Merge changes from the Perl side

This contains many changes from https://80x24.org/mwrap-perl.git
commit

* Built-in RCU-friendly version of dlmalloc, no more fragile dlsym(3m)
  resolution of malloc-family functions in the constructor

* Allocations are now backed by O_TMPFILE on $TMPDIR on modern Linux.
  Since mwrap increases memory usage greatly and I needed to use it
  on a system where I needed more VM space but lacked the ability
  to add swap.

* Configurable C backtrace level via MWRAP=bt:$DEPTH where $DEPTH
  is a non-negative integer.  Be careful about increasing it, even
  a depth of 3-4 can be orders-of-magnitude more expensive in
  time and space.  This can be changed dynamically at runtime via
  local HTTP (see below).

* Embedded per-process local-socket-only HTTP server obsoletes
  MwrapRack when combined with mwrap-rproxy from the Perl dist
  (set `MWRAP=socket_dir:/dir/of/sockets')
  See https://80x24.org/mwrap-perl/20221210015518.272576-4-e@80x24.org/
  for more info.

  It now supports downloading CSV (suitable for importing into sqlite 3.32.0+)

* License switched to GPL-3+ to be compatible with GNU binutils
  since we may take code from addr2line in the future.

* libxxhash supported if XXH3_64bits is available.

1 files changed, 55 insertions, 0 deletions

diff --git a/bin/mwrap b/bin/mwrap
new file mode 100755
index 0000000..054b3a3
--- /dev/null
+++ b/bin/mwrap
@@ -0,0 +1,55 @@
+#!/usr/bin/ruby
+# frozen_string_literal: true
+# Copyright (C) mwrap hackers <mwrap-public@80x24.org>
+# License: GPL-2.0+ <https://www.gnu.org/licenses/gpl-2.0.txt>
+help = <<EOM
+usage: mwrap COMMAND [ARGS]
+see https://80x24.org/mwrap/README.html for more info
+EOM
+ARGV.empty? and abort help
+ARGV.each do |x|
+  case x
+  when '--version', '-v'
+    require 'mwrap/version'
+    puts "mwrap #{Mwrap::VERSION} - #{RUBY_DESCRIPTION}"
+    exit 0
+  when '--help', '-h'
+    puts help
+    exit 0
+  else # don't intercept --version/--help intended for commands we wrap
+    break
+  end
+end
+
+require 'mwrap'
+mwrap_so = $".grep(%r{/mwrap\.so\z})[0] or abort "mwrap.so not loaded"
+cur = ENV['LD_PRELOAD']
+if cur
+  cur = cur.split(/[:\s]+/)
+  if !cur.include?(mwrap_so)
+    # drop old versions
+    cur.delete_if { |path| path.end_with?('/mwrap.so') }
+    cur.unshift(mwrap_so)
+    ENV['LD_PRELOAD'] = cur.join(':')
+  end
+else
+  ENV['LD_PRELOAD'] = mwrap_so
+end
+
+# work around close-on-exec by default behavior in Ruby:
+opts = {}
+if ENV['MWRAP'] =~ /dump_fd:(\d+)/
+  dump_fd = $1.to_i
+  if dump_fd > 2
+    dump_io = IO.new(dump_fd)
+    opts[dump_fd] = dump_io
+  end
+end
+
+# allow inheriting FDs from systemd
+n = ENV['LISTEN_FDS']
+if n && ENV['LISTEN_PID'].to_i == $$
+  n = 3 + n.to_i
+  (3...n).each { |fd| opts[fd] = IO.new(fd) }
+end
+exec *ARGV, opts