Convert file to Gzip memory stream, then convert that to Base64 before exporting to text file (or var)

Question

How do I change the below so i can use the Gzip data with [System.Convert]::ToBase64String() instead of an outfile then send THAT output(the b64) to an outfile

**I Received these answers from help on a previous post from an awesome member. It was marked as an answer but my goals were misunderstood.

Right now this does INFILE>Compress>OUTFILE, I want to do INFILE>Compress>Convert>OUTBase64

$infile = Get-Item path\to\myfiletocompress.ext
$instream = $infile.OpenRead()
$outstream = (New-Item path\to\mygzfile.gz).OpenWrite()
$gzip = [System.IO.Compression.GZipStream]::new(
    $outstream,
    [System.IO.Compression.CompressionLevel]::Optimal)
$instream.CopyTo($gzip)

$gzip.Dispose()
$outstream.Dispose()
$instream.Dispose()

And with this the reverse, I want to use Base64 for the input from a Var, and have that get converted from base64 first then get decompressed into an outfile.

This is currently INFILE>Decompress>OUTFILE I would like to INBase64>Convert>Decompress>OUTFILE

$infile = Get-Item path\to\mygzfile.gz
$instream = $infile.OpenRead()
$outstream = (New-Item path\to\myexpandedgzfile.ext -Force).OpenWrite()
$gzip = [System.IO.Compression.GZipStream]::new(
    $instream,
    [System.IO.Compression.CompressionMode]::Decompress)
$gzip.CopyTo($outstream)

$gzip.Dispose()
$outstream.Dispose()
$instream.Dispose()

The way I'm doing it now is with no compression, using IO.File ReadAllBytes, WriteAllBytes.

File>B64

[Convert]::ToBase64String([IO.File]::ReadAllBytes('anyfile.ext')) | Out-File 'anyfile.txt"

B64>File

[IO.File]::WriteAllBytes('anyfile.ext', [Convert]::FromBase64String('anyfile.txt'))

I tested the results of using gzip files instead of originals when encoding to B64 and the B64 encoded files were smaller than the originals, so this would be worth it.

---

EDIT: Using the below code with a temp file I can get a working result:

$filename = 'reflect_setup_free_x64.exe'
$infile = Get-Item $filename
$instream = $infile.OpenRead()
$outstream = (New-Item "$filename.gz").OpenWrite()
$gzip = [System.IO.Compression.GZipStream]::new(
    $outstream,
    [System.IO.Compression.CompressionLevel]::Optimal)
$instream.CopyTo($gzip)

$gzip.Dispose()
$outstream.Dispose()
$instream.Dispose()
[Convert]::ToBase64String([IO.File]::ReadAllBytes("$filename.gz")) | SC "$filename-encoded.txt" -NoNewline

But using the updated code in the solution gives me a larger file by min ~20%, something is wrong with it. Fails on decompression as well:

$content = Get-Content 'reflect_setup_free_x64.exe' -Raw
$outstream = [System.IO.MemoryStream]::new()
$gzip = [System.IO.Compression.GZipStream]::new(
    $outstream,
    [System.IO.Compression.CompressionLevel]::Optimal)
$bytes = [System.Text.Encoding]::UTF8.GetBytes($content)
$gzip.Write($bytes, 0, $bytes.Length)
$gzip.Dispose()

# This is the b64 gzip string
[System.Convert]::ToBase64String($outstream.ToArray()) | SC 'reflectencoded.txt'
$outstream.Dispose()

---

And lasty I'm stuck on the reverse command to recreate the file from b64 ->->. This works with a temp file can you show me how to add the stream to this as well? Normally I can pick apart the answers and context to proceed on my own, but i do not understand this yet..

$filename ='reflect_setup_free_x64.exe'
$encoded = GC "$filename-encoded.txt"
[IO.File]::WriteAllBytes("$filename.gz", [Convert]::FromBase64String($encoded))
$infile = Get-Item "$filename.gz"
$instream = $infile.OpenRead()
$outstream = (New-Item "$filename" -Force).OpenWrite()
$gzip = [System.IO.Compression.GZipStream]::new(
    $instream,
    [System.IO.Compression.CompressionMode]::Decompress)
$gzip.CopyTo($outstream)

$gzip.Dispose()
$outstream.Dispose()
$instream.Dispose()

---

LAST EDIT - For the reverse process the below was used:

$filename ='reflect_setup_free_x64.exe'
$encoded = GC "$filename-encoded.txt"
$instream = [System.IO.MemoryStream]::new(
[Convert]::FromBase64String($encoded)
)
$outstream = (New-Item "$filename" -Force).OpenWrite()
$gzip = [System.IO.Compression.GZipStream]::new(
    $instream,
    [System.IO.Compression.CompressionMode]::Decompress)
$gzip.CopyTo($outstream)

$gzip.Dispose()
$outstream.Dispose()
$instream.Dispose()

Answer 1

You need to use a MemoryStream instead of a FileStream.

• For a plain text file or hardcoded string:

# `$content` could also be a hardcoded string here
$content = Get-Content path\to\file.txt -Raw
$outstream = [System.IO.MemoryStream]::new()
$gzip = [System.IO.Compression.GZipStream]::new(
    $outstream,
    [System.IO.Compression.CompressionLevel]::Optimal)
$bytes = [System.Text.Encoding]::UTF8.GetBytes($content)
$gzip.Write($bytes, 0, $bytes.Length)

$gzip.Dispose()
$outstream.Dispose()

# This is the b64 gzip string
[System.Convert]::ToBase64String($outstream.ToArray())

• For a binary:

$filename = 'reflect_setup_free_x64.exe'
$infile = Get-Item $filename
$instream = $infile.OpenRead()
$outstream = [System.IO.MemoryStream]::new()
$gzip = [System.IO.Compression.GZipStream]::new(
    $outstream,
    [System.IO.Compression.CompressionLevel]::Optimal)
$instream.CopyTo($gzip)

$gzip.Dispose()
$outstream.Dispose()
$instream.Dispose()

[Convert]::ToBase64String($outstream.ToArray()) |
    Set-Content "$filename-encoded.txt" -NoNewline

You need to ensure that you will be using the same encoding to read this file back, as explained in previous answer, storing a gzip b64 string in a file (specially if it is a binary) doesn't make sense, [Convert]::ToBase64String(..) should be out of this equation. Gzip b64 is mainly used for transport of data not for storage.