Adds support for Lua struct library so one can pack/unpack binary structures

This is based on Roberto Ierusalimschy's struct library, along with additional
options based on Flemming Madsen's patch to the lua-users mailing list, and
some changes I made to support 64-bit integer packing/unpacking.  Details
are in the top comments for wslua_struct.c.  This also includes a test script.

Change-Id: Ifcd0116ba013d5c760927721c8d6e9f28965534b
Reviewed-on: https://code.wireshark.org/review/98
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>
Tested-by: Alexis La Goutte <alexis.lagoutte@gmail.com>

7 files changed, 554 insertions, 11 deletions

diff --git a/epan/wslua/CMakeLists.txt b/epan/wslua/CMakeLists.txt
index 4332200a72..8968938281 100644
--- a/epan/wslua/CMakeLists.txt
+++ b/epan/wslua/CMakeLists.txt
@@ -34,6 +34,7 @@ set(WSLUA_MODULES
 	${CMAKE_CURRENT_SOURCE_DIR}/wslua/wslua_gui.c
 	${CMAKE_CURRENT_SOURCE_DIR}/wslua/wslua_util.c
 	${CMAKE_CURRENT_SOURCE_DIR}/wslua/wslua_field.c
+  ${CMAKE_CURRENT_SOURCE_DIR}/wslua/wslua_struct.c
 	${CMAKE_CURRENT_SOURCE_DIR}/wslua/wslua_dumper.c
 )
 
diff --git a/epan/wslua/Makefile.am b/epan/wslua/Makefile.am
index e5789c1d7d..241a2a63ad 100644
--- a/epan/wslua/Makefile.am
+++ b/epan/wslua/Makefile.am
@@ -40,6 +40,7 @@ wslua_modules = 	\
 	$(srcdir)/wslua_gui.c \
 	$(srcdir)/wslua_util.c \
 	$(srcdir)/wslua_field.c \
+	$(srcdir)/wslua_struct.c \
 	$(srcdir)/wslua_dumper.c
 
 libwslua_la_SOURCES = \
@@ -129,7 +130,8 @@ checkapi:
 	wslua_int64.c \
 	wslua_pinfo.c \
 	wslua_proto.c \
-	wslua_listener.c \
+	wslua_struct.c \
+	wslua_tree.c \
 	wslua_tree.c \
 	wslua_tvb.c \
 	wslua_util.c
diff --git a/epan/wslua/Makefile.nmake b/epan/wslua/Makefile.nmake
index f9c63d21a4..32e1789eaf 100644
--- a/epan/wslua/Makefile.nmake
+++ b/epan/wslua/Makefile.nmake
@@ -25,6 +25,7 @@ MODULES = 	\
 	wslua_gui.c \
 	wslua_util.c \
 	wslua_field.c \
+	wslua_struct.c \
 	wslua_dumper.c
 
 OBJECTS= \
@@ -39,6 +40,7 @@ OBJECTS= \
 	wslua_proto.obj \
 	wslua_listener.obj \
 	wslua_int64.obj \
+	wslua_struct.obj \
 	wslua_tree.obj \
 	wslua_tvb.obj \
 	wslua_util.obj
diff --git a/epan/wslua/template-init.lua b/epan/wslua/template-init.lua
index 74380263d9..f036c2460a 100644
--- a/epan/wslua/template-init.lua
+++ b/epan/wslua/template-init.lua
@@ -61,7 +61,7 @@ end
 
 function typeof(obj)
     local mt = getmetatable(obj)
-    return mt and mt.__typeof or type(obj)
+    return mt and mt.__typeof or obj.__typeof or type(obj)
 end
 
 function file_exists(name)
diff --git a/epan/wslua/wslua.h b/epan/wslua/wslua.h
index 4cb16d2588..6deef65468 100644
--- a/epan/wslua/wslua.h
+++ b/epan/wslua/wslua.h
@@ -256,6 +256,7 @@ typedef tvbparse_action_t* Shortcut;
 typedef struct _wslua_main* WireShark;
 typedef struct _wslua_dir* Dir;
 typedef struct _wslua_private_table* PrivateTable;
+typedef gchar* Struct;
 
