SignCheck fails with IOException attempting to write to the error log

[natemcmaster]

I'm attempting to setup SignCheck on https://github.com/aspnet/Extensions, but Microsoft.DotNet.SignCheck.exe always fails while attempting to write an error log file.

Repro
Arguments:

.\Microsoft.DotNet.SignCheck.exe --verbosity Detailed --error-log-file C:\src\aspnet\Extensions\artifacts\logs\signcheck-errors.log --generate-exclusions-file C:\src\aspnet\Extensions\artifacts\logs\signcheck.exclusions.g.txt --input-files C:\src\aspnet\Extensions\artifacts\ --recursive --verify-jar --verify-strongname 

Result
Verification partially completes, but then fails with a fatal error:

Ironically, I believe it is SignCheck.exe that has created the file, because this file is created and contains this:

System.IO.IOException: The process cannot access the file 'C:\src\aspnet\Extensions\artifacts\logs\signcheck-errors.log' because it is being used by another process.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)
   at Microsoft.SignCheck.Verification.SignatureVerificationManager.GetFileVerifierByHeader(String path)
   at Microsoft.SignCheck.Verification.SignatureVerificationManager.GetFileVerifier(String path)
   at Microsoft.SignCheck.Verification.SignatureVerificationManager.VerifyFiles(IEnumerable`1 files)
   at SignCheck.SignCheck.Run()

Details
I'm using SignCheck 1.0.0-beta.18558.2

cc @joeloff

[joeloff]

Is it running multiple instances of the SignCheck?

[natemcmaster]

No. It looks like the same process attempts to open the same file multiple times.

[joeloff]

What happens if you switch to using the shortform parameters, e.g. -e instead of error-log-file? Also, for the input files, if you're giving it a folder, try something like c:\foo*.* and pass -t to scan sub-folders.

I need to check, but I can't recall if it will just scan the files in the folder automatically. That might be a bug.

[joeloff]

Ignore my last comment. I tried the internal version I wrote for WebTools and it's happy with just root folders for the input files. I'll take a look at what's going on here

[natemcmaster]

What happens if you switch to using the shortform parameters, e.g. -e instead of error-log-file?

Same error.

[natemcmaster]

I think I understand why. If the log is in the directory being recursively searched, the tool attempts to open the log file to check for signing.

[joeloff]

Ah, yeah, that might be an issue. I can set up a PR to make sure the error log itself is always excluded.