Support excluding files by size

changelog/unreleased/issue-2569

@@ -0,0 +1,8 @@
+Enhancement: Support excluding files by their size
+
+The `backup` command now supports the `--exclude-larger-than` option to exclude files which are
+larger than the specified maximum size. This can for example be useful to exclude unimportant
+files with a large file size.
+
+https://github.com/restic/restic/issues/2569
+https://github.com/restic/restic/pull/2914

cmd/restic/cmd_backup.go

@@ -87,6 +87,7 @@ type BackupOptions struct {
 	ExcludeOtherFS          bool
 	ExcludeIfPresent        []string
 	ExcludeCaches           bool
+	ExcludeLargerThan       string
 	Stdin                   bool
 	StdinFilename           string
 	Tags                    []string
@@ -115,6 +116,7 @@ func init() {
 	f.BoolVarP(&backupOptions.ExcludeOtherFS, "one-file-system", "x", false, "exclude other file systems")
 	f.StringArrayVar(&backupOptions.ExcludeIfPresent, "exclude-if-present", nil, "takes `filename[:header]`, exclude contents of directories containing filename (except filename itself) if header of that file is as provided (can be specified multiple times)")
 	f.BoolVar(&backupOptions.ExcludeCaches, "exclude-caches", false, `excludes cache directories that are marked with a CACHEDIR.TAG file. See https://bford.info/cachedir/ for the Cache Directory Tagging Standard`)
+	f.StringVar(&backupOptions.ExcludeLargerThan, "exclude-larger-than", "", "max `size` of the files to be backed up (allowed suffixes: k/K, m/M, g/G, t/T)")
 	f.BoolVar(&backupOptions.Stdin, "stdin", false, "read backup from stdin")
 	f.StringVar(&backupOptions.StdinFilename, "stdin-filename", "stdin", "`filename` to use when reading from stdin")
 	f.StringArrayVar(&backupOptions.Tags, "tag", nil, "add a `tag` for the new snapshot (can be specified multiple times)")
@@ -285,6 +287,14 @@ func collectRejectFuncs(opts BackupOptions, repo *repository.Repository, targets
 		fs = append(fs, f)
 	}
 
+	if len(opts.ExcludeLargerThan) != 0 && !opts.Stdin {
+		f, err := rejectBySize(opts.ExcludeLargerThan)
+		if err != nil {
+			return nil, err
+		}
+		fs = append(fs, f)
+	}
+
 	return fs, nil
 }
 

cmd/restic/exclude.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"sync"
 
@@ -292,3 +293,50 @@ func rejectResticCache(repo *repository.Repository) (RejectByNameFunc, error) {
 		return false
 	}, nil
 }
+
+func rejectBySize(maxSizeStr string) (RejectFunc, error) {
+	maxSize, err := parseSizeStr(maxSizeStr)
+	if err != nil {
+		return nil, err
+	}
+
+	return func(item string, fi os.FileInfo) bool {
+		// directory will be ignored
+		if fi.IsDir() {
+			return false
+		}
+
+		filesize := fi.Size()
+		if filesize > maxSize {
+			debug.Log("file %s is oversize: %d", item, filesize)
+			return true
+		}
+
+		return false
+	}, nil
+}
+
+func parseSizeStr(sizeStr string) (int64, error) {
+	numStr := sizeStr[:len(sizeStr)-1]
+	var unit int64 = 1
+
+	switch sizeStr[len(sizeStr)-1] {
+	case 'b', 'B':
+		// use initialized values, do nothing here
+	case 'k', 'K':
+		unit = 1024
+	case 'm', 'M':
+		unit = 1024 * 1024
+	case 'g', 'G':
+		unit = 1024 * 1024 * 1024
+	case 't', 'T':
+		unit = 1024 * 1024 * 1024 * 1024
+	default:
+		numStr = sizeStr
+	}
+	value, err := strconv.ParseInt(numStr, 10, 64)
+	if err != nil {
+		return 0, nil
+	}
+	return value * unit, nil
+}

