String buffers, part 1: object serialization.

Sponsored by fmad.io.

11 files changed, 494 insertions, 18 deletions

diff --git a/src/Makefile b/src/Makefile
index 6f17bafd..a6e25ba1 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -482,13 +482,15 @@ LJVM_BOUT= $(LJVM_S)
 LJVM_MODE= elfasm
 
 LJLIB_O= lib_base.o lib_math.o lib_bit.o lib_string.o lib_table.o \
-         lib_io.o lib_os.o lib_package.o lib_debug.o lib_jit.o lib_ffi.o
+         lib_io.o lib_os.o lib_package.o lib_debug.o lib_jit.o lib_ffi.o \
+         lib_buffer.o
 LJLIB_C= $(LJLIB_O:.o=.c)
 
 LJCORE_O= lj_assert.o lj_gc.o lj_err.o lj_char.o lj_bc.o lj_obj.o lj_buf.o \
           lj_str.o lj_tab.o lj_func.o lj_udata.o lj_meta.o lj_debug.o \
           lj_prng.o lj_state.o lj_dispatch.o lj_vmevent.o lj_vmmath.o \
-          lj_strscan.o lj_strfmt.o lj_strfmt_num.o lj_api.o lj_profile.o \
+          lj_strscan.o lj_strfmt.o lj_strfmt_num.o lj_serialize.o \
+          lj_api.o lj_profile.o \
           lj_lex.o lj_parse.o lj_bcread.o lj_bcwrite.o lj_load.o \
           lj_ir.o lj_opt_mem.o lj_opt_fold.o lj_opt_narrow.o \
           lj_opt_dce.o lj_opt_loop.o lj_opt_split.o lj_opt_sink.o \
diff --git a/src/Makefile.dep b/src/Makefile.dep
index 3f26599e..315bf632 100644
--- a/src/Makefile.dep
+++ b/src/Makefile.dep
@@ -10,6 +10,9 @@ lib_bit.o: lib_bit.c lua.h luaconf.h lauxlib.h lualib.h lj_obj.h lj_def.h \
  lj_arch.h lj_err.h lj_errmsg.h lj_buf.h lj_gc.h lj_str.h lj_strscan.h \
  lj_strfmt.h lj_ctype.h lj_cdata.h lj_cconv.h lj_carith.h lj_ff.h \
  lj_ffdef.h lj_lib.h lj_libdef.h
+lib_buffer.o: lib_buffer.c lua.h luaconf.h lauxlib.h lualib.h lj_obj.h \
+ lj_def.h lj_arch.h lj_gc.h lj_buf.h lj_str.h lj_serialize.h lj_lib.h \
+ lj_libdef.h
 lib_debug.o: lib_debug.c lua.h luaconf.h lauxlib.h lualib.h lj_obj.h \
  lj_def.h lj_arch.h lj_gc.h lj_err.h lj_errmsg.h lj_debug.h lj_lib.h \
  lj_libdef.h
@@ -170,15 +173,18 @@ lj_parse.o: lj_parse.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
  lj_gc.h lj_err.h lj_errmsg.h lj_debug.h lj_buf.h lj_str.h lj_tab.h \
  lj_func.h lj_state.h lj_bc.h lj_ctype.h lj_strfmt.h lj_lex.h lj_parse.h \
  lj_vm.h lj_vmevent.h
+lj_prng.o: lj_prng.c lj_def.h lua.h luaconf.h lj_arch.h lj_prng.h
 lj_profile.o: lj_profile.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
  lj_buf.h lj_gc.h lj_str.h lj_frame.h lj_bc.h lj_debug.h lj_dispatch.h \
  lj_jit.h lj_ir.h lj_trace.h lj_traceerr.h lj_profile.h luajit.h
-lj_prng.o: lj_prng.c lj_def.h lua.h luaconf.h lj_arch.h lj_prng.h
 lj_record.o: lj_record.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
  lj_err.h lj_errmsg.h lj_str.h lj_tab.h lj_meta.h lj_frame.h lj_bc.h \
  lj_ctype.h lj_gc.h lj_ff.h lj_ffdef.h lj_debug.h lj_ir.h lj_jit.h \
