Reuse Windows update source cache

install.ps1

@@ -11,6 +11,7 @@ param(
     [string]$BinaryBase = $env:DOSH_BINARY_BASE,
     [string]$BinaryName = $env:DOSH_BINARY_NAME,
     [string]$BinaryVersion = $(if ($env:DOSH_BINARY_VERSION) { $env:DOSH_BINARY_VERSION } else { "latest" }),
+    [string]$UpdateCache = $(if ($env:DOSH_UPDATE_CACHE) { $env:DOSH_UPDATE_CACHE } else { Join-Path $HOME ".cache\dosh\source" }),
     [switch]$BinaryRequired = $($env:DOSH_BINARY_REQUIRED -and $env:DOSH_BINARY_REQUIRED -ne "0"),
     [switch]$ForceConfig
 )
@@ -268,6 +269,27 @@ function Install-Binary($Source, $Destination) {
     }
 }
 
+function Normalize-PathForCompare($Path) {
+    [System.IO.Path]::GetFullPath($Path).TrimEnd(
+        [System.IO.Path]::DirectorySeparatorChar,
+        [System.IO.Path]::AltDirectorySeparatorChar
+    )
+}
+
+function Assert-SafeUpdateCache($Path) {
+    if (-not $Path) {
+        throw "refusing unsafe update cache path: $Path"
+    }
+    $full = Normalize-PathForCompare $Path
+    $root = Normalize-PathForCompare ([System.IO.Path]::GetPathRoot($full))
+    $homePath = Normalize-PathForCompare $HOME
+    $homeCache = Normalize-PathForCompare (Join-Path $HOME ".cache")
+    if ($full -eq $root -or $full -eq $homePath -or $full -eq $homeCache) {
+        throw "refusing unsafe update cache path: $Path"
+    }
+    $full
+}
+
 $bindir = Join-Path $Prefix "bin"
 $configDir = Join-Path $HOME ".config\dosh"
 New-Item -ItemType Directory -Force -Path $bindir, $configDir | Out-Null
@@ -316,7 +338,6 @@ function Install-Prebuilt {
 
 function Install-FromSource {
     Require-Command cargo
-    $tmp = $null
     if (Test-Path "Cargo.toml") {
         $src = (Get-Location).Path
     } else {
@@ -324,9 +345,20 @@ function Install-FromSource {
             throw "DOSH_REPO is required when running the installer from irm/iex"
         }
         Require-Command git
-        $tmp = Join-Path ([System.IO.Path]::GetTempPath()) ("dosh-" + [guid]::NewGuid())
-        git clone --depth 1 $Repo $tmp | Out-Null
-        $src = $tmp
+        $sourceCache = Assert-SafeUpdateCache $UpdateCache
+        $parent = Split-Path -Parent $sourceCache
+        New-Item -ItemType Directory -Force -Path $parent | Out-Null
+        if (Test-Path (Join-Path $sourceCache ".git")) {
+            git -C $sourceCache remote set-url origin $Repo
+            git -C $sourceCache fetch --depth 1 origin main
+            git -C $sourceCache checkout -q -B main FETCH_HEAD
+        } else {
+            if (Test-Path $sourceCache) {
+                Remove-Item -Recurse -Force $sourceCache
+            }
+            git clone --depth 1 --branch main $Repo $sourceCache | Out-Null
+        }
+        $src = $sourceCache
     }
 
     try {
@@ -338,9 +370,6 @@ function Install-FromSource {
     }
     finally {
         Pop-Location
-        if ($tmp) {
-            Remove-Item -Recurse -Force $tmp
-        }
     }
 }
 

tests/release_scripts.rs

@@ -95,6 +95,20 @@ fn installers_refuse_prebuilts_without_checksums() {
     );
 }
 
+#[test]
+fn windows_installer_reuses_persistent_source_update_cache() {
+    let ps1 = include_str!("../install.ps1");
+    assert!(ps1.contains("DOSH_UPDATE_CACHE"));
+    assert!(ps1.contains("$sourceCache = Assert-SafeUpdateCache $UpdateCache"));
+    assert!(ps1.contains("git -C $sourceCache fetch --depth 1 origin main"));
+    assert!(ps1.contains("git -C $sourceCache checkout -q -B main FETCH_HEAD"));
+    assert!(ps1.contains("git clone --depth 1 --branch main $Repo $sourceCache"));
+    assert!(
+        !ps1.contains("git clone --depth 1 $Repo $tmp"),
+        "Windows source updates should reuse a persistent cache instead of recloning into temp"
+    );
+}
+
 #[test]
 fn package_check_verifies_only_artifacts_it_builds() {
     let makefile = include_str!("../Makefile");