Changes to Lua module loading, and file generation.

This change has several parts:

1. Resurrected tools/upbc.  The code was all there but the build was
   broken for open-source.  Now you can type "make tools/upbc" and
   it will build all necessary Lua modules and create a robust shell
   script for running upbc.

2. Changed Lua module loading to no longer rely on OS-level .so
   dependencies.  The net effect of this is that you now only need
   to set LUA_PATH and LUA_CPATH; setting LD_LIBRARY_PATH or rpaths
   is no longer required.  Downside: this drops compatibility with
   Lua 5.1, since it depends on a feature that only exists in Lua >=5.2
   (and LuaJIT).

3. Since upbc works again, I fixed the re-generation of the descriptor
   files (descriptor.upb.h, descriptor.upb.c).  "make genfiles" will
   re-generate these as well as the JIT code generator.

4. Added a Travis test target that ensures that the checked-in generated
   files are not out of date.  I would do this for the Ragel generated
   file also, but we can't count on all versions of Ragel to necessarily
   generate identical output.

5. Changed Makefile to no longer automatically run Ragel to regenerate
   the JSON parser.  This is unfortuante, because it's convenient when
   you're developing the JSON parser.  However, "git clone" sometimes
   skews the timestamps a little bit so that "make" thinks it needs to
   regenerate these files for a fresh "git clone."  This would normally
   be harmless, but if the user doesn't have Ragel installed, it makes
   the build fail completely.  So now you have to explicitly regenerate
   the Ragel output.  If you want to you can uncomment the auto-generation
   during development.

6 files changed, 156 insertions, 139 deletions

diff --git a/upb/bindings/lua/upb.c b/upb/bindings/lua/upb.c
index b35af24..aebf9f7 100644
--- a/upb/bindings/lua/upb.c
+++ b/upb/bindings/lua/upb.c
@@ -33,10 +33,6 @@
 #include "upb/pb/glue.h"
 #include "upb/shim/shim.h"
 
-static const char upb_lua[] = {
-#include "upb/bindings/lua/upb.lua.h"
-};
-
 // Lua metatable types.
 #define LUPB_MSG "lupb.msg"
 #define LUPB_ARRAY "lupb.array"
@@ -1771,9 +1767,9 @@ static void lupb_setfieldi(lua_State *L, const char *field, int i) {
   lua_setfield(L, -2, field);
 }
 
-int luaopen_upb(lua_State *L) {
+int luaopen_upb_c(lua_State *L) {
   static char module_key;
-  if (lupb_openlib(L, &module_key, "upb", lupb_toplevel_m)) {
+  if (lupb_openlib(L, &module_key, "upb_c", lupb_toplevel_m)) {
     return 1;
   }
 
@@ -1858,14 +1854,5 @@ int luaopen_upb(lua_State *L) {
   lupb_setfieldi(L, "HANDLER_STARTSEQ",    UPB_HANDLER_STARTSEQ);
   lupb_setfieldi(L, "HANDLER_ENDSEQ",      UPB_HANDLER_ENDSEQ);
 
-  // Call the chunk that will define the extra functions on upb, passing our
-  // package dictionary as the argument.
-  if (luaL_loadbuffer(L, upb_lua, sizeof(upb_lua), "upb.lua") ||
-      lua_pcall(L, 0, LUA_MULTRET, 0)) {
-    lua_error(L);
-  }
-  lua_pushvalue(L, -2);
-  lua_call(L, 1, 0);
-
   return 1;  // Return package table.
 }
diff --git a/upb/bindings/lua/upb.lua b/upb/bindings/lua/upb.lua
index bda9dfe..4090b37 100644
--- a/upb/bindings/lua/upb.lua
+++ b/upb/bindings/lua/upb.lua
@@ -1,146 +1,156 @@
+--[[--------------------------------------------------------------------
+
+  upb - a minimalist implementation of protocol buffers.
+
+  Copyright (c) 2009 Google Inc.  See LICENSE for details.
+  Author: Josh Haberman <jhaberman@gmail.com>
+
+--------------------------------------------------------------------]]--
+
+-- Before calling require on "upb_c", we need to load the same library
+-- as RTLD_GLOBAL, for the benefit of other C extensions that depend on
+-- C functions in the core.
 --
--- upb - a minimalist implementation of protocol buffers.
---
--- Copyright (c) 2009 Google Inc.  See LICENSE for details.
--- Author: Josh Haberman <jhaberman@gmail.com>
+-- This has to happen *before* the require call, because if the module
+-- is loaded RTLD_LOCAL first, a subsequent load as RTLD_GLOBAL won't
+-- have the proper effect, at least on some platforms.
+package.loadlib(package.searchpath("upb_c", package.cpath), "*")
+
+local upb = require("upb_c")
+
+-- A convenience function for building/linking/freezing defs
+-- while maintaining their original order.
 --
--- Pure-Lua support functions that are part of the "upb" module.
--- This file is embedded and packaged into the "upb" C module binary -- it
--- should not be installed or used directly!
-
-return function(upb)
-  -- A convenience function for building/linking/freezing defs
-  -- while maintaining their original order.
-  --
-  -- Sample usage:
-  --   local m1, m2 = upb.build_defs{
-  --     upb.MessageDef{full_name = "M1", fields = {
-  --         upb.FieldDef{
-  --           name = "m2",
-  --           number = 1,
-  --           type = upb.TYPE_MESSAGE,
-  --           subdef_name = ".M2"
-  --         },
-  --       }
-  --     },
-  --     upb.MessageDef{full_name = "M2"}
-  --   }
-  upb.build_defs = function(defs)
-    upb.SymbolTable(defs)
-    -- Lua 5.2 puts unpack in the table library.
-    return (unpack or table.unpack)(defs)
-  end
+-- Sample usage:
+--   local m1, m2 = upb.build_defs{
+--     upb.MessageDef{full_name = "M1", fields = {
+--         upb.FieldDef{
+--           name = "m2",
+--           number = 1,
+--           type = upb.TYPE_MESSAGE,
+--           subdef_name = ".M2"
+--         },
+--       }
+--     },
+--     upb.MessageDef{full_name = "M2"}
+--   }
+upb.build_defs = function(defs)
+  upb.SymbolTable(defs)
+  -- Lua 5.2 puts unpack in the table library.
+  return (unpack or table.unpack)(defs)
+end
 
