DMARC-Filter: OpenDMARC Filter v1.4.2 delorie.com 59EIxqjJ3843065
DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 5C1533858D35
MIME-Version: 1.0
Date: Tue, 14 Oct 2025 14:59:11 -0400
Message-ID: <CAAM_cieBo_M76sqZMGgF+tXxswvT=jUHL_pShff+aRv9P1Eiug@mail.gmail.com>
Subject: Windows App execution alias doesn't forward stdin properly
To: cygwin AT cygwin DOT com
From: Cody Tapscott via Cygwin <cygwin AT cygwin DOT com>
Reply-To: Cody Tapscott <cody AT tapscott DOT me>
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Sender: "Cygwin" <cygwin-bounces~archive-cygwin=delorie DOT com AT cygwin DOT com>

Hello,

I'm trying to create a basic console application on Windows:

#include <stdio.h>
#include <string.h>

int main() {
    char buffer[1024];
    fprintf(stdout, "Enter text: ");
    if (fgets(buffer, sizeof(buffer), stdin)) {
        buffer[strcspn(buffer, "\n")] = '\0';
        fprintf(stdout, "You entered: \"%s\"\n", buffer);
    } else {
        fprintf(stderr, "Error reading input.\n");
        return 1;
    }
    return 0;
}

I compile this with MinGW and bundle it into an app with makeappx.exe
from the Windows SDK:
$ x86_64-w64-mingw32-gcc SimpleApp/simple.c -o SimpleApp/simple.exe
$ /cygdrive/c/Program\ Files\ \(x86\)/Windows\
Kits/10/bin/10.0.26100.0/x64/makeappx pack /d SimpleApp /p Simple.msix
...
Package creation succeeded.

Finally I install this in Powershell using:
PS > Add-AppxPackage -Path .\Simple.msix -AllowUnsigned
PS > Get-AppxPackage -Name "SimpleApp.Simple" | Select-Object
-ExpandProperty InstallLocation
C:\Program Files\WindowsApps\SimpleApp.Simple_1.0.0.0_x64__enwe9x4v0qrt

In Windows Terminal / cmd.exe, this seems to work great.

The problem is that an execution alias does not work under Cygwin / MinTTY:
$ simple_console_app.exe # alias requested in AppxManifest.xml
<hangs in fgets() - nothing is printed to terminal>

However using the application directly from its install path works fine:
$ /cygdrive/c/Program\
Files/WindowsApps/SimpleApp.Simple_1.0.0.0_x64__enwe9x4v0qrtw/simple.exe
Enter text: 1+1
You entered: "1+1"

Is this a conpty or related issue? I don't know how Windows implements
its app execution aliases.

For reference, this is my AppxManifest.xml:
<?xml version="1.0" encoding="utf-8"?>

<Package xmlns="http://schemas.microsoft.com/appx/manifest/foundation/windows10"
  xmlns:uap="http://schemas.microsoft.com/appx/manifest/uap/windows10"
  xmlns:uap5="http://schemas.microsoft.com/appx/manifest/uap/windows10/5"
  xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
  xmlns:desktop="http://schemas.microsoft.com/appx/manifest/desktop/windows10"
  xmlns:desktop4="http://schemas.microsoft.com/appx/manifest/desktop/windows10/4"
  IgnorableNamespaces="uap uap5 rescap desktop desktop4">

  <Identity Name="SimpleApp.Simple" Publisher="CN=AppModelSamples,
OID.2.25.311729368913984317654407730594956997722=1" Version="1.0.0.0"
ProcessorArchitecture="x64"/>

  <Properties>
    <DisplayName>SimpleApp</DisplayName>
    <PublisherDisplayName>Simple</PublisherDisplayName>
    <Logo>Logo.png</Logo>
  </Properties>

  <Dependencies>
    <TargetDeviceFamily Name="Windows.Desktop"
MinVersion="10.0.18362.0" MaxVersionTested="10.0.19043.0" />
    <TargetDeviceFamily Name="Windows.Universal"
MinVersion="10.0.18362.0" MaxVersionTested="10.0.19043.0" />
    <PackageDependency Name="Microsoft.VCLibs.140.00.UWPDesktop"
MinVersion="14.0.29231.0" Publisher="CN=Microsoft Corporation,
O=Microsoft Corporation, L=Redmond, S=Washington, C=US" />
  </Dependencies>

  <Resources>
    <Resource Language="en-us"/>
  </Resources>

  <Applications>
    <Application Id="Simple" Executable="simple.exe"
EntryPoint="Windows.FullTrustApplication" desktop4:Subsystem="console"
desktop4:SupportsMultipleInstances="true">
  <uap:VisualElements DisplayName="Simple" Description="Simple console
app" BackgroundColor="transparent" Square150x150Logo="Logo.png"
Square44x44Logo="Logo.png">
        <uap:DefaultTile
          ShortName="SimpleApp">
        </uap:DefaultTile >
      </uap:VisualElements>
      <Extensions>
        <uap5:Extension Category="windows.appExecutionAlias"
Executable="simple.exe" EntryPoint="Windows.FullTrustApplication">
          <uap5:AppExecutionAlias desktop4:Subsystem="console">
            <uap5:ExecutionAlias Alias="simple_console_app.exe" />
          </uap5:AppExecutionAlias>
        </uap5:Extension>
      </Extensions>
    </Application>
  </Applications>

  <Capabilities>
    <rescap:Capability Name="runFullTrust" />
    <rescap:Capability Name="unvirtualizedResources"/>
  </Capabilities>
</Package>

Thanks for any help / insights.

Cody T.

-- 
Problem reports:      https://cygwin.com/problems.html
FAQ:                  https://cygwin.com/faq/
Documentation:        https://cygwin.com/docs.html
Unsubscribe info:     https://cygwin.com/ml/#unsubscribe-simple