  lj_ircall.h lj_iropt.h lj_trace.h lj_dispatch.h lj_traceerr.h \
  lj_record.h lj_ffrecord.h lj_snap.h lj_vm.h lj_prng.h
+lj_serialize.o: lj_serialize.c lj_obj.h lua.h luaconf.h lj_def.h \
+ lj_arch.h lj_err.h lj_errmsg.h lj_buf.h lj_gc.h lj_str.h lj_tab.h \
+ lj_udata.h lj_ctype.h lj_cdata.h lj_serialize.h
 lj_snap.o: lj_snap.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h lj_gc.h \
  lj_tab.h lj_state.h lj_frame.h lj_bc.h lj_ir.h lj_jit.h lj_iropt.h \
  lj_trace.h lj_dispatch.h lj_traceerr.h lj_snap.h lj_target.h \
@@ -189,7 +195,7 @@ lj_state.o: lj_state.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
  lj_ir.h lj_dispatch.h lj_traceerr.h lj_vm.h lj_prng.h lj_lex.h \
  lj_alloc.h luajit.h
 lj_str.o: lj_str.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h lj_gc.h \
- lj_err.h lj_errmsg.h lj_str.h lj_char.h
+ lj_err.h lj_errmsg.h lj_str.h lj_char.h lj_prng.h
 lj_strfmt.o: lj_strfmt.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
  lj_buf.h lj_gc.h lj_str.h lj_state.h lj_char.h lj_strfmt.h
 lj_strfmt_num.o: lj_strfmt_num.c lj_obj.h lua.h luaconf.h lj_def.h \
@@ -204,7 +210,7 @@ lj_trace.o: lj_trace.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
  lj_dispatch.h lj_traceerr.h lj_snap.h lj_gdbjit.h lj_record.h lj_asm.h \
  lj_vm.h lj_vmevent.h lj_target.h lj_target_*.h lj_prng.h
 lj_udata.o: lj_udata.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
- lj_gc.h lj_udata.h
+ lj_gc.h lj_err.h lj_errmsg.h lj_udata.h
 lj_vmevent.o: lj_vmevent.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
  lj_str.h lj_tab.h lj_state.h lj_dispatch.h lj_bc.h lj_jit.h lj_ir.h \
  lj_vm.h lj_vmevent.h
@@ -216,23 +222,23 @@ ljamalg.o: ljamalg.c lua.h luaconf.h lauxlib.h lj_assert.c lj_obj.h \
  lj_bc.h lj_ctype.h lj_cdata.h lj_trace.h lj_jit.h lj_ir.h lj_dispatch.h \
  lj_traceerr.h lj_vm.h lj_err.c lj_debug.h lj_ff.h lj_ffdef.h lj_strfmt.h \
  lj_char.c lj_char.h lj_bc.c lj_bcdef.h lj_obj.c lj_buf.c lj_str.c \
- lj_tab.c lj_func.c lj_udata.c lj_meta.c lj_strscan.h lj_lib.h lj_debug.c \
- lj_prng.c lj_prng.h lj_state.c lj_lex.h lj_alloc.h luajit.h \
+ lj_prng.h lj_tab.c lj_func.c lj_udata.c lj_meta.c lj_strscan.h lj_lib.h \
+ lj_debug.c lj_prng.c lj_state.c lj_lex.h lj_alloc.h luajit.h \
  lj_dispatch.c lj_ccallback.h lj_profile.h lj_vmevent.c lj_vmevent.h \
- lj_vmmath.c lj_strscan.c lj_strfmt.c lj_strfmt_num.c lj_api.c \
- lj_profile.c lj_lex.c lualib.h lj_parse.h lj_parse.c lj_bcread.c \
- lj_bcdump.h lj_bcwrite.c lj_load.c lj_ctype.c lj_cdata.c lj_cconv.h \
- lj_cconv.c lj_ccall.c lj_ccall.h lj_ccallback.c lj_target.h \
- lj_target_*.h lj_mcode.h lj_carith.c lj_carith.h lj_clib.c lj_clib.h \
- lj_cparse.c lj_cparse.h lj_lib.c lj_ir.c lj_ircall.h lj_iropt.h \
- lj_opt_mem.c lj_opt_fold.c lj_folddef.h lj_opt_narrow.c lj_opt_dce.c \
