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#include <assert.h>
#include <ctype.h>
#include <limits.h>
#include <string.h>
#include "lua.h"
#include "lauxlib.h"
/*
** {======================================================
** Library for packing/unpacking structures.
** $Id: struct.c,v 1.2 2008/04/18 20:06:01 roberto Exp $
** See Copyright Notice at the end of this file
** =======================================================
*/
/*
** Valid formats:
** > - big endian
** < - little endian
** ![num] - alignment
** x - pading
** b/B - signed/unsigned byte
** h/H - signed/unsigned short
** l/L - signed/unsigned long
** i/In - signed/unsigned integer with size `n' (default is size of int)
** 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
** f - float
** d - doulbe
** ' ' - ignored
*/
/* is 'x' a power of 2? */
#define isp2(x) ((x) > 0 && ((x) & ((x) - 1)) == 0)
/* dummy structure to get alignment requirements */
struct cD {
char c;
double d;
};
#define PADDING (sizeof(struct cD) - sizeof(double))
#define MAXALIGN (PADDING > sizeof(int) ? PADDING : sizeof(int))
/* endian options */
#define BIG 0
#define LITTLE 1
static union {
int dummy;
char endian;
} const native = {1};
typedef struct Header {
int endian;
int align;
} Header;
static size_t getnum (const char **fmt, size_t df) {
if (!isdigit(**fmt)) /* no number? */
return df; /* return default value */
else {
size_t a = 0;
do {
a = a*10 + *((*fmt)++) - '0';
} while (isdigit(**fmt));
return a;
}
}
#define defaultoptions(h) ((h)->endian = native.endian, (h)->align = 1)
static size_t optsize (lua_State *L, char opt, const char **fmt) {
switch (opt) {
case 'B': case 'b': return sizeof(char);
case 'H': case 'h': return sizeof(short);
case 'L': case 'l': return sizeof(long);
case 'f': return sizeof(float);
case 'd': return sizeof(double);
case 'x': return 1;
case 'c': return getnum(fmt, 1);
case 's': case ' ': case '<': case '>': case '!': return 0;
case 'i': case 'I': {
int sz = getnum(fmt, sizeof(int));
if (!isp2(sz))
luaL_error(L, "integral size %d is not a power of 2", sz);
return sz;
}
default: {
const char *msg = lua_pushfstring(L, "invalid format option [%c]", opt);
return luaL_argerror(L, 1, msg);
}
}
}
static int gettoalign (size_t len, Header *h, int opt, size_t size) {
if (size == 0 || opt == 'c') return 0;
if (size > (size_t)h->align) size = h->align; /* respect max. alignment */
return (size - (len & (size - 1))) & (size - 1);
}
static void commoncases (lua_State *L, int opt, const char **fmt, Header *h) {
switch (opt) {
case ' ': return; /* ignore white spaces */
case '>': h->endian = BIG; return;
case '<': h->endian = LITTLE; 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: assert(0);
}
}
static void putinteger (lua_State *L, luaL_Buffer *b, int arg, int endian,
int size) {
lua_Number n = luaL_checknumber(L, arg);
unsigned long value;
if (n < (lua_Number)LONG_MAX)
value = (long)n;
else
value = (unsigned long)n;
if (endian == LITTLE) {
int i;
for (i = 0; i < size; i++)
luaL_addchar(b, (value >> 8*i) & 0xff);
}
else {
int i;
for (i = size - 1; i >= 0; i--)
luaL_addchar(b, (value >> 8*i) & 0xff);
}
}
static void correctbytes (char *b, int size, int endian) {
if (endian != native.endian) {
int i = 0;
while (i < --size) {
char temp = b[i];
b[i++] = b[size];
b[size] = temp;
}
}
}
static int b_pack (lua_State *L) {
luaL_Buffer b;
const char *fmt = luaL_checkstring(L, 1);
Header h;
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_putchar(&b, '\0');
switch (opt) {
case 'b': case 'B': case 'h': case 'H':
case 'l': case 'L': case 'i': case 'I': { /* integer types */
putinteger(L, &b, arg++, h.endian, size);
break;
}
case 'x': {
luaL_putchar(&b, '\0');
break;
}
case 'f': {
float f = (float)luaL_checknumber(L, arg++);
correctbytes((char *)&f, size, h.endian);
luaL_addlstring(&b, (char *)&f, size);
break;
}
case 'd': {
double d = luaL_checknumber(L, arg++);
correctbytes((char *)&d, size, h.endian);
luaL_addlstring(&b, (char *)&d, size);
break;
}
case 'c': case 's': {
size_t l;
const char *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_putchar(&b, '\0'); /* add zero at the end */
size++;
}
break;
}
default: commoncases(L, opt, &fmt, &h);
}
totalsize += size;
}
luaL_pushresult(&b);
return 1;
}
static lua_Number getinteger (const char *buff, int endian,
int issigned, int size) {
unsigned long l = 0;
if (endian == BIG) {
int i;
for (i = 0; i < size; i++)
l |= (unsigned long)(unsigned char)buff[size - i - 1] << (i*8);
}
else {
int i;
for (i = 0; i < size; i++)
l |= (unsigned long)(unsigned char)buff[i] << (i*8);
}
if (!issigned)
return (lua_Number)l;
else { /* signed format */
unsigned long mask = ~(0UL) << (size*8 - 1);
if (l & mask) /* negative value? */
l |= mask; /* signal extension */
return (lua_Number)(long)l;
}
}
static int b_unpack (lua_State *L) {
Header h;
const char *fmt = luaL_checkstring(L, 1);
size_t ld;
const char *data = luaL_checklstring(L, 2, &ld);
size_t pos = luaL_optinteger(L, 3, 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");
switch (opt) {
case 'b': case 'B': case 'h': case 'H':
case 'l': case 'L': case 'i': case 'I': { /* integer types */
int issigned = islower(opt);
lua_Number res = getinteger(data+pos, h.endian, issigned, size);
lua_pushnumber(L, res);
break;
}
case 'x': {
break;
}
case 'f': {
float f;
memcpy(&f, data+pos, size);
correctbytes((char *)&f, sizeof(f), h.endian);
lua_pushnumber(L, f);
break;
}
case 'd': {
double d;
memcpy(&d, data+pos, size);
correctbytes((char *)&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");
}
lua_pushlstring(L, data+pos, size);
break;
}
case 's': {
const char *e = (const char *)memchr(data+pos, '\0', ld - pos);
if (e == NULL)
luaL_error(L, "unfinished string in data");
size = (e - (data+pos)) + 1;
lua_pushlstring(L, data+pos, size - 1);
break;
}
default: commoncases(L, opt, &fmt, &h);
}
pos += size;
}
lua_pushinteger(L, pos + 1);
return lua_gettop(L) - 2;
}
/* }====================================================== */
static const struct luaL_reg thislib[] = {
{"pack", b_pack},
{"unpack", b_unpack},
{NULL, NULL}
};
LUALIB_API int luaopen_struct (lua_State *L) {
luaL_register(L, "struct", thislib);
return 1;
}
/******************************************************************************
* Copyright (C) 2010 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.
******************************************************************************/
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