Re: [PATCH 2/5] difftool: don't overwrite modified files
From: Junio C Hamano <hidden>
Date: 2016-06-15 22:56:34
John Keeping [off-list ref] writes:
After running the user's diff tool, git-difftool will copy any files that differ between the working tree and the temporary tree. This is useful when the user edits the file in their diff tool but is wrong if they edit the working tree file while examining the diff.
Thanks. I should drop the t7800-modernize topic and queue this under a better name. Perhaps "difftool-no-overwrite-on-copyback", or something.
Instead of copying unconditionally when the files differ, create and index from the working tree files and only copy the temporary file back if it was modified and the working tree file was not. If both files have been modified, print a warning and exit with an error. Note that we cannot use an existing index in git-difftool since those contain the modified files that need to be checked out but here we are looking at those files which are copied from the working tree and not checked out. These are precisely the files which are not in the existing indices.
quoted hunk
Signed-off-by: John Keeping <redacted> --- Changes since v2: - Set TMPDIR to $TRASH_DIRECTORY in the test where difftool fails git-difftool.perl | 73 +++++++++++++++++++++++++++++++++++++++++++---------- t/t7800-difftool.sh | 30 ++++++++++++++++++++++ 2 files changed, 89 insertions(+), 14 deletions(-)diff --git a/git-difftool.perl b/git-difftool.perl index 663640d..844f619 100755 --- a/git-difftool.perl +++ b/git-difftool.perl@@ -13,9 +13,9 @@ use 5.008; use strict; use warnings; +use Error qw(:try); use File::Basename qw(dirname); use File::Copy; -use File::Compare; use File::Find; use File::stat; use File::Path qw(mkpath rmtree);@@ -88,14 +88,45 @@ sub use_wt_file my ($repo, $workdir, $file, $sha1, $symlinks) = @_; my $null_sha1 = '0' x 40; - if ($sha1 eq $null_sha1) { - return 1; - } elsif (not $symlinks) { + if ($sha1 ne $null_sha1 and not $symlinks) { return 0; } my $wt_sha1 = $repo->command_oneline('hash-object', "$workdir/$file"); - return $sha1 eq $wt_sha1; + my $use = ($sha1 eq $null_sha1) || ($sha1 eq $wt_sha1); + return ($use, $wt_sha1); +} + +sub changed_files +{ + my ($repo_path, $index, $worktree) = @_; + $ENV{GIT_INDEX_FILE} = $index; + $ENV{GIT_WORK_TREE} = $worktree; + my $must_unset_git_dir = 0; + if (not defined($ENV{GIT_DIR})) { + $must_unset_git_dir = 1; + $ENV{GIT_DIR} = $repo_path; + } + + my @refreshargs = qw/update-index --really-refresh -q --unmerged/; + my @gitargs = qw/diff-files --name-only -z/; + try { + Git::command_oneline(@refreshargs); + } catch Git::Error::Command with {}; + + my $line = Git::command_oneline(@gitargs); + my @files; + if (defined $line) { + @files = split('\0', $line); + } else { + @files = (); + } + + delete($ENV{GIT_INDEX_FILE}); + delete($ENV{GIT_WORK_TREE}); + delete($ENV{GIT_DIR}) if ($must_unset_git_dir); + + return map { $_ => 1 } @files; } sub setup_dir_diff@@ -121,6 +152,7 @@ sub setup_dir_diff my $null_sha1 = '0' x 40; my $lindex = ''; my $rindex = ''; + my $wtindex = ''; my %submodule; my %symlink; my @working_tree = ();@@ -174,8 +206,12 @@ EOF } if ($rmode ne $null_mode) { - if (use_wt_file($repo, $workdir, $dst_path, $rsha1, $symlinks)) { - push(@working_tree, $dst_path); + my ($use, $wt_sha1) = use_wt_file($repo, $workdir, + $dst_path, $rsha1, + $symlinks); + if ($use) { + push @working_tree, $dst_path; + $wtindex .= "$rmode $wt_sha1\t$dst_path\0"; } else { $rindex .= "$rmode $rsha1\t$dst_path\0"; }@@ -218,6 +254,12 @@ EOF $rc = system('git', 'checkout-index', '--all', "--prefix=$rdir/"); exit_cleanup($tmpdir, $rc) if $rc != 0; + $ENV{GIT_INDEX_FILE} = "$tmpdir/wtindex"; + ($inpipe, $ctx) = + $repo->command_input_pipe(qw(update-index --info-only -z --index-info)); + print($inpipe $wtindex); + $repo->command_close_pipe($inpipe, $ctx); + # If $GIT_DIR was explicitly set just for the update/checkout # commands, then it should be unset before continuing. delete($ENV{GIT_DIR}) if ($must_unset_git_dir);@@ -390,19 +432,22 @@ sub dir_diff # should be copied back to the working tree. # Do not copy back files when symlinks are used and the # external tool did not replace the original link with a file. + my %wt_modified = changed_files($repo->repo_path(), + "$tmpdir/wtindex", "$workdir"); + my %tmp_modified = changed_files($repo->repo_path(), + "$tmpdir/wtindex", "$b");
Do we need to run these two comparisons unconditionally? It appears to me that in a sane and safe setting (i.e. $symlinks is set and the "diff viewer" touches the file through the symbolic link) does not ever look at wt_modified/tmp_modified at all because the first check in the loop will always trigger. I wonder if it makes sense to populate these two hashes lazily so that the safe case does not have to pay the penalty at all.
for my $file (@worktree) {
next if $symlinks && -l "$b/$file";
next if ! -f "$b/$file";
+ if (exists $wt_modified{$file} and exists $tmp_modified{$file}) {
+ my $errmsg = "warning: Both files modified: ";
+ $errmsg .= "'$workdir/$file' and '$b/$file'.\n";
+ $errmsg .= "warning: Working tree file has been left.\n";
+ $errmsg .= "warning:\n";
warn $errmsg;
$error = 1;
+ } elsif ($tmp_modified{$file}) {"exists" if only for consistency?