backup: return exit code 3 if not all targets are available (#5347)

to make the exit code behaviour consistent with files inaccessible during the backup phase, making this change to exit with code 3 if not all target files/folders are accessible for backup

---------

Co-authored-by: Michael Eischer <michael.eischer@fau.de>

changelog/unreleased/issue-4467

@@ -0,0 +1,11 @@
+Bugfix: Exit with code 3 when some `backup` source files do not exist
+
+Restic used to exit with code 0 even when some backup sources did not exist. Restic
+would exit with code 3 only when child directories or files did not exist. This
+could cause confusion and unexpected behavior in scripts that relied on the exit
+code to determine if the backup was successful.
+
+Restic now exits with code 3 when some backup sources do not exist.
+
+https://github.com/restic/restic/issues/4467
+https://github.com/restic/restic/pull/5347

cmd/restic/cmd_backup.go

@@ -157,6 +157,9 @@ var backupFSTestHook func(fs fs.FS) fs.FS
 // ErrInvalidSourceData is used to report an incomplete backup
 var ErrInvalidSourceData = errors.New("at least one source file could not be read")
 
+// ErrNoSourceData is used to report that no source data was found
+var ErrNoSourceData = errors.Fatal("all source directories/files do not exist")
+
 // filterExisting returns a slice of all existing items, or an error if no
 // items exist at all.
 func filterExisting(items []string, warnf func(msg string, args ...interface{})) (result []string, err error) {
@@ -171,10 +174,12 @@ func filterExisting(items []string, warnf func(msg string, args ...interface{}))
 	}
 
 	if len(result) == 0 {
-		return nil, errors.Fatal("all source directories/files do not exist")
+		return nil, ErrNoSourceData
+	} else if len(result) < len(items) {
+		return result, ErrInvalidSourceData
 	}
 
-	return
+	return result, nil
 }
 
 // readLines reads all lines from the named file and returns them as a
@@ -437,12 +442,7 @@ func collectTargets(opts BackupOptions, args []string, warnf func(msg string, ar
 		return nil, errors.Fatal("nothing to backup, please specify source files/dirs")
 	}
 
-	targets, err = filterExisting(targets, warnf)
-	if err != nil {
-		return nil, err
-	}
-
-	return targets, nil
+	return filterExisting(targets, warnf)
 }
 
 // parent returns the ID of the parent snapshot. If there is none, nil is
@@ -496,9 +496,14 @@ func runBackup(ctx context.Context, opts BackupOptions, gopts GlobalOptions, ter
 		return err
 	}
 
+	success := true
 	targets, err := collectTargets(opts, args, printer.E, term.InputRaw())
 	if err != nil {
-		return err
+		if errors.Is(err, ErrInvalidSourceData) {
+			success = false
+		} else {
+			return err
+		}
 	}
 
 	timeStamp := time.Now()
@@ -632,7 +637,7 @@ func runBackup(ctx context.Context, opts BackupOptions, gopts GlobalOptions, ter
 	arch.SelectByName = selectByNameFilter
 	arch.Select = selectFilter
 	arch.WithAtime = opts.WithAtime
-	success := true
+
 	arch.Error = func(item string, err error) error {
 		success = false
 		reterr := progressReporter.Error(item, err)

cmd/restic/cmd_backup_integration_test.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"github.com/restic/restic/internal/data"
+	"github.com/restic/restic/internal/errors"
 	"github.com/restic/restic/internal/fs"
 	"github.com/restic/restic/internal/restic"
 	rtest "github.com/restic/restic/internal/test"
@@ -271,7 +272,17 @@ func TestBackupNonExistingFile(t *testing.T) {
 
 	opts := BackupOptions{}
 
-	testRunBackup(t, "", dirs, opts, env.gopts)
+	// mix of existing and non-existing files
+	err := testRunBackupAssumeFailure(t, "", dirs, opts, env.gopts)
+	rtest.Assert(t, err != nil, "expected error for non-existing file")
+	rtest.Assert(t, errors.Is(err, ErrInvalidSourceData), "expected ErrInvalidSourceData; got %v", err)
+	// only non-existing file
+	dirs = []string{
+		filepath.Join(p, "nonexisting"),
+	}
+	err = testRunBackupAssumeFailure(t, "", dirs, opts, env.gopts)
+	rtest.Assert(t, err != nil, "expected error for non-existing file")
+	rtest.Assert(t, errors.Is(err, ErrNoSourceData), "expected ErrNoSourceData; got %v", err)
 }
 
 func TestBackupSelfHealing(t *testing.T) {

cmd/restic/cmd_backup_test.go

@@ -71,6 +71,9 @@ func TestCollectTargets(t *testing.T) {
 	rtest.OK(t, err)
 	sort.Strings(targets)
 	rtest.Equals(t, expect, targets)
+
+	_, err = collectTargets(opts, []string{filepath.Join(dir, "cmdline arg"), filepath.Join(dir, "non-existing-file")}, t.Logf, nil)
+	rtest.Assert(t, err == ErrInvalidSourceData, "expected error when not all targets exist")
 }
 
 func TestReadFilenamesRaw(t *testing.T) {