Normalize paths within fs.FS

The shrt command provides an fs.FS rooted at "/" to the ShrtHandler.
Files are accessed within the FS as relative paths. As a consequence,
paths passed into the ShrtHandler Config must be relative to the root
of the file system. This is equivalent to saying paths must be
absolute, but must trim the leading "/".

This commit modifies the env subcommand to satisfy this requirement.
Paths provided to override SHRT_DBPATH must now be absolute.

cmd/shrt/internal/env/env.go

@@ -122,7 +122,11 @@ func runEnvW(args []string) {
 
 	for k, v := range envToWrite {
 		if k == base.SHRTENV {
-			log.Print(base.SHRTENV, " can only be set using the OS environment")
+			log.Println(base.SHRTENV, "can only be set using the OS environment")
+			continue
+		}
+		if k == base.SHRT_DBPATH && !filepath.IsAbs(v) {
+			log.Println(base.SHRT_DBPATH, "must be an absolute path ... ignoring")
 			continue
 		}
 		curEnv[k] = v
@@ -182,7 +186,8 @@ func ConfigFromEnv() shrt.Config {
 		Suffix:  envOrDefault(base.SHRT_SUFFIX, suffixDefault),
 		RdrName: envOrDefault(base.SHRT_RDRNAME, rdrNameDefault),
 		BareRdr: envOrDefault(base.SHRT_BARERDR, bareRdrDefault),
-		DbPath:  envOrDefault(base.SHRT_DBPATH, dbPathDefault),
+		// Trim the leading / to satisfy fs.FS
+		DbPath: strings.TrimPrefix(envOrDefault(base.SHRT_DBPATH, dbPathDefault), "/"),
 	}
 }
 

cmd/shrt/internal/env/env_test.go

@@ -49,7 +49,7 @@ func TestRunEnvUW(t *testing.T) {
 	if _, ok := envMap[base.SHRT_DBPATH]; ok {
 		t.Fatalf("%s key found in %s", base.SHRT_DBPATH, envPath)
 	}
-	runEnvW([]string{base.SHRT_DBPATH + "=bar"})
+	runEnvW([]string{base.SHRT_DBPATH + "=/bar"})
 	envMap = readEnvFile(envPath)
 	if _, ok := envMap[base.SHRT_DBPATH]; !ok {
 		t.Fatalf("%s key not found in %s", base.SHRT_DBPATH, envPath)

cmd/shrt/internal/env/env_unix.go

@@ -1,4 +1,5 @@
 // See LICENSE file for copyright and license details
+//go:build unix
 
 package env
 

cmd/shrt/internal/env/env_windows.go

@@ -3,6 +3,6 @@
 package env
 
 const (
-	envDefault    = "C:\\ProgramData\\shrt\\config"
-	dbPathDefault = "C:\\ProgramData\\shrt\\shrt.db"
+	envDefault    = `C:\ProgramData\shrt\config`
+	dbPathDefault = `C:\ProgramData\shrt\shrt.db`
 )

cmd/shrt/internal/env/testdata/env

@@ -1,2 +1,2 @@
 SHRT_SRVNAME=foo
-SHRT_DBPATH=bar
+SHRT_DBPATH=/bar

cmd/shrt/internal/serve/lockdown_openbsd.go

@@ -4,24 +4,20 @@ package serve
 
 import (
 	"fmt"
-	"path/filepath"
 
 	"golang.org/x/sys/unix"
 )
 
 func init() {
 	lockdown = func(dbPath string) {
-		path, err := filepath.Abs(dbPath)
+		path := "/" + dbPath
+		err := unix.Unveil(path, "r")
 		if err != nil {
-			panic(fmt.Sprint("provided path cannot be made absolute", dbPath))
+			panic(fmt.Sprint("lockdown: ", err))
 		}
-		err = unix.Unveil(path, "r")
+		err = unix.Pledge("stdio rpath dns inet flock", "")
 		if err != nil {
-			panic(fmt.Sprint("lockdown: %s", err))
-		}
-		unix.Pledge("stdio rpath dns inet flock", "")
-		if err != nil {
-			panic(fmt.Sprint("lockdown: %s", err))
+			panic(fmt.Sprint("lockdown: ", err))
 		}
 	}
 }

cmd/shrt/internal/serve/serve.go

@@ -11,7 +11,6 @@ import (
 	"net/http"
 	"net/url"
 	"os"
-	"strings"
 
 	"djmo.ch/go-shrt"
 	"djmo.ch/go-shrt/cmd/shrt/internal/base"
@@ -51,7 +50,7 @@ func runServe(ctx context.Context) {
 
 	shrtfile := shrt.NewShrtFile()
 	fsys := os.DirFS("/").(fs.StatFS)
-	f, err := fsys.Open(strings.TrimPrefix(cfg.DbPath, "/"))
+	f, err := fsys.Open(cfg.DbPath)
 	if err != nil {
 		log.Println("fs error:", err)
 		os.Exit(1)

shrtfile.go

@@ -52,6 +52,8 @@ func (s *ShrtFile) ReadShrtFile(f fs.File) error {
 	s.mux.Lock()
 	defer s.mux.Unlock()
 
+	s.m = make(map[string]ShrtEntry)
+
 	scnr := bufio.NewScanner(f)
 
 	for scnr.Scan() {