dotfiles: give git the ssh.exe that pushes at line rate

core.sshCommand pointed at the in-box System32 client, which reads its stdin
3KB at a time -- the same limit that held an rsync push to ~17MB/s, and it
applies to anything git pushes through it too.  The elevated half now unpacks a
client without that limit beside rsync.exe, so prefer it and keep the in-box one
as the fallback.  Same client from the same source: same ~/.ssh, same ssh-agent
named pipe, same known_hosts.

Candidates are tried by RUNNING them rather than by Test-Path.  The fast build
carries no libcrypto of its own -- it links the one the OpenSSH Client
capability puts in System32 -- so on an image without that capability it is a
file that exists and a binary that will not start, and the next `git push` is a
bad place to discover it.  Two traps in doing that from this script: with
$ErrorActionPreference = 'Stop' a native command's stderr becomes a terminating
error, and `ssh -V` writes its version to stderr, so the WORKING client is the
one that looks broken; and an exe that cannot start never sets $LASTEXITCODE,
leaving the stale 0 from the last native command that did run to read as
success.  Hence the EAP dance and the explicit $global:LASTEXITCODE = $null.

setup-windows.bat runs the elevated half first for this: the fast ssh.exe has to
be on disk before the git config step can prefer it.  The non-elevated half
still runs when the elevated one failed -- nothing in it depends on that half,
and the fallback is the client Windows already has -- and the elevated exit code
is still what the batch file exits with.

Exercised against real binaries under Windows PowerShell 5.1, with
GIT_CONFIG_GLOBAL pointed at a scratch file: fast client present picks
10.0p2, install directory empty falls back to the in-box 9.5p1, a candidate
that exits non-zero and one that cannot start at all both warn and fall back.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01D4ozcQcqMSJBi2Ez4Pfxyc

diff --git a/README.md b/README.md
index 063056a142c969531ac610b8bad1eea65caee9c6..dfe024e6efa0f2594889dcfe22b7e2875302e414 100644 (file)
--- a/README.md
+++ b/README.md
@@ -14,7 +14,7 @@ throwaway VM reachable from a Linux host.
 
 | File | Purpose |
 | --- | --- |
 
 | File | Purpose |
 | --- | --- |

-| `setup-windows.bat` | Entry point. Runs the winget installs, then the non-elevated script, then launches the elevated half and prints its log. |
+| `setup-windows.bat` | Entry point. Runs the winget installs, then launches the elevated half and prints its log, then runs the non-elevated script. |

 | `setup-windows-no-uac.ps1` | The non-elevated, per-user half: WinMerge and BinSkim on the user `PATH`, and the global git config (identity, plus `core.sshCommand`). Can also be run directly from an ordinary prompt. |
 | `setup-windows-with-uac.ps1` | The elevated half, started via UAC by the batch file. Enables `ssh-agent`, installs the OpenSSH Client and Server capabilities and starts `sshd`, unpacks the `rsync-windows` release zip for this architecture (`rsync.exe` plus the `ssh.exe` it runs) into `C:\Tools\rsync` on the machine `PATH`, then installs Visual Studio 2022 Community with the required components, the WDK, and the Windows Performance Toolkit. Can also be run directly from an Administrator prompt. |
 
 | `setup-windows-no-uac.ps1` | The non-elevated, per-user half: WinMerge and BinSkim on the user `PATH`, and the global git config (identity, plus `core.sshCommand`). Can also be run directly from an ordinary prompt. |
 | `setup-windows-with-uac.ps1` | The elevated half, started via UAC by the batch file. Enables `ssh-agent`, installs the OpenSSH Client and Server capabilities and starts `sshd`, unpacks the `rsync-windows` release zip for this architecture (`rsync.exe` plus the `ssh.exe` it runs) into `C:\Tools\rsync` on the machine `PATH`, then installs Visual Studio 2022 Community with the required components, the WDK, and the Windows Performance Toolkit. Can also be run directly from an Administrator prompt. |
 


@@ -50,15 +50,27 @@ throwaway VM reachable from a Linux host.
 - The elevated half writes a transcript to `setup-windows-uac.log` next to the
   script; the batch file prints it when the elevated window closes. The log is
   gitignored, as it contains local paths.
 - The elevated half writes a transcript to `setup-windows-uac.log` next to the
   script; the batch file prints it when the elevated window closes. The log is
   gitignored, as it contains local paths.