-  local ipairs_iter = function(array, last_index)
-    local next_index = last_index + 1
-    if next_index > #array then
-      return nil
-    end
-    return next_index, array[next_index]
+local ipairs_iter = function(array, last_index)
+  local next_index = last_index + 1
+  if next_index > #array then
+    return nil
   end
+  return next_index, array[next_index]
+end
 
-  -- For iterating over the indexes and values of a upb.Array.
-  --
-  -- for i, val in upb.ipairs(array) do
-  --   -- ...
-  -- end
-  upb.ipairs = function(array)
-    return ipairs_iter, array, 0
-  end
+-- For iterating over the indexes and values of a upb.Array.
+--
+-- for i, val in upb.ipairs(array) do
+--   -- ...
+-- end
+upb.ipairs = function(array)
+  return ipairs_iter, array, 0
+end
 
-  local set_named = function(obj, init)
-    for k, v in pairs(init) do
-      local func = obj["set_" .. k]
-      if not func then
-        error("Cannot set member: " .. k)
-      end
-      func(obj, v)
+local set_named = function(obj, init)
+  for k, v in pairs(init) do
+    local func = obj["set_" .. k]
+    if not func then
+      error("Cannot set member: " .. k)
     end
+    func(obj, v)
   end
+end
+
+-- Capture references to the functions we're wrapping.
+local RealFieldDef = upb.FieldDef
+local RealEnumDef = upb.EnumDef
+local RealMessageDef = upb.MessageDef
+local RealSymbolTable = upb.SymbolTable
 
-  -- Capture references to the functions we're wrapping.
-  local RealFieldDef = upb.FieldDef
-  local RealEnumDef = upb.EnumDef
-  local RealMessageDef = upb.MessageDef
-  local RealSymbolTable = upb.SymbolTable
-
-  -- FieldDef constructor; a wrapper around the real constructor that can
-  -- set initial properties.
-  --
-  -- User can specify initialization values like so:
-  --   upb.FieldDef{label=upb.LABEL_REQUIRED, name="my_field", number=5,
-  --                type=upb.TYPE_INT32, default_value=12, type_name="Foo"}
-  upb.FieldDef = function(init)
-    local f = RealFieldDef()
-
-    if init then
-      -- Other members are often dependent on type, so set that first.
-      if init.type then
-        f:set_type(init.type)
-        init.type = nil
-      end
-
-      set_named(f, init)
+-- FieldDef constructor; a wrapper around the real constructor that can
+-- set initial properties.
+--
+-- User can specify initialization values like so:
+--   upb.FieldDef{label=upb.LABEL_REQUIRED, name="my_field", number=5,
+--                type=upb.TYPE_INT32, default_value=12, type_name="Foo"}
+upb.FieldDef = function(init)
+  local f = RealFieldDef()
+
+  if init then
+    -- Other members are often dependent on type, so set that first.
+    if init.type then
+      f:set_type(init.type)
+      init.type = nil
     end
 
-    return f
+    set_named(f, init)
   end
 
+  return f
+end
 
-  -- MessageDef constructor; a wrapper around the real constructor that can
-  -- set initial properties.
-  --
-  -- User can specify initialization values like so:
-  --   upb.MessageDef{full_name="MyMessage", extstart=8000, fields={...}}
-  upb.MessageDef = function(init)
-    local m = RealMessageDef()
-
-    if init then
-      for _, f in pairs(init.fields or {}) do
-        m:add(f)
-      end
-      init.fields = nil
 
