Merge pull request #15100 from jaredpar/fix-nuget

Fix NuGet.exe caching

build/scripts/LoadNuGetInfo.cmd

@@ -8,8 +8,5 @@ set NuGetExe=%NuGetExeFolder%\NuGet.exe
 set NuGetAdditionalCommandLineArgs=-verbosity quiet -configfile "%NuGetExeFolder%\nuget.config" -Project2ProjectTimeOut 1200
 
 REM Download NuGet.exe if we haven't already
-if not exist "%NuGetExe%" (
-    echo Downloading NuGet %NuGetExeVersion%
-    powershell -noprofile -executionPolicy Bypass -file "%~dp0download-nuget.ps1" "%NuGetExeVersion%" "%NuGetExeFolder%" || goto :DownloadNuGetFailed
-)
+powershell -noprofile -executionPolicy Bypass -file "%~dp0download-nuget.ps1" "%NuGetExeVersion%" "%NuGetExeFolder%" "%NuGetExeFolder%\Binaries"
 

build/scripts/download-nuget.ps1

 param (
     [string]$nugetVersion = $(throw "Need a nuget version"),
-    [string]$destPath = $(throw "Need a path to download too"))
+    [string]$destDir = $(throw "Need a path to download too"),
+    [string]$binariesDir = $(throw "Need path to Binaries directory"))
 set-strictmode -version 2.0
 $ErrorActionPreference="Stop"
 
-if (-not (test-path $destPath)) {
-    mkdir $destPath | out-null
-}
+try
+{
+    $scratchDir = join-path $binariesDir "NuGet"
+    if (-not (test-path $scratchDir)) {
+        mkdir $scratchDir | out-null
+    }
+
+    if (-not (test-path $destDir)) {
+        mkdir $destDir | out-null
+    }
+
+    $destFile = join-path $destDir "NuGet.exe"
+    $scratchFile = join-path $scratchDir "NuGet.exe"
+    $versionFile = join-path $scratchDir "version.txt"
 
-$webClient = New-Object -TypeName "System.Net.WebClient"
-$webClient.DownloadFile("https://dist.nuget.org/win-x86-commandline/v$nugetVersion/NuGet.exe", (join-path $destPath "NuGet.exe"))
+    # Check and see if we already have a NuGet.exe which exists and is the correct
+    # version.
+    if ((test-path $destFile) -and (test-path $scratchFile) -and (test-path $versionFile)) {
+        $destHash = (get-filehash $destFile -algorithm MD5).Hash
+        $scratchHash = (get-filehash $scratchFile -algorithm MD5).Hash
+        $scratchVersion = gc $versionFile
+        if (($destHash -eq $scratchHash) -and ($scratchVersion -eq $nugetVersion)) {
+            write-host "Using existing NuGet.exe at version $nuGetVersion"
+            exit 0
+        }
+    }
+
+    write-host "Downloading NuGet.exe"
+    $webClient = New-Object -TypeName "System.Net.WebClient"
+    $webClient.DownloadFile("https://dist.nuget.org/win-x86-commandline/v$nugetVersion/NuGet.exe", $scratchFile)
+    $nugetVersion | out-file $versionFile
+    cp $scratchFile $destFile
+    exit 0
+}
+catch [exception]
+{
+    write-host $_.Exception
+    exit -1
+}