-- **git uses the Windows SSH client.** `setup-windows-no-uac.ps1` sets
-  `core.sshCommand` to `%WINDIR%/System32/OpenSSH/ssh.exe`. Git for Windows
-  otherwise prefers its own bundled MSYS2 `ssh.exe`, which cannot reach the
-  Windows `ssh-agent` service that the elevated half enables - Win32-OpenSSH
-  publishes the agent on a named pipe the MSYS2 build does not speak. Without
-  this, keys loaded with `ssh-add` from PowerShell are invisible to `git`, and a
-  push falls back to hunting for a key file and prompting for its passphrase.
-  The value uses forward slashes on purpose: git parses `core.sshCommand` with
-  shell quoting rules, in which a backslash is an escape character.
+- **git uses a Win32-OpenSSH client.** `setup-windows-no-uac.ps1` sets
+  `core.sshCommand`. Git for Windows otherwise prefers its own bundled MSYS2
+  `ssh.exe`, which cannot reach the Windows `ssh-agent` service that the elevated
+  half enables - Win32-OpenSSH publishes the agent on a named pipe the MSYS2
+  build does not speak. Without this, keys loaded with `ssh-add` from PowerShell
+  are invisible to `git`, and a push falls back to hunting for a key file and
+  prompting for its passphrase. The value uses forward slashes on purpose: git
+  parses `core.sshCommand` with shell quoting rules, in which a backslash is an
+  escape character.
+- **Which `ssh.exe` git gets.** `C:\Tools\rsync\ssh.exe` — the fast build the
+  elevated half unpacks — if it is there, `%WINDIR%/System32/OpenSSH/ssh.exe`
+  otherwise. It is the same client with the same `~/.ssh`, agent and
+  `known_hosts`; the difference is the stdin pump, and without it anything git
+  *pushes* is capped at ~17 MB/s. Candidates are tried by **running** them
+  (`ssh -V`), not by `Test-Path`: the fast build needs a `libcrypto.dll` that an
+  image without the OpenSSH Client capability does not have, and a client that
+  will not start should be found here rather than on the next `git push`.
+  This is also why `setup-windows.bat` now runs the elevated half **first** — the
+  fast `ssh.exe` has to exist before the git config step can prefer it. The
+  non-elevated half still runs even when the elevated one failed; it just falls
+  back. Re-run `setup-windows-no-uac.ps1` on its own at any time to re-pick.

 - All three scripts are idempotent — re-running skips anything already installed.
   BinSkim in particular checks NuGet for the newest stable version *before*
   downloading: the package is a self-contained .NET build well over 100 MB, and
 - All three scripts are idempotent — re-running skips anything already installed.
   BinSkim in particular checks NuGet for the newest stable version *before*
   downloading: the package is a self-contained .NET build well over 100 MB, and

diff --git a/setup-windows-no-uac.ps1 b/setup-windows-no-uac.ps1
index e1d5bebaca3b37e0932d3a70608c7e8cd5174b61..f6500b8973361bfba96915fed5c2185ccf44ff90 100644 (file)
--- a/setup-windows-no-uac.ps1
+++ b/setup-windows-no-uac.ps1
@@ -14,8 +14,9 @@
     - WinMerge on the user PATH
     - BinSkim (binary hardening analyzer) in %LOCALAPPDATA%\Programs\BinSkim,
       on the user PATH
     - WinMerge on the user PATH
     - BinSkim (binary hardening analyzer) in %LOCALAPPDATA%\Programs\BinSkim,
       on the user PATH

-    - Global git identity, and core.sshCommand pointed at the Windows OpenSSH
-      client so git shares the Windows ssh-agent
+    - Global git identity, and core.sshCommand pointed at a Win32-OpenSSH
+      client so git shares the Windows ssh-agent: the fast ssh.exe the elevated
+      half unpacks beside rsync.exe if it is there, the in-box one otherwise

 
   FILL IN $GitUserName / $GitUserEmail below before the first run.
 
 
   FILL IN $GitUserName / $GitUserEmail below before the first run.
 


@@ -48,6 +49,11 @@ $GitUserEmail = ''   # e.g. 'ada@example.com'
 $BinSkimPackage = 'microsoft.codeanalysis.binskim'
 $BinSkimDir     = Join-Path $env:LOCALAPPDATA 'Programs\BinSkim'
 
 $BinSkimPackage = 'microsoft.codeanalysis.binskim'
 $BinSkimDir     = Join-Path $env:LOCALAPPDATA 'Programs\BinSkim'
 

+# Where the elevated half puts rsync.exe and the ssh.exe it ships with. Only
+# read here, to prefer that ssh.exe for git - keep it in step with $RsyncDir in
+# setup-windows-with-uac.ps1 if you move the install.
+$RsyncDir = 'C:\Tools\rsync'
+

 function Write-Step([string]$Msg) {
     Write-Host "`n==> $Msg" -ForegroundColor Cyan
 }
 function Write-Step([string]$Msg) {
     Write-Host "`n==> $Msg" -ForegroundColor Cyan
 }


