git

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#!/usr/bin/perl
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use 5.008001;
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use strict;
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use warnings;
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use Getopt::Std;
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use File::Temp qw(tempdir);
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use Data::Dumper;
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use File::Basename qw(basename dirname);
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use File::Spec;
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use Git;
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our ($opt_h, $opt_P, $opt_p, $opt_v, $opt_c, $opt_f, $opt_a, $opt_m, $opt_d, $opt_u, $opt_w, $opt_W, $opt_k);
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getopts('uhPpvcfkam:d:w:W');
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$opt_h && usage();
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die "Need at least one commit identifier!" unless @ARGV;
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# Get git-config settings
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my $repo = Git->repository();
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$opt_w = $repo->config('cvsexportcommit.cvsdir') unless defined $opt_w;
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my $tmpdir = File::Temp::tempdir(CLEANUP => 1);
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my $hash_algo = $repo->config('extensions.objectformat') || 'sha1';
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my $hexsz = $hash_algo eq 'sha256' ? 64 : 40;
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if ($opt_w || $opt_W) {
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	# Remember where GIT_DIR is before changing to CVS checkout
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	unless ($ENV{GIT_DIR}) {
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		# No GIT_DIR set. Figure it out for ourselves
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		my $gd =`git rev-parse --git-dir`;
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		chomp($gd);
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		$ENV{GIT_DIR} = $gd;
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	}
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	# On MSYS, convert a Windows-style path to an MSYS-style path
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	# so that rel2abs() below works correctly.
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	if ($^O eq 'msys') {
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		$ENV{GIT_DIR} =~ s#^([[:alpha:]]):/#/$1/#;
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	}
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	# Make sure GIT_DIR is absolute
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	$ENV{GIT_DIR} = File::Spec->rel2abs($ENV{GIT_DIR});
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}
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if ($opt_w) {
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	if (! -d $opt_w."/CVS" ) {
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		die "$opt_w is not a CVS checkout";
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	}
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	chdir $opt_w or die "Cannot change to CVS checkout at $opt_w";
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}
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unless ($ENV{GIT_DIR} && -r $ENV{GIT_DIR}){
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    die "GIT_DIR is not defined or is unreadable";
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}
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my @cvs;
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if ($opt_d) {
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	@cvs = ('cvs', '-d', $opt_d);
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} else {
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	@cvs = ('cvs');
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}
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# resolve target commit
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my $commit;
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$commit = pop @ARGV;
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$commit = safe_pipe_capture('git', 'rev-parse', '--verify', "$commit^0");
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chomp $commit;
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if ($?) {
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    die "The commit reference $commit did not resolve!";
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}
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# resolve what parent we want
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my $parent;
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if (@ARGV) {
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    $parent = pop @ARGV;
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    $parent =  safe_pipe_capture('git', 'rev-parse', '--verify', "$parent^0");
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    chomp $parent;
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    if ($?) {
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	die "The parent reference did not resolve!";
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    }
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}
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# find parents from the commit itself
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my @commit  = safe_pipe_capture('git', 'cat-file', 'commit', $commit);
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my @parents;
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my $committer;
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my $author;
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my $stage = 'headers'; # headers, msg
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my $title;
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my $msg = '';
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foreach my $line (@commit) {
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    chomp $line;
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    if ($stage eq 'headers' && $line eq '') {
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	$stage = 'msg';
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	next;
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    }
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    if ($stage eq 'headers') {
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	if ($line =~ m/^parent ([0-9a-f]{$hexsz})$/) { # found a parent
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	    push @parents, $1;
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	} elsif ($line =~ m/^author (.+) \d+ [-+]\d+$/) {
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	    $author = $1;
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	} elsif ($line =~ m/^committer (.+) \d+ [-+]\d+$/) {
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	    $committer = $1;
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	}
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    } else {
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	$msg .= $line . "\n";
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	unless ($title) {
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	    $title = $line;
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	}
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    }
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}
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my $noparent = "0" x $hexsz;
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if ($parent) {
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    my $found;
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    # double check that it's a valid parent
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    foreach my $p (@parents) {
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	if ($p eq $parent) {
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	    $found = 1;
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	    last;
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	}; # found it
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    }
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    die "Did not find $parent in the parents for this commit!" if !$found and !$opt_P;
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} else { # we don't have a parent from the cmdline...
