Compress the backup output stream
Zlib compression, with a full flush between each application's
data. Encryption will be performed on the already-compressed data
once that's implemented.
On restore, the streamed data is similarly uncompressed on the fly.
Change-Id: I19b65c88e759a66527d10913d18fffa9df0bc011
diff --git a/libs/utils/BackupHelpers.cpp b/libs/utils/BackupHelpers.cpp
index 87549fe..7ef30f9 100644
--- a/libs/utils/BackupHelpers.cpp
+++ b/libs/utils/BackupHelpers.cpp
@@ -481,6 +481,14 @@
return sprintf(buf, "%d %s=%s\n", len, key, value);
}
+// Wire format to the backup manager service is chunked: each chunk is prefixed by
+// a 4-byte count of its size. A chunk size of zero (four zero bytes) indicates EOD.
+void send_tarfile_chunk(BackupDataWriter* writer, const char* buffer, size_t size) {
+ uint32_t chunk_size_no = htonl(size);
+ writer->WriteEntityData(&chunk_size_no, 4);
+ if (size != 0) writer->WriteEntityData(buffer, size);
+}
+
int write_tarfile(const String8& packageName, const String8& domain,
const String8& rootpath, const String8& filepath, BackupDataWriter* writer)
{
@@ -660,16 +668,16 @@
// Checksum and write the pax block header
calc_tar_checksum(paxHeader);
- writer->WriteEntityData(paxHeader, 512);
+ send_tarfile_chunk(writer, paxHeader, 512);
// Now write the pax data itself
int paxblocks = (paxLen + 511) / 512;
- writer->WriteEntityData(paxData, 512 * paxblocks);
+ send_tarfile_chunk(writer, paxData, 512 * paxblocks);
}
// Checksum and write the 512-byte ustar file header block to the output
calc_tar_checksum(buf);
- writer->WriteEntityData(buf, 512);
+ send_tarfile_chunk(writer, buf, 512);
// Now write the file data itself, for real files. We honor tar's convention that
// only full 512-byte blocks are sent to write().
@@ -699,7 +707,7 @@
memset(buf + nRead, 0, remainder);
nRead += remainder;
}
- writer->WriteEntityData(buf, nRead);
+ send_tarfile_chunk(writer, buf, nRead);
toWrite -= nRead;
}
}