difftool --dir-diff: symlink all files matching the working tree

johnkeeping · gitster · commit 02c56314aab9 · 2013-03-14T14:33:06.000-07:00
Some users like to edit files in their diff tool when using "git
difftool --dir-diff --symlink" to compare against the working tree but
difftool currently only created symlinks when a file contains unstaged
changes.

Change this behaviour so that symlinks are created whenever the
right-hand side of the comparison has the same SHA1 as the file in the
working tree.

Note that textconv filters are handled in the same way as by git-diff
and if a clean filter is not the inverse of its smudge filter we already
get a null SHA1 from "diff --raw" and will symlink the file without
going through the new hash-object based check.

Signed-off-by: John Keeping &lt;john@keeping.me.uk&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
diff --git a/Documentation/git-difftool.txt b/Documentation/git-difftool.txt
@@ -72,7 +72,9 @@ with custom merge tool commands and has the same value as `$MERGED`.
 --symlinks::
 --no-symlinks::
 	'git difftool''s default behavior is create symlinks to the
-	working tree when run in `--dir-diff` mode.
+	working tree when run in `--dir-diff` mode and the right-hand
+	side of the comparison yields the same content as the file in
+	the working tree.
 +
 Specifying `--no-symlinks` instructs 'git difftool' to create copies
 instead.  `--no-symlinks` is the default on Windows.
diff --git a/git-difftool.perl b/git-difftool.perl
@@ -83,6 +83,21 @@ sub exit_cleanup
 	exit($status | ($status >> 8));
 }
 
+sub use_wt_file
+{
+	my ($repo, $workdir, $file, $sha1, $symlinks) = @_;
+	my $null_sha1 = '0' x 40;
+
+	if ($sha1 eq $null_sha1) {
+		return 1;
+	} elsif (not $symlinks) {
+		return 0;
+	}
+
+	my $wt_sha1 = $repo->command_oneline('hash-object', "$workdir/$file");
+	return $sha1 eq $wt_sha1;
+}
+
 sub setup_dir_diff
 {
 	my ($repo, $workdir, $symlinks) = @_;
@@ -159,10 +174,10 @@ sub setup_dir_diff
 		}
 
 		if ($rmode ne $null_mode) {
-			if ($rsha1 ne $null_sha1) {
-				$rindex .= "$rmode $rsha1\t$dst_path\0";
-			} else {
+			if (use_wt_file($repo, $workdir, $dst_path, $rsha1, $symlinks)) {
 				push(@working_tree, $dst_path);
+			} else {
+				$rindex .= "$rmode $rsha1\t$dst_path\0";
 			}
 		}
 	}
diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
@@ -370,6 +370,28 @@ test_expect_success PERL 'difftool --dir-diff' '
 	echo "$diff" | stdin_contains file
 '
 
+write_script .git/CHECK_SYMLINKS <<\EOF
+for f in file file2 sub/sub
+do
+	echo "$f"
+	readlink "$2/$f"
+done >actual
+EOF
+
+test_expect_success PERL,SYMLINKS 'difftool --dir-diff --symlink without unstaged changes' '
+	cat >expect <<-EOF &&
+	file
+	$(pwd)/file
+	file2
+	$(pwd)/file2
+	sub/sub
+	$(pwd)/sub/sub
+	EOF
+	git difftool --dir-diff --symlink \
+		--extcmd "./.git/CHECK_SYMLINKS" branch HEAD &&
+	test_cmp actual expect
+'
+
 test_expect_success PERL 'difftool --dir-diff ignores --prompt' '
 	diff=$(git difftool --dir-diff --prompt --extcmd ls branch) &&
 	echo "$diff" | stdin_contains sub &&

Original file line number	Diff line number	Diff line change
`@@ -83,6 +83,21 @@ sub exit_cleanup`
`83`	`83`	`exit($status \| ($status >> 8));`
`84`	`84`	`}`
`85`	`85`
	`86`	`+sub use_wt_file`
	`87`	`+{`
	`88`	`+ my ($repo, $workdir, $file, $sha1, $symlinks) = @_;`
	`89`	`+ my $null_sha1 = '0' x 40;`
	`90`	`+`
	`91`	`+ if ($sha1 eq $null_sha1) {`
	`92`	`+ return 1;`
	`93`	`+ } elsif (not $symlinks) {`
	`94`	`+ return 0;`
	`95`	`+ }`
	`96`	`+`
	`97`	`+ my $wt_sha1 = $repo->command_oneline('hash-object', "$workdir/$file");`
	`98`	`+ return $sha1 eq $wt_sha1;`
	`99`	`+}`
	`100`	`+`
`86`	`101`	`sub setup_dir_diff`
`87`	`102`	`{`
`88`	`103`	`my ($repo, $workdir, $symlinks) = @_;`
`@@ -159,10 +174,10 @@ sub setup_dir_diff`
`159`	`174`	`}`
`160`	`175`
`161`	`176`	`if ($rmode ne $null_mode) {`
`162`		`- if ($rsha1 ne $null_sha1) {`
`163`		`- $rindex .= "$rmode $rsha1\t$dst_path\0";`
`164`		`- } else {`
	`177`	`+ if (use_wt_file($repo, $workdir, $dst_path, $rsha1, $symlinks)) {`
`165`	`178`	`push(@working_tree, $dst_path);`
	`179`	`+ } else {`
	`180`	`+ $rindex .= "$rmode $rsha1\t$dst_path\0";`
`166`	`181`	`}`
`167`	`182`	`}`
`168`	`183`	`}`