Automate the building of libgit2 native libraries with Powershell

UpdateLibgit2ToSha.ps1

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+<#
+.SYNOPSIS
+	Builds a version of libgit2 and copies it to Lib/NativeBinaries.
+.PARAMETER sha
+	Desired libgit2 version. This is run through `git rev-parse`, so branch names are okay too.
+.PARAMETER vs
+	Version of Visual Studio project files to generate. Cmake supports "10" (default) and "11".
+.PARAMETER test
+	If set, run the libgit2 tests on the desired version.
+.PARAMETER debug
+	If set, build the "Debug" configuration of libgit2, rather than "RelWithDebInfo" (default).
+#>
+
+Param(
+	[string]$sha = 'HEAD',
+	[string]$vs = '10',
+	[switch]$test,
+	[switch]$debug
+)
+
+Set-StrictMode -Version Latest
+
+$self = Split-Path -Leaf $MyInvocation.MyCommand.Path
+$libgit2sharpDirectory = Split-Path $MyInvocation.MyCommand.Path
+$libgit2Directory = Join-Path $libgit2sharpDirectory "libgit2"
+$x86Directory = Join-Path $libgit2sharpDirectory "Lib\NativeBinaries\x86"
+$x64Directory = Join-Path $libgit2sharpDirectory "Lib\NativeBinaries\amd64"
+
+$build_clar = 'OFF'
+if ($test.IsPresent) { $build_clar = 'ON' }
+$configuration = "RelWithDebInfo"
+if ($debug.IsPresent) { $configuration = "Debug" }
+
+function Run-Command([scriptblock]$Command, [switch]$Fatal, [switch]$Quiet) {
+    $output = ""
+    if ($Quiet) {
+        $output = & $Command 2>&1
+    } else {
+        & $Command
+    }
+
+    if (!$Fatal) {
+        return
+    }
+
+    $exitCode = 0
+    if ($LastExitCode -ne 0) {
+        $exitCode = $LastExitCode
+    } elseif (!$?) {
+        $exitCode = 1
+    } else {
+        return
+    }
+
+    $error = "``$Command`` failed"
+    if ($output) {
+        Write-Host -ForegroundColor yellow $output
+        $error += ". See output above."
+    }
+    Throw $error
+}
+
+function Find-CMake {
+    # Look for cmake.exe in $Env:PATH.
+    $cmake = @(Get-Command cmake.exe)[0] 2>$null
+    if ($cmake) {
+        $cmake = $cmake.Definition
+    } else {
+        # Look for the highest-versioned cmake.exe in its default location.
+        $cmake = @(Resolve-Path (Join-Path ${Env:ProgramFiles(x86)} "CMake *\bin\cmake.exe"))
+        if ($cmake) {
+            $cmake = $cmake[-1].Path
+        }
+    }
+    if (!$cmake) {
+        throw "Error: Can't find cmake.exe"
+    }
+    $cmake
+}
+
+function Find-Git {
+	$git = @(Get-Command git)[0] 2>$null
+	if ($git) {
+		$git = $git.Definition
+        Write-Host -ForegroundColor Gray "Using git: $git"
+		& $git --version | write-host -ForegroundColor Gray
+		return $git
+	}
+	throw "Error: Can't find git"
+}
+
+Push-Location $libgit2Directory
+
+& {
+	trap {
+		Pop-Location
+		break
+	}
+
+	$cmake = Find-CMake
+	$ctest = Join-Path (Split-Path -Parent $cmake) "ctest.exe"
+	$git = Find-Git
+
+	Write-Output "Fetching..."
+	Run-Command -Quiet { & $git fetch }
+
+	Write-Output "Verifying $sha..."
+	$sha = & $git rev-parse $sha
+	if ($LASTEXITCODE -ne 0) {
+		write-host -foregroundcolor red "Error: invalid SHA. USAGE: $self <SHA>"
+		popd
+		break
+	}
+
+	Write-Output "Checking out $sha..."
+	Run-Command -Quiet -Fatal { & $git checkout $sha }
+
+	Write-Output "Building 32-bit..."
+	Run-Command -Quiet { & remove-item build -recurse -force }
+	Run-Command -Quiet { & mkdir build }
+	cd build
+	Run-Command -Quiet -Fatal { & $cmake -G "Visual Studio $vs" -D THREADSAFE=ON -D "BUILD_CLAR=$build_clar" .. }
+	Run-Command -Quiet -Fatal { & $cmake --build . --config $configuration }
+	if ($test.IsPresent) { Run-Command -Quiet -Fatal { & $ctest -V . } }
+	cd $configuration
+	Run-Command -Quiet { & rm *.exp }
+	Run-Command -Quiet -Fatal { & copy -fo * $x86Directory }
+
+	Write-Output "Building 64-bit..."
+	cd ..
+	Run-Command -Quiet { & mkdir build64 }
+	cd build64
+	Run-Command -Quiet -Fatal { & $cmake -G "Visual Studio $vs Win64" -D THREADSAFE=ON -D "BUILD_CLAR=$build_clar" ../.. }
+	Run-Command -Quiet -Fatal { & $cmake --build . --config $configuration }
+	if ($test.IsPresent) { Run-Command -Quiet -Fatal { & $ctest -V . } }
+	cd $configuration
+	Run-Command -Quiet { & rm *.exp }
+	Run-Command -Quiet -Fatal { & copy -fo * $x64Directory }
+
+	Write-Output "Done!"
+	pop-location
+	sc -Encoding UTF8 libgit2sharp\libgit2_hash.txt $sha
+}
+exit