Make the BackupHelperDispatcher properly handle multiple helpers.

1 files changed, 251 insertions, 0 deletions

diff --git a/core/jni/android_backup_BackupHelperDispatcher.cpp b/core/jni/android_backup_BackupHelperDispatcher.cpp
new file mode 100644
index 0000000..24d529b
--- /dev/null
+++ b/core/jni/android_backup_BackupHelperDispatcher.cpp
@@ -0,0 +1,251 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "BackupHelperDispatcher_native"
+#include <utils/Log.h>
+
+#include "JNIHelp.h"
+#include <android_runtime/AndroidRuntime.h>
+
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <unistd.h>
+
+
+#define VERSION_1_HEADER 0x01706c48  // 'Hlp'1 little endian
+
+namespace android
+{
+
+struct chunk_header_v1 {
+    int headerSize;
+    int version;
+    int dataSize; // corresponds to Header.chunkSize
+    int nameLength; // not including the NULL terminator, which is not written to the file
+};
+
+// java.io.FileDescriptor
+static jfieldID s_descriptorField = 0;
+static jfieldID s_chunkSizeField = 0;
+static jfieldID s_keyPrefixField = 0;
+
+static int
+readHeader_native(JNIEnv* env, jobject clazz, jobject headerObj, jobject fdObj)
+{
+    chunk_header_v1 flattenedHeader;
+    int fd;
+    ssize_t amt;
+    String8 keyPrefix;
+    char* buf;
+
+    fd = env->GetIntField(fdObj, s_descriptorField);
+
+    amt = read(fd, &flattenedHeader.headerSize, sizeof(flattenedHeader.headerSize));
+    if (amt != sizeof(flattenedHeader.headerSize)) {
+        return -1;
+    }
+
+    int remainingHeader = flattenedHeader.headerSize - sizeof(flattenedHeader.headerSize);
+
+    if (flattenedHeader.headerSize < (int)sizeof(chunk_header_v1)) {
+        LOGW("Skipping unknown header: %d bytes", flattenedHeader.headerSize);
+        if (remainingHeader > 0) {
+            lseek(fd, remainingHeader, SEEK_CUR);
+            // >0 means skip this chunk
+            return 1;
+        }
+    }
+
+    amt = read(fd, &flattenedHeader.version,
+            sizeof(chunk_header_v1)-sizeof(flattenedHeader.headerSize));
+    if (amt <= 0) {
+        LOGW("Failed reading chunk header");
+        return -1;
+    }
+    remainingHeader -= sizeof(chunk_header_v1)-sizeof(flattenedHeader.headerSize);
+
+    if (flattenedHeader.version != VERSION_1_HEADER) {
+        LOGW("Skipping unknown header version: 0x%08x, %d bytes", flattenedHeader.version,
+                flattenedHeader.headerSize);
+        if (remainingHeader > 0) {
+            lseek(fd, remainingHeader, SEEK_CUR);
+            // >0 means skip this chunk
+            return 1;
+        }
+    }
+
+    if (flattenedHeader.dataSize < 0 || flattenedHeader.nameLength < 0 ||
+            remainingHeader < flattenedHeader.nameLength) {
+        LOGW("Malformed V1 header remainingHeader=%d dataSize=%d nameLength=%d", remainingHeader,
+                flattenedHeader.dataSize, flattenedHeader.nameLength);
+        return -1;
+    }
+
+    buf = keyPrefix.lockBuffer(flattenedHeader.nameLength);
+    if (buf == NULL) {
+        LOGW("unable to allocate %d bytes", flattenedHeader.nameLength);
+        return -1;
+    }
+
+    amt = read(fd, buf, flattenedHeader.nameLength);
+
+    keyPrefix.unlockBuffer(flattenedHeader.nameLength);
+
+    remainingHeader -= flattenedHeader.nameLength;
+
+    LOGD("remainingHeader=%d", remainingHeader);
+
+    if (remainingHeader > 0) {
+        lseek(fd, remainingHeader, SEEK_CUR);
+    }
+
+    env->SetIntField(headerObj, s_chunkSizeField, flattenedHeader.dataSize);
+    env->SetObjectField(headerObj, s_keyPrefixField, env->NewStringUTF(keyPrefix.string()));
+
+    return 0;
+}
+
+static int
+skipChunk_native(JNIEnv* env, jobject clazz, jobject fdObj, jint bytesToSkip)
+{
+    int fd;
+
+    fd = env->GetIntField(fdObj, s_descriptorField);
+
+    lseek(fd, bytesToSkip, SEEK_CUR);
+