 /*
  * toXxx(L,idx) gets a Xxx from an index (Lua Error if fails)
@@ -450,6 +451,11 @@ extern void lua_prime_all_fields(proto_tree* tree);
 
 extern int Proto_commit(lua_State* L);
 
+extern void Int64_pack(lua_State* L, luaL_Buffer *b, gint idx, gboolean asLittleEndian);
+extern int Int64_unpack(lua_State* L, const gchar *buff, gboolean asLittleEndian);
+extern void UInt64_pack(lua_State* L, luaL_Buffer *b, gint idx, gboolean asLittleEndian);
+extern int UInt64_unpack(lua_State* L, const gchar *buff, gboolean asLittleEndian);
+
 extern Tvb* push_Tvb(lua_State* L, tvbuff_t* tvb);
 extern gboolean push_TvbRange(lua_State* L, tvbuff_t* tvb, int offset, int len);
 extern void clear_outstanding_Tvb(void);
diff --git a/epan/wslua/wslua_int64.c b/epan/wslua/wslua_int64.c
index b5cae7bbd5..3534e3a5f3 100644
--- a/epan/wslua/wslua_int64.c
+++ b/epan/wslua/wslua_int64.c
@@ -52,7 +52,7 @@ WSLUA_CLASS_DEFINE_BASE(Int64,NOP,NOP,0);
   Lua uses one single number representation which can be chosen at compile time and since
   it is often set to IEEE 754 double precision floating point, we cannot store a 64 bit integer
   with full precision.
-  For details, see: http://lua-users.org/wiki/FloatingPoint
+  For details, see: http://wiki.wireshark.org/LuaAPI/Int64
  */
 
 /* these declarations are here because some funcs in Int64 need to know about UInt64 */
@@ -222,9 +222,10 @@ WSLUA_METHOD Int64_tonumber(lua_State* L) {
 }
 
 WSLUA_CONSTRUCTOR Int64_fromhex(lua_State* L) { /* Creates an Int64 object from the given hex string */
+#define WSLUA_ARG_Int64_fromhex_HEX 1 /* The hex-ascii Lua string */
     guint64 result = 0;
     size_t len = 0;
-    const gchar *s = luaL_checklstring(L,1,&len);
+    const gchar *s = luaL_checklstring(L,WSLUA_ARG_Int64_fromhex_HEX,&len);
 
     if (s && len > 0) {
         sscanf(s, "%" G_GINT64_MODIFIER "x", &result);
@@ -252,11 +253,11 @@ WSLUA_METHOD Int64_higher(lua_State* L) {
     /* Returns a Lua number of the higher 32-bits of the Int64 value. (negative Int64 will return a negative Lua number) */
     gint64 num = getInt64(L,1);
     gint64 b = num;
-    lua_Number n;
+    lua_Number n = 0;
     if (b < 0) b = -b; /* masking/shifting negative int64 isn't working on some platforms */
     b &= G_GUINT64_CONSTANT(0x7FFFFFFF00000000);
     b >>= 32;
-    n = (lua_Number)(guint32)(b & 0x00000000FFFFFFFFF);
+    n = (lua_Number)(guint32)(b & G_GUINT64_CONSTANT(0x00000000FFFFFFFFF));
     if (num < 0) n = -n;
     lua_pushnumber(L,n);
     WSLUA_RETURN(1); /* The Lua number */
@@ -515,7 +516,8 @@ LUALIB_API int Int64_register(lua_State* L) {
 
 
 WSLUA_CLASS_DEFINE_BASE(UInt64,NOP,NOP,0);
-    /* UInt64 represents a 64 bit unsigned integer, similar to Int64. */
+    /* UInt64 represents a 64 bit unsigned integer, similar to Int64.
+       For details, see: http://wiki.wireshark.org/LuaAPI/Int64 */
 
 /* A checkUInt64 but that also auto-converts numbers, strings, and Int64 to a guint64 */
 static guint64 getUInt64(lua_State *L, int i)
@@ -687,9 +689,10 @@ WSLUA_METAMETHOD UInt64__tostring(lua_State* L) {
 }
 
