Re: [PATCH 6/9] difftool: replace system call with Git::command_noisy
On Fri, Mar 16, 2012 at 6:59 PM, Tim Henigan <tim.henigan@gmail.com> wrote:
> The Git.pm module includes functions intended to standardize working
> with Git repositories in Perl scripts. This commit teaches difftool
> to use Git::command_noisy rather than a system call to run the diff
> command.
Git::command_noisy() calls _cmd_exec() which calls _execv_git_cmd() which does a fork() + exec('git', @_) + waitpid();
We were avoiding exec() for portability reasons, as Alex explained in 677fbff88f368ed6ac52438ddbb530166ec1d5d1:
# ActiveState Perl for Win32 does not implement POSIX semantics of # exec* system call. It just spawns the given executable and finishes # the starting program, exiting with code 0. # system will at least catch the errors returned by git diff, # allowing the caller of git difftool better handling of failures.
Is this no longer a concern? Does Git.pm need a similar portability
caveat, or does it avoid the problem altogether since it uses fork()
+ exec() + waitpid()? (if this is true then it implies that this
change is fine).
I have not read the rest of this series yet, so apologies if these questions were answered elsewhere.
In general, I am a little nervous about having difftool copy worktree content somewhere temporary only to copy it back in later. Is there some way to make the diff machinery reuse the worktree? I was under the impression that we could do some GIT_INDEX tricks to do it, though I will admit that I did not read that suggestion in depth, nor did I grasp whether this was the problem it was meant to address.
Thoughts?
Show 27 quoted lines
>
> Signed-off-by: Tim Henigan <tim.henigan@gmail.com>
> ---
> git-difftool.perl | 10 +---------
> 1 file changed, 1 insertion(+), 9 deletions(-)
>
> diff --git a/git-difftool.perl b/git-difftool.perl
> index 9495f14..8498089 100755
> --- a/git-difftool.perl
> +++ b/git-difftool.perl
> @@ -72,12 +72,4 @@ elsif (defined($no_prompt)) {
>
> $ENV{GIT_PAGER} = '';
> $ENV{GIT_EXTERNAL_DIFF} = 'git-difftool--helper';
> -my @command = ('git', 'diff', @ARGV);
> -
> -# ActiveState Perl for Win32 does not implement POSIX semantics of
> -# exec* system call. It just spawns the given executable and finishes
> -# the starting program, exiting with code 0.
> -# system will at least catch the errors returned by git diff,
> -# allowing the caller of git difftool better handling of failures.
> -my $rc = system(@command);
> -exit($rc | ($rc >> 8));
> +git_cmd_try { Git::command_noisy(('diff', @ARGV)) } 'exit code %d';
> --
> 1.7.9.1.290.gbd444
>--
David
Tim Henigan
