X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=src%2Fceph%2Fsrc%2Fcls%2Flua%2Fcls_lua.cc;fp=src%2Fceph%2Fsrc%2Fcls%2Flua%2Fcls_lua.cc;h=3c84570c5dfbf4b3108161d898473aed8bffadca;hb=812ff6ca9fcd3e629e49d4328905f33eee8ca3f5;hp=0000000000000000000000000000000000000000;hpb=15280273faafb77777eab341909a3f495cf248d9;p=stor4nfv.git

diff --git a/src/ceph/src/cls/lua/cls_lua.cc b/src/ceph/src/cls/lua/cls_lua.cc
new file mode 100644
index 0000000..3c84570
--- /dev/null
+++ b/src/ceph/src/cls/lua/cls_lua.cc
@@ -0,0 +1,1052 @@
+/*
+ * Lua Bindings for RADOS Object Class
+ */
+#include <errno.h>
+#include <setjmp.h>
+#include <string>
+#include <sstream>
+#include <lua.hpp>
+#include "include/types.h"
+#include "objclass/objclass.h"
+#include "json_spirit/json_spirit.h"
+#include "cls_lua.h"
+#include "cls_lua_ops.h"
+
+CLS_VER(1,0)
+CLS_NAME(lua)
+
+/*
+ * Jump point for recovering from Lua panic.
+ */
+static jmp_buf cls_lua_panic_jump;
+
+/*
+ * Handle Lua panic.
+ */
+static int cls_lua_atpanic(lua_State *lua)
+{
+  CLS_ERR("error: Lua panic: %s", lua_tostring(lua, -1));
+  longjmp(cls_lua_panic_jump, 1);
+  return 0;
+}
+
+struct clslua_err {
+  bool error;
+  int ret;
+};
+
+/*
+ * Input parameter encoding.
+ */
+enum InputEncoding {
+  JSON_ENC,
+  BUFFERLIST_ENC,
+};
+
+struct clslua_hctx {
+  struct clslua_err error;
+  InputEncoding in_enc;
+  int ret;
+
+  cls_method_context_t *hctx;
+  bufferlist *inbl;   // raw cls input
+  bufferlist *outbl;  // raw cls output
+
+  string script;      // lua script
+  string handler;     // lua handler
+  bufferlist input;   // lua handler input
+};
+
+/* Lua registry key for method context */
+static char clslua_hctx_reg_key;
+
+/*
+ * Grabs the full method handler context
+ */
+static clslua_hctx *__clslua_get_hctx(lua_State *L)
+{
+  /* lookup registry value */
+  lua_pushlightuserdata(L, &clslua_hctx_reg_key);
+  lua_gettable(L, LUA_REGISTRYINDEX);
+
+  /* check cls_lua assumptions */
+  assert(!lua_isnil(L, -1));
+  assert(lua_type(L, -1) == LUA_TLIGHTUSERDATA);
+
+  /* cast and cleanup stack */
+  clslua_hctx *hctx = (struct clslua_hctx *)lua_touserdata(L, -1);
+  lua_pop(L, 1);
+
+  return hctx;
+}
+
+/*
+ * Get the method context out of the registry. This is called at the beginning
+ * of each clx_cxx_* wrapper, and must be set before there is any chance a Lua
+ * script calling a 'cls' module function that requires it.
+ */
+static cls_method_context_t clslua_get_hctx(lua_State *L)
+{
+  struct clslua_hctx *hctx = __clslua_get_hctx(L);
+  return *hctx->hctx;
+}
+
+/*
+ * Returns a reference to cls_lua error state from registry.
+ */
+struct clslua_err *clslua_checkerr(lua_State *L)
+{
+  struct clslua_hctx *hctx = __clslua_get_hctx(L);
+  struct clslua_err *err = &hctx->error;
+  return err;
+}
+
+
+/* Registry key for real `pcall` function */
+static char clslua_pcall_reg_key;
+
+/*
+ * Wrap Lua pcall to check for errors thrown by cls_lua (e.g. I/O errors or
+ * bufferlist decoding errors). The global error is cleared before returning
+ * to the caller.
