fix(shim): rewrite x64 only system program path for x86 shim

CHANGELOG.md

@@ -32,6 +32,7 @@
 - **core:** Fix substitute handling of substring keys ([#6561](https://github.com/ScoopInstaller/Scoop/issues/6561))
 - **core:** Check `$deprecated_dir` exists before accessing it ([#6574](https://github.com/ScoopInstaller/Scoop/issues/6574))
 - **checkver:** Remove redundant always-true condition in GitHub checkver logic ([#6571](https://github.com/ScoopInstaller/Scoop/issues/6571))
+- **shim:** Fix WoW64 file system redirection for x86 shim executables on x64 OS by rewriting System32/SysWOW64 paths in `.shim` config ([#6619](https://github.com/ScoopInstaller/Scoop/issues/6619))
 
 ### Code Refactoring
 

lib/core.ps1

@@ -21,6 +21,26 @@ function Get-PESubsystem($filePath) {
     }
 }
 
+function Get-PEMachine($filePath) {
+    try {
+        $fileStream = [System.IO.FileStream]::new($filePath, [System.IO.FileMode]::Open, [System.IO.FileAccess]::Read)
+        $binaryReader = [System.IO.BinaryReader]::new($fileStream)
+
+        $fileStream.Seek(0x3C, [System.IO.SeekOrigin]::Begin) | Out-Null
+        $peOffset = $binaryReader.ReadInt32()
+
+        # Machine field is at PE signature (4 bytes) + offset 0 of COFF header
+        $fileStream.Seek($peOffset + 4, [System.IO.SeekOrigin]::Begin) | Out-Null
+
+        return $binaryReader.ReadUInt16()
+    } catch {
+        return 0
+    } finally {
+        $binaryReader.Close()
+        $fileStream.Close()
+    }
+}
+
 function Set-PESubsystem($filePath, $targetSubsystem) {
     try {
         $fileStream = [System.IO.FileStream]::new($filePath, [System.IO.FileMode]::Open, [System.IO.FileAccess]::ReadWrite)
@@ -908,7 +928,27 @@ function shim($path, $global, $name, $arg) {
         # for programs with no awareness of any shell
         warn_on_overwrite "$shim.shim" $path
         Copy-Item (get_shim_path) "$shim.exe" -Force
-        Write-Output "path = `"$resolved_path`"" | Out-UTF8File "$shim.shim"
+
+        $rewrote_path = $resolved_path
+
+        # If the shim exe is x86 on a x64 OS, rewrite paths so the shim resolves correctly:
+        #   System32 -> Sysnative  (x64 resolve x64 program in System32, and it should be Sysnative in x86 program)
+        #   SysWOW64 -> System32   (x64 resolve x86 program in SysWOW64, and it should be System32 in x86 program)
+        $shim_machine = Get-PEMachine "$shim.exe"
+        # 0x014c is IMAGE_FILE_MACHINE_I386
+        # https://learn.microsoft.com/en-us/windows/win32/sysinfo/image-file-machine-constants
+        if ($shim_machine -eq 0x014c -and [System.Environment]::Is64BitOperatingSystem) {
+            $sysdir = [System.IO.Path]::Combine($env:SystemRoot, 'System32')
+            $sysnative = [System.IO.Path]::Combine($env:SystemRoot, 'Sysnative')
+            $syswow = [System.IO.Path]::Combine($env:SystemRoot, 'SysWOW64')
+            if ($rewrote_path -like "$sysdir\*") {
+                $rewrote_path = $rewrote_path -replace [regex]::Escape($sysdir), $sysnative
+            } elseif ($rewrote_path -like "$syswow\*") {
+                $rewrote_path = $rewrote_path -replace [regex]::Escape($syswow), $sysdir
+            }
+        }
+
+        Write-Output "path = `"$rewrote_path`"" | Out-UTF8File "$shim.shim"
         if ($arg) {
             Write-Output "args = $arg" | Out-UTF8File "$shim.shim" -Append
         }

test/Scoop-Core.Tests.ps1

@@ -357,6 +357,71 @@ Describe 'app' -Tag 'Scoop' {
     }
 }
 
+Describe 'Get-PEMachine' -Tag 'Scoop' {
+    It 'returns machine type for a valid PE file' {
+        $shim_path = get_shim_path
+        if ($shim_path -and (Test-Path $shim_path)) {
+            $machine = Get-PEMachine $shim_path
+            # Should be a known machine type (I386 (x86): 0x014c, amd64 (x64): 0x8664, arm64: 0xAA64)
+            # https://learn.microsoft.com/en-us/windows/win32/sysinfo/image-file-machine-constants
+            $machine | Should -BeIn @(0x014c, 0x8664, 0xAA64)
+        } else {
+            Set-ItResult -Skipped -Because 'shim exe not found'
+        }
+    }
+
+    It 'returns 0 for a non-existent file' {
+        Get-PEMachine 'C:\nonexistent\fake.exe' | Should -Be 0
+    }
+
+    It 'returns 0 for a non-PE file' {
+        $working_dir = setup_working 'shim'
+        Get-PEMachine "$working_dir\shim-test.ps1" | Should -Be 0
+    }
+}
+
+Describe 'WoW64 path rewriting in shim' -Tag 'Scoop' {
+    It 'rewrites System32 to Sysnative for x86 shim on x64 OS' {
+        $sysdir = [System.IO.Path]::Combine($env:SystemRoot, 'System32')
+        $sysnative = [System.IO.Path]::Combine($env:SystemRoot, 'Sysnative')
+        $testPath = "$sysdir\notepad.exe"
+
+        if ([System.Environment]::Is64BitOperatingSystem) {
+            $result = $testPath -replace [regex]::Escape($sysdir), $sysnative
+            $result | Should -Be "$sysnative\notepad.exe"
+        } else {
+            Set-ItResult -Skipped -Because 'not a x64 OS'
+        }
+    }
+
+    It 'rewrites SysWOW64 to System32 for x86 shim on x64 OS' {
+        $sysdir = [System.IO.Path]::Combine($env:SystemRoot, 'System32')
+        $syswow = [System.IO.Path]::Combine($env:SystemRoot, 'SysWOW64')
+        $testPath = "$syswow\notepad.exe"
+
+        if ([System.Environment]::Is64BitOperatingSystem) {
+            $result = $testPath -replace [regex]::Escape($syswow), $sysdir
+            $result | Should -Be "$sysdir\notepad.exe"
+        } else {
+            Set-ItResult -Skipped -Because 'not a x64 OS'
+        }
+    }
+
+    It 'does not rewrite paths outside System32 and SysWOW64' {
+        $sysdir = [System.IO.Path]::Combine($env:SystemRoot, 'System32')
+        $syswow = [System.IO.Path]::Combine($env:SystemRoot, 'SysWOW64')
+        $testPath = 'C:\Program Files\test\app.exe'
+
+        $result = $testPath
+        if ($result -like "$sysdir\*") {
+            $result = $result -replace [regex]::Escape($sysdir), 'Sysnative'
+        } elseif ($result -like "$syswow\*") {
+            $result = $result -replace [regex]::Escape($syswow), $sysdir
+        }
+        $result | Should -Be $testPath
+    }
+}
+
 Describe 'Format Architecture String' -Tag 'Scoop' {
     It 'should keep correct architectures' {
         Format-ArchitectureString '32bit' | Should -Be '32bit'