git: expand macros when reading gitattributes files

Read and expand macros when reading the gitattributes files so that
users can use shorthands such as "lfs" for "filter=lfs diff=lfs
merge=lfs".  Pass the same macro processor into each attribute lookup
function, since macros can be defined in the system or global file and
then used in per-repository files.

Author: bk2204

commands/command_track.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/git-lfs/git-lfs/git"
+	"github.com/git-lfs/git-lfs/git/gitattr"
 	"github.com/git-lfs/git-lfs/tools"
 	"github.com/spf13/cobra"
 )
@@ -50,9 +51,11 @@ func trackCommand(cmd *cobra.Command, args []string) {
 		return
 	}
 
+	mp := gitattr.NewMacroProcessor()
+
 	// Intentionally do _not_ consider global- and system-level
 	// .gitattributes here.
-	knownPatterns := git.GetAttributePaths(cfg.LocalWorkingDir(), cfg.LocalGitDir())
+	knownPatterns := git.GetAttributePaths(mp, cfg.LocalWorkingDir(), cfg.LocalGitDir())
 	lineEnd := getAttributeLineEnding(knownPatterns)
 	if len(lineEnd) == 0 {
 		lineEnd = gitLineEnding(cfg.Git)
@@ -243,9 +246,10 @@ func listPatterns() {
 }
 
 func getAllKnownPatterns() []git.AttributePath {
-	knownPatterns := git.GetAttributePaths(cfg.LocalWorkingDir(), cfg.LocalGitDir())
-	knownPatterns = append(knownPatterns, git.GetRootAttributePaths(cfg.Git)...)
-	knownPatterns = append(knownPatterns, git.GetSystemAttributePaths(cfg.Os)...)
+	mp := gitattr.NewMacroProcessor()
+	knownPatterns := git.GetAttributePaths(mp, cfg.LocalWorkingDir(), cfg.LocalGitDir())
+	knownPatterns = append(knownPatterns, git.GetRootAttributePaths(mp, cfg.Git)...)
+	knownPatterns = append(knownPatterns, git.GetSystemAttributePaths(mp, cfg.Os)...)
 
 	return knownPatterns
 }

git/attribs.go

@@ -43,20 +43,20 @@ func (s *AttributeSource) String() string {
 
 // GetRootAttributePaths beahves as GetRootAttributePaths, and loads information
 // only from the global gitattributes file.
-func GetRootAttributePaths(cfg Env) []AttributePath {
+func GetRootAttributePaths(mp *gitattr.MacroProcessor, cfg Env) []AttributePath {
 	af, ok := cfg.Get("core.attributesfile")
 	if !ok {
 		return nil
 	}
 
 	// The working directory for the root gitattributes file is blank.
-	return attrPaths(af, "")
+	return attrPaths(mp, af, "", true)
 }
 
 // GetSystemAttributePaths behaves as GetAttributePaths, and loads information
 // only from the system gitattributes file, respecting the $PREFIX environment
 // variable.
-func GetSystemAttributePaths(env Env) []AttributePath {
+func GetSystemAttributePaths(mp *gitattr.MacroProcessor, env Env) []AttributePath {
 	prefix, _ := env.Get("PREFIX")
 	if len(prefix) == 0 {
 		prefix = string(filepath.Separator)
@@ -68,24 +68,24 @@ func GetSystemAttributePaths(env Env) []AttributePath {
 		return nil
 	}
 
-	return attrPaths(path, "")
+	return attrPaths(mp, path, "", true)
 }
 
 // GetAttributePaths returns a list of entries in .gitattributes which are
 // configured with the filter=lfs attribute
 // workingDir is the root of the working copy
 // gitDir is the root of the git repo
-func GetAttributePaths(workingDir, gitDir string) []AttributePath {
+func GetAttributePaths(mp *gitattr.MacroProcessor, workingDir, gitDir string) []AttributePath {
 	paths := make([]AttributePath, 0)
 
 	for _, file := range findAttributeFiles(workingDir, gitDir) {
-		paths = append(paths, attrPaths(file.path, workingDir)...)
+		paths = append(paths, attrPaths(mp, file.path, workingDir, file.readMacros)...)
 	}
 
 	return paths
 }
 
-func attrPaths(path, workingDir string) []AttributePath {
+func attrPaths(mp *gitattr.MacroProcessor, path, workingDir string, readMacros bool) []AttributePath {
 	attributes, err := os.Open(path)
 	if err != nil {
 		return nil
@@ -103,6 +103,8 @@ func attrPaths(path, workingDir string) []AttributePath {
 		return nil
 	}
 
+	lines = mp.ProcessLines(lines, readMacros)
+
 	for _, line := range lines {
 		lockable := false
 		tracked := false
@@ -145,7 +147,7 @@ func attrPaths(path, workingDir string) []AttributePath {
 // workingDir is the root of the working copy
 // gitDir is the root of the git repo
 func GetAttributeFilter(workingDir, gitDir string) *filepathfilter.Filter {
-	paths := GetAttributePaths(workingDir, gitDir)
+	paths := GetAttributePaths(gitattr.NewMacroProcessor(), workingDir, gitDir)
 	patterns := make([]filepathfilter.Pattern, 0, len(paths))
 
 	for _, path := range paths {

locking/lockable.go

@@ -10,6 +10,7 @@ import (
 	"github.com/git-lfs/git-lfs/errors"
 	"github.com/git-lfs/git-lfs/filepathfilter"
 	"github.com/git-lfs/git-lfs/git"
+	"github.com/git-lfs/git-lfs/git/gitattr"
 	"github.com/git-lfs/git-lfs/tools"
 )
 
@@ -39,7 +40,7 @@ func (c *Client) ensureLockablesLoaded() {
 // Internal function to repopulate lockable patterns
 // You must have locked the c.lockableMutex in the caller
 func (c *Client) refreshLockablePatterns() {
-	paths := git.GetAttributePaths(c.LocalWorkingDir, c.LocalGitDir)
+	paths := git.GetAttributePaths(gitattr.NewMacroProcessor(), c.LocalWorkingDir, c.LocalGitDir)
 	// Always make non-nil even if empty
 	c.lockablePatterns = make([]string, 0, len(paths))
 	for _, p := range paths {

t/t-attributes.sh

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+. "$(dirname "$0")/testlib.sh"
+
+begin_test "macros"
+(
+  set -e
+
+  reponame="$(basename "$0" ".sh")"
+  clone_repo "$reponame" repo
+
+  mkdir dir
+  printf '[attr]lfs filter=lfs diff=lfs merge=lfs -text\n*.dat lfs\n' \
+    > .gitattributes
+  printf '[attr]lfs2 filter=lfs diff=lfs merge=lfs -text\n*.bin lfs2\n' \
+    > dir/.gitattributes
+  git add .gitattributes dir
+  git commit -m 'initial import'
+
+  contents="some data"
+  printf "$contents" > foo.dat
+  git add *.dat
+  git commit -m 'foo.dat'
+  assert_local_object "$(calc_oid "$contents")" 9
+
+  contents2="other data"
+  printf "$contents2" > dir/foo.bin
+  git add dir
+  git commit -m 'foo.bin'
+  refute_local_object "$(calc_oid "$contents2")"
+
+  git lfs track '*.dat' 2>&1 | tee track.log
+  grep '"*.dat" already supported' track.log
+
+  git lfs track 'dir/*.bin' 2>&1 | tee track.log
+  ! grep '"dir/*.bin" already supported' track.log
+)
+end_test