-      set_named(m, init)
+-- MessageDef constructor; a wrapper around the real constructor that can
+-- set initial properties.
+--
+-- User can specify initialization values like so:
+--   upb.MessageDef{full_name="MyMessage", extstart=8000, fields={...}}
+upb.MessageDef = function(init)
+  local m = RealMessageDef()
+
+  if init then
+    for _, f in pairs(init.fields or {}) do
+      m:add(f)
     end
+    init.fields = nil
 
-    return m
+    set_named(m, init)
   end
 
-  -- EnumDef constructor; a wrapper around the real constructor that can
-  -- set initial properties.
-  --
-  -- User can specify initialization values like so:
-  --   upb.EnumDef{full_name="MyEnum",
-  --     values={
-  --       {"FOO_VALUE_1", 1},
-  --       {"FOO_VALUE_2", 2}
-  --     }
-  --   }
-  upb.EnumDef = function(init)
-    local e = RealEnumDef()
-
-    if init then
-      for _, val in pairs(init.values or {}) do
-        e:add(val[1], val[2])
-      end
-      init.values = nil
-
-      set_named(e, init)
+  return m
+end
+
+-- EnumDef constructor; a wrapper around the real constructor that can
+-- set initial properties.
+--
+-- User can specify initialization values like so:
+--   upb.EnumDef{full_name="MyEnum",
+--     values={
+--       {"FOO_VALUE_1", 1},
+--       {"FOO_VALUE_2", 2}
+--     }
+--   }
+upb.EnumDef = function(init)
+  local e = RealEnumDef()
+
+  if init then
+    for _, val in pairs(init.values or {}) do
+      e:add(val[1], val[2])
     end
+    init.values = nil
 
-    return e
+    set_named(e, init)
   end
 
-  -- SymbolTable constructor; a wrapper around the real constructor that can
-  -- add an initial set of defs.
-  upb.SymbolTable = function(defs)
-    local s = RealSymbolTable()
+  return e
+end
 
-    if defs then
-      s:add(defs)
-    end
+-- SymbolTable constructor; a wrapper around the real constructor that can
+-- add an initial set of defs.
+upb.SymbolTable = function(defs)
+  local s = RealSymbolTable()
 
-    return s
+  if defs then
+    s:add(defs)
   end
+
+  return s
 end
+
+return upb
diff --git a/upb/bindings/lua/upb/pb.c b/upb/bindings/lua/upb/pb.c
index 920648f..bf82a9b 100644
--- a/upb/bindings/lua/upb/pb.c
+++ b/upb/bindings/lua/upb/pb.c
@@ -92,11 +92,9 @@ static const struct luaL_Reg toplevel_m[] = {
   {NULL, NULL}
 };
 
-int luaopen_upb_pb(lua_State *L) {
-  luaopen_upb(L);
-
+int luaopen_upb_pb_c(lua_State *L) {
   static char module_key;
-  if (lupb_openlib(L, &module_key, "upb.pb", toplevel_m)) {
+  if (lupb_openlib(L, &module_key, "upb.pb_c", toplevel_m)) {
     return 1;
   }
 
diff --git a/upb/bindings/lua/upb/pb.lua b/upb/bindings/lua/upb/pb.lua
new file mode 100644
index 0000000..66b3909
--- /dev/null
+++ b/upb/bindings/lua/upb/pb.lua
@@ -0,0 +1,11 @@
+--[[--------------------------------------------------------------------
+
+  upb - a minimalist implementation of protocol buffers.
+
+  Copyright (c) 2009 Google Inc.  See LICENSE for details.
+  Author: Josh Haberman <jhaberman@gmail.com>
+
+--------------------------------------------------------------------]]--
+
+require "upb"
+return require "upb.pb_c"
diff --git a/upb/bindings/lua/table.c b/upb/bindings/lua/upb/table.c
index e15382b..0907f58 100644
--- a/upb/bindings/lua/table.c
+++ b/upb/bindings/lua/upb/table.c
@@ -162,7 +162,7 @@ static const struct luaL_Reg lupbtable_toplevel_m[] = {
   {NULL, NULL}
 };
 
-int luaopen_upbtable(lua_State *L) {
+int luaopen_upb_table_c(lua_State *L) {
   static char module_key;
   if (lupb_openlib(L, &module_key, "upb.table", lupbtable_toplevel_m)) {
     return 1;
diff --git a/upb/bindings/lua/upb/table.lua b/upb/bindings/lua/upb/table.lua
new file mode 100644
index 0000000..8a0a9c9
--- /dev/null
+++ b/upb/bindings/lua/upb/table.lua
@@ -0,0 +1,11 @@
+--[[--------------------------------------------------------------------
+
+  upb - a minimalist implementation of protocol buffers.
+
+  Copyright (c) 2009 Google Inc.  See LICENSE for details.
+  Author: Josh Haberman <jhaberman@gmail.com>
+
+--------------------------------------------------------------------]]--
+
+require "upb"
+return require "upb.table_c"