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    if (@parents == 1) { # it's safe to get it from the commit
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	$parent = $parents[0];
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    } elsif (@parents == 0) { # there is no parent
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        $parent = $noparent;
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    } else { # cannot choose automatically from multiple parents
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        die "This commit has more than one parent -- please name the parent you want to use explicitly";
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    }
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}
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my $go_back_to = 0;
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if ($opt_W) {
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    $opt_v && print "Resetting to $parent\n";
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    $go_back_to = `git symbolic-ref HEAD 2> /dev/null ||
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	git rev-parse HEAD` || die "Could not determine current branch";
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    system("git checkout -q $parent^0") && die "Could not check out $parent^0";
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}
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$opt_v && print "Applying to CVS commit $commit from parent $parent\n";
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# grab the commit message
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open(MSG, ">.msg") or die "Cannot open .msg for writing";
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if ($opt_m) {
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    print MSG $opt_m;
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}
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print MSG $msg;
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if ($opt_a) {
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    print MSG "\n\nAuthor: $author\n";
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    if ($author ne $committer) {
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	print MSG "Committer: $committer\n";
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    }
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}
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close MSG;
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if ($parent eq $noparent) {
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    `git diff-tree --binary -p --root $commit >.cvsexportcommit.diff`;# || die "Cannot diff";
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} else {
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    `git diff-tree --binary -p $parent $commit >.cvsexportcommit.diff`;# || die "Cannot diff";
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}
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## apply non-binary changes
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# In pedantic mode require all lines of context to match.  In normal
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# mode, be compatible with diff/patch: assume 3 lines of context and
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# require at least one line match, i.e. ignore at most 2 lines of
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# context, like diff/patch do by default.
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my $context = $opt_p ? '' : '-C1';
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print "Checking if patch will apply\n";
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my @stat;
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open APPLY, "GIT_INDEX_FILE=$tmpdir/index git apply $context --summary --numstat<.cvsexportcommit.diff|" || die "cannot patch";
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@stat=<APPLY>;
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close APPLY || die "Cannot patch";
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my (@bfiles,@files,@afiles,@dfiles);
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chomp @stat;
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foreach (@stat) {
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	push (@bfiles,$1) if m/^-\t-\t(.*)$/;
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	push (@files, $1) if m/^-\t-\t(.*)$/;
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	push (@files, $1) if m/^\d+\t\d+\t(.*)$/;
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	push (@afiles,$1) if m/^ create mode [0-7]+ (.*)$/;
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	push (@dfiles,$1) if m/^ delete mode [0-7]+ (.*)$/;
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}
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map { s/^"(.*)"$/$1/g } @bfiles,@files;
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map { s/\\([0-7]{3})/sprintf('%c',oct $1)/eg } @bfiles,@files;
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# check that the files are clean and up to date according to cvs
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my $dirty;
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my @dirs;
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foreach my $p (@afiles) {
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    my $path = dirname $p;
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    while (!-d $path and ! grep { $_ eq $path } @dirs) {
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	unshift @dirs, $path;
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	$path = dirname $path;
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    }
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}
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# ... check dirs,
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foreach my $d (@dirs) {
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    if (-e $d) {
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	$dirty = 1;
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	warn "$d exists and is not a directory!\n";
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    }
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}
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# ... query status of all files that we have a directory for and parse output of 'cvs status' to %cvsstat.
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my @canstatusfiles;
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foreach my $f (@files) {
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    my $path = dirname $f;
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    next if (grep { $_ eq $path } @dirs);
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    push @canstatusfiles, $f;
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}
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my %cvsstat;
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if (@canstatusfiles) {
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    if ($opt_u) {
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      my @updated = xargs_safe_pipe_capture([@cvs, 'update'], @canstatusfiles);
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      print @updated;
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    }
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    # "cvs status" reorders the parameters, notably when there are multiple
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    # arguments with the same basename.  So be precise here.
