From bb308b1a87ca090d639fb3745b3ef139820a82d7 Mon Sep 17 00:00:00 2001
From: Michel Engelen <32863416+michelengelen@users.noreply.github.com>
Date: Wed, 27 Apr 2022 18:27:06 +0200
Subject: [PATCH] [MM-43393]: replace .Decoder() method with .Token() (#19988)

Automatic Merge
---
 app/imaging/svg.go      | 86 +++++++++++++++++++++++++++--------------
 app/imaging/svg_test.go | 10 +++++
 2 files changed, 67 insertions(+), 29 deletions(-)

diff --git a/app/imaging/svg.go b/app/imaging/svg.go
index c45c134a5a..04defeaa81 100644
--- a/app/imaging/svg.go
+++ b/app/imaging/svg.go
@@ -5,9 +5,9 @@ package imaging
 
 import (
 	"encoding/xml"
+	"fmt"
 	"io"
-	"regexp"
-	"strconv"
+	"strings"
 
 	"github.com/pkg/errors"
 )
@@ -20,39 +20,67 @@ type SVGInfo struct {
 
 // ParseSVG returns information for the given SVG input data.
 func ParseSVG(svgReader io.Reader) (SVGInfo, error) {
-	var parsedSVG struct {
-		Width   string `xml:"width,attr,omitempty"`
-		Height  string `xml:"height,attr,omitempty"`
-		ViewBox string `xml:"viewBox,attr,omitempty"`
-	}
 	svgInfo := SVGInfo{
 		Width:  0,
 		Height: 0,
 	}
-	viewBoxPattern := regexp.MustCompile("^([0-9]+)[, ]+([0-9]+)[, ]+([0-9]+)[, ]+([0-9]+)$")
-	dimensionPattern := regexp.MustCompile("(?i)^([0-9]+)(?:px)?$")
 
-	// decode provided SVG
-	if err := xml.NewDecoder(svgReader).Decode(&parsedSVG); err != nil {
-		return svgInfo, err
-	}
+	decoder := xml.NewDecoder(svgReader)
 
-	// prefer viewbox for SVG dimensions over width/height
-	if viewBoxMatches := viewBoxPattern.FindStringSubmatch(parsedSVG.ViewBox); len(viewBoxMatches) == 5 {
-		svgInfo.Width, _ = strconv.Atoi(viewBoxMatches[3])
-		svgInfo.Height, _ = strconv.Atoi(viewBoxMatches[4])
-	} else if parsedSVG.Width != "" && parsedSVG.Height != "" {
-		widthMatches := dimensionPattern.FindStringSubmatch(parsedSVG.Width)
-		heightMatches := dimensionPattern.FindStringSubmatch(parsedSVG.Height)
-		if len(widthMatches) == 2 && len(heightMatches) == 2 {
-			svgInfo.Width, _ = strconv.Atoi(widthMatches[1])
-			svgInfo.Height, _ = strconv.Atoi(heightMatches[1])
+	for {
+		token, err := decoder.Token()
+		if err != nil {
+			return svgInfo, err
+		}
+		switch t := token.(type) {
+		case xml.StartElement:
+			for _, attr := range t.Attr {
+				if attr.Name.Local == "viewBox" {
+					values := strings.Fields(attr.Value)
+					if len(values) == 4 {
+						width := 0
+						_, widthErr := fmt.Sscan(values[2], &width)
+
+						height := 0
+						_, heightErr := fmt.Sscan(values[3], &height)
+
+						if widthErr != nil || heightErr != nil {
+							return svgInfo, err
+						}
+
+						svgInfo.Width = width
+						svgInfo.Height = height
+
+						return svgInfo, nil
+					}
+				}
+				if attr.Name.Local == "width" {
+					width := 0
+					_, err := fmt.Sscan(attr.Value, &width)
+
+					if err != nil {
+						return svgInfo, err
+					}
+
+					svgInfo.Width = width
+				}
+				if attr.Name.Local == "height" {
+					height := 0
+					_, err := fmt.Sscan(attr.Value, &height)
+
+					if err != nil {
+						return svgInfo, err
+					}
+
+					svgInfo.Height = height
+				}
+			}
+
+			if svgInfo.Width == 0 || svgInfo.Height == 0 {
+				return svgInfo, errors.New("unable to extract SVG dimensions")
+			}
+
+			return svgInfo, nil
 		}
 	}
-
-	// if width and/or height are still zero, create new error
-	if svgInfo.Width == 0 || svgInfo.Height == 0 {
-		return svgInfo, errors.New("unable to extract SVG dimensions")
-	}
-	return svgInfo, nil
 }
diff --git a/app/imaging/svg_test.go b/app/imaging/svg_test.go
index c9e5bbdc5e..63c5c3bd9f 100644
--- a/app/imaging/svg_test.go
+++ b/app/imaging/svg_test.go
@@ -8,6 +8,8 @@ import (
 	"io"
 	"strings"
 	"testing"
+
+	"github.com/stretchr/testify/require"
 )
 
 //nolint:unparam
@@ -74,3 +76,11 @@ func TestParseInvalidSVGData(t *testing.T) {
 		}
 	}
 }
+
+func TestParseProcInstOnlySVGData(t *testing.T) {
+	svg := strings.NewReader("<?xml version='1.0' encoding='utf-8'?>")
+	svgInfo, err := ParseSVG(svg)
+	require.Error(t, err)
+	require.Equal(t, 0, svgInfo.Width)
+	require.Equal(t, 0, svgInfo.Height)
+}