+ */
+static int clslua_pcall(lua_State *L)
+{
+  int nargs = lua_gettop(L);
+  lua_pushlightuserdata(L, &clslua_pcall_reg_key);
+  lua_gettable(L, LUA_REGISTRYINDEX);
+  lua_insert(L, 1);
+  lua_call(L, nargs, LUA_MULTRET);
+  struct clslua_err *err = clslua_checkerr(L);
+  assert(err);
+  if (err->error) {
+    err->error = false;
+    lua_pushinteger(L, err->ret);
+    lua_insert(L, -2);
+  }
+  return lua_gettop(L);
+}
+
+
+/*
+ * cls_log
+ */
+static int clslua_log(lua_State *L)
+{
+  int nargs = lua_gettop(L);
+
+  if (!nargs)
+    return 0;
+
+  int loglevel = LOG_LEVEL_DEFAULT;
+  bool custom_ll = false;
+
+  /* check if first arg can be a log level */
+  if (nargs > 1 && lua_isnumber(L, 1)) {
+    int ll = (int)lua_tonumber(L, 1);
+    if (ll >= 0) {
+      loglevel = ll;
+      custom_ll = true;
+    }
+  }
+
+  /* check space for args and seperators (" ") */
+  int nelems = ((nargs - (custom_ll ? 1 : 0)) * 2) - 1;
+  luaL_checkstack(L, nelems, "rados.log(..)");
+
+  for (int i = custom_ll ? 2 : 1; i <= nargs; i++) {
+    const char *part = lua_tostring(L, i);
+    if (!part) {
+      if (lua_type(L, i) == LUA_TBOOLEAN)
+        part = lua_toboolean(L, i) ? "true" : "false";
+      else
+        part = luaL_typename(L, i);
+    }
+    lua_pushstring(L, part);
+    if ((i+1) <= nargs)
+      lua_pushstring(L, " ");
+  }
+
+  /* join string parts and send to Ceph/reply log */
+  lua_concat(L, nelems);
+  CLS_LOG(loglevel, "%s", lua_tostring(L, -1));
+
+  /* concat leaves result at top of stack */
+  return 1;
+}
+
+static char clslua_registered_handle_reg_key;
+
+/*
+ * Register a function to be used as a handler target
+ */
+static int clslua_register(lua_State *L)
+{
+  luaL_checktype(L, 1, LUA_TFUNCTION);
+
+  /* get table of registered handlers */
+  lua_pushlightuserdata(L, &clslua_registered_handle_reg_key);
+  lua_gettable(L, LUA_REGISTRYINDEX);
+  assert(lua_type(L, -1) == LUA_TTABLE);
+
+  /* lookup function argument */
+  lua_pushvalue(L, 1);
+  lua_gettable(L, -2);
+
+  if (lua_isnil(L, -1)) {
+    lua_pushvalue(L, 1);
+    lua_pushvalue(L, 1);
+    lua_settable(L, -4);
+  } else {
+    lua_pushstring(L, "Cannot register handler more than once");
+    return lua_error(L);
+  }
+
+  return 0;
+}
+
+/*
+ * Check if a function is registered as a handler
+ */
+static void clslua_check_registered_handler(lua_State *L)
+{
+  luaL_checktype(L, -1, LUA_TFUNCTION);
+
+  /* get table of registered handlers */
+  lua_pushlightuserdata(L, &clslua_registered_handle_reg_key);
+  lua_gettable(L, LUA_REGISTRYINDEX);
+  assert(lua_type(L, -1) == LUA_TTABLE);
+
+  /* lookup function argument */
+  lua_pushvalue(L, -2);
+  lua_gettable(L, -2);
+
+  if (!lua_rawequal(L, -1, -3)) {
+    lua_pushstring(L, "Handler is not registered");
+    lua_error(L);
+  }
+
+  lua_pop(L, 2);
+}
+
+/*
+ * Handle result of a cls_cxx_* call. If @ok is non-zero then we return with
+ * the number of Lua return arguments on the stack. Otherwise we save error
+ * information in the registry and throw a Lua error.