 WSLUA_CONSTRUCTOR UInt64_fromhex(lua_State* L) { /* Creates a UInt64 object from the given hex string */
+#define WSLUA_ARG_UInt64_fromhex_HEX 1 /* The hex-ascii Lua string */
     guint64 result = 0;
     size_t len = 0;
-    const gchar *s = luaL_checklstring(L,1,&len);
+    const gchar *s = luaL_checklstring(L,WSLUA_ARG_UInt64_fromhex_HEX,&len);
 
     if (s && len > 0) {
         sscanf(s, "%" G_GINT64_MODIFIER "x", &result);
@@ -700,9 +703,9 @@ WSLUA_CONSTRUCTOR UInt64_fromhex(lua_State* L) { /* Creates a UInt64 object from
 
 WSLUA_METHOD UInt64_tohex(lua_State* L) {
     /* Returns a hex string of the UInt64 value. */
-#define WSLUA_OPTARG_Int64_new_NUMBYTES 2 /* The number of hex-chars/nibbles to generate, negative means uppercase (default=16) */
+#define WSLUA_OPTARG_UInt64_new_NUMBYTES 2 /* The number of hex-chars/nibbles to generate, negative means uppercase (default=16) */
     guint64 b = getUInt64(L,1);
-    gint n = luaL_optint(L, WSLUA_OPTARG_Int64_new_NUMBYTES, 16);
+    gint n = luaL_optint(L, WSLUA_OPTARG_UInt64_new_NUMBYTES, 16);
     const gchar *hexdigits = "0123456789abcdef";
     gchar buf[16];
     gint i;
@@ -717,7 +720,7 @@ WSLUA_METHOD UInt64_higher(lua_State* L) {
     /* Returns a Lua number of the higher 32-bits of the UInt64 value. */
     guint64 num = getUInt64(L,1);
     guint64 b = num;
-    lua_Number n;
+    lua_Number n = 0;
     b &= G_GUINT64_CONSTANT(0xFFFFFFFF00000000);
     b >>= 32;
     n = (lua_Number)(guint32)(b & G_GUINT64_CONSTANT(0x00000000FFFFFFFFF));
diff --git a/epan/wslua/wslua_struct.c b/epan/wslua/wslua_struct.c
new file mode 100644
index 0000000000..cf27a73cc5
--- /dev/null
+++ b/epan/wslua/wslua_struct.c
@@ -0,0 +1,529 @@
+/*
+** {======================================================
+** Library for packing/unpacking structures.
+** $Id: struct.c,v 1.4 2012/07/04 18:54:29 roberto Exp $
+** See Copyright Notice at the end of this file
+**
+** Small changes were made by Hadriel Kaplan - those changes 
+** are in the Public Domain.
+**
+** Some changes are based on a patch to struct.h from
+** Flemming Madsen, from here:
+** http://lua-users.org/lists/lua-l/2009-10/msg00572.html
+** In particular, these changes from him:
+** -Can handle 'long long' integers (i8 / I8); though they're converted to doubles
+** -Can insert/specify padding anywhere in a struct. ('X' eg. when a string is following a union)
+** -Can report current offset in both pack and unpack ('=')
+** -Can mask out return values when you only want to calculate sizes or unmarshal pascal-style strings. '(' & ')'
+**
+** Changes I made:
+** -Added support for Int64/UIn64 being packed/unpacked, using 'e'/'E'
+** -Made it follow Wireshark's conventions so we could get API docs
+** =======================================================
+*/
+/*
+** Valid formats:
+** > - big endian
+** < - little endian
+** ![num] - alignment
+** x[num]   - pad num bytes, default 1
+** X[num]   - pad to num align, default MAXALIGN
+**
+** Following are system-dependent sizes:
+** b/B - signed/unsigned byte
+** h/H - signed/unsigned short
+** i/I - signed/unsigned int
+** l/L - signed/unsigned long
+** f - float
+** d - double
+** T   - size_t
+**
+** Following are system-independent sizes:
+** in/In - signed/unsigned integer of size `n' bytes
+          Note: unpack of i/I is done to a Lua_number, typically a double,
+          so unpacking a 64-bit field (i8/I8) will lose precision.
+          Use e/E to unpack into a Wireshark Int64/UInt64 object/userdata instead.
+** e/E - signed/unsigned eight-byte Integer (64bits, long long), to/from Int64/UInt64 object
+** cn - sequence of `n' chars (from/to a string); when packing, n==0 means