- lj_opt_loop.c lj_snap.h lj_opt_split.c lj_opt_sink.c lj_mcode.c \
- lj_snap.c lj_record.c lj_record.h lj_ffrecord.h lj_crecord.c \
+ lj_vmmath.c lj_strscan.c lj_strfmt.c lj_strfmt_num.c lj_serialize.c \
+ lj_serialize.h lj_api.c lj_profile.c lj_lex.c lualib.h lj_parse.h \
+ lj_parse.c lj_bcread.c lj_bcdump.h lj_bcwrite.c lj_load.c lj_ctype.c \
+ lj_cdata.c lj_cconv.h lj_cconv.c lj_ccall.c lj_ccall.h lj_ccallback.c \
+ lj_target.h lj_target_*.h lj_mcode.h lj_carith.c lj_carith.h lj_clib.c \
+ lj_clib.h lj_cparse.c lj_cparse.h lj_lib.c lj_ir.c lj_ircall.h \
+ lj_iropt.h lj_opt_mem.c lj_opt_fold.c lj_folddef.h lj_opt_narrow.c \
+ lj_opt_dce.c lj_opt_loop.c lj_snap.h lj_opt_split.c lj_opt_sink.c \
+ lj_mcode.c lj_snap.c lj_record.c lj_record.h lj_ffrecord.h lj_crecord.c \
  lj_crecord.h lj_ffrecord.c lj_recdef.h lj_asm.c lj_asm.h lj_emit_*.h \
  lj_asm_*.h lj_trace.c lj_gdbjit.h lj_gdbjit.c lj_alloc.c lib_aux.c \
  lib_base.c lj_libdef.h lib_math.c lib_string.c lib_table.c lib_io.c \
  lib_os.c lib_package.c lib_debug.c lib_bit.c lib_jit.c lib_ffi.c \
- lib_init.c
+ lib_buffer.c lib_init.c
 luajit.o: luajit.c lua.h luaconf.h lauxlib.h lualib.h luajit.h lj_arch.h
 host/buildvm.o: host/buildvm.c host/buildvm.h lj_def.h lua.h luaconf.h \
  lj_arch.h lj_obj.h lj_def.h lj_arch.h lj_gc.h lj_obj.h lj_bc.h lj_ir.h \
diff --git a/src/lib_buffer.c b/src/lib_buffer.c
new file mode 100644
index 00000000..e4555596
--- /dev/null
+++ b/src/lib_buffer.c
@@ -0,0 +1,66 @@
+/*
+** Buffer library.
+** Copyright (C) 2005-2021 Mike Pall. See Copyright Notice in luajit.h
+*/
+
+#define lib_buffer_c
+#define LUA_LIB
+
+#include "lua.h"
+#include "lauxlib.h"
+#include "lualib.h"
+
+#include "lj_obj.h"
+
+#if LJ_HASBUFFER
+#include "lj_gc.h"
+#include "lj_buf.h"
+#include "lj_serialize.h"
+#include "lj_lib.h"
+
+/* ------------------------------------------------------------------------ */
+
+#define LJLIB_MODULE_buffer
+
+/* Note: this uses interim structs until the SBuf reorg. */
+
+LJLIB_CF(buffer_encode)
+{
+  cTValue *o = lj_lib_checkany(L, 1);
+  StrBuf sbuf;
+  sbuf.sb = lj_buf_tmp_(L);
+  lj_serialize_put(&sbuf, o);
+  setstrV(L, L->top++, lj_buf_str(L, sbuf.sb));
+  lj_gc_check(L);
+  return 1;
+}
+
+LJLIB_CF(buffer_decode)
+{
+  GCstr *str = lj_lib_checkstr(L, 1);
+  const char *p = strdata(str);
+  SBuf sb;
+  StrBuf sbuf;
+  setsbufL(&sb, L);
+  setmref(sb.b, p);
+  setmref(sb.p, p + str->len);
+  setmref(sb.e, p + str->len);
+  sbuf.sb = &sb;
+  sbuf.r = (char *)p;
+  setnilV(L->top++);
+  lj_serialize_get(&sbuf, L->top-1);
+  lj_gc_check(L);
+  return 1;
+}
+
+/* ------------------------------------------------------------------------ */
+
+#include "lj_libdef.h"
+
+int luaopen_string_buffer(lua_State *L)