+ */
+static int clslua_opresult(lua_State *L, int ok, int ret, int nargs,
+    bool error_on_stack = false)
+{
+  struct clslua_err *err = clslua_checkerr(L);
+
+  assert(err);
+  if (err->error) {
+    CLS_ERR("error: cls_lua state machine: unexpected error");
+    ceph_abort();
+  }
+
+  /* everything is cherry */
+  if (ok)
+    return nargs;
+
+  /* set error in registry */
+  err->error = true;
+  err->ret = ret;
+
+  /* push error message */
+  if (!error_on_stack)
+    lua_pushfstring(L, "%s", strerror(-ret));
+
+  return lua_error(L);
+}
+
+/*
+ * cls_cxx_create
+ */
+static int clslua_create(lua_State *lua)
+{
+  cls_method_context_t hctx = clslua_get_hctx(lua);
+  int exclusive = lua_toboolean(lua, 1);
+
+  int ret = cls_cxx_create(hctx, exclusive);
+  return clslua_opresult(lua, (ret == 0), ret, 0);
+}
+
+/*
+ * cls_cxx_remove
+ */
+static int clslua_remove(lua_State *lua)
+{
+  cls_method_context_t hctx = clslua_get_hctx(lua);
+
+  int ret = cls_cxx_remove(hctx);
+  return clslua_opresult(lua, (ret == 0), ret, 0);
+}
+
+/*
+ * cls_cxx_stat
+ */
+static int clslua_stat(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+
+  uint64_t size;
+  time_t mtime;
+  int ret = cls_cxx_stat(hctx, &size, &mtime);
+  if (!ret) {
+    lua_pushinteger(L, size);
+    lua_pushinteger(L, mtime);
+  }
+  return clslua_opresult(L, (ret == 0), ret, 2);
+}
+
+/*
+ * cls_cxx_read
+ */
+static int clslua_read(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  int offset = luaL_checkinteger(L, 1);
+  int length = luaL_checkinteger(L, 2);
+  bufferlist *bl = clslua_pushbufferlist(L, NULL);
+  int ret = cls_cxx_read(hctx, offset, length, bl);
+  return clslua_opresult(L, (ret >= 0), ret, 1);
+}
+
+/*
+ * cls_cxx_write
+ */
+static int clslua_write(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  int offset = luaL_checkinteger(L, 1);
+  int length = luaL_checkinteger(L, 2);
+  bufferlist *bl = clslua_checkbufferlist(L, 3);
+  int ret = cls_cxx_write(hctx, offset, length, bl);
+  return clslua_opresult(L, (ret == 0), ret, 0);
+}
+
+/*
+ * cls_cxx_write_full
+ */
+static int clslua_write_full(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  bufferlist *bl = clslua_checkbufferlist(L, 1);
+  int ret = cls_cxx_write_full(hctx, bl);
+  return clslua_opresult(L, (ret == 0), ret, 0);
+}
+
+/*
+ * cls_cxx_getxattr
+ */
+static int clslua_getxattr(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  const char *name = luaL_checkstring(L, 1);
+  bufferlist  *bl = clslua_pushbufferlist(L, NULL);
+  int ret = cls_cxx_getxattr(hctx, name, bl);
+  return clslua_opresult(L, (ret >= 0), ret, 1);
+}
+
+/*
+ * cls_cxx_getxattrs
+ */
+static int clslua_getxattrs(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+
+  map<string, bufferlist> attrs;
+  int ret = cls_cxx_getxattrs(hctx, &attrs);
+  if (ret < 0)
+    return clslua_opresult(L, 0, ret, 0);
+
+  lua_createtable(L, 0, attrs.size());
+
+  for (auto it = attrs.cbegin(); it != attrs.cend(); it++) {
+    lua_pushstring(L, it->first.c_str());
+    bufferlist  *bl = clslua_pushbufferlist(L, NULL);
+    *bl = it->second; // xfer ownership... will be GC'd
+    lua_settable(L, -3);
+  }
+
+  return clslua_opresult(L, 1, ret, 1);
+}
+
+/*
+ * cls_cxx_setxattr
+ */
+static int clslua_setxattr(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  const char *name = luaL_checkstring(L, 1);
+  bufferlist *bl = clslua_checkbufferlist(L, 2);