+    return 0;
+}
+
+static int
+padding_len(int len)
+{
+    len = len % 4;
+    return len == 0 ? len : 4 - len;
+}
+
+static int
+allocateHeader_native(JNIEnv* env, jobject clazz, jobject headerObj, jobject fdObj)
+{
+    int pos;
+    jstring nameObj;
+    int nameLength;
+    int namePadding;
+    int headerSize;
+    int fd;
+
+    fd = env->GetIntField(fdObj, s_descriptorField);
+
+    nameObj = (jstring)env->GetObjectField(headerObj, s_keyPrefixField);
+
+    nameLength = env->GetStringUTFLength(nameObj);
+    namePadding = padding_len(nameLength);
+
+    headerSize = sizeof(chunk_header_v1) + nameLength + namePadding;
+
+    pos = lseek(fd, 0, SEEK_CUR);
+
+    lseek(fd, headerSize, SEEK_CUR);
+    
+    return pos;
+}
+
+static int
+writeHeader_native(JNIEnv* env, jobject clazz, jobject headerObj, jobject fdObj, jint pos)
+{
+    int err;
+    chunk_header_v1 header;
+    int fd;
+    int namePadding;
+    int prevPos;
+    jstring nameObj;
+    const char* buf;
+
+    fd = env->GetIntField(fdObj, s_descriptorField);
+    prevPos = lseek(fd, 0, SEEK_CUR);
+
+    nameObj = (jstring)env->GetObjectField(headerObj, s_keyPrefixField);
+    header.nameLength = env->GetStringUTFLength(nameObj);
+    namePadding = padding_len(header.nameLength);
+
+    header.headerSize = sizeof(chunk_header_v1) + header.nameLength + namePadding;
+    header.version = VERSION_1_HEADER;
+
+    lseek(fd, pos, SEEK_SET);
+    err = write(fd, &header, sizeof(chunk_header_v1));
+    if (err != sizeof(chunk_header_v1)) {
+        return errno;
+    }
+
+    buf = env->GetStringUTFChars(nameObj, NULL);
+    err = write(fd, buf, header.nameLength);
+    env->ReleaseStringUTFChars(nameObj, buf);
+    if (err != header.nameLength) {
+        return errno;
+    }
+
+    if (namePadding != 0) {
+        int zero = 0;
+        err = write(fd, &zero, namePadding);
+        if (err != namePadding) {
+            return errno;
+        }
+    }
+
+    lseek(fd, prevPos, SEEK_SET);
+    return 0;
+}
+
+static const JNINativeMethod g_methods[] = {
+    { "readHeader_native",
+       "(Landroid/backup/BackupHelperDispatcher$Header;Ljava/io/FileDescriptor;)I",
+       (void*)readHeader_native },
+    { "skipChunk_native",
+        "(Ljava/io/FileDescriptor;I)I",
+        (void*)skipChunk_native },
+    { "allocateHeader_native",
+        "(Landroid/backup/BackupHelperDispatcher$Header;Ljava/io/FileDescriptor;)I",
+        (void*)allocateHeader_native },
+    { "writeHeader_native",
+       "(Landroid/backup/BackupHelperDispatcher$Header;Ljava/io/FileDescriptor;I)I",
+       (void*)writeHeader_native },
+};
+
+int register_android_backup_BackupHelperDispatcher(JNIEnv* env)
+{
+    jclass clazz;
+
+    clazz = env->FindClass("java/io/FileDescriptor");
+    LOG_FATAL_IF(clazz == NULL, "Unable to find class java.io.FileDescriptor");
+    s_descriptorField = env->GetFieldID(clazz, "descriptor", "I");
+    LOG_FATAL_IF(s_descriptorField == NULL,
+            "Unable to find descriptor field in java.io.FileDescriptor");
+    
+    clazz = env->FindClass("android/backup/BackupHelperDispatcher$Header");
+    LOG_FATAL_IF(clazz == NULL,
+            "Unable to find class android.backup.BackupHelperDispatcher.Header");
+    s_chunkSizeField = env->GetFieldID(clazz, "chunkSize", "I");
+    LOG_FATAL_IF(s_chunkSizeField == NULL,
+            "Unable to find chunkSize field in android.backup.BackupHelperDispatcher.Header");
+    s_keyPrefixField = env->GetFieldID(clazz, "keyPrefix", "Ljava/lang/String;");
+    LOG_FATAL_IF(s_keyPrefixField == NULL,
+            "Unable to find keyPrefix field in android.backup.BackupHelperDispatcher.Header");
+    
+    return AndroidRuntime::registerNativeMethods(env, "android/backup/BackupHelperDispatcher",
+            g_methods, NELEM(g_methods));
+}
+
+}