+{
+  LJ_LIB_REG(L, NULL, buffer);
+  return 1;
+}
+
+#endif
diff --git a/src/lib_string.c b/src/lib_string.c
index 51d1c4b0..4a3ff372 100644
--- a/src/lib_string.c
+++ b/src/lib_string.c
@@ -743,6 +743,9 @@ LUALIB_API int luaopen_string(lua_State *L)
   setgcref(basemt_it(g, LJ_TSTR), obj2gco(mt));
   settabV(L, lj_tab_setstr(L, mt, mmname_str(g, MM_index)), tabV(L->top-1));
   mt->nomm = (uint8_t)(~(1u<<MM_index));
+#if LJ_HASBUFFER
+  lj_lib_prereg(L, LUA_STRLIBNAME ".buffer", luaopen_string_buffer, tabV(L->top-1));
+#endif
   return 1;
 }
 
diff --git a/src/lj_arch.h b/src/lj_arch.h
index 0a6e1b9f..ae999467 100644
--- a/src/lj_arch.h
+++ b/src/lj_arch.h
@@ -549,6 +549,13 @@
 #define LJ_HASFFI               1
 #endif
 
+/* Disable or enable the string buffer extension. */
+#if defined(LUAJIT_DISABLE_BUFFER)
+#define LJ_HASBUFFER            0
+#else
+#define LJ_HASBUFFER            1
+#endif
+
 #if defined(LUAJIT_DISABLE_PROFILE)
 #define LJ_HASPROFILE           0
 #elif LJ_TARGET_POSIX
diff --git a/src/lj_buf.h b/src/lj_buf.h
index ae875298..a720f83b 100644
--- a/src/lj_buf.h
+++ b/src/lj_buf.h
@@ -10,7 +10,7 @@
 #include "lj_gc.h"
 #include "lj_str.h"
 
-/* Resizable string buffers. Struct definition in lj_obj.h. */
+/* Resizable string buffers. SBuf struct definition in lj_obj.h. */
 #define sbufB(sb)       (mref((sb)->b, char))
 #define sbufP(sb)       (mref((sb)->p, char))
 #define sbufE(sb)       (mref((sb)->e, char))
@@ -100,4 +100,11 @@ static LJ_AINLINE GCstr *lj_buf_str(lua_State *L, SBuf *sb)
   return lj_str_new(L, sbufB(sb), sbuflen(sb));
 }
 
+/* Interim user-accessible string buffer. */
+typedef struct StrBuf {
+  SBuf *sb;             /* Pointer to system buffer. */
+  char *r;              /* String buffer read pointer. */
+  int depth;            /* Remaining recursion depth. */
+} StrBuf;
+
 #endif
diff --git a/src/lj_errmsg.h b/src/lj_errmsg.h
index 9ff4553d..a6f638ce 100644
--- a/src/lj_errmsg.h
+++ b/src/lj_errmsg.h
@@ -179,6 +179,16 @@ ERRDEF(FFI_NYIPACKBIT,	"NYI: packed bit fields")
 ERRDEF(FFI_NYICALL,     "NYI: cannot call this C function (yet)")
 #endif
 
+#if LJ_HASBUFFER
+/* String buffer errors. */
+ERRDEF(BUFFER_BADENC,   "cannot serialize " LUA_QS)
+ERRDEF(BUFFER_BADDEC,   "cannot deserialize tag 0x%02x")
+ERRDEF(BUFFER_DEPTH,    "too deep to serialize")
+ERRDEF(BUFFER_DUPKEY,   "duplicate table key")
+ERRDEF(BUFFER_EOB,      "unexpected end of buffer")
+ERRDEF(BUFFER_LEFTOV,   "left-over data in buffer")
+#endif
+
 #undef ERRDEF
 
 /* Detecting unused error messages:
diff --git a/src/lj_serialize.c b/src/lj_serialize.c
new file mode 100644
index 00000000..5d7b7721
--- /dev/null
+++ b/src/lj_serialize.c
@@ -0,0 +1,351 @@
+/*
+** Object de/serialization.
