converts webP to png using go library

-uses `golang.org/x/image/webp` to convert webP to PNG in memory
- adds modules to `go.mod` and `go.sum`

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/mattn/go-sqlite3 v1.14.8
 	github.com/prometheus/client_golang v1.11.0
 	github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e
+	golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d // indirect
 	gopkg.in/yaml.v2 v2.4.0
 	maunium.net/go/mauflag v1.0.0
 	maunium.net/go/maulogger/v2 v2.3.0

go.sum

@@ -148,6 +148,8 @@ golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPh
 golang.org/x/crypto v0.0.0-20210220033148-5ea612d1eb83/go.mod h1:jdWPYTVW3xRLrWPugEBEK3UY2ZEsg3UU495nc5E+M+I=
 golang.org/x/crypto v0.0.0-20210506145944-38f3c27a63bf h1:B2n+Zi5QeYRDAEodEu72OS36gmTWjgpXr2+cWcBW90o=
 golang.org/x/crypto v0.0.0-20210506145944-38f3c27a63bf/go.mod h1:P+XmwS30IXTQdn5tA2iutPOUgjI07+tq3H3K9MVA1s8=
+golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d h1:RNPAfi2nHY7C2srAV8A49jpsYr0ADedCk1wq6fTMTvs=
+golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d/go.mod h1:023OzeP/+EPmXeapQh35lcL3II3LrY8Ic+EFFKVhULM=
 golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20180906233101-161cd47e91fd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20181114220301-adae6a3d119a/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
@@ -184,6 +186,7 @@ golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9sn
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

portal.go

@@ -27,6 +27,7 @@ import (
 	"image/gif"
 	"image/jpeg"
 	"image/png"
+	"golang.org/x/image/webp"
 	"io/ioutil"
 	"math"
 	"math/rand"
@@ -1889,47 +1890,20 @@ func (portal *Portal) downloadThumbnail(content *event.MessageEventContent, id i
 	return buf.Bytes()
 }
 
-func (portal *Portal) convertWebPtoPng(webp []byte) ([]byte, error) {
-	dir, err := ioutil.TempDir("", "webp-convert-*")
-	if err != nil {
-		return nil, fmt.Errorf("failed to make temp dir: %w", err)
+func (portal *Portal) convertWebPtoPng(webp_image []byte) ([]byte, error) {
+	webp_decoded, err := webp.Decode(bytes.NewReader(webp_image))
+	if err != nil {	
+		return nil, fmt.Errorf("failed to decode webp image: %w", err)
 	}
-	defer os.RemoveAll(dir)
 
-	inputFile, err := os.OpenFile(filepath.Join(dir, "input.webp"), os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0600)
-	if err != nil {
-		return nil, fmt.Errorf("failed open input file: %w", err)
+	var png_buffer bytes.Buffer; 
+	if err := png.Encode(&png_buffer, webp_decoded); err != nil {
+		return nil, fmt.Errorf("failed to encode png image: %w", err)
 	}
-	_, err = inputFile.Write(webp)
-	if err != nil {
-		_ = inputFile.Close()
-		return nil, fmt.Errorf("failed to write gif to input file: %w", err)
-	}
-	_ = inputFile.Close()
-
-	outputFileName := filepath.Join(dir, "output.png")
-	cmd := exec.Command("dwebp", inputFile.Name(), "-o", outputFileName)
-	vcLog := portal.log.Sub("WebPconverter").Writer(log.LevelWarn)
-	cmd.Stdout = vcLog
-	cmd.Stderr = vcLog
 
-	err = cmd.Run()
-	if err != nil {
-		return nil, fmt.Errorf("failed to run dwebp: %w", err)
-	}
-	outputFile, err := os.OpenFile(filepath.Join(dir, "output.png"), os.O_RDONLY, 0)
-	if err != nil {
-		return nil, fmt.Errorf("failed to open output file: %w", err)
-	}
-	defer func() {
-		_ = outputFile.Close()
-		_ = os.Remove(outputFile.Name())
-	}()
-	png, err := ioutil.ReadAll(outputFile)
-	if err != nil {
-		return nil, fmt.Errorf("failed to read png from output file: %w", err)
-	}
-	return png, nil
+	var png_file = png_buffer.Bytes()
+	portal.log.Debugf("Converted png file of size %f", len(png_file))
+	return png_file, nil
 }
 
 func (portal *Portal) convertGifToVideo(gif []byte) ([]byte, error) {