+  int ret = cls_cxx_setxattr(hctx, name, bl);
+  return clslua_opresult(L, (ret == 0), ret, 1);
+}
+
+/*
+ * cls_cxx_map_get_val
+ */
+static int clslua_map_get_val(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  const char *key = luaL_checkstring(L, 1);
+  bufferlist  *bl = clslua_pushbufferlist(L, NULL);
+  int ret = cls_cxx_map_get_val(hctx, key, bl);
+  return clslua_opresult(L, (ret == 0), ret, 1);
+}
+
+/*
+ * cls_cxx_map_set_val
+ */
+static int clslua_map_set_val(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  const char *key = luaL_checkstring(L, 1);
+  bufferlist *val = clslua_checkbufferlist(L, 2);
+  int ret = cls_cxx_map_set_val(hctx, key, val);
+  return clslua_opresult(L, (ret == 0), ret, 0);
+}
+
+/*
+ * cls_cxx_map_clear
+ */
+static int clslua_map_clear(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  int ret = cls_cxx_map_clear(hctx);
+  return clslua_opresult(L, (ret == 0), ret, 0);
+}
+
+/*
+ * cls_cxx_map_get_keys
+ */
+static int clslua_map_get_keys(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  const char *start_after = luaL_checkstring(L, 1);
+  int max_to_get = luaL_checkinteger(L, 2);
+
+  std::set<string> keys;
+  bool more;
+  int ret = cls_cxx_map_get_keys(hctx, start_after, max_to_get, &keys, &more);
+  if (ret < 0)
+    return clslua_opresult(L, 0, ret, 0);
+
+  lua_createtable(L, 0, keys.size());
+
+  for (auto it = keys.cbegin(); it != keys.cend(); it++) {
+    const std::string& key = *it;
+    lua_pushstring(L, key.c_str());
+    lua_pushboolean(L, 1);
+    lua_settable(L, -3);
+  }
+
+  return clslua_opresult(L, 1, ret, 1);
+}
+
+/*
+ * cls_cxx_map_get_vals
+ */
+static int clslua_map_get_vals(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  const char *start_after = luaL_checkstring(L, 1);
+  const char *filter_prefix= luaL_checkstring(L, 2);
+  int max_to_get = luaL_checkinteger(L, 3);
+
+  map<string, bufferlist> kvpairs;
+  bool more;
+  int ret = cls_cxx_map_get_vals(hctx, start_after, filter_prefix,
+      max_to_get, &kvpairs, &more);
+  if (ret < 0)
+    return clslua_opresult(L, 0, ret, 0);
+
+  lua_createtable(L, 0, kvpairs.size());
+
+  for (auto it = kvpairs.cbegin(); it != kvpairs.cend(); it++) {
+    lua_pushstring(L, it->first.c_str());
+    bufferlist  *bl = clslua_pushbufferlist(L, NULL);
+    *bl = it->second; // xfer ownership... will be GC'd
+    lua_settable(L, -3);
+  }
+
+  return clslua_opresult(L, 1, ret, 1);
+}
+
+/*
+ * cls_cxx_map_read_header
+ */
+static int clslua_map_read_header(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  bufferlist *bl = clslua_pushbufferlist(L, NULL);
+  int ret = cls_cxx_map_read_header(hctx, bl);
+  return clslua_opresult(L, (ret >= 0), ret, 1);
+}
+
+/*
+ * cls_cxx_map_write_header
+ */
+static int clslua_map_write_header(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  bufferlist *bl = clslua_checkbufferlist(L, 1);
+  int ret = cls_cxx_map_write_header(hctx, bl);
+  return clslua_opresult(L, (ret == 0), ret, 0);
+}
+
+/*
+ * cls_cxx_map_set_vals
+ */
+static int clslua_map_set_vals(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  luaL_checktype(L, 1, LUA_TTABLE);
+
+  map<string, bufferlist> kvpairs;
+
+  for (lua_pushnil(L); lua_next(L, 1); lua_pop(L, 1)) {
+    /*
+     * In the case of a numeric key a copy is made on the stack because
+     * converting to a string would otherwise manipulate the original key and
+     * cause problems for iteration.
+     */
+    string key;
+    int type_code = lua_type(L, -2);
+    switch (type_code) {
+      case LUA_TSTRING:
+        key.assign(lua_tolstring(L, -2, NULL));
+        break;
+
+      case LUA_TNUMBER:
+        lua_pushvalue(L, -2);
+        key.assign(lua_tolstring(L, -1, NULL));
+        lua_pop(L, 1);
+        break;
+
+      default:
+        lua_pushfstring(L, "map_set_vals: invalid key type (%s)",
+            lua_typename(L, type_code));
+        return clslua_opresult(L, 0, -EINVAL, 0, true);
+    }
+
+    bufferlist val;
+    type_code = lua_type(L, -1);
+    switch (type_code) {
+      case LUA_TSTRING:
+        {
+          size_t len;
+          const char *data = lua_tolstring(L, -1, &len);
+          val.append(data, len);
+        }
+        break;
+
+      default:
+        lua_pushfstring(L, "map_set_vals: invalid val type (%s) for key (%s)",
+            lua_typename(L, type_code), key.c_str());
+        return clslua_opresult(L, 0, -EINVAL, 0, true);
+    }
+
+    kvpairs[key] = val;
+  }
+
+  int ret = cls_cxx_map_set_vals(hctx, &kvpairs);
+
+  return clslua_opresult(L, (ret == 0), ret, 0);
+}
+
+/*
+ * cls_cxx_map_remove_key
+ */
+static int clslua_map_remove_key(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  const char *key = luaL_checkstring(L, 1);
+  int ret = cls_cxx_map_remove_key(hctx, key);
+  return clslua_opresult(L, (ret == 0), ret, 0);
+}
+
+/*
+ * cls_current_version
+ */
+static int clslua_current_version(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  uint64_t version = cls_current_version(hctx);
+  lua_pushinteger(L, version);
+  return clslua_opresult(L, 1, 0, 1);
+}
+
+/*
+ * cls_current_subop_num
+ */
+static int clslua_current_subop_num(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  int num = cls_current_subop_num(hctx);
+  lua_pushinteger(L, num);
+  return clslua_opresult(L, 1, 0, 1);
+}
+
+/*
+ * cls_current_subop_version
+ */
+static int clslua_current_subop_version(lua_State *L)
+{
+  cls_method_context_t hctx = clslua_get_hctx(L);
+  string s;
+  cls_cxx_subop_version(hctx, &s);
+  lua_pushstring(L, s.c_str());
+  return clslua_opresult(L, 1, 0, 1);
+}
+
+/*
+ * Functions registered in the 'cls' module.
+ */
+static const luaL_Reg clslua_lib[] = {
+  // mgmt
+  {"register", clslua_register},
+  {"log", clslua_log},
+
+  // data
+  {"create", clslua_create},
+  {"remove", clslua_remove},
+  {"stat", clslua_stat},
+  {"read", clslua_read},
+  {"write", clslua_write},
+  {"write_full", clslua_write_full},
+
+  // xattr
+  {"getxattr", clslua_getxattr},
+  {"getxattrs", clslua_getxattrs},
+  {"setxattr", clslua_setxattr},
+
+  // omap
+  {"map_clear", clslua_map_clear},
+  {"map_get_keys", clslua_map_get_keys},
+  {"map_get_vals", clslua_map_get_vals},
+  {"map_read_header", clslua_map_read_header},
+  {"map_write_header", clslua_map_write_header},
+  {"map_get_val", clslua_map_get_val},
+  {"map_set_val", clslua_map_set_val},
+  {"map_set_vals", clslua_map_set_vals},
+  {"map_remove_key", clslua_map_remove_key},
+
+  // env
+  {"current_version", clslua_current_version},
+  {"current_subop_num", clslua_current_subop_num},
+  {"current_subop_version", clslua_current_subop_version},
+
+  {NULL, NULL}
+};
+
+/*
+ * Set const int in table at top of stack
+ */
+#define SET_INT_CONST(var) do { \
+  lua_pushinteger(L, var); \
+  lua_setfield(L, -2, #var); \
+} while (0)
+
+/*
+ *
+ */
+static int luaopen_objclass(lua_State *L)
+{
+  lua_newtable(L);
+
+  /*
+   * Register cls functions (cls.log, etc...)