+** Copyright (C) 2005-2021 Mike Pall. See Copyright Notice in luajit.h
+*/
+
+#define lj_serialize_c
+#define LUA_CORE
+
+#include "lj_obj.h"
+#include "lj_err.h"
+#include "lj_buf.h"
+#include "lj_str.h"
+#include "lj_tab.h"
+#include "lj_udata.h"
+#if LJ_HASFFI
+#include "lj_ctype.h"
+#include "lj_cdata.h"
+#endif
+#include "lj_serialize.h"
+
+/* Tags for internal serialization format. */
+enum {
+  SER_TAG_NIL,          /* 0x00 */
+  SER_TAG_FALSE,
+  SER_TAG_TRUE,
+  SER_TAG_NULL,
+  SER_TAG_LIGHTUD32,
+  SER_TAG_LIGHTUD64,
+  SER_TAG_INT,
+  SER_TAG_NUM,
+  SER_TAG_TAB,          /* 0x08 */
+  SER_TAG_0x0e = SER_TAG_TAB+6,
+  SER_TAG_0x0f,
+  SER_TAG_INT64,        /* 0x10 */
+  SER_TAG_UINT64,
+  SER_TAG_COMPLEX,
+  SER_TAG_0x13,
+  SER_TAG_0x14,
+  SER_TAG_0x15,
+  SER_TAG_0x16,
+  SER_TAG_0x17,
+  SER_TAG_0x18,         /* 0x18 */
+  SER_TAG_0x19,
+  SER_TAG_0x1a,
+  SER_TAG_0x1b,
+  SER_TAG_0x1c,
+  SER_TAG_0x1d,
+  SER_TAG_0x1e,
+  SER_TAG_0x1f,
+  SER_TAG_STR,          /* 0x20 + str->len */
+};
+LJ_STATIC_ASSERT((SER_TAG_TAB & 7) == 0);
+
+/* -- Helper functions ---------------------------------------------------- */
+
+static LJ_AINLINE char *serialize_more(char *w, StrBuf *sbuf, MSize sz)
+{
+  if (LJ_UNLIKELY(sz > (MSize)(sbufE(sbuf->sb) - w))) {
+    setsbufP(sbuf->sb, w);
+    w = lj_buf_more2(sbuf->sb, sz);
+  }
+  return w;
+}
+
+/* Write U124 to buffer. */
+static LJ_NOINLINE char *serialize_wu124_(char *w, uint32_t v)
+{
+  if (v < 0x1fe0) {
+    v -= 0xe0;
+    *w++ = (char)(0xe0 | (v >> 8)); *w++ = (char)v;
+  } else {
+    *w++ = (char)0xff;
+#if LJ_BE
+    v = lj_bswap(v);
+#endif
+    memcpy(w, &v, 4); w += 4;
+  }
+  return w;
+}
+
+static LJ_AINLINE char *serialize_wu124(char *w, uint32_t v)
+{
+  if (LJ_LIKELY(v < 0xe0)) {
+    *w++ = (char)v;
+    return w;
+  } else {
+    return serialize_wu124_(w, v);
+  }
+}
+
+static LJ_NOINLINE char *serialize_ru124_(char *r, char *e, uint32_t *pv)
+{
+  uint32_t v = *pv;
+  if (v != 0xff) {
+    if (r >= e) return NULL;
+    v = ((v & 0x1f) << 8) + *(uint8_t *)r + 0xe0; r++;
+  } else {
+    if (r + 4 > e) return NULL;
+    v = lj_getu32(r); r += 4;
+#if LJ_BE
+    v = lj_bswap(v);
+#endif
+  }
+  *pv = v;
+  return r;
+}
+
+static LJ_AINLINE char *serialize_ru124(char *r, char *e, uint32_t *pv)
+{
+  if (LJ_LIKELY(r < e)) {
+    uint32_t v = *(uint8_t *)r; r++;
+    *pv = v;
+    if (LJ_UNLIKELY(v >= 0xe0)) {
+      r = serialize_ru124_(r, e, pv);
+    }
+    return r;
+  }
+  return NULL;
+}
+
+/* -- Internal serializer ------------------------------------------------- */
+
+/* Put serialized object into buffer. */
+static char *serialize_put(char *w, StrBuf *sbuf, cTValue *o)
+{
+  if (LJ_LIKELY(tvisstr(o))) {
+    const GCstr *str = strV(o);
+    MSize len = str->len;
+    w = serialize_more(w, sbuf, 5+len);
+    w = serialize_wu124(w, SER_TAG_STR + len);
+    w = lj_buf_wmem(w, strdata(str), len);