+        the whole string; when unpacking, n==0 means use the previous
+        read number as the string length
+** s - zero-terminated string
+** ' ' - ignored
+** '(' ')'  - stop assigning items. ')' start assigning (padding when packing)
+** '='      - return current position / offset
+*/
+
+
+#include <assert.h>
+#include <ctype.h>
+#include <limits.h>
+#include <stddef.h>
+#include <string.h>
+
+#include <stdio.h>
+
+#include "config.h"
+
+#include "wslua.h"
+
+    /* WSLUA_MODULE Struct Binary encode/decode support */
+
+/* TODO: figure out a way for wslua Module's to have (possibly long) description text */
+
+/* The following line is here so that make-reg.pl does the right thing.  This 'Struct' class
+  isn't really a class, so it doesn't have the checkStruct/pushStruct/etc. functions
+  the following macro would generate; but it does need to be registered and such. 
+  WSLUA_CLASS_DEFINE_BASE(Struct,NOP,NOP,0); 
+  */
+
+/* basic integer type - yes this is system-specific size - it's meant to be */
+#if !defined(STRUCT_INT)
+#define STRUCT_INT  long
+#endif
+
+typedef STRUCT_INT Inttype;
+
+/* corresponding unsigned version */
+typedef unsigned STRUCT_INT Uinttype;
+
+/* maximum size (in bytes) for integral types */
+#define MAXINTSIZE	32
+
+/* is 'x' a power of 2? */
+#define isp2(x)		((x) > 0 && ((x) & ((x) - 1)) == 0)
+
+/* dummy structure to get padding/alignment requirements */
+struct cD {
+  gchar c;
+  gdouble d;
+};
+
+
+#define PADDING		(sizeof(struct cD) - sizeof(gdouble))
+#define MAXALIGN  	(PADDING > sizeof(int) ? PADDING : sizeof(int))
+
+
+/* endian options */
+#define BIG	0
+#define LITTLE	1
+
+/* trick to determine native endianess of system */
+static union {
+  int dummy;
+  gchar endian;
+} const native = {1};
+
+/* settings info */
+typedef struct Header {
+  int endian;
+  int align;
+  gboolean noassign;
+} Header;
+
+/* For options that take a number argument, gets the number  */
+static int getnum (const gchar **fmt, int df) {
+  if (!isdigit(**fmt))  /* no number? */
+    return df;  /* return default value */
+  else {
+    int a = 0;
+    do {
+      a = a*10 + *((*fmt)++) - '0';
+    } while (isdigit(**fmt));
+    return a;
+  }
+}
+
+
+#define defaultoptions(h)	((h)->endian = native.endian, (h)->align = 1, (h)->noassign = FALSE)
+
+
+/* gets size (number of bytes) for a given type */
+static size_t optsize (lua_State *L, gchar opt, const gchar **fmt) {
+  switch (opt) {
+    case 'B': case 'b': return sizeof(gchar);
+    case 'H': case 'h': return sizeof(gshort);
+    case 'L': case 'l': return sizeof(glong);
+    case 'E': case 'e': return sizeof(gint64);
+    case 'T': return sizeof(size_t);
+    case 'f': return sizeof(gfloat);
+    case 'd': return sizeof(gdouble);
+    case 'x': return getnum(fmt, 1);
+    case 'X': return getnum(fmt, MAXALIGN);
+    case 'c': return getnum(fmt, 1);
+    case 'i': case 'I': {
+      int sz = getnum(fmt, sizeof(int));
+      if (sz > MAXINTSIZE)
+        luaL_error(L, "integral size %d is larger than limit of %d",
+                       sz, MAXINTSIZE);
+      return sz;
+    }
+    case 's': case ' ':
+    case '<': case '>':
+    case '(': case ')':
+    case '!': case '=':
+              return 0;  /* these cases do not have a size */
+    default: {
+      const gchar *msg = lua_pushfstring(L, "invalid format option [%c]", opt);
+      return luaL_argerror(L, 1, msg);
+    }
+  }
+}
+
+
+/*
+** return number of bytes needed to align an element of size 'size'
+** at current position 'len'
+*/
+static int gettoalign (size_t len, Header *h, int opt, size_t size) {
+  if (size == 0 || opt == 'c' || opt == 's') return 0;
