Zip file entries with backslashes does not get converted to slashes on nix platforms in FastZip.Extract

[ArtemAvramenko]

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Steps to reproduce

1. Create zip on Windows with backslash separators in paths
2. Extract zip on Linux new FastZip().ExtractZip(storageZipPath, storageBaseFolder)

Expected behavior

Backslashes should be changed to slashes on Linux

Actual behavior

Backslashes extracted as part of filename

Version of SharpZipLib

1.3.0, 1.3.1

Everything works fine in 1.2.0, maybe the bug relates to #54

[piksel]

Whoa, that sounds odd... How did you create that zip file? Zip files should never contain backslashes in the file names: https://p1k.se/appnote.md#s4.4.17.1

What is the output of unzip -Z -l YOUR_FILE.zip?

[ArtemAvramenko]

I use this command to compress files:

powershell Compress-Archive 'c:\my_folder\*' -DestinationPath my_backup.zip

The version of PowerShell is 5.1.18362.1474

[ArtemAvramenko]

Archive:  test.zip
Zip file size: 42183935 bytes, number of entries: 431
-rw----     2.0 fat        0 b-        0 stor 19-Jul-05 10:24 folder\sub\
-rw----     2.0 fat   132135 b-    79653 defN 19-Jul-05 10:00 folder\sub\file.ext
...

[piksel]

Yep, confirmed. Powershell 5 creates zip-files with the wrong directory separator:

❯ unzip -Z -l test-ps5-wildcard.zip
Archive:  test-wildcard.zip
Zip file size: 270 bytes, number of entries: 2
-rw----     2.0 fat        0 b-        0 stor 21-May-25 14:42 TestFolder\TestFile1.txt
-rw----     2.0 fat        0 b-        0 stor 21-May-25 14:42 TestFolder\TestFile2.txt
2 files, 0 bytes uncompressed, 0 bytes compressed:  0.0%

It works correctly in Powershell 7 though:

❯ unzip -Z -l test-ps7-wildcard.zip
Archive:  test-ps7-wildcard.zip
Zip file size: 270 bytes, number of entries: 2
-rw----     2.0 fat        0 b-        0 stor 21-May-25 14:42 TestFolder/TestFile1.txt
-rw----     2.0 fat        0 b-        0 stor 21-May-25 14:42 TestFolder/TestFile2.txt
2 files, 0 bytes uncompressed, 0 bytes compressed:  0.0%

We could do the same thing as infozip does and replace them:

❯ unzip test-ps5-wildcard.zip
Archive:  test-ps5-wildcard.zip
warning:  test-ps5-wildcard.zip appears to use backslashes as path separators
 extracting: TestFolder/TestFile1.txt
 extracting: TestFolder/TestFile2.txt

[piksel]

Reference zip file with backslash (path\file):

UEsDBBQAAAAAAA14uVIAAAAAAAAAAAAAAAAJAAAAcGF0aFxmaWxlUEsBAhQAFAAAAAAADXi5UgAA
AAAAAAAAAAAAAAkAAAAAAAAAAAAAAAAAAAAAAHBhdGhcZmlsZVBLBQYAAAAAAQABADcAAAAnAAAA
AAA=

[Deplored]

I've prepared a patch draft at https://github.com/Deplored/SharpZipLib/commit/f4f5641c7b99bf878a921a77984539867d01a323

[SourceproStudio]

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