# git-filehistory (first cut at detecting renames)

2 messages from 2005-10-20 to 2005-10-20. Participants: David Ho.
Thread: https://gitlist.dev/t/2167

## David Ho, 2005-10-20 19:51

Subject: git-filehistory (first cut at detecting renames)
Message-ID: <4dd15d180510201251p57bea756s18b2e77d4be4ec35@mail.gmail.com>
URL: https://gitlist.dev/e/4dd15d180510201251p57bea756s18b2e77d4be4ec35%40mail.gmail.com

```
Hi all,

This is my stupid perl script to detect renames all the way to it's
origin.  This is my first attempt at writing a perl script so it looks
a bit awful.  It's not perfect, if a file is renamed, the entire
commit is dumped out.  Maybe if git-diff-tree -M <pathname> does post
processing to output changes relevant to <pathname> then it will work
quite well.

David

[davidho@penguin git-tutorial]$ cat git-filehistory.perl
#!/usr/bin/perl

use warnings;
use strict;

sub usage($);

# Sanity checks:
my $GIT_DIR = $ENV{'GIT_DIR'} || ".git";

unless ( -d $GIT_DIR && -d $GIT_DIR . "/objects" &&
        -d $GIT_DIR . "/objects/" && -d $GIT_DIR . "/refs") {
        usage("Git repository not found.");
}

usage("") if scalar @ARGV != 1;

my ($file) = @ARGV;

unless (-f $file) {
        usage("git filehistory: '$file' does not exist");
}

open(F,"-|","git-rev-parse",,"--default","HEAD","--revs-only",$file);
my $git_rev_args = <F>;
chomp ($git_rev_args);
close (F);

open(F,"-|","git-rev-list", $git_rev_args);
my @commits = <F>;
close (F);

my $nextname = $file;
for (my $i=0; $i < scalar @commits; $i++)
{
        my $commit = $commits[$i];
        chomp ($commit);

        open(F,"-|","git-diff-tree","-r","-M", $commit)
                or die "Failed to open pipe from git-diff-tree: " . $!;
        my @lines = grep /R\d{3}.+$nextname/, <F>;
        close(F);
        if (scalar @lines >=1) {
                #The file is renamed!
                my $rc = system
("git-diff-tree","-r","-M","-p","--pretty=medium",$commit);
                die "git-diff-tree failed" if $rc;
                print "\n";
                if ($lines[0] =~ /R\d{3}\t(.+)\t(.+)/) {
                        $nextname = $1;
                }
        }
        else {
                #Not renamed
                my $rc = system
("git-diff-tree","-r","-m","-p","--pretty=medium",$commit, $nextname);
                die "git-diff-tree failed" if $rc;
                print "\n";
        }
}

sub usage($) {
        my $s = shift;
        print $s, "\n" if (length $s != 0);
        print <<EOT;
$0 <file>
This script traces renames to find the origin of the file
EOT
        exit(1);
}

```

## David Ho, 2005-10-20 20:19

Subject: Re: git-filehistory (first cut at detecting renames)
Message-ID: <4dd15d180510201319k6beeb1f3j89eae34322d12c90@mail.gmail.com>
URL: https://gitlist.dev/e/4dd15d180510201319k6beeb1f3j89eae34322d12c90%40mail.gmail.com
In-Reply-To: <4dd15d180510201251p57bea756s18b2e77d4be4ec35@mail.gmail.com>

```
Actually, just tried it on the git repository.  It is very slow. 
Maybe because I'm doing a complete diff-tree on each commit.  Mmm...
maybe there is a better way to detect renames  when walking up the
file history.

David

On 10/20/05, David Ho <davidkwho@gmail.com> wrote:
> Hi all,
>
> This is my stupid perl script to detect renames all the way to it's
> origin.  This is my first attempt at writing a perl script so it looks
> a bit awful.  It's not perfect, if a file is renamed, the entire
> commit is dumped out.  Maybe if git-diff-tree -M <pathname> does post
> processing to output changes relevant to <pathname> then it will work
> quite well.
>
> David
>
> [davidho@penguin git-tutorial]$ cat git-filehistory.perl
> #!/usr/bin/perl
>
> use warnings;
> use strict;
>
> sub usage($);
>
> # Sanity checks:
> my $GIT_DIR = $ENV{'GIT_DIR'} || ".git";
>
> unless ( -d $GIT_DIR && -d $GIT_DIR . "/objects" &&
>         -d $GIT_DIR . "/objects/" && -d $GIT_DIR . "/refs") {
>         usage("Git repository not found.");
> }
>
> usage("") if scalar @ARGV != 1;
>
> my ($file) = @ARGV;
>
> unless (-f $file) {
>         usage("git filehistory: '$file' does not exist");
> }
>
> open(F,"-|","git-rev-parse",,"--default","HEAD","--revs-only",$file);
> my $git_rev_args = <F>;
> chomp ($git_rev_args);
> close (F);
>
> open(F,"-|","git-rev-list", $git_rev_args);
> my @commits = <F>;
> close (F);
>
> my $nextname = $file;
> for (my $i=0; $i < scalar @commits; $i++)
> {
>         my $commit = $commits[$i];
>         chomp ($commit);
>
>         open(F,"-|","git-diff-tree","-r","-M", $commit)
>                 or die "Failed to open pipe from git-diff-tree: " . $!;
>         my @lines = grep /R\d{3}.+$nextname/, <F>;
>         close(F);
>         if (scalar @lines >=1) {
>                 #The file is renamed!
>                 my $rc = system
> ("git-diff-tree","-r","-M","-p","--pretty=medium",$commit);
>                 die "git-diff-tree failed" if $rc;
>                 print "\n";
>                 if ($lines[0] =~ /R\d{3}\t(.+)\t(.+)/) {
>                         $nextname = $1;
>                 }
>         }
>         else {
>                 #Not renamed
>                 my $rc = system
> ("git-diff-tree","-r","-m","-p","--pretty=medium",$commit, $nextname);
>                 die "git-diff-tree failed" if $rc;
>                 print "\n";
>         }
> }
>
> sub usage($) {
>         my $s = shift;
>         print $s, "\n" if (length $s != 0);
>         print <<EOT;
> $0 <file>
> This script traces renames to find the origin of the file
> EOT
>         exit(1);
> }
>

```