+  if (size > (size_t)h->align)
+    size = h->align;  /* respect max. alignment */
+  return (int)((size - (len & (size - 1))) & (size - 1));
+}
+
+
+/*
+** options to control endianess and alignment settings
+*/
+static void controloptions (lua_State *L, int opt, const gchar **fmt,
+                            Header *h) {
+  switch (opt) {
+    case ' ': return;  /* ignore white spaces */
+    case '>': h->endian = BIG; return;
+    case '<': h->endian = LITTLE; return;
+    case '(': h->noassign = TRUE; return;
+    case ')': h->noassign = FALSE; return;
+    case '!': {
+      int a = getnum(fmt, MAXALIGN);
+      if (!isp2(a))
+        luaL_error(L, "alignment %d is not a power of 2", a);
+      h->align = a;
+      return;
+    }
+    default: {
+      const char *msg = lua_pushfstring(L, "invalid format option '%c'", opt);
+      luaL_argerror(L, 1, msg);
+    }
+  }
+}
+
+/* Encodes a Lua number as an integer of given size and endiannes into a string struct */
+static void putinteger (lua_State *L, luaL_Buffer *b, int arg, int endian,
+                        int size) {
+  lua_Number n = luaL_checknumber(L, arg);
+  /* this one's not system dependent size - it's a long long */
+  gint64 value;
+  gchar buff[MAXINTSIZE];
+  if (n < 0)
+    value = (guint64)(gint64)n;
+  else
+    value = (guint64)n;
+  if (endian == LITTLE) {
+    int i;
+    for (i = 0; i < size; i++) {
+      buff[i] = (value & 0xff);
+      value >>= 8;
+    }
+  }
+  else {
+    int i;
+    for (i = size - 1; i >= 0; i--) {
+      buff[i] = (value & 0xff);
+      value >>= 8;
+    }
+  }
+  luaL_addlstring(b, buff, size);
+}
+
+/* corrects endiannes - usually done by other functions themselves, but is 
+ * used for float/doubles, since on some platforms they're endian'ed as well
+ */
+static void correctbytes (gchar *b, int size, int endian) {
+  if (endian != native.endian) {
+    int i = 0;
+    while (i < --size) {
+      gchar temp = b[i];
+      b[i++] = b[size];
+      b[size] = temp;
+    }
+  }
+}
+
+
+WSLUA_CONSTRUCTOR Struct_pack (lua_State *L) {
+  /* Returns a string containing the values arg1, arg2, etc. packed/encoded according to the format string. */
+#define WSLUA_ARG_Struct_unpack_FORMAT 1 /* The format string */
+#define WSLUA_ARG_Struct_unpack_STRUCT 2 /* One or more Lua value(s) to encode, based on the given format. */
+  luaL_Buffer b;
+  const char *fmt = luaL_checkstring(L, WSLUA_ARG_Struct_unpack_FORMAT);
+  Header h;
+  int poscnt = 0;
+  int posBuf[10];
+  int arg = 2;
+  size_t totalsize = 0;
+  defaultoptions(&h);
+  lua_pushnil(L);  /* mark to separate arguments from string buffer */
+  luaL_buffinit(L, &b);
+  while (*fmt != '\0') {
+    int opt = *fmt++;
+    size_t size = optsize(L, opt, &fmt);
+    int toalign = gettoalign(totalsize, &h, opt, size);
+    totalsize += toalign;
+    while (toalign-- > 0) luaL_addchar(&b, '\0');
+    if (opt == 'X') size = 0; /* 'X' is about alignment, not size */
+    if (h.noassign && size) opt = 'x'; /* for pack, "(i4)" is the same as "x4" */
+    switch (opt) {
+      case 'b': case 'B': case 'h': case 'H':
+      case 'l': case 'L': case 'T': case 'i': case 'I': {  /* integer types */
+        putinteger(L, &b, arg++, h.endian, (int)size);
+        break;
+      }
+      case 'e': {
+        Int64_pack(L, &b, arg++, h.endian == LITTLE);
+        break;
+      }
+      case 'E': {
+        UInt64_pack(L, &b, arg++, h.endian == LITTLE);
+        break;
+      }
+      case 'x': case 'X': {
+        size_t len = size;
+        while (len-- > 0)
+          luaL_addchar(&b, '\0');
+        break;
+      }
+      case 'f': {
+        gfloat f = (gfloat)luaL_checknumber(L, arg++);
