Re-add thumbnailing

Dockerfile

@@ -2,16 +2,16 @@ FROM golang:1-alpine AS build
 WORKDIR /src
 COPY go.* ./
 RUN go mod download -x
-COPY pkg ./pkg/
 COPY cmd ./cmd/
-RUN CGO_ENABLED=0 GOOS=linux go install ./...
+RUN go install ./...
 
 FROM alpine AS runtime
 WORKDIR /target
 COPY web web
 COPY --from=build /go/bin/ .
 
-FROM scratch
+FROM alpine
+RUN apk --no-cache add ffmpeg ffprobe
 COPY --from=runtime /target /
 WORKDIR /web
 ENTRYPOINT ["/webfs"]

cmd/webfs/main.go

@@ -1,16 +1,25 @@
 package main
 
 import (
+	"context"
 	"flag"
+	"fmt"
 	"log"
 	"net/http"
+	"os"
+	"os/exec"
+	"path"
 	"strings"
 
+	ffprobe "gopkg.in/vansante/go-ffprobe.v2"
+
 	"golang.org/x/net/webdav"
 )
 
 type Handler struct {
 	webdav.Handler
+	dataRoot      string
+	thumbnailRoot string
 }
 
 func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@@ -19,18 +28,95 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		if strings.HasSuffix(r.URL.Path, "/") {
 			r.URL.Path += "index.html"
 		}
+		if r.FormValue("thumbnail") != "" {
+			h.ServeThumbnail(w, r)
+			return
+		}
 	}
 	h.Handler.ServeHTTP(w, r)
 }
 
+/* cleanPath returns a sanitized HTTP path.
+ *
+ * This removes .. from everything,
+ * and will never return any path above /
+ */
+func cleanPath(p string) string {
+	if p == "" {
+		return "/"
+	}
+	if p[0] != '/' {
+		p = "/" + p
+	}
+	return path.Clean(p)
+}
+
+func (h *Handler) ServeThumbnail(w http.ResponseWriter, req *http.Request) {
+	reqPath := cleanPath(req.URL.Path)
+	reqPath = strings.TrimLeft(reqPath, "/")
+	thumbnailPath := path.Join(h.thumbnailRoot, reqPath) + ".webp"
+
+	// If there's not already a thumbnail, make one
+	if _, err := os.Stat(thumbnailPath); err != nil {
+		srcPath := path.Join(h.dataRoot, reqPath)
+
+		ffdata, err := ffprobe.ProbeURL(context.Background(), srcPath, "-hide_banner")
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		isVideo := ffdata.Format.DurationSeconds > 0.0
+
+		// XXX: some day soon you will want CommandContext
+		cmd := exec.Command("ffmpeg", "-hide_banner", "-loglevel", "error")
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+
+		if isVideo {
+			skipSeconds := ffdata.Format.StartTimeSeconds + (ffdata.Format.DurationSeconds * 0.25)
+			cmd.Args = append(cmd.Args,
+				"-ss", fmt.Sprintf("%f", skipSeconds),
+				"-i", srcPath,
+				"-frames:v", "5",
+				"-filter:v", "scale='min(320,iw)':'min(200,ih)':force_original_aspect_ratio=decrease,fps=2",
+				"-loop", "0",
+				thumbnailPath,
+			)
+		} else {
+			cmd.Args = append(cmd.Args,
+				"-i", srcPath,
+				"-filter:v", "scale='min(320,iw)':'min(200,ih)':force_original_aspect_ratio=decrease",
+				thumbnailPath,
+			)
+		}
+
+		if err := os.MkdirAll(path.Dir(thumbnailPath), 0755); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		if err := cmd.Run(); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+	}
+
+	http.ServeFile(w, req, thumbnailPath)
+}
+
 func main() {
 	address := flag.String("listen", ":8080", "Address to listen to")
-	directory := flag.String("root", ".", "Directory to serve")
+	dataRoot := flag.String("root", ".", "Directory to serve")
+	thumbnailRoot := flag.String("thumbnails", "/thumbnails", "Where to store thumbnails")
 	flag.Parse()
 
-	handler := &Handler{}
-	handler.FileSystem = webdav.Dir(*directory)
-	handler.LockSystem = webdav.NewMemLS()
+	handler := &Handler{
+		Handler: webdav.Handler{
+			FileSystem: webdav.Dir(*dataRoot),
+			LockSystem: webdav.NewMemLS(),
+		},
+		dataRoot:      *dataRoot,
+		thumbnailRoot: *thumbnailRoot,
+	}
 
 	log.Println("Listening on", *address)
 	http.ListenAndServe(*address, handler)

docker-compose.yaml

@@ -0,0 +1,6 @@
+services:
+  webfs:
+    image: git.woozle.org/neale/webfs
+    build: .
+    ports:
+      - 8080:8080

go.mod

@@ -2,4 +2,7 @@ module woozle.org/neale/webfs
 
 go 1.15
 
-require golang.org/x/net v0.7.0
+require (
+	golang.org/x/net v0.7.0
+	gopkg.in/vansante/go-ffprobe.v2 v2.1.1
+)

go.sum

@@ -26,3 +26,5 @@ golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGm
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+gopkg.in/vansante/go-ffprobe.v2 v2.1.1 h1:DIh5fMn+tlBvG7pXyUZdemVmLdERnf2xX6XOFF+0BBU=
+gopkg.in/vansante/go-ffprobe.v2 v2.1.1/go.mod h1:qF0AlAjk7Nqzqf3y333Ly+KxN3cKF2JqA3JT5ZheUGE=