fix: make windows installer checksum independent of get-filehash

refs #751

2 files changed, 13 insertions, 1 deletions

diff --git a/src/update.rs b/src/update.rs
index bedcc1b0..bceef7b0 100644
--- a/src/update.rs
+++ b/src/update.rs
@@ -638,6 +638,12 @@ fn install_windows_update_with_installer(channel: UpdateChannel) -> Result<(), S
             "irm https://herdr.dev/install.ps1 | iex",
         ])
         .env("HERDR_CHANNEL", channel.as_str())
+        // Drop any inherited PSModulePath. When herdr is launched from
+        // PowerShell 7, its Core module paths come first and Windows
+        // PowerShell 5.1 (this `powershell`) fails to autoload cmdlets like
+        // Get-FileHash. Removing it lets 5.1 compute its own default path.
+        // See PowerShell/PowerShell#8635.
+        .env_remove("PSModulePath")
         .status()
         .map_err(|err| format!("failed to run Windows installer: {err}"))?;
 
diff --git a/website/install.ps1 b/website/install.ps1
index ccf08239..37ad8f78 100644
--- a/website/install.ps1
+++ b/website/install.ps1
@@ -147,7 +147,13 @@ function Test-FileDigest {
         return
     }
 
-    $actual = (Get-FileHash -LiteralPath $Path -Algorithm SHA256).Hash.ToLowerInvariant()
+    $sha256 = [System.Security.Cryptography.SHA256]::Create()
+    try {
+        $bytes = [System.IO.File]::ReadAllBytes($Path)
+        $actual = [System.BitConverter]::ToString($sha256.ComputeHash($bytes)).Replace("-", "").ToLowerInvariant()
+    } finally {
+        $sha256.Dispose()
+    }
     if ($actual -ne $ExpectedDigest.ToLowerInvariant()) {
         throw "Downloaded Herdr checksum did not match. Expected $ExpectedDigest but got $actual."
     }