@@ -211,18 +217,57 @@ function Set-GlobalGitConfig {
         Write-Host "    identity: $GitUserName <$GitUserEmail>"
     }
 
         Write-Host "    identity: $GitUserName <$GitUserEmail>"
     }
 

-    # --- Make git use the Windows OpenSSH client ---
+    # --- Make git use a Win32-OpenSSH client ---

     # Git for Windows ships its own MSYS2 ssh.exe and prefers it, and that client
     # cannot reach the Windows ssh-agent service that the elevated half enables:
     # Win32-OpenSSH publishes the agent on a named pipe the MSYS2 build does not
     # speak. So keys added with `ssh-add` from PowerShell stay invisible to git,
     # and a push falls back to hunting for a key file and prompting for its
     # Git for Windows ships its own MSYS2 ssh.exe and prefers it, and that client
     # cannot reach the Windows ssh-agent service that the elevated half enables:
     # Win32-OpenSSH publishes the agent on a named pipe the MSYS2 build does not
     # speak. So keys added with `ssh-add` from PowerShell stay invisible to git,
     # and a push falls back to hunting for a key file and prompting for its

-    # passphrase. Pointing core.sshCommand at the in-box ssh.exe gives git the
-    # same client, the same agent, and the same %USERPROFILE%\.ssh\config as
+    # passphrase. Pointing core.sshCommand at a Win32-OpenSSH ssh.exe gives git
+    # the same client, the same agent, and the same %USERPROFILE%\.ssh\config as

     # `ssh` from an ordinary shell.
     # `ssh` from an ordinary shell.

-    $winSsh = Join-Path $env:WINDIR 'System32\OpenSSH\ssh.exe'
-    if (-not (Test-Path $winSsh)) {
-        Write-Warning "No Windows OpenSSH client at $winSsh. Add the 'OpenSSH Client' optional feature and re-run; until then git uses its own bundled ssh.exe, which cannot see keys held by the Windows ssh-agent service."
+    #
+    # Two of those are on the box, and the one beside rsync.exe is preferred.
+    # It is the same client from the same source, with the same ~/.ssh, agent
+    # and known_hosts, built with a pump on its stdin: the in-box one reads
+    # stdin 3KB at a time, which holds anything git PUSHES to ~17MB/s however
+    # fast the link is. It only exists once the elevated half has run, so the
+    # in-box client stays the fallback - and on a first provisioning run from
+    # setup-windows.bat it is the elevated half that runs first, so the fast one
+    # is normally already there.
+    $sshCandidates = @(
+        (Join-Path $RsyncDir 'ssh.exe'),
+        (Join-Path $env:WINDIR 'System32\OpenSSH\ssh.exe')
+    )
+    $winSsh = $null
+    foreach ($cand in $sshCandidates) {
+        if (-not (Test-Path $cand)) { continue }
+        # Run it, rather than just believing the file is there: the build beside
+        # rsync.exe links against the libcrypto.dll the OpenSSH Client capability
+        # puts in System32, and without that capability it is a binary that does
+        # not start. Better to find that out here than on the next `git push`.
+        #
+        # EAP back to Continue for the call: ssh -V writes its version to
+        # STDERR, and with $ErrorActionPreference = 'Stop' a native command's
+        # stderr becomes a terminating RemoteException - so the working client
+        # would look like the broken one.
+        $prevEap = $ErrorActionPreference
+        $ErrorActionPreference = 'Continue'
+        $version = $null
+        # Clear the exit code first, explicitly at global scope. An exe that
+        # cannot start at all - the missing-libcrypto case - throws here without
+        # ever setting one, and the stale 0 from the last native command that DID
+        # run would otherwise read as success. $global: because a bare assignment
+        # would make a local copy that the native call then does not update.
+        $global:LASTEXITCODE = $null
+        try { $version = (& $cand -V 2>&1 | Select-Object -First 1) } catch { }
+        finally { $ErrorActionPreference = $prevEap }
+        if ($LASTEXITCODE -eq 0) { $winSsh = $cand; break }
+        $why = if ($null -eq $LASTEXITCODE) { 'it would not start' } else { "exit $LASTEXITCODE" }
+        Write-Warning "$cand did not run ($why)$(if ($version) { ": $version" })"
+    }
+    if (-not $winSsh) {
+        Write-Warning "No working Win32-OpenSSH client found (looked in $($sshCandidates -join ', ')). Add the 'OpenSSH Client' optional feature and re-run; until then git uses its own bundled ssh.exe, which cannot see keys held by the Windows ssh-agent service."

         return
     }
     # Forward slashes on purpose: git parses core.sshCommand with shell quoting
         return
     }
     # Forward slashes on purpose: git parses core.sshCommand with shell quoting