+   */
+  luaL_setfuncs(L, clslua_lib, 0);
+
+  /*
+   * Register generic errno values under 'cls'
+   */
+  SET_INT_CONST(EPERM);
+  SET_INT_CONST(ENOENT);
+  SET_INT_CONST(ESRCH);
+  SET_INT_CONST(EINTR);
+  SET_INT_CONST(EIO);
+  SET_INT_CONST(ENXIO);
+  SET_INT_CONST(E2BIG);
+  SET_INT_CONST(ENOEXEC);
+  SET_INT_CONST(EBADF);
+  SET_INT_CONST(ECHILD);
+  SET_INT_CONST(EAGAIN);
+  SET_INT_CONST(ENOMEM);
+  SET_INT_CONST(EACCES);
+  SET_INT_CONST(EFAULT);
+  SET_INT_CONST(EBUSY);
+  SET_INT_CONST(EEXIST);
+  SET_INT_CONST(EXDEV);
+  SET_INT_CONST(ENODEV);
+  SET_INT_CONST(ENOTDIR);
+  SET_INT_CONST(EISDIR);
+  SET_INT_CONST(EINVAL);
+  SET_INT_CONST(ENFILE);
+  SET_INT_CONST(EMFILE);
+  SET_INT_CONST(ENOTTY);
+  SET_INT_CONST(EFBIG);
+  SET_INT_CONST(ENOSPC);
+  SET_INT_CONST(ESPIPE);
+  SET_INT_CONST(EROFS);
+  SET_INT_CONST(EMLINK);
+  SET_INT_CONST(EPIPE);
+  SET_INT_CONST(EDOM);
+  SET_INT_CONST(ERANGE);
+
+  return 1;
+}
+
+/*
+ * Setup the execution environment. Our sandbox currently is not
+ * sophisticated. With a new Lua state per-request we don't need to work about
+ * users stepping on each other, but we do rip out access to the local file
+ * system. All this will change when/if we decide to use some shared Lua
+ * states, most likely for performance reasons.
+ */
+static void clslua_setup_env(lua_State *L)
+{
+  luaL_requiref(L, "_G", luaopen_base, 1);
+  lua_pop(L, 1);
+
+  /*
+   * Wrap `pcall` to intercept errors. First save a reference to the default
+   * Lua `pcall` function, and then replace `pcall` with our version.
+   */
+  lua_pushlightuserdata(L, &clslua_pcall_reg_key);
+  lua_getglobal(L, "pcall");
+  lua_settable(L, LUA_REGISTRYINDEX);
+
+  lua_pushcfunction(L, clslua_pcall);
+  lua_setglobal(L, "pcall");
+
+  /* mask unsafe */
+  lua_pushnil(L);
+  lua_setglobal(L, "loadfile");
+
+  /* mask unsafe */
+  lua_pushnil(L);
+  lua_setglobal(L, "dofile");
+
+  /* not integrated into our error handling */
+  lua_pushnil(L);
+  lua_setglobal(L, "xpcall");
+
+  luaL_requiref(L, LUA_TABLIBNAME, luaopen_table, 1);
+  lua_pop(L, 1);
+
+  luaL_requiref(L, LUA_STRLIBNAME, luaopen_string, 1);
+  lua_pop(L, 1);
+
+  luaL_requiref(L, LUA_MATHLIBNAME, luaopen_math, 1);
+  lua_pop(L, 1);
+
+  luaL_requiref(L, "objclass", luaopen_objclass, 1);
+  lua_pop(L, 1);
+
+  luaL_requiref(L, "bufferlist", luaopen_bufferlist, 1);
+  lua_pop(L, 1);
+}
+
+/*
+ * Schema:
+ * {
+ *   "script": "...",
+ *   "handler": "...",
+ *   "input": "..." # optional
+ * }
+ */
+static int unpack_json_command(lua_State *L, struct clslua_hctx *ctx,
+    std::string& script, std::string& handler, std::string& input,
+    size_t *input_len)
+{
+  std::string json_input(ctx->inbl->c_str());
+  json_spirit::mValue value;
+
+  if (!json_spirit::read(json_input, value)) {
+    CLS_ERR("error: unparseable JSON");
+    ctx->ret = -EINVAL;
+    return 1;
+  }
+
+  if (value.type() != json_spirit::obj_type) {
+    CLS_ERR("error: input not a JSON object");
+    ctx->ret = -EINVAL;
+    return 1;
+  }
+  json_spirit::mObject obj = value.get_obj();
+
+  // grab the script
+  std::map<std::string, json_spirit::mValue>::const_iterator it = obj.find("script");
+  if (it == obj.end()) {
+    CLS_ERR("error: 'script' field found in JSON object");
+    ctx->ret = -EINVAL;
+    return 1;
+  }
+
+  if (it->second.type() != json_spirit::str_type) {
+    CLS_ERR("error: script is not a string");
+    ctx->ret = -EINVAL;
+    return 1;
+  }
+  script = it->second.get_str();
+
+  // grab the target function/handler name
+  it = obj.find("handler");
+  if (it == obj.end()) {