+        correctbytes((gchar *)&f, (int)size, h.endian);
+        luaL_addlstring(&b, (gchar *)&f, size);
+        break;
+      }
+      case 'd': {
+        gdouble d = luaL_checknumber(L, arg++);
+        correctbytes((gchar *)&d, (int)size, h.endian);
+        luaL_addlstring(&b, (gchar *)&d, size);
+        break;
+      }
+      case 'c': case 's': {
+        size_t l;
+        const gchar *s = luaL_checklstring(L, arg++, &l);
+        if (size == 0) size = l;
+        luaL_argcheck(L, l >= (size_t)size, arg, "string too short");
+        luaL_addlstring(&b, s, size);
+        if (opt == 's') {
+          luaL_addchar(&b, '\0');  /* add zero at the end */
+          size++;
+        }
+        break;
+      }
+      case '=': {
+        if (poscnt < (int)(sizeof(posBuf)/sizeof(posBuf[0])))
+          posBuf[poscnt++] = (int)totalsize + 1;
+        break;
+      }
+      default: controloptions(L, opt, &fmt, &h);
+    }
+    totalsize += size;
+  }
+  luaL_pushresult(&b);
+  for (arg = 0; arg < poscnt; arg++)
+    lua_pushinteger(L, posBuf[arg]);
+  return poscnt + 1;
+}
+
+/* Decodes an integer from a string struct into a Lua number, based on 
+ * given endianess and size. If the integer type is signed, this makes
+ * the Lua number be +/- correctly as well.
+ */
+static lua_Number getinteger (const gchar *buff, int endian,
+                        int issigned, int size) {
+  Uinttype l = 0;
+  int i;
+  if (endian == BIG) {
+    for (i = 0; i < size; i++) {
+      l <<= 8;
+      l |= (Uinttype)(guchar)buff[i];
+    }
+  }
+  else {
+    for (i = size - 1; i >= 0; i--) {
+      l <<= 8;
+      l |= (Uinttype)(guchar)buff[i];
+    }
+  }
+  if (!issigned)
+    return (lua_Number)l;
+  else {  /* signed format */
+    Uinttype mask = (Uinttype)(~((Uinttype)0)) << (size*8 - 1);
+    if (l & mask)  /* negative value? */
+      l |= mask;  /* signal extension */
+    return (lua_Number)(Inttype)l;
+  }
+}
+
+#define b_pushnumber(n) { if (!h.noassign) lua_pushnumber(L, (lua_Number)(n)); }
+
+WSLUA_CONSTRUCTOR Struct_unpack (lua_State *L) {
+  /*  Unpacks/decodes multiple Lua values from a given struct-like binary Lua string. 
+      The number of returned values depends on the format given, plus an addtional value of the position where it stopped reading is returned. */
+#define WSLUA_ARG_Struct_unpack_FORMAT 1 /* The format string */
+#define WSLUA_ARG_Struct_unpack_STRUCT 2 /* The binary Lua string to unpack */
+#define WSLUA_OPTARG_Struct_unpack_BEGIN  3 /* The position to begin reading from (default=1) */
+  Header h;
+  const char *fmt = luaL_checkstring(L, WSLUA_ARG_Struct_unpack_FORMAT);
+  size_t ld;
+  const char *data = luaL_checklstring(L, WSLUA_ARG_Struct_unpack_STRUCT, &ld);
+  size_t pos = luaL_optinteger(L, WSLUA_OPTARG_Struct_unpack_BEGIN, 1) - 1;
+  defaultoptions(&h);
+  lua_settop(L, 2);
+  while (*fmt) {
+    int opt = *fmt++;
+    size_t size = optsize(L, opt, &fmt);
+    pos += gettoalign(pos, &h, opt, size);
+    luaL_argcheck(L, pos+size <= ld, 2, "data string too short");
+
+    if (opt == 'X') size = 0;
+    if (h.noassign && size > 0) {
+      /* if we're not assigning, and the opt type has a size, then loop again */
+      /* this will not be the case for controloptions, 'c0', 's', and '=' */
+      pos += size;
+      continue;
+    }
+
+    luaL_checkstack(L, 1, "too many results");
+    switch (opt) {
+      case 'b': case 'B': case 'h': case 'H':
+      case 'l': case 'L': case 'T': case 'i':  case 'I': {  /* integer types */
+        int issigned = islower(opt);
+        lua_Number res = getinteger(data+pos, h.endian, issigned, (int)size);
