+sub _us () {
+ $::us // ($0 =~ m#[^/]*$#, $&);
+}
+
+sub fail {
+ my $s = "@_\n";
+ my $prefix = _us().": ";
+ $s =~ s/^/$prefix/gm;
+ die $s;
+}
+
+sub ensuredir ($) {
+ my ($dir) = @_; # does not create parents
+ return if mkdir $dir;
+ return if $! == EEXIST;
+ die "mkdir $dir: $!";
+}
+
+sub executable_on_path ($) {
+ my ($program) = @_;
+ return 1 if $program =~ m{/};
+ my @path = split /:/, ($ENV{PATH} // "/usr/local/bin:/bin:/usr/bin");
+ foreach my $pe (@path) {
+ my $here = "$pe/$program";
+ return $here if stat_exists $here && -x _;
+ }
+ return undef;
+}
+
+our @signames = split / /, $Config{sig_name};
+
+sub waitstatusmsg () {
+ if (!$?) {
+ return "terminated, reporting successful completion";
+ } elsif (!($? & 255)) {
+ return "failed with error exit status ".WEXITSTATUS($?);
+ } elsif (WIFSIGNALED($?)) {
+ my $signum=WTERMSIG($?);
+ return "died due to fatal signal ".
+ ($signames[$signum] // "number $signum").
+ ($? & 128 ? " (core dumped)" : ""); # POSIX(3pm) has no WCOREDUMP
+ } else {
+ return "failed with unknown wait status ".$?;
+ }
+}
+
+sub failedcmd {
+ # Expects $!,$? as set by close - see below.
+ # To use with system(), set $?=-1 first.
+ #
+ # Actual behaviour of perl operations:
+ # success $!==0 $?==0 close of piped open
+ # program failed $!==0 $? >0 close of piped open
+ # syscall failure $! >0 $?=-1 close of piped open
+ # failure $! >0 unchanged close of something else
+ # success trashed $?==0 system
+ # program failed trashed $? >0 system
+ # syscall failure $! >0 unchanged system
+ { local ($!); printcmd \*STDERR, _us().": failed command:", @_ or die $!; };
+ if ($? < 0) {
+ fail "failed to fork/exec: $!";
+ } elsif ($?) {
+ fail "subprocess ".waitstatusmsg();
+ } else {
+ fail "subprocess produced invalid output";
+ }
+}
+
+sub cmdoutput_errok {
+ confess Dumper(\@_)." ?" if grep { !defined } @_;
+ debugcmd "|",@_;
+ open P, "-|", @_ or die "$_[0] $!";
+ my $d;
+ $!=0; $?=0;
+ { local $/ = undef; $d = <P>; }
+ die $! if P->error;
+ if (!close P) { printdebug "=>!$?\n"; return undef; }
+ chomp $d;
+ if ($debuglevel > 0) {
+ $d =~ m/^.*/;
+ my $dd = $&;
+ my $more = (length $' ? '...' : ''); #');
+ $dd =~ s{[^\n -~]|\\}{ sprintf "\\x%02x", ord $& }ge;
+ printdebug "=> \`$dd'",$more,"\n";
+ }
+ return $d;
+}
+
+sub cmdoutput {
+ my $d = cmdoutput_errok @_;
+ defined $d or failedcmd @_;
+ return $d;
+}
+
+sub link_ltarget ($$) {
+ my ($old,$new) = @_;
+ lstat $old or return undef;
+ if (-l _) {
+ $old = cmdoutput qw(realpath --), $old;
+ }
+ link $old, $new or die "link $old $new: $!";
+}
+
+sub hashfile ($) {
+ my ($fn) = @_;
+ my $h = Digest::SHA->new(256);
+ $h->addfile($fn);
+ return $h->hexdigest();
+}
+
+sub git_rev_parse ($) {
+ return cmdoutput qw(git rev-parse), "$_[0]~0";
+}
+
+sub git_for_each_ref ($$;$) {
+ my ($pattern,$func,$gitdir) = @_;