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    my %added = map { $_ => 1 } @afiles;
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    my %todo = map { $_ => 1 } @canstatusfiles;
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    while (%todo) {
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      my @canstatusfiles2 = ();
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      my %fullname = ();
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      foreach my $name (keys %todo) {
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	my $basename = basename($name);
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	# CVS reports files that don't exist in the current revision as
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	# "no file $basename" in its "status" output, so we should
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	# anticipate that.  Totally unknown files will have a status
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	# "Unknown". However, if they exist in the Attic, their status
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	# will be "Up-to-date" (this means they were added once but have
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	# been removed).
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	$basename = "no file $basename" if $added{$basename};
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	$basename =~ s/^\s+//;
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	$basename =~ s/\s+$//;
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	if (!exists($fullname{$basename})) {
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	  $fullname{$basename} = $name;
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	  push (@canstatusfiles2, $name);
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	  delete($todo{$name});
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	}
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      }
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      my @cvsoutput;
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      @cvsoutput = xargs_safe_pipe_capture([@cvs, 'status'], @canstatusfiles2);
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      foreach my $l (@cvsoutput) {
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	chomp $l;
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	next unless
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	    my ($file, $status) = $l =~ /^File:\s+(.*\S)\s+Status: (.*)$/;
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	my $fullname = $fullname{$file};
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	print STDERR "Huh? Status '$status' reported for unexpected file '$file'\n"
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	    unless defined $fullname;
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	# This response means the file does not exist except in
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	# CVS's attic, so set the status accordingly
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	$status = "In-attic"
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	    if $file =~ /^no file /
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		&& $status eq 'Up-to-date';
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	$cvsstat{$fullname{$file}} = $status
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	    if defined $fullname{$file};
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      }
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    }
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}
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# ... Validate that new files have the correct status
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foreach my $f (@afiles) {
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    next unless defined(my $stat = $cvsstat{$f});
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    # This means the file has never been seen before
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    next if $stat eq 'Unknown';
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    # This means the file has been seen before but was removed
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    next if $stat eq 'In-attic';
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    $dirty = 1;
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	warn "File $f is already known in your CVS checkout -- perhaps it has been added by another user. Or this may indicate that it exists on a different branch. If this is the case, use -f to force the merge.\n";
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	warn "Status was: $cvsstat{$f}\n";
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}
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# ... validate known files.
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foreach my $f (@files) {
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    next if grep { $_ eq $f } @afiles;
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    # TODO:we need to handle removed in cvs
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    unless (defined ($cvsstat{$f}) and $cvsstat{$f} eq "Up-to-date") {
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	$dirty = 1;
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	warn "File $f not up to date but has status '$cvsstat{$f}' in your CVS checkout!\n";
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    }
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    # Depending on how your GIT tree got imported from CVS you may
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    # have a conflict between expanded keywords in your CVS tree and
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    # unexpanded keywords in the patch about to be applied.
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    if ($opt_k) {
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	my $orig_file ="$f.orig";
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	rename $f, $orig_file;
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	open(FILTER_IN, "<$orig_file") or die "Cannot open $orig_file\n";
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	open(FILTER_OUT, ">$f") or die "Cannot open $f\n";
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	while (<FILTER_IN>)
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	{
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	    my $line = $_;
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	    $line =~ s/\$([A-Z][a-z]+):[^\$]+\$/\$$1\$/g;
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	    print FILTER_OUT $line;
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	}
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	close FILTER_IN;
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	close FILTER_OUT;
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    }
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}
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if ($dirty) {
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    if ($opt_f) {	warn "The tree is not clean -- forced merge\n";
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	$dirty = 0;
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    } else {
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	die "Exiting: your CVS tree is not clean for this merge.";
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    }
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}
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print "Applying\n";
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if ($opt_W) {
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    system("git checkout -q $commit^0") && die "cannot patch";
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} else {
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    `GIT_INDEX_FILE=$tmpdir/index git apply $context --summary --numstat --apply <.cvsexportcommit.diff` || die "cannot patch";
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}
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print "Patch applied successfully. Adding new files and directories to CVS\n";
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my $dirtypatch = 0;
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#
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# We have to add the directories in order otherwise we will have
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# problems when we try and add the sub-directory of a directory we
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# have not added yet.
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#
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# Luckily this is easy to deal with by sorting the directories and
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# dealing with the shortest ones first.
