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structmodule.c
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structmodule.c
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/* struct module -- pack values into and (out of) strings */
/* New version supporting byte order, alignment and size options,
character strings, and unsigned numbers */
#include "Python.h"
#include <ctype.h>
PyDoc_STRVAR(struct__doc__,
"Functions to convert between Python values and C structs.\n\
Python strings are used to hold the data representing the C struct\n\
and also as format strings to describe the layout of data in the C struct.\n\
\n\
The optional first format char indicates byte order, size and alignment:\n\
@: native order, size & alignment (default)\n\
=: native order, std. size & alignment\n\
<: little-endian, std. size & alignment\n\
>: big-endian, std. size & alignment\n\
!: same as >\n\
\n\
The remaining chars indicate types of args and must match exactly;\n\
these can be preceded by a decimal repeat count:\n\
x: pad byte (no data); c:char; b:signed byte; B:unsigned byte;\n\
h:short; H:unsigned short; i:int; I:unsigