From 13546aa4058d6f64363a4ff5d8382ed5ee2ddc52 Mon Sep 17 00:00:00 2001
From: DarthSim <darthsim@gmail.com>
Date: Wed, 22 Apr 2020 19:02:05 +0600
Subject: [PATCH] Fix unhandled panics during animated images processing

---
 panic_group.go | 39 +++++++++++++++++++++++++++++++++++++++
 process.go     | 15 ++++++---------
 2 files changed, 45 insertions(+), 9 deletions(-)
 create mode 100644 panic_group.go

diff --git a/panic_group.go b/panic_group.go
new file mode 100644
index 00000000..78a24c41
--- /dev/null
+++ b/panic_group.go
@@ -0,0 +1,39 @@
+package main
+
+import "sync"
+
+type panicGroup struct {
+	wg      sync.WaitGroup
+	errOnce sync.Once
+	err     error
+}
+
+func (g *panicGroup) Wait() error {
+	g.wg.Wait()
+	return g.err
+}
+
+func (g *panicGroup) Go(f func() error) {
+	g.wg.Add(1)
+
+	go func() {
+		defer g.wg.Done()
+		defer func() {
+			if r := recover(); r != nil {
+				if err, ok := r.(error); ok {
+					g.errOnce.Do(func() {
+						g.err = err
+					})
+				} else {
+					panic(r)
+				}
+			}
+		}()
+
+		if err := f(); err != nil {
+			g.errOnce.Do(func() {
+				g.err = err
+			})
+		}
+	}()
+}
diff --git a/process.go b/process.go
index 9cf7a13c..a70293ac 100644
--- a/process.go
+++ b/process.go
@@ -8,7 +8,6 @@ import (
 	"runtime"
 
 	"github.com/imgproxy/imgproxy/v2/imagemeta"
-	"golang.org/x/sync/errgroup"
 )
 
 const msgSmartCropNotSupported = "Smart crop is not supported by used version of libvips"
@@ -546,23 +545,21 @@ func transformAnimated(ctx context.Context, img *vipsImage, data []byte, po *pro
 	po.Watermark.Enabled = false
 	defer func() { po.Watermark.Enabled = watermarkEnabled }()
 
-	var errg errgroup.Group
+	var errg panicGroup
 
 	for i := 0; i < framesCount; i++ {
 		ind := i
 		errg.Go(func() error {
-			frame := new(vipsImage)
+			frames[ind] = new(vipsImage)
 
-			if err = img.Extract(frame, 0, ind*frameHeight, imgWidth, frameHeight); err != nil {
-				return err
+			if ferr := img.Extract(frames[ind], 0, ind*frameHeight, imgWidth, frameHeight); ferr != nil {
+				return ferr
 			}
 
-			if err = transformImage(ctx, frame, nil, po, imgtype); err != nil {
-				return err
+			if ferr := transformImage(ctx, frames[ind], nil, po, imgtype); ferr != nil {
+				return ferr
 			}
 
-			frames[ind] = frame
-
 			return nil
 		})
 	}