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Compress the backup output stream

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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
This commit is contained in:
Christopher Tate 2011-07-11 11:31:57 -07:00 • committed by Alex Ray
parent 37ba34b487
commit 8c79cc91e4
1 changed files with 12 additions and 4 deletions
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16
libs/utils/BackupHelpers.cpp
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@ -481,6 +481,14 @@ static int write_pax_header_entry(char* buf, const char* key, const char* value)
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 @@ int write_tarfile(const String8& packageName, const String8& domain,
// 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 @@ int write_tarfile(const String8& packageName, const String8& domain,
memset(buf + nRead, 0, remainder);
nRead += remainder;
}
writer->WriteEntityData(buf, nRead);
send_tarfile_chunk(writer, buf, nRead);
toWrite -= nRead;
}
}