+    CLS_ERR("error: no target handler found in JSON object");
+    ctx->ret = -EINVAL;
+    return 1;
+  }
+
+  if (it->second.type() != json_spirit::str_type) {
+    CLS_ERR("error: target handler is not a string");
+    ctx->ret = -EINVAL;
+    return 1;
+  }
+  handler = it->second.get_str();
+
+  // grab the input (optional)
+  it = obj.find("input");
+  if (it != obj.end()) {
+    if (it->second.type() != json_spirit::str_type) {
+      CLS_ERR("error: handler input is not a string");
+      ctx->ret = -EINVAL;
+      return 1;
+    }
+    input = it->second.get_str();
+    *input_len = input.size();
+  }
+
+  return 0;
+}
+
+/*
+ * Runs the script, and calls handler.
+ */
+static int clslua_eval(lua_State *L)
+{
+  struct clslua_hctx *ctx = __clslua_get_hctx(L);
+  ctx->ret = -EIO; /* assume failure */
+
+  /*
+   * Load modules, errno value constants, and other environment goodies. Must
+   * be done before loading/compiling the chunk.
+   */
+  clslua_setup_env(L);
+
+  /*
+   * Deserialize the input that contains the script, the name of the handler
+   * to call, and the handler input.
+   */
+  switch (ctx->in_enc) {
+    case JSON_ENC:
+      {
+        std::string input_str;
+        size_t input_str_len = 0;
+
+        // if there is an error decoding json then ctx->ret will be set and we
+        // return normally from this function.
+        if (unpack_json_command(L, ctx, ctx->script, ctx->handler, input_str,
+              &input_str_len))
+          return 0;
+
+        bufferptr bp(input_str.c_str(), input_str_len);
+        ctx->input.push_back(bp);
+      }
+      break;
+
+    case BUFFERLIST_ENC:
+      {
+        cls_lua_eval_op op;
+
+        try {
+          bufferlist::iterator it = ctx->inbl->begin();
+          ::decode(op, it);
+        } catch (const buffer::error &err) {
+          CLS_ERR("error: could not decode ceph encoded input");
+          ctx->ret = -EINVAL;
+          return 0;
+        }
+
+        ctx->script.swap(op.script);
+        ctx->handler.swap(op.handler);
+        ctx->input = op.input;
+      }
+      break;
+
+    default:
+      CLS_ERR("error: unknown encoding type");
+      ctx->ret = -EFAULT;
+      ceph_abort();
+      return 0;
+  }
+
+  /*
+   * Create table to hold registered (valid) handlers.
+   *
+   * Must be done before running the script for the first time because the
+   * script will immediately try to register one or more handlers using
+   * cls.register(function), which depends on this table.
+   */
+  lua_pushlightuserdata(L, &clslua_registered_handle_reg_key);
+  lua_newtable(L);
+  lua_settable(L, LUA_REGISTRYINDEX);
+
+  /* load and compile chunk */
+  if (luaL_loadstring(L, ctx->script.c_str()))
+    return lua_error(L);
+
+  /* execute chunk */
+  lua_call(L, 0, 0);
+
+  /* no error, but nothing left to do */
+  if (!ctx->handler.size()) {
+    CLS_LOG(10, "no handler name provided");
+    ctx->ret = 0; /* success */
+    return 0;
+  }
+
+  lua_getglobal(L, ctx->handler.c_str());
+  if (lua_type(L, -1) != LUA_TFUNCTION) {
+    CLS_ERR("error: unknown handler or not function: %s", ctx->handler.c_str());
+    ctx->ret = -EOPNOTSUPP;
+    return 0;
+  }
+
+  /* throw error if function is not registered */
+  clslua_check_registered_handler(L);
+
+  /* setup the input/output bufferlists */
+  clslua_pushbufferlist(L, &ctx->input);
+  clslua_pushbufferlist(L, ctx->outbl);
+
+  /*
+   * Call the target Lua object class handler. If the call is successful then
+   * we will examine the return value here and store it in the context. Errors
+   * that occur are handled in the top-level eval() function.