@@ -230,6 +275,7 @@ function Set-GlobalGitConfig {
     $value = $winSsh -replace '\\', '/'
     & $git config --global core.sshCommand $value
     Write-Host "    core.sshCommand: $value"
     $value = $winSsh -replace '\\', '/'
     & $git config --global core.sshCommand $value
     Write-Host "    core.sshCommand: $value"

+    Write-Host "    $version"

 }
 
 # ---------------------------------------------------------------------------
 }
 
 # ---------------------------------------------------------------------------

diff --git a/setup-windows.bat b/setup-windows.bat
index f69eceda8eea2af3c0bd5ec2ce4ceaf45cc34f09..1d202afd260adbed163662149bdce5c4d9645761 100644 (file)
--- a/setup-windows.bat
+++ b/setup-windows.bat
@@ -17,21 +17,6 @@ winget install WiXToolset.WiXCLI
 @rem which it reads). The installer elevates via UAC.\r
 winget install OpenCppCoverage.OpenCppCoverage\r
 \r
 @rem which it reads). The installer elevates via UAC.\r
 winget install OpenCppCoverage.OpenCppCoverage\r
 \r

-@rem --- Non-elevated PowerShell half ---\r
-@rem WinMerge on the user PATH, BinSkim, and the global git config (identity +\r
-@rem core.sshCommand -> the Windows OpenSSH client, so git shares the Windows\r
-@rem ssh-agent). EDIT THE GIT IDENTITY at the top of setup-windows-no-uac.ps1\r
-@rem before the first run.\r
-@rem\r
-@rem Deliberately NOT elevated: every step writes per-user state (the HKCU PATH,\r
-@rem the .gitconfig under %USERPROFILE%), which the elevated half would write to\r
-@rem the administrator profile instead.\r
-@rem\r
-@rem Non-fatal: these are conveniences, and the elevated half below is the part\r
-@rem worth the UAC prompt. A failure warns and provisioning continues.\r
-powershell -NoProfile -ExecutionPolicy Bypass -File "%~dp0setup-windows-no-uac.ps1"\r
-if not "%ERRORLEVEL%"=="0" echo [setup-windows] WARNING: setup-windows-no-uac.ps1 reported a failure ^(see above^); continuing.\r
-\r

 @rem ---------------------------------------------------------------------------\r
 @rem No package manager needed for the Windows build\r
 @rem\r
 @rem ---------------------------------------------------------------------------\r
 @rem No package manager needed for the Windows build\r
 @rem\r


@@ -59,6 +44,27 @@ if exist "%UAC_LOG%" (
     echo [setup-windows] The elevated window may have been cancelled at the UAC prompt.\r
 )\r
 \r
     echo [setup-windows] The elevated window may have been cancelled at the UAC prompt.\r
 )\r
 \r

+@rem --- Non-elevated PowerShell half ---\r
+@rem WinMerge on the user PATH, BinSkim, and the global git config (identity +\r
+@rem core.sshCommand -> a Win32-OpenSSH client, so git shares the Windows\r
+@rem ssh-agent). EDIT THE GIT IDENTITY at the top of setup-windows-no-uac.ps1\r
+@rem before the first run.\r
+@rem\r
+@rem Deliberately NOT elevated: every step writes per-user state (the HKCU PATH,\r
+@rem the .gitconfig under %USERPROFILE%), which the elevated half would write to\r
+@rem the administrator profile instead.\r
+@rem\r
+@rem AFTER the elevated half on purpose: core.sshCommand prefers the ssh.exe that\r
+@rem half unpacks beside rsync.exe - a push through the in-box client is capped\r
+@rem at ~17MB/s - and it can only prefer it once it is on disk. Run either way,\r
+@rem including when the elevated half failed above: nothing here depends on it,\r
+@rem and the fallback is the in-box client that Windows already has.\r
+@rem\r
+@rem Non-fatal: these are conveniences, and the elevated half is the part worth\r
+@rem the UAC prompt. A failure warns and provisioning continues.\r
+powershell -NoProfile -ExecutionPolicy Bypass -File "%~dp0setup-windows-no-uac.ps1"\r
+if not "%ERRORLEVEL%"=="0" echo [setup-windows] WARNING: setup-windows-no-uac.ps1 reported a failure ^(see above^); continuing.\r
+\r

 if not "%UAC_RC%"=="0" (\r
     echo.\r
     echo [setup-windows] ELEVATED SETUP FAILED ^(exit code %UAC_RC%^). See log above.\r
 if not "%UAC_RC%"=="0" (\r
     echo.\r
     echo [setup-windows] ELEVATED SETUP FAILED ^(exit code %UAC_RC%^). See log above.\r