looks for git branches whose head is the same ref as HEAD

git-matching-branches.pl

#!/usr/bin/env perl

##### git-matching-branches #####
# aws codebuild checks out webhook payloads in a detached head state
# This script looks for branches whose head is the same ref as HEAD
# It prints the short branch names, newline separated, and should play nicely with xargs
# e.g. ./git-matching-branches | xargs -n1 -I '{}' cp tarball_version.tar.gz tarball_version-'{}'.tar.gz
#
# N.B. Branches whose name does not satisfy semver 2.0.0 item 9 will cause this script to exit abnormally
# and probably break the build [0-9A-Za-Z.-]
# This is because the branch-name is used as a pre-release suffix in the semver
# TODO add a pre-commit hook to catch this
# 
# LICENSE: MIT LICENSE
# @afirth 08/2018


### STOP! ###
# recent git supports --points-to for git-branch, git-tag, and git-for-each-ref
# try e.g. git for-each-ref --format="%(refname:lstrip=1)" --points-at `git rev-parse HEAD`
die("use git")

use strict; use warnings;
use v5.10;

my $sha = `git rev-parse HEAD`;
chomp $sha;

my @branches;

open my $cmd, '-|', 'git show-ref --heads';
while ( <$cmd> ) {
  chomp();
  if (  m|^(?<sha>\w+) refs/heads/(?<branch>.*)$| ) {
    if ( $sha eq $+{sha} ) {
      must_comply_semver( $+{branch} );
      push( @branches, $+{branch} );
    }
  }
  else { # defensive
    die "Unable to parse output of git show-ref --heads: $_"
  }
}
close $cmd;

say join( " ", @branches );

sub must_comply_semver{
  my $str = shift;
  unless ( $str =~ m/^[0-9A-Za-z.-]+$/ ) {
    die ( "Branch is not semver 2.0.0 item 9 compliant. Builds at this SHA broken. Delete the branch: $str\n" );
  }
}