1 files changed, 78 insertions, 0 deletions
diff --git a/script/mwrap-perl b/script/mwrap-perl
index 78e71e3..53eaa10 100644
--- a/script/mwrap-perl
+++ b/script/mwrap-perl
@@ -6,6 +6,10 @@ use Devel::Mwrap;
  my ($so) = grep(m!/Mwrap\.so\z!, @DynaLoader::dl_shared_objects);
  defined($so) or die 'Mwrap.so not loaded';
  my $cur = $ENV{LD_PRELOAD};
+if (!@ARGV || ($ARGV[0] // '') =~ /\A(?:-h|--help)\z/) {
+        require Pod::Usage;
+        Pod::Usage::pod2usage(@ARGV ? 0 : 1);
+}
  if (defined $cur) {
          my @cur = split(/[: \t]+/, $cur);
          if (!grep(/\A\Q$so\E\z/, @cur)) {
@@ -17,3 +21,77 @@ if (defined $cur) {
          $ENV{LD_PRELOAD} = $so;
  }
  exec @ARGV;
+__END__
+=head1 NAME
+
+mwrap-perl - run any command under mwrap
+
+=head1 SYNOPSIS
+
+  # to trace a long-running program and access it via $DIRECTORY/$PID.sock:
+  MWRAP=socket_dir:$DIRECTORY mwrap-perl COMMAND
+
+  # to trace a short-lived command and dump its output to a log:
+  MWRAP=dump_path:$FILENAME mwrap-perl COMMAND
+
+=head1 DESCRIPTION
+
+mwrap-perl is a command-line to automatically add Mwrap.so as an
+LD_PRELOAD for any command.  It will resolve malloc-family calls
+to a Perl file and line number, and it can also provide a backtrace
+of native (C/C++) functions for non-Perl programs.
+
+=head1 ENVIRONMENT
+
+C<MWRAP> is the only environment variable read.  It contains multiple
+options delimited by C<,> with names and values delimited by C<:>
+
+=item socket_dir:$DIRECTORY
+
+This launches an embedded HTTP server in each process and binds it
+to C<$DIRECTORY/$PID.sock>.  C<curl --unix-socket $DIRECTORY/$PID.sock>
+or L<mwrap-rproxy(1p)> may be used to access various endpoints in
+the HTTP server.
+
+=item: bt:$DEPTH
+
+The backtrace depth for L<backtrace(3)> in addition to the Perl
+file and line number where C<$DEPTH> is a non-negative number.
+
+The maximum allowed value is 32, though values of 5 or less are
+typically useful.  Increasing this to even 2 or 3 can significantly
+increase the amount of memory mwrap (and liburcu) itself uses.
+
+This is only useful in conjunction with C<socket_dir>
+
+Default: 0
+
+=item dump_path:$FILENAME
+
+Dumps the output
+
+        total_bytes        call_count        location
+
+In the future, dumping to a self-describing CSV will be supported
+
+=back
+
+=head1 CONTACT
+
+Feedback welcome via plain-text mail to L<mailto:mwrap-perl@80x24.org>
+
+Mail archives are hosted at L<https://80x24.org/mwrap-perl/>
+
+=head1 COPYRIGHT
+
+Copyright all contributors L<mailto:mwrap-perl@80x24.org>
+
+License: GPL-2.0+ L<https://www.gnu.org/licenses/gpl-2.0.txt>
+
+Source code is at L<https://80x24.org/mwrap-perl.git/>
+
+=head1 SEE ALSO
+
+L<mwrap-rproxy(1)>, L<Devel::Mwrap(3pm)>
+
+=cut