cmd/restic/exclude_test.go

@@ -189,3 +189,113 @@ func TestMultipleIsExcludedByFile(t *testing.T) {
 		}
 	}
 }
+
+func TestParseSizeStr(t *testing.T) {
+	sizeStrTests := []struct {
+		in       string
+		expected int64
+	}{
+		{"1024", 1024},
+		{"1024b", 1024},
+		{"1024B", 1024},
+		{"1k", 1024},
+		{"100k", 102400},
+		{"100K", 102400},
+		{"10M", 10485760},
+		{"100m", 104857600},
+		{"20G", 21474836480},
+		{"10g", 10737418240},
+		{"2T", 2199023255552},
+		{"2t", 2199023255552},
+	}
+
+	for _, tt := range sizeStrTests {
+		actual, err := parseSizeStr(tt.in)
+		test.OK(t, err)
+
+		if actual != tt.expected {
+			t.Errorf("parseSizeStr(%s) = %d; expected %d", tt.in, actual, tt.expected)
+		}
+	}
+}
+
+// TestIsExcludedByFileSize is for testing the instance of
+// --exclude-larger-than parameters
+func TestIsExcludedByFileSize(t *testing.T) {
+	tempDir, cleanup := test.TempDir(t)
+	defer cleanup()
+
+	// Max size of file is set to be 1k
+	maxSizeStr := "1k"
+
+	// Create some files in a temporary directory.
+	// Files in UPPERCASE will be used as exclusion triggers later on.
+	// We will test the inclusion later, so we add the expected value as
+	// a bool.
+	files := []struct {
+		path string
+		size int64
+		incl bool
+	}{
+		{"42", 100, true},
+
+		// everything in foodir except the FOOLARGE tagfile
+		// should not be included.
+		{"foodir/FOOLARGE", 2048, false},
+		{"foodir/foo", 1002, true},
+		{"foodir/foosub/underfoo", 100, true},
+
+		// everything in bardir except the BARLARGE tagfile
+		// should not be included.
+		{"bardir/BARLARGE", 1030, false},
+		{"bardir/bar", 1000, true},
+		{"bardir/barsub/underbar", 500, true},
+
+		// everything in bazdir should be included.
+		{"bazdir/baz", 100, true},
+		{"bazdir/bazsub/underbaz", 200, true},
+	}
+	var errs []error
+	for _, f := range files {
+		// create directories first, then the file
+		p := filepath.Join(tempDir, filepath.FromSlash(f.path))
+		errs = append(errs, os.MkdirAll(filepath.Dir(p), 0700))
+		file, err := os.OpenFile(p, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600)
+		errs = append(errs, err)
+		if err == nil {
+			// create a file with given size
+			errs = append(errs, file.Truncate(f.size))
+		}
+		errs = append(errs, file.Close())
+	}
+	test.OKs(t, errs) // see if anything went wrong during the creation
+
+	// create rejection function
+	sizeExclude, _ := rejectBySize(maxSizeStr)
+
+	// To mock the archiver scanning walk, we create filepath.WalkFn
+	// that tests against the two rejection functions and stores
+	// the result in a map against we can test later.
+	m := make(map[string]bool)
+	walk := func(p string, fi os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		excluded := sizeExclude(p, fi)
+		// the log message helps debugging in case the test fails
+		t.Logf("%q: dir:%t; size:%d; excluded:%v", p, fi.IsDir(), fi.Size(), excluded)
+		m[p] = !excluded
+		return nil
+	}
+	// walk through the temporary file and check the error
+	test.OK(t, filepath.Walk(tempDir, walk))
+
+	// compare whether the walk gave the expected values for the test cases
+	for _, f := range files {
+		p := filepath.Join(tempDir, filepath.FromSlash(f.path))
+		if m[p] != f.incl {
+			t.Errorf("inclusion status of %s is wrong: want %v, got %v", f.path, f.incl, m[p])
+		}
+	}
+}

doc/040_backup.rst

@@ -144,6 +144,7 @@ the exclude options are:
 -  ``--exclude-file`` Specified one or more times to exclude items listed in a given file
 -  ``--iexclude-file`` Same as ``exclude-file`` but ignores cases like in ``--iexclude``
 -  ``--exclude-if-present foo`` Specified one or more times to exclude a folder's content if it contains a file called ``foo`` (optionally having a given header, no wildcards for the file name supported)
+-  ``--exclude-larger-than size`` Specified once to excludes files larger than the given size
 
 Please see ``restic help backup`` for more specific information about each exclude option.
 
@@ -240,6 +241,21 @@ include other filesystems like ``/sys`` and ``/proc``.
 .. note:: ``--one-file-system`` is currently unsupported on Windows, and will
     cause the backup to immediately fail with an error.
 
+Files larger than a given size can be excluded using the `--exclude-larger-than`
+option:
+
+.. code-block:: console
+
+    $ restic -r /srv/restic-repo backup ~/work --exclude-larger-than 1M
+
+This excludes files in ``~/work`` which are larger than 1 MB from the backup.
+
+The default unit for the size value is bytes, so e.g. ``--exclude-larger-than 2048``
+would exclude files larger than 2048 bytes (2 kilobytes). To specify other units,
+suffix the size value with one of ``k``/``K`` for kilobytes, ``m``/``M`` for megabytes,
+``g``/``G`` for gigabytes and ``t``/``T`` for terabytes (e.g. ``1k``, ``10K``, ``20m``,
+``20M``,  ``30g``, ``30G``, ``2t`` or ``2T``).
+
 Including Files
 ***************