Change error handling

1 files changed, 50 insertions, 39 deletions

diff --git a/main.go b/main.go
index 09ff161..b57042e 100644
--- a/main.go
+++ b/main.go
@@ -64,35 +64,36 @@ func dbCollect(query string) ([]string, error) {
 
 // cmdInit initializes a "gallery directory" that contains gallery.sqlite,
 // images, thumbs.
-func cmdInit(args []string) {
+func cmdInit(args []string) error {
 	if len(args) != 1 {
-		log.Fatalln("usage: GD")
+		return errors.New("usage: GD")
 	}
 
 	if err := openDB(args[0]); err != nil {
-		log.Fatalln(err)
+		return err
 	}
 	if _, err := db.Exec(initializeSQL); err != nil {
-		log.Fatalln(err)
+		return err
 	}
 
 	// XXX: There's technically no reason to keep images as symlinks,
 	// we might just keep absolute paths in the database as well.
 	if err := os.MkdirAll(filepath.Join(gd, "images"), 0755); err != nil {
-		log.Fatalln(err)
+		return err
 	}
 	if err := os.MkdirAll(filepath.Join(gd, "thumbs"), 0755); err != nil {
-		log.Fatalln(err)
+		return err
 	}
+	return nil
 }
 
 // cmdRun runs a web UI against GD on ADDRESS.
-func cmdRun(args []string) {
+func cmdRun(args []string) error {
 	if len(args) != 2 {
-		log.Fatalln("usage: GD ADDRESS")
+		return errors.New("usage: GD ADDRESS")
 	}
 	if err := openDB(args[0]); err != nil {
-		log.Fatalln(err)
+		return err
 	}
 
 	address := args[1]
@@ -120,7 +121,7 @@ func cmdRun(args []string) {
 		WriteTimeout:   60 * time.Second,
 		MaxHeaderBytes: 32 << 10,
 	}
-	log.Fatalln(s.ListenAndServe())
+	return s.ListenAndServe()
 }
 
 func isImage(path string) (bool, error) {
@@ -202,46 +203,49 @@ func importFunc(path string, d fs.DirEntry, err error) error {
 }
 
 // cmdImport adds files to the "entry" table.
-func cmdImport(args []string) {
+func cmdImport(args []string) error {
 	if len(args) < 1 {
-		log.Fatalln("usage: GD ROOT...")
+		return errors.New("usage: GD ROOT...")
 	}
 	if err := openDB(args[0]); err != nil {
-		log.Fatalln(err)
+		return err
 	}
 
 	// TODO: This would better be done in parallel (making hashes).
 	// TODO: Show progress in some manner. Perhaps port my propeller code.
 	for _, name := range args[1:] {
 		if err := filepath.WalkDir(name, importFunc); err != nil {
-			log.Fatalln(err)
+			return err
 		}
 	}
+	return nil
 }
 
 // cmdSync is like import, but clears the "entry" table beforehands.
-func cmdSync(args []string) {
+func cmdSync(args []string) error {
 	if len(args) < 1 {
-		log.Fatalln("usage: GD ROOT...")
+		return errors.New("usage: GD ROOT...")
 	}
 	if err := openDB(args[0]); err != nil {
-		log.Fatalln(err)
+		return err
 	}
 
 	// TODO
+	return nil
 }
 
 // cmdCheck checks if all files tracked in the DB are accessible.
-func cmdCheck(args []string) {
+func cmdCheck(args []string) error {
 	if len(args) != 1 {
-		log.Fatalln("usage: GD")
+		return errors.New("usage: GD")
 	}
 	if err := openDB(args[0]); err != nil {
-		log.Fatalln(err)
+		return err
 	}
 
 	// TODO: Check if all hashes of DB entries have a statable image file,
 	// and that all images with thumb{w,h} have a thumbnail file. Perhaps.
+	return nil
 }
 
 func makeThumbnail(pathImage, pathThumb string) (int, int, error) {
@@ -275,12 +279,12 @@ func makeThumbnail(pathImage, pathThumb string) (int, int, error) {
 }
 
 // cmdThumbnail generates missing thumbnails, in parallel.
-func cmdThumbnail(args []string) {
+func cmdThumbnail(args []string) error {
 	if len(args) < 1 {
-		log.Fatalln("usage: GD [SHA1...]")
+		return errors.New("usage: GD [SHA1...]")
 	}
 	if err := openDB(args[0]); err != nil {
-		log.Fatalln(err)
+		return err
 	}
 
 	hexSHA1 := args[1:]
@@ -291,7 +295,7 @@ func cmdThumbnail(args []string) {
 			LEFT OUTER JOIN image ON entry.sha1 = image.sha1
 			WHERE thumbw IS NULL OR thumbh IS NULL`)
 		if err != nil {
-			log.Fatalln(err)
+			return err
 		}
 	}
 
@@ -302,16 +306,17 @@ func cmdThumbnail(args []string) {
 		pathThumb := thumbPath(sha1)
 		w, h, err := makeThumbnail(pathImage, pathThumb)
 		if err != nil {
-			log.Fatalln(err)
+			return err
 		}
 
 		_, err = db.Exec(`INSERT INTO image(
 			sha1, thumbw, thumbh, dhash
 		) VALUES (?, ?, ?, NULL)`, sha1, w, h)
 		if err != nil {
-			log.Fatalln(err)
+			return err
 		}
 	}
+	return nil
 }
 
 func makeDhash(hasher, pathThumb string) (uint64, error) {
@@ -337,12 +342,12 @@ func makeDhash(hasher, pathThumb string) (uint64, error) {
 }
 
 // cmdDhash generates perceptual hash from thumbnails.
-func cmdDhash(args []string) {
+func cmdDhash(args []string) error {
 	if len(args) < 1 {
-		log.Fatalln("usage: GD HASHER [SHA1...]")
+		return errors.New("usage: GD HASHER [SHA1...]")
 	}
 	if err := openDB(args[0]); err != nil {
-		log.Fatalln(err)
+		return err
 	}
 
 	hasher, hexSHA1 := args[1], args[2:]
@@ -350,7 +355,7 @@ func cmdDhash(args []string) {
 		var err error
 		hexSHA1, err = dbCollect(`SELECT sha1 FROM image WHERE dhash IS NULL`)
 		if err != nil {
-			log.Fatalln(err)
+			return err
 		}
 	}
 
@@ -359,19 +364,20 @@ func cmdDhash(args []string) {
 		pathThumb := thumbPath(sha1)
 		hash, err := makeDhash(hasher, pathThumb)
 		if err != nil {
-			log.Fatalln(err)
+			return err
 		}
 
 		_, err = db.Exec(`UPDATE image SET dhash = ? WHERE sha1 = ?`,
 			int64(hash), sha1)
 		if err != nil {
-			log.Fatalln(err)
+			return err
 		}
 	}
+	return nil
 }
 
 var commands = map[string]struct {
-	handler func(args []string)
+	handler func(args []string) error
 }{
 	"init":      {cmdInit},
 	"run":       {cmdRun},
@@ -392,12 +398,17 @@ func main() {
 		log.Fatalln("Unknown command: " + os.Args[1])
 	}
 
-	// TODO: Check if this runs on fatal errors.
-	defer func() {
-		if db != nil {
-			db.Close()
+	err := cmd.handler(os.Args[2:])
+
+	// Note that the database object has a closing finalizer,
+	// we just additionally print any errors coming from there.
+	if db != nil {
+		if err := db.Close(); err != nil {
+			log.Println(err)
 		}
-	}()
+	}
 
-	cmd.handler(os.Args[2:])
+	if err != nil {
+		log.Fatalln(err)
+	}
 }