From 4b9501590eea6c8fe2fdec17dc67811590727559 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sybren=20A=2E=20St=C3=BCvel?= <sybren@blender.org>
Date: Fri, 25 Mar 2022 14:08:09 +0100
Subject: [PATCH] Shaman: only add random suffix to checkout dir if already
 existing

Only add a random suffix to the checkout dir if it is necessary to ensure
uniqueness. If the client-supplied checkout directory doesn't exist yet,
it will be used as-is.
---
 pkg/shaman/checkout/manager.go | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/pkg/shaman/checkout/manager.go b/pkg/shaman/checkout/manager.go
index 1dabdbae..86cfdd77 100644
--- a/pkg/shaman/checkout/manager.go
+++ b/pkg/shaman/checkout/manager.go
@@ -110,11 +110,11 @@ func (m *Manager) PrepareCheckout(checkoutPath string) (ResolvedCheckoutInfo, er
 	defer m.checkoutUniquenessMutex.Unlock()
 
 	var lastErr error
-	// Just try 10 different random tokens. If that still doesn't work, fail.
-	for try := 0; try < 10; try++ {
-		randomisedPath := fmt.Sprintf("%s-%s", checkoutPath, randomisedToken())
+	attemptCheckoutPath := checkoutPath
 
-		checkoutPaths, err := m.pathForCheckout(randomisedPath)
+	// Just try 10 different random suffixes. If that still doesn't work, fail.
+	for try := 0; try < 10; try++ {
+		checkoutPaths, err := m.pathForCheckout(attemptCheckoutPath)
 		if err != nil {
 			return ResolvedCheckoutInfo{}, err
 		}
@@ -127,13 +127,15 @@ func (m *Manager) PrepareCheckout(checkoutPath string) (ResolvedCheckoutInfo, er
 		if stat, err := os.Stat(checkoutPaths.absolutePath); !os.IsNotExist(err) {
 			if err == nil {
 				// No error stat'ing this path, indicating it's an existing checkout.
-				// Just retry another random token.
 				lastErr = ErrCheckoutAlreadyExists
 				if stat.IsDir() {
 					logger.Debug().Msg("shaman: checkout path exists")
 				} else {
 					logger.Warn().Msg("shaman: checkout path exists but is not a directory")
 				}
+
+				// Retry with (another) random suffix.
+				attemptCheckoutPath = fmt.Sprintf("%s-%s", checkoutPath, randomisedToken())
 				continue
 			}
 			// If it's any other error, it's really a problem on our side. Don't retry.