+  } else if (tvisint(o)) {
+    uint32_t x = LJ_BE ? lj_bswap((uint32_t)intV(o)) : (uint32_t)intV(o);
+    w = serialize_more(w, sbuf, 1+4);
+    *w++ = SER_TAG_INT; memcpy(w, &x, 4); w += 4;
+  } else if (tvisnum(o)) {
+    uint64_t x = LJ_BE ? lj_bswap64(o->u64) : o->u64;
+    w = serialize_more(w, sbuf, 1+sizeof(lua_Number));
+    *w++ = SER_TAG_NUM; memcpy(w, &x, 8); w += 8;
+  } else if (tvispri(o)) {
+    w = serialize_more(w, sbuf, 1);
+    *w++ = (char)(SER_TAG_NIL + ~itype(o));
+  } else if (tvistab(o)) {
+    const GCtab *t = tabV(o);
+    uint32_t narray = 0, nhash = 0, one = 2;
+    if (sbuf->depth <= 0) lj_err_caller(sbufL(sbuf->sb), LJ_ERR_BUFFER_DEPTH);
+    sbuf->depth--;
+    if (t->asize > 0) {  /* Determine max. length of array part. */
+      ptrdiff_t i;
+      TValue *array = tvref(t->array);
+      for (i = (ptrdiff_t)t->asize-1; i >= 0; i--)
+        if (!tvisnil(&array[i]))
+          break;
+      narray = (uint32_t)(i+1);
+      if (narray && tvisnil(&array[0])) one = 4;
+    }
+    if (t->hmask > 0) {  /* Count number of used hash slots. */
+      uint32_t i, hmask = t->hmask;
+      Node *node = noderef(t->node);
+      for (i = 0; i <= hmask; i++)
+        nhash += !tvisnil(&node[i].val);
+    }
+    /* Write number of array slots and hash slots. */
+    w = serialize_more(w, sbuf, 1+2*5);
+    *w++ = (char)(SER_TAG_TAB + (nhash ? 1 : 0) + (narray ? one : 0));
+    if (narray) w = serialize_wu124(w, narray);
+    if (nhash) w = serialize_wu124(w, nhash);
+    if (narray) {  /* Write array entries. */
+      cTValue *oa = tvref(t->array) + (one >> 2);
+      cTValue *oe = tvref(t->array) + narray;
+      while (oa < oe) w = serialize_put(w, sbuf, oa++);
+    }
+    if (nhash) {  /* Write hash entries. */
+      const Node *node = noderef(t->node) + t->hmask;
+      for (;; node--)
+        if (!tvisnil(&node->val)) {
+          w = serialize_put(w, sbuf, &node->key);
+          w = serialize_put(w, sbuf, &node->val);
+          if (--nhash == 0) break;
+        }
+    }
+    sbuf->depth++;
+#if LJ_HASFFI
+  } else if (tviscdata(o)) {
+    CTState *cts = ctype_cts(sbufL(sbuf->sb));
+    CType *s = ctype_raw(cts, cdataV(o)->ctypeid);
+    uint8_t *sp = cdataptr(cdataV(o));
+    if (ctype_isinteger(s->info) && s->size == 8) {
+      w = serialize_more(w, sbuf, 1+8);
+      *w++ = (s->info & CTF_UNSIGNED) ? SER_TAG_UINT64 : SER_TAG_INT64;
+#if LJ_BE
+      { uint64_t u = lj_bswap64(*(uint64_t *)sp); memcpy(w, &u, 8); }
+#else
+      memcpy(w, sp, 8);
+#endif
+      w += 8;
+    } else if (ctype_iscomplex(s->info) && s->size == 16) {
+      w = serialize_more(w, sbuf, 1+16);
+      *w++ = SER_TAG_COMPLEX;
+#if LJ_BE
+      {  /* Only swap the doubles. The re/im order stays the same. */
+        uint64_t u = lj_bswap64(((uint64_t *)sp)[0]); memcpy(w, &u, 8);
+        u = lj_bswap64(((uint64_t *)sp)[1]); memcpy(w+8, &u, 8);
+      }
+#else
+      memcpy(w, sp, 16);
