                r >>= 1;
-            }
-        }
-    }
-    return r;
-}
-
-void egl_cache_t::saveBlobCacheLocked() {
-    if (mFilename.length() > 0 && mBlobCache != NULL) {
-        size_t cacheSize = mBlobCache->getFlattenedSize();
-        size_t headerSize = cacheFileHeaderSize;
-        const char* fname = mFilename.c_str();
-
-        // Try to create the file with no permissions so we can write it
-        // without anyone trying to read it.
-        int fd = open(fname, O_CREAT | O_EXCL | O_RDWR, 0);
-        if (fd == -1) {
-            if (errno == EEXIST) {
-                // The file exists, delete it and try again.
-                if (unlink(fname) == -1) {
-                    // No point in retrying if the unlink failed.
-                    ALOGE("error unlinking cache file %s: %s (%d)", fname,
-                            strerror(errno), errno);
-                    return;
-                }
-                // Retry now that we've unlinked the file.
-                fd = open(fname, O_CREAT | O_EXCL | O_RDWR, 0);
-            }
-            if (fd == -1) {
-                ALOGE("error creating cache file %s: %s (%d)", fname,
-                        strerror(errno), errno);
-                return;
-            }
-        }
-
-        size_t fileSize = headerSize + cacheSize;
-
-        uint8_t* buf = new uint8_t [fileSize];
-        if (!buf) {
-            ALOGE("error allocating buffer for cache contents: %s (%d)",
-                    strerror(errno), errno);
-            close(fd);
-            unlink(fname);
-            return;
-        }
-
-        int err = mBlobCache->flatten(buf + headerSize, cacheSize);
-        if (err < 0) {
-            ALOGE("error writing cache contents: %s (%d)", strerror(-err),
-                    -err);
-            delete [] buf;
-            close(fd);
-            unlink(fname);
-            return;
-        }
-
-        // Write the file magic and CRC
-        memcpy(buf, cacheFileMagic, 4);
-        uint32_t* crc = reinterpret_cast<uint32_t*>(buf + 4);
-        *crc = crc32c(buf + headerSize, cacheSize);
-
-        if (write(fd, buf, fileSize) == -1) {
-            ALOGE("error writing cache file: %s (%d)", strerror(errno),
-                    errno);
-            delete [] buf;
-            close(fd);
-            unlink(fname);
-            return;
-        }
-
-        delete [] buf;
-        fchmod(fd, S_IRUSR);
-        close(fd);
-    }
-}
-
-void egl_cache_t::loadBlobCacheLocked() {
-    if (mFilename.length() > 0) {
-        size_t headerSize = cacheFileHeaderSize;
-
-        int fd = open(mFilename.c_str(), O_RDONLY, 0);
-        if (fd == -1) {
-            if (errno != ENOENT) {
-                ALOGE("error opening cache file %s: %s (%d)", mFilename.c_str(),
-                        strerror(errno), errno);
-            }
-            return;
-        }
-
-        struct stat statBuf;
-        if (fstat(fd, &statBuf) == -1) {
-            ALOGE("error stat'ing cache file: %s (%d)", strerror(errno), errno);
-            close(fd);
-            return;
-        }
-
-        // Sanity check the size before trying to mmap it.
-        size_t fileSize = statBuf.st_size;
-        if (fileSize > maxTotalSize * 2) {
-            ALOGE("cache file is too large: %#" PRIx64,
-                  static_cast<off64_t>(statBuf.st_size));
-            close(fd);
-            return;
-        }
-
-        uint8_t* buf = reinterpret_cast<uint8_t*>(mmap(NULL, fileSize,
-                PROT_READ, MAP_PRIVATE, fd, 0));
-        if (buf == MAP_FAILED) {
-            ALOGE("error mmaping cache file: %s (%d)", strerror(errno),
-                    errno);
-            close(fd);
-            return;
-        }
-
-        // Check the file magic and CRC
-        size_t cacheSize = fileSize - headerSize;
-        if (memcmp(buf, cacheFileMagic, 4) != 0) {
-            ALOGE("cache file has bad mojo");
-            close(fd);
-            return;
-        }
-        uint32_t* crc = reinterpret_cast<uint32_t*>(buf + 4);
-        if (crc32c(buf + headerSize, cacheSize) != *crc) {
-            ALOGE("cache file failed CRC check");
-            close(fd);
-            return;
-        }
-
-        int err = mBlobCache->unflatten(buf + headerSize, cacheSize);
-        if (err < 0) {
-            ALOGE("error reading cache contents: %s (%d)", strerror(-err),
-                    -err);
-            munmap(buf, fileSize);
-            close(fd);
-            return;
-        }
-
-        munmap(buf, fileSize);
-        close(fd);
-    }
-}
-
 // ----------------------------------------------------------------------------
 }; // namespace android
 // ----------------------------------------------------------------------------