fortify: clean up config loading

Move duplicate code to function. Also handle - as config from stdin.

Signed-off-by: Ophestra <cat@gensokyo.uk>

parse.go

@@ -0,0 +1,78 @@
+package main
+
+import (
+	"encoding/json"
+	"io"
+	direct "os"
+	"strings"
+
+	"git.gensokyo.uk/security/fortify/fst"
+	"git.gensokyo.uk/security/fortify/internal/fmsg"
+	"git.gensokyo.uk/security/fortify/internal/state"
+)
+
+func tryPath(name string) (config *fst.Config) {
+	var r io.Reader
+	config = new(fst.Config)
+
+	if name != "-" {
+		if f, err := os.Open(name); err != nil {
+			fmsg.Fatalf("cannot access configuration file %q: %s", name, err)
+			panic("unreachable")
+		} else {
+			// finalizer closes f
+			r = f
+		}
+	} else {
+		r = direct.Stdin
+	}
+
+	if err := json.NewDecoder(r).Decode(&config); err != nil {
+		fmsg.Fatalf("cannot load configuration: %v", err)
+		panic("unreachable")
+	}
+
+	return
+}
+
+func tryShort(name string) (config *fst.Config, instance *state.State) {
+	likePrefix := false
+	if len(name) <= 32 {
+		likePrefix = true
+		for _, c := range name {
+			if c >= '0' && c <= '9' {
+				continue
+			}
+			if c >= 'a' && c <= 'f' {
+				continue
+			}
+			likePrefix = false
+			break
+		}
+	}
+
+	// try to match from state store
+	if likePrefix && len(name) >= 8 {
+		fmsg.VPrintln("argument looks like prefix")
+
+		s := state.NewMulti(os.Paths().RunDirPath)
+		if entries, err := state.Join(s); err != nil {
+			fmsg.Printf("cannot join store: %v", err)
+			// drop to fetch from file
+		} else {
+			for id := range entries {
+				v := id.String()
+				if strings.HasPrefix(v, name) {
+					// match, use config from this state entry
+					instance = entries[id]
+					config = instance.Config
+					break
+				}
+
+				fmsg.VPrintf("instance %s skipped", v)
+			}
+		}
+	}
+
+	return
+}