(Tcl) File Read Blocks

Demonstrates how to read a file in fixed-size blocks (except for the very last block).

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load ./chilkat.dll

# Demonstrates how to read a file in blocks,
# which can be useful when uploading to cloud storage
# services such as Azure, S3, Google, etc.

# For this example, we're simply writing the blocks
# to an output file, and then checking to see if the
# resulting file contents equals the original file contents.

set dataBlock [new_CkByteData]

set facSrc [new_CkFileAccess]

set facDest [new_CkFileAccess]

set srcPath "qa_data/xml/hamlet.xml"
set destPath "qa_output/hamletOut.xml"

set success [CkFileAccess_OpenForRead $facSrc $srcPath]
set success [CkFileAccess_OpenForWrite $facDest $destPath]
# Assuming success for the example..

# How many 1024-byte blocks?  (Including 1 for the last partial block)
set numBlocks [CkFileAccess_GetNumBlocks $facSrc 1024]

set i 0
while {$i < $numBlocks} {
    set success [CkFileAccess_ReadBlock $facSrc $i 1024 $dataBlock]
    if {[CkFileAccess_get_LastMethodSuccess $facSrc] != 1} then {
        puts [CkFileAccess_lastErrorText $facSrc]
        delete_CkByteData $dataBlock
        delete_CkFileAccess $facSrc
        delete_CkFileAccess $facDest
        exit
    }

    set success [CkFileAccess_FileWrite $facDest $dataBlock]
    if {$success != 1} then {
        puts [CkFileAccess_lastErrorText $facDest]
        delete_CkByteData $dataBlock
        delete_CkFileAccess $facSrc
        delete_CkFileAccess $facDest
        exit
    }

    set i [expr $i + 1]
}

CkFileAccess_FileClose $facSrc
CkFileAccess_FileClose $facDest

set bEqual [CkFileAccess_FileContentsEqual $facSrc $srcPath $destPath]
if {$bEqual != 1} then {
    puts "Something went wrong!"
    delete_CkByteData $dataBlock
    delete_CkFileAccess $facSrc
    delete_CkFileAccess $facDest
    exit
}

puts "File successfully copied by blocks."

delete_CkByteData $dataBlock
delete_CkFileAccess $facSrc
delete_CkFileAccess $facDest