1 files changed, 349 insertions, 0 deletions
diff --git a/libs/utils/BackupData.cpp b/libs/utils/BackupData.cpp
new file mode 100644
index 0000000..cce754a
--- /dev/null
+++ b/libs/utils/BackupData.cpp
@@ -0,0 +1,349 @@
+/*
+ * 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 "backup_data"
+
+#include <utils/BackupHelpers.h>
+#include <utils/ByteOrder.h>
+
+#include <stdio.h>
+#include <unistd.h>
+
+#include <cutils/log.h>
+
+namespace android {
+
+/*
+ * File Format (v1):
+ *
+ * All ints are stored little-endian.
+ *
+ *  - An app_header_v1 struct.
+ *  - The name of the package, utf-8, null terminated, padded to 4-byte boundary.
+ *  - A sequence of zero or more key/value paires (entities), each with
+ *      - A entity_header_v1 struct
+ *      - The key, utf-8, null terminated, padded to 4-byte boundary.
+ *      - The value, padded to 4 byte boundary
+ */
+
+const static int ROUND_UP[4] = { 0, 3, 2, 1 };
+
+static inline size_t
+round_up(size_t n)
+{
+    return n + ROUND_UP[n % 4];
+}
+
+static inline size_t
+padding_extra(size_t n)
+{
+    return ROUND_UP[n % 4];
+}
+
+BackupDataWriter::BackupDataWriter(int fd)
+    :m_fd(fd),
+     m_status(NO_ERROR),
+     m_pos(0),
+     m_entityCount(0)
+{
+}
+
+BackupDataWriter::~BackupDataWriter()
+{
+}
+
+// Pad out anything they've previously written to the next 4 byte boundary.
+status_t
+BackupDataWriter::write_padding_for(int n)
+{
+    ssize_t amt;
+    ssize_t paddingSize;
+
+    paddingSize = padding_extra(n);
+    if (paddingSize > 0) {
+        uint32_t padding = 0xbcbcbcbc;
+        amt = write(m_fd, &padding, paddingSize);
+        if (amt != paddingSize) {
+            m_status = errno;
+            return m_status;
+        }
+        m_pos += amt;
+    }
+    return NO_ERROR;
+}
+
+status_t
+BackupDataWriter::WriteEntityHeader(const String8& key, size_t dataSize)
+{
+    if (m_status != NO_ERROR) {
+        return m_status;
+    }
+
+    ssize_t amt;
+
+    amt = write_padding_for(m_pos);
+    if (amt != 0) {
+        return amt;
+    }
+
+    String8 k;
+    if (m_keyPrefix.length() > 0) {
+        k = m_keyPrefix;
+        k += ":";
+        k += key;
+    } else {
+        k = key;
+    }
+    if (true) {
+        LOGD("Writing entity: prefix='%s' key='%s' dataSize=%d", m_keyPrefix.string(), key.string(),
+                dataSize);
+    }
+
+    entity_header_v1 header;
+    ssize_t keyLen;
+
+    keyLen = k.length();
+
+    header.type = tolel(BACKUP_HEADER_ENTITY_V1);
+    header.keyLen = tolel(keyLen);
+    header.dataSize = tolel(dataSize);
+
+    amt = write(m_fd, &header, sizeof(entity_header_v1));
+    if (amt != sizeof(entity_header_v1)) {
+        m_status = errno;
+        return m_status;
+    }
+    m_pos += amt;
+
+    amt = write(m_fd, k.string(), keyLen+1);
+    if (amt != keyLen+1) {
+        m_status = errno;
+        return m_status;
+    }
+    m_pos += amt;
+
+    amt = write_padding_for(keyLen+1);
+
+    m_entityCount++;
+
+    return amt;
+}
+
+status_t
+BackupDataWriter::WriteEntityData(const void* data, size_t size)
+{
+    if (m_status != NO_ERROR) {
+        return m_status;
+    }
+
+    // We don't write padding here, because they're allowed to call this several
+    // times with smaller buffers.  We write it at the end of WriteEntityHeader
+    // instead.
+    ssize_t amt = write(m_fd, data, size);
+    if (amt != (ssize_t)size) {
+        m_status = errno;
+        return m_status;
+    }
+    m_pos += amt;
+    return NO_ERROR;
+}
+
+void
+BackupDataWriter::SetKeyPrefix(const String8& keyPrefix)
+{
+    m_keyPrefix = keyPrefix;
+}
+
+
+BackupDataReader::BackupDataReader(int fd)
+    :m_fd(fd),
+     m_done(false),
+     m_status(NO_ERROR),
+     m_pos(0),
+     m_entityCount(0)
+{
+    memset(&m_header, 0, sizeof(m_header));
+}
+
+BackupDataReader::~BackupDataReader()
+{
+}
+
+status_t
+BackupDataReader::Status()
+{
+    return m_status;
+}
+
+#define CHECK_SIZE(actual, expected) \
+    do { \
+        if ((actual) != (expected)) { \
+            if ((actual) == 0) { \
+                m_status = EIO; \
+            } else { \
+                m_status = errno; \
+            } \
+            return m_status; \
+        } \
+    } while(0)
+#define SKIP_PADDING() \
+    do { \
+        status_t err = skip_padding(); \
+        if (err != NO_ERROR) { \
+            m_status = err; \
+            return err; \
+        } \
+    } while(0)
+
+status_t
+BackupDataReader::ReadNextHeader(bool* done, int* type)
+{
+    *done = m_done;
+    if (m_status != NO_ERROR) {
+        return m_status;
+    }
+
+    int amt;
+
+    // No error checking here, in case we're at the end of the stream.  Just let read() fail.