+   */
+  int top = lua_gettop(L);
+  lua_call(L, 2, LUA_MULTRET);
+
+  /* store return value in context */
+  if (!(lua_gettop(L) + 3 - top))
+    lua_pushinteger(L, 0);
+  ctx->ret = luaL_checkinteger(L, -1);
+
+  return 0;
+}
+
+/*
+ * Main handler. Proxies the Lua VM and the Lua-defined handler.
+ */
+static int eval_generic(cls_method_context_t hctx, bufferlist *in, bufferlist *out,
+    InputEncoding in_enc)
+{
+  struct clslua_hctx ctx;
+  lua_State *L = NULL;
+  int ret = -EIO;
+
+  /* stash context for use in Lua VM */
+  ctx.hctx = &hctx;
+  ctx.inbl = in;
+  ctx.in_enc = in_enc;
+  ctx.outbl = out;
+  ctx.error.error = false;
+
+  /* build lua vm state */
+  L = luaL_newstate();
+  if (!L) {
+    CLS_ERR("error creating new Lua state");
+    goto out;
+  }
+
+  /* panic handler for unhandled errors */
+  lua_atpanic(L, &cls_lua_atpanic);
+
+  if (setjmp(cls_lua_panic_jump) == 0) {
+
+    /*
+     * Stash the handler context in the register. It contains the objclass
+     * method context, global error state, and the command and reply structs.
+     */
+    lua_pushlightuserdata(L, &clslua_hctx_reg_key);
+    lua_pushlightuserdata(L, &ctx);
+    lua_settable(L, LUA_REGISTRYINDEX);
+
+    /* Process the input and run the script */
+    lua_pushcfunction(L, clslua_eval);
+    ret = lua_pcall(L, 0, 0, 0);
+
+    /* Encountered an error? */
+    if (ret) {
+      struct clslua_err *err = clslua_checkerr(L);
+      if (!err) {
+        CLS_ERR("error: cls_lua state machine: unexpected error");
+        ceph_abort();
+      }
+
+      /* Error origin a cls_cxx_* method? */
+      if (err->error) {
+        ret = err->ret; /* cls_cxx_* return value */
+
+        /* Errors always abort. Fix up ret and log error */
+        if (ret >= 0) {
+          CLS_ERR("error: unexpected handler return value");
+          ret = -EFAULT;
+        }
+
+      } else
+        ret = -EIO; /* Generic error code */
+
+      CLS_ERR("error: %s", lua_tostring(L, -1));
+
+    } else {
+      /*
+       * No Lua error encountered while running the script, but the handler
+       * may still have returned an error code (e.g. an errno value).
+       */
+      ret = ctx.ret;
+    }
+
+  } else {
+    CLS_ERR("error: recovering from Lua panic");
+    ret = -EFAULT;
+  }
+
+out:
+  if (L)
+    lua_close(L);
+  return ret;
+}
+
+static int eval_json(cls_method_context_t hctx, bufferlist *in, bufferlist *out)
+{
+  return eval_generic(hctx, in, out, JSON_ENC);
+}
+
+static int eval_bufferlist(cls_method_context_t hctx, bufferlist *in, bufferlist *out)
+{
+  return eval_generic(hctx, in, out, BUFFERLIST_ENC);
+}
+
+CLS_INIT(lua)
+{
+  CLS_LOG(20, "Loaded lua class!");
+
+  cls_handle_t h_class;
+  cls_method_handle_t h_eval_json;
+  cls_method_handle_t h_eval_bufferlist;
+
+  cls_register("lua", &h_class);
+
+  cls_register_cxx_method(h_class, "eval_json",
+      CLS_METHOD_RD | CLS_METHOD_WR, eval_json, &h_eval_json);
+
+  cls_register_cxx_method(h_class, "eval_bufferlist",
+      CLS_METHOD_RD | CLS_METHOD_WR, eval_bufferlist, &h_eval_bufferlist);
+}