tpl: Fix crash when using imageConfig

defaultImageConfigCache is now initialized statically instead of relying on it
being initialized in the reset function.

Fixes #2806

diff --git a/tpl/template_funcs.go b/tpl/template_funcs.go
index db3ba37bc4fbadebd62f5b510cef5bc0907db808..c6bf66106061d9e778731c74426366b0054e1654 100644 (file)
--- a/tpl/template_funcs.go
+++ b/tpl/template_funcs.go
@@ -393,19 +393,23 @@ func ResetCaches() {
 
 // imageConfigCache is a lockable cache for image.Config objects. It must be
 // locked before reading or writing to config.
-var imageConfigCache struct {
-       sync.RWMutex
+type imageConfigCache struct {
        config map[string]image.Config
+       sync.RWMutex
+}
+
+var defaultImageConfigCache = imageConfigCache{
+       config: map[string]image.Config{},
 }
 
 // resetImageConfigCache initializes and resets the imageConfig cache for the
 // imageConfig template function. This should be run once before every batch of
 // template renderers so the cache is cleared for new data.
 func resetImageConfigCache() {
-       imageConfigCache.Lock()
-       defer imageConfigCache.Unlock()
+       defaultImageConfigCache.Lock()
+       defer defaultImageConfigCache.Unlock()
 
-       imageConfigCache.config = map[string]image.Config{}
+       defaultImageConfigCache.config = map[string]image.Config{}
 }
 
 // imageConfig returns the image.Config for the specified path relative to the
@@ -421,9 +425,9 @@ func imageConfig(path interface{}) (image.Config, error) {
        }
 
        // Check cache for image config.
-       imageConfigCache.RLock()
-       config, ok := imageConfigCache.config[filename]
-       imageConfigCache.RUnlock()
+       defaultImageConfigCache.RLock()
+       config, ok := defaultImageConfigCache.config[filename]
+       defaultImageConfigCache.RUnlock()
 
        if ok {
                return config, nil
@@ -436,9 +440,9 @@ func imageConfig(path interface{}) (image.Config, error) {
 
        config, _, err = image.DecodeConfig(f)
 
-       imageConfigCache.Lock()
-       imageConfigCache.config[filename] = config
-       imageConfigCache.Unlock()
+       defaultImageConfigCache.Lock()
+       defaultImageConfigCache.config[filename] = config
+       defaultImageConfigCache.Unlock()
 
        return config, err
 }

diff --git a/tpl/template_funcs_test.go b/tpl/template_funcs_test.go
index 8e167cf819a3eca373409772118d51b0607b9685..0f3519e2daf925fffca76e6697300e69587594bf 100644 (file)
--- a/tpl/template_funcs_test.go
+++ b/tpl/template_funcs_test.go
@@ -629,6 +629,17 @@ func TestImageConfig(t *testing.T) {
                input      []byte
                expected   image.Config
        }{
+               // Make sure that the cache is initialized by default.
+               {
+                       resetCache: false,
+                       path:       "a.png",
+                       input:      blankImage(10, 10),
+                       expected: image.Config{
+                               Width:      10,
+                               Height:     10,
+                               ColorModel: color.NRGBAModel,
+                       },
+               },
                {
                        resetCache: true,
                        path:       "a.png",
@@ -685,8 +696,8 @@ func TestImageConfig(t *testing.T) {
                        t.Errorf("[%d] imageConfig: expected '%v', got '%v'", i, this.expected, result)
                }
 
-               if len(imageConfigCache.config) == 0 {
-                       t.Error("imageConfigCache should have at least 1 item")
+               if len(defaultImageConfigCache.config) == 0 {
+                       t.Error("defaultImageConfigCache should have at least 1 item")
                }
        }
 
@@ -705,8 +716,8 @@ func TestImageConfig(t *testing.T) {
        // test cache clearing
        ResetCaches()
 
-       if len(imageConfigCache.config) != 0 {
-               t.Error("ResetCaches should have cleared imageConfigCache")
+       if len(defaultImageConfigCache.config) != 0 {
+               t.Error("ResetCaches should have cleared defaultImageConfigCache")
        }
 }