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#
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@dirs = sort { length $a <=> length $b} @dirs;
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foreach my $d (@dirs) {
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    if (system(@cvs,'add',$d)) {
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	$dirtypatch = 1;
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	warn "Failed to cvs add directory $d -- you may need to do it manually";
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    }
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}
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foreach my $f (@afiles) {
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    if (grep { $_ eq $f } @bfiles) {
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      system(@cvs, 'add','-kb',$f);
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    } else {
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      system(@cvs, 'add', $f);
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    }
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    if ($?) {
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	$dirtypatch = 1;
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	warn "Failed to cvs add $f -- you may need to do it manually";
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    }
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}
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foreach my $f (@dfiles) {
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    system(@cvs, 'rm', '-f', $f);
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    if ($?) {
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	$dirtypatch = 1;
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	warn "Failed to cvs rm -f $f -- you may need to do it manually";
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    }
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}
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print "Commit to CVS\n";
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print "Patch title (first comment line): $title\n";
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my @commitfiles = map { unless (m/\s/) { '\''.$_.'\''; } else { $_; }; } (@files);
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my $cmd = join(' ', @cvs)." commit -F .msg @commitfiles";
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if ($dirtypatch) {
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    print "NOTE: One or more hunks failed to apply cleanly.\n";
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    print "You'll need to apply the patch in .cvsexportcommit.diff manually\n";
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    print "using a patch program. After applying the patch and resolving the\n";
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    print "problems you may commit using:";
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    print "\n    cd \"$opt_w\"" if $opt_w;
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    print "\n    $cmd\n";
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    print "\n    git checkout $go_back_to\n" if $go_back_to;
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    print "\n";
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    exit(1);
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}
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if ($opt_c) {
397
    print "Autocommit\n  $cmd\n";
398
    print xargs_safe_pipe_capture([@cvs, 'commit', '-F', '.msg'], @files);
399
    if ($?) {
400
	die "Exiting: The commit did not succeed";
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    }
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    print "Committed successfully to CVS\n";
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    # clean up
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    unlink(".msg");
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} else {
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    print "Ready for you to commit, just run:\n\n   $cmd\n";
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}
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# clean up
410
unlink(".cvsexportcommit.diff");
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if ($opt_W) {
413
    system("git checkout $go_back_to") && die "cannot move back to $go_back_to";
414
    if (!($go_back_to =~ /^[0-9a-fA-F]{$hexsz}$/)) {
415
	system("git symbolic-ref HEAD $go_back_to") &&
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	    die "cannot move back to $go_back_to";
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    }
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}
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# CVS version 1.11.x and 1.12.x sleeps the wrong way to ensure the timestamp
421
# used by CVS and the one set by subsequence file modifications are different.
422
# If they are not different CVS will not detect changes.
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sleep(1);
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sub usage {
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	print STDERR <<END;
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usage: GIT_DIR=/path/to/.git git cvsexportcommit [-h] [-p] [-v] [-c] [-f] [-u] [-k] [-w cvsworkdir] [-m msgprefix] [ parent ] commit
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END
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	exit(1);
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}
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432
# An alternative to `command` that allows input to be passed as an array
433
# to work around shell problems with weird characters in arguments
434
# if the exec returns non-zero we die
435
sub safe_pipe_capture {
436
    my @output;
437
    if (my $pid = open my $child, '-|') {
438
	binmode($child, ":crlf");
439
	@output = (<$child>);
440
	close $child or die join(' ',@_).": $! $?";
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    } else {
442
	exec(@_) or die "$! $?"; # exec() can fail the executable can't be found
443
    }
444
    return wantarray ? @output : join('',@output);
445
}
446

447
sub xargs_safe_pipe_capture {
448
	my $MAX_ARG_LENGTH = 65536;
449
	my $cmd = shift;
450
	my @output;
451
	my $output;
452
	while(@_) {
453
		my @args;
454
		my $length = 0;
455
		while(@_ && $length < $MAX_ARG_LENGTH) {
456
			push @args, shift;
457
			$length += length($args[$#args]);
458
		}
459
		if (wantarray) {
460
			push @output, safe_pipe_capture(@$cmd, @args);
461
		}
462
		else {
463
			$output .= safe_pipe_capture(@$cmd, @args);
464
		}
465
	}
466
	return wantarray ? @output : $output;
467
}
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