From 27da543a41dd2ce01cb0532ea9a615c0f8be2de7 Mon Sep 17 00:00:00 2001
From: Emil Sit <sit@emilsit.net>
Date: Sat, 20 Jul 2013 00:19:05 -0400
Subject: [PATCH] packer/cache: Preserve any extension found on keys

This allows us to hand cache paths to any programs that may want to
interpret file extensions in order to behave differently. For
example, VirtualBox may want ISO images to end with .iso.
---
 packer/cache.go      | 12 +++++++++++-
 packer/cache_test.go | 13 +++++++++----
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/packer/cache.go b/packer/cache.go
index 6c2ed0207..9d69f0c56 100644
--- a/packer/cache.go
+++ b/packer/cache.go
@@ -4,6 +4,7 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"path/filepath"
+	"regexp"
 	"sync"
 )
 
@@ -14,6 +15,9 @@ type Cache interface {
 	// Packer guarantees that no other process will write to this file while
 	// the lock is held.
 	//
+	// If the key has an extension (e.g., file.ext), the resulting path
+	// will have that extension as well.
+	//
 	// The cache will block and wait for the lock.
 	Lock(string) string
 
@@ -68,7 +72,13 @@ func (f *FileCache) RUnlock(key string) {
 }
 
 func (f *FileCache) cachePath(key string, hashKey string) string {
-	return filepath.Join(f.CacheDir, hashKey)
+	var suffixPattern = regexp.MustCompile(`(\.\w+)$`)
+	matches := suffixPattern.FindStringSubmatch(key)
+	suffix := ""
+	if matches != nil {
+		suffix = matches[0]
+	}
+	return filepath.Join(f.CacheDir, hashKey+suffix)
 }
 
 func (f *FileCache) hashKey(key string) string {
diff --git a/packer/cache_test.go b/packer/cache_test.go
index 1be344ecc..5fe6f50d0 100644
--- a/packer/cache_test.go
+++ b/packer/cache_test.go
@@ -3,6 +3,7 @@ package packer
 import (
 	"io/ioutil"
 	"os"
+	"strings"
 	"testing"
 )
 
@@ -36,19 +37,23 @@ func TestFileCache(t *testing.T) {
 	defer os.RemoveAll(cacheDir)
 
 	cache := &FileCache{CacheDir: cacheDir}
-	path := cache.Lock("foo")
+	path := cache.Lock("foo.iso")
+
+	if !strings.HasSuffix(path, ".iso") {
+		t.Fatalf("path doesn't end with suffix '%s': '%s'", ".iso", path)
+	}
 	err = ioutil.WriteFile(path, []byte("data"), 0666)
 	if err != nil {
 		t.Fatalf("error writing: %s", err)
 	}
 
-	cache.Unlock("foo")
+	cache.Unlock("foo.iso")
 
-	path, ok := cache.RLock("foo")
+	path, ok := cache.RLock("foo.iso")
 	if !ok {
 		t.Fatal("cache says key doesn't exist")
 	}
-	defer cache.RUnlock("foo")
+	defer cache.RUnlock("foo.iso")
 
 	data, err := ioutil.ReadFile(path)
 	if err != nil {