(Tcl) Unzip Binary File to Stream

Demonstrates how to unzip a large binary file to a stream to allow the application to process the uncompressed bytes chunk by chunk.

Note: This example requires Chilkat v9.5.0.67 or greater.

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load ./chilkat.dll

# This requires the Chilkat Zip API to have been previously unlocked.
# See Unlock Chilkat Zip for sample code.

set zip [new_CkZip]

# First open a .zip.
set success [CkZip_OpenZip $zip "qa_data/zips/big.zip"]
if {$success != 1} then {
    puts [CkZip_lastErrorText $zip]
    delete_CkZip $zip
    exit
}

# Get the entry to be unzipped to a stream..
# entry is a CkZipEntry
set entry [CkZip_GetEntryByIndex $zip 0]
if {[CkZip_get_LastMethodSuccess $zip] != 1} then {
    puts [CkZip_lastErrorText $zip]
    delete_CkZip $zip
    exit
}

set dataStream [new_CkStream]

# unzipTask is a CkTask
set unzipTask [CkZipEntry_UnzipToStreamAsync $entry $dataStream]
if {[CkZipEntry_get_LastMethodSuccess $entry] != 1} then {
    puts [CkZipEntry_lastErrorText $entry]
    delete_CkZipEntry $entry

    delete_CkZip $zip
    delete_CkStream $dataStream
    exit
}

# Start the background unzip thread.
CkTask_Run $unzipTask

# We'll read the uncompressed data chunk-by-chunk and write to an output file.
set fac [new_CkFileAccess]

set success [CkFileAccess_OpenForWrite $fac "qa_output/out.dat"]
if {$success != 1} then {
    puts [CkFileAccess_lastErrorText $fac]
    delete_CkZipEntry $entry

    delete_CkZip $zip
    delete_CkStream $dataStream
    delete_CkFileAccess $fac
    exit
}

# Read the stream.  (this is reading the unzipped file data)
set bd [new_CkBinData]

while {[CkStream_get_EndOfStream $dataStream] != 1} {
    # Get the next chunk of decompressed bytes.
    CkStream_ReadBd $dataStream $bd
    # Do something with it..
    # In this simple example, we'll just write to the file.
    CkFileAccess_FileWriteBd $fac $bd 0 0
    # Clear for the next read.
    CkBinData_Clear $bd
}

CkFileAccess_FileClose $fac

delete_CkZipEntry $entry

delete_CkTask $unzipTask

puts "Success."

delete_CkZip $zip
delete_CkStream $dataStream
delete_CkFileAccess $fac
delete_CkBinData $bd