+        lua_pushnumber(L, res);
+        break;
+      }
+      case 'e': {
+        Int64_unpack(L, data+pos, h.endian == LITTLE);
+        break;
+      }
+      case 'E': {
+        UInt64_unpack(L, data+pos, h.endian == LITTLE);
+        break;
+      }
+      case 'x': case 'X': {
+        break;
+      }
+      case 'f': {
+        gfloat f;
+        memcpy(&f, data+pos, size);
+        correctbytes((gchar *)&f, sizeof(f), h.endian);
+        lua_pushnumber(L, f);
+        break;
+      }
+      case 'd': {
+        gdouble d;
+        memcpy(&d, data+pos, size);
+        correctbytes((gchar *)&d, sizeof(d), h.endian);
+        lua_pushnumber(L, d);
+        break;
+      }
+      case 'c': {
+        if (size == 0) {
+          if (!lua_isnumber(L, -1))
+            luaL_error(L, "format `c0' needs a previous size");
+          size = lua_tonumber(L, -1);
+          lua_pop(L, 1);
+          luaL_argcheck(L, pos+size <= ld, 2, "data string too short");
+        }
+        if (!h.noassign)
+          lua_pushlstring(L, data+pos, size);
+        break;
+      }
+      case 's': {
+        const gchar *e = (const char *)memchr(data+pos, '\0', ld - pos);
+        if (e == NULL)
+          luaL_error(L, "unfinished string in data");
+        size = (e - (data+pos)) + 1;
+        if (!h.noassign)
+          lua_pushlstring(L, data+pos, size - 1);
+        break;
+      }
+      case '=': {
+        lua_pushinteger(L, pos + 1);
+        break;
+      }
+      default: controloptions(L, opt, &fmt, &h);
+    }
+    pos += size;
+  }
+  lua_pushinteger(L, pos + 1);
+  return lua_gettop(L) - 2;
+}
+
+
+WSLUA_CONSTRUCTOR Struct_size (lua_State *L) {
+  /* Returns the length of the binary string struct that would be consumed/handled by the given format string. */
+  Header h;
+  const gchar *fmt = luaL_checkstring(L, 1);
+  size_t pos = 0;
+  defaultoptions(&h);
+  while (*fmt) {
+    int opt = *fmt++;
+    size_t size = optsize(L, opt, &fmt);
+    pos += gettoalign(pos, &h, opt, size);
+    if (opt == 's')
+      luaL_argerror(L, 1, "option 's' has no fixed size");
+    else if (opt == 'c' && size == 0)
+      luaL_argerror(L, 1, "option 'c0' has no fixed size");
+    if (!isalnum(opt))
+      controloptions(L, opt, &fmt, &h);
+    pos += size;
+  }
+  lua_pushinteger(L, pos);
+  return 1;
+}
+
+/* }====================================================== */
+
+/* Gets registered as metamethod automatically by WSLUA_REGISTER_CLASS/META */
+static int Struct__gc(lua_State* L _U_) {
+    return 0;
+}
+
+static const luaL_Reg Struct_methods[] = {
+  {"pack", Struct_pack},
+  {"unpack", Struct_unpack},
+  {"size", Struct_size},
+  {NULL, NULL}
+};
+
+static const luaL_Reg Struct_meta[] = {
+    { NULL, NULL }
+};
+
+LUALIB_API int Struct_register(lua_State* L) {
+    WSLUA_REGISTER_CLASS(Struct);
+    return 0;
+}
+
+
+/******************************************************************************
+* Copyright (C) 2010-2012 Lua.org, PUC-Rio.  All rights reserved.
+*
+* Permission is hereby granted, free of charge, to any person obtaining
+* a copy of this software and associated documentation files (the
+* "Software"), to deal in the Software without restriction, including
+* without limitation the rights to use, copy, modify, merge, publish,
+* distribute, sublicense, and/or sell copies of the Software, and to
+* permit persons to whom the Software is furnished to do so, subject to
+* the following conditions:
+*
+* The above copyright notice and this permission notice shall be
+* included in all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+******************************************************************************/
+