+    skip_padding();
+    amt = read(m_fd, &m_header, sizeof(m_header));
+    *done = m_done = (amt == 0);
+    CHECK_SIZE(amt, sizeof(m_header));
+    m_pos += sizeof(m_header);
+    if (type) {
+        *type = m_header.type;
+    }
+
+    // validate and fix up the fields.
+    m_header.type = fromlel(m_header.type);
+    switch (m_header.type)
+    {
+        case BACKUP_HEADER_ENTITY_V1:
+        {
+            m_header.entity.keyLen = fromlel(m_header.entity.keyLen);
+            if (m_header.entity.keyLen <= 0) {
+                LOGD("Entity header at %d has keyLen<=0: 0x%08x\n", (int)m_pos,
+                        (int)m_header.entity.keyLen);
+                m_status = EINVAL;
+            }
+            m_header.entity.dataSize = fromlel(m_header.entity.dataSize);
+            m_entityCount++;
+
+            // read the rest of the header (filename)
+            size_t size = m_header.entity.keyLen;
+            char* buf = m_key.lockBuffer(size);
+            if (buf == NULL) {
+                m_status = ENOMEM;
+                return m_status;
+            }
+            int amt = read(m_fd, buf, size+1);
+            CHECK_SIZE(amt, (int)size+1);
+            m_key.unlockBuffer(size);
+            m_pos += size+1;
+            SKIP_PADDING();
+            m_dataEndPos = m_pos + m_header.entity.dataSize;
+
+            break;
+        }
+        default:
+            LOGD("Chunk header at %d has invalid type: 0x%08x", (int)m_pos, (int)m_header.type);
+            m_status = EINVAL;
+    }
+    
+    return m_status;
+}
+
+bool
+BackupDataReader::HasEntities()
+{
+    return m_status == NO_ERROR && m_header.type == BACKUP_HEADER_ENTITY_V1;
+}
+
+status_t
+BackupDataReader::ReadEntityHeader(String8* key, size_t* dataSize)
+{
+    if (m_status != NO_ERROR) {
+        return m_status;
+    }
+    if (m_header.type != BACKUP_HEADER_ENTITY_V1) {
+        return EINVAL;
+    }
+    *key = m_key;
+    *dataSize = m_header.entity.dataSize;
+    return NO_ERROR;
+}
+
+status_t
+BackupDataReader::SkipEntityData()
+{
+    if (m_status != NO_ERROR) {
+        return m_status;
+    }
+    if (m_header.type != BACKUP_HEADER_ENTITY_V1) {
+        return EINVAL;
+    }
+    if (m_header.entity.dataSize > 0) {
+        int pos = lseek(m_fd, m_dataEndPos, SEEK_SET);
+        return pos == -1 ? (int)errno : (int)NO_ERROR;
+    } else {
+        return NO_ERROR;
+    }
+}
+
+ssize_t
+BackupDataReader::ReadEntityData(void* data, size_t size)
+{
+    if (m_status != NO_ERROR) {
+        return -1;
+    }
+    int remaining = m_dataEndPos - m_pos;
+    //LOGD("ReadEntityData size=%d m_pos=0x%x m_dataEndPos=0x%x remaining=%d\n",
+    //        size, m_pos, m_dataEndPos, remaining);
+    if (remaining <= 0) {
+        return 0;
+    }
+    if (((int)size) > remaining) {
+        size = remaining;
+    }
+    //LOGD("   reading %d bytes", size);
+    int amt = read(m_fd, data, size);
+    if (amt < 0) {
+        m_status = errno;
+        return -1;
+    }
+    m_pos += amt;
+    return amt;
+}
+
+status_t
+BackupDataReader::skip_padding()
+{
+    ssize_t amt;
+    ssize_t paddingSize;
+
+    paddingSize = padding_extra(m_pos);
+    if (paddingSize > 0) {
+        uint32_t padding;
+        amt = read(m_fd, &padding, paddingSize);
+        CHECK_SIZE(amt, paddingSize);
+        m_pos += amt;
+    }
+    return NO_ERROR;
+}
+
+
+} // namespace android