+#endif
+      w += 16;
+    } else {
+      goto badenc;  /* NYI other cdata */
+    }
+#endif
+  } else if (tvislightud(o)) {
+    uintptr_t ud = (uintptr_t)lightudV(G(sbufL(sbuf->sb)), o);
+    w = serialize_more(w, sbuf, 1+sizeof(ud));
+    if (ud == 0) {
+      *w++ = SER_TAG_NULL;
+    } else if (LJ_32 || checku32(ud)) {
+#if LJ_BE && LJ_64
+      ud = lj_bswap64(ud);
+#elif LJ_BE
+      ud = lj_bswap(ud);
+#endif
+      *w++ = SER_TAG_LIGHTUD32; memcpy(w, &ud, 4); w += 4;
+    } else {
+#if LJ_BE
+      ud = lj_bswap64(ud);
+#endif
+      *w++ = SER_TAG_LIGHTUD64; memcpy(w, &ud, 8); w += 8;
+    }
+  } else {
+    /* NYI userdata */
+#if LJ_HASFFI
+  badenc:
+#endif
+    lj_err_callerv(sbufL(sbuf->sb), LJ_ERR_BUFFER_BADENC, lj_typename(o));
+  }
+  return w;
+}
+
+/* Get serialized object from buffer. */
+static char *serialize_get(char *r, StrBuf *sbuf, TValue *o)
+{
+  char *e = sbufE(sbuf->sb);
+  uint32_t tp;
+  r = serialize_ru124(r, e, &tp); if (LJ_UNLIKELY(!r)) goto eob;
+  if (LJ_LIKELY(tp >= SER_TAG_STR)) {
+    uint32_t len = tp - SER_TAG_STR;
+    if (LJ_UNLIKELY(len > (uint32_t)(e - r))) goto eob;
+    setstrV(sbufL(sbuf->sb), o, lj_str_new(sbufL(sbuf->sb), r, len));
+    r += len;
+  } else if (tp == SER_TAG_INT) {
+    if (LJ_UNLIKELY(r + 4 > e)) goto eob;
+    setintV(o, (int32_t)(LJ_BE ? lj_bswap(lj_getu32(r)) : lj_getu32(r)));
+    r += 4;
+  } else if (tp == SER_TAG_NUM) {
+    if (LJ_UNLIKELY(r + 8 > e)) goto eob;
+    memcpy(o, r, 8); r += 8;
+#if LJ_BE
+    o->u64 = lj_bswap64(o->u64);
+#endif
+    if (!tvisnum(o)) setnanV(o);
+  } else if (tp <= SER_TAG_TRUE) {
+    setpriV(o, ~tp);
+  } else if (tp >= SER_TAG_TAB && tp < SER_TAG_TAB+6) {
+    uint32_t narray = 0, nhash = 0;
+    GCtab *t;
+    if (tp >= SER_TAG_TAB+2) {
+      r = serialize_ru124(r, e, &narray); if (LJ_UNLIKELY(!r)) goto eob;
+    }
+    if ((tp & 1)) {
+      r = serialize_ru124(r, e, &nhash); if (LJ_UNLIKELY(!r)) goto eob;
+    }
+    t = lj_tab_new(sbufL(sbuf->sb), narray, hsize2hbits(nhash));
+    settabV(sbufL(sbuf->sb), o, t);
+    if (narray) {
+      TValue *oa = tvref(t->array) + (tp >= SER_TAG_TAB+4);
+      TValue *oe = tvref(t->array) + narray;
+      while (oa < oe) r = serialize_get(r, sbuf, oa++);
+    }
+    if (nhash) {
+      do {
+        TValue k, *v;
+        r = serialize_get(r, sbuf, &k);
+        v = lj_tab_set(sbufL(sbuf->sb), t, &k);
+        if (LJ_UNLIKELY(!tvisnil(v)))
+          lj_err_caller(sbufL(sbuf->sb), LJ_ERR_BUFFER_DUPKEY);
+        r = serialize_get(r, sbuf, v);
+      } while (--nhash);
+    }
+#if LJ_HASFFI
+  } else if (tp >= SER_TAG_INT64 &&  tp <= SER_TAG_COMPLEX) {
+    uint32_t sz = tp == SER_TAG_COMPLEX ? 16 : 8;
+    GCcdata *cd;
+    if (LJ_UNLIKELY(r + sz > e)) goto eob;
+    cd = lj_cdata_new_(sbufL(sbuf->sb),
+           tp == SER_TAG_INT64 ? CTID_INT64 :
+           tp == SER_TAG_UINT64 ? CTID_UINT64 : CTID_COMPLEX_DOUBLE,
+           sz);
+    memcpy(cdataptr(cd), r, sz); r += sz;
+#if LJ_BE
+    *(uint64_t *)cdataptr(cd) = lj_bswap64(*(uint64_t *)cdataptr(cd));
+    if (sz == 16)
+      ((uint64_t *)cdataptr(cd))[1] = lj_bswap64(((uint64_t *)cdataptr(cd))[1]);
+#endif
+    setcdataV(sbufL(sbuf->sb), o, cd);
+#endif
+  } else if (tp <= (LJ_64 ? SER_TAG_LIGHTUD64 : SER_TAG_LIGHTUD32)) {
+    uintptr_t ud = 0;
+    if (tp == SER_TAG_LIGHTUD32) {
+      if (LJ_UNLIKELY(r + 4 > e)) goto eob;
+      ud = (uintptr_t)(LJ_BE ? lj_bswap(lj_getu32(r)) : lj_getu32(r));
+      r += 4;
+    }
+#if LJ_64
+    else if (tp == SER_TAG_LIGHTUD64) {
+      if (LJ_UNLIKELY(r + 8 > e)) goto eob;
+      memcpy(&ud, r, 8); r += 8;
+#if LJ_BE
+      ud = lj_bswap64(ud);
+#endif
+    }
+    setrawlightudV(o, lj_lightud_intern(sbufL(sbuf->sb), (void *)ud));
+#else
+    setrawlightudV(o, (void *)ud);
+#endif
+  } else {
+    lj_err_callerv(sbufL(sbuf->sb), LJ_ERR_BUFFER_BADDEC, tp);
+  }
+  return r;
+eob:
+  lj_err_caller(sbufL(sbuf->sb), LJ_ERR_BUFFER_EOB);
+  return NULL;
+}
+
+StrBuf * LJ_FASTCALL lj_serialize_put(StrBuf *sbuf, cTValue *o)
+{
+  sbuf->depth = LJ_SERIALIZE_DEPTH;
+  setsbufP(sbuf->sb, serialize_put(sbufP(sbuf->sb), sbuf, o));
+  return sbuf;
+}
+
+StrBuf * LJ_FASTCALL lj_serialize_get(StrBuf *sbuf, TValue *o)
+{
+  char *r = serialize_get(sbuf->r, sbuf, o);
+  if (r != sbufP(sbuf->sb))
+    lj_err_caller(sbufL(sbuf->sb), LJ_ERR_BUFFER_LEFTOV);
+  sbuf->r = r;
+  return sbuf;
+}
+
diff --git a/src/lj_serialize.h b/src/lj_serialize.h
new file mode 100644
index 00000000..95d62f4e
--- /dev/null
+++ b/src/lj_serialize.h
@@ -0,0 +1,21 @@
+/*
+** Object de/serialization.
+** Copyright (C) 2005-2021 Mike Pall. See Copyright Notice in luajit.h
+*/
+
+#ifndef _LJ_SERIALIZE_H
+#define _LJ_SERIALIZE_H
+
+#include "lj_obj.h"
+#include "lj_buf.h"
+
+#if LJ_HASBUFFER
+
+#define LJ_SERIALIZE_DEPTH      100     /* Default depth. */
+
+LJ_FUNC StrBuf * LJ_FASTCALL lj_serialize_put(StrBuf *sb, cTValue *o);
+LJ_FUNC StrBuf * LJ_FASTCALL lj_serialize_get(StrBuf *sb, TValue *o);
+
+#endif
+
+#endif
diff --git a/src/ljamalg.c b/src/ljamalg.c
index 8e2d4937..384b3cc1 100644
--- a/src/ljamalg.c
+++ b/src/ljamalg.c
@@ -39,6 +39,7 @@
 #include "lj_strscan.c"
 #include "lj_strfmt.c"
 #include "lj_strfmt_num.c"
+#include "lj_serialize.c"
 #include "lj_api.c"
 #include "lj_profile.c"
 #include "lj_lex.c"
@@ -85,5 +86,6 @@
 #include "lib_bit.c"
 #include "lib_jit.c"
 #include "lib_ffi.c"
+#include "lib_buffer.c"
 #include "lib_init.c"
 
diff --git a/src/lualib.h b/src/lualib.h
index 9cd39880..5c18e9ec 100644
--- a/src/lualib.h
+++ b/src/lualib.h
@@ -33,6 +33,7 @@ LUALIB_API int luaopen_debug(lua_State *L);
 LUALIB_API int luaopen_bit(lua_State *L);
 LUALIB_API int luaopen_jit(lua_State *L);
 LUALIB_API int luaopen_ffi(lua_State *L);
+LUALIB_API int luaopen_string_buffer(lua_State *L);
 
 LUALIB_API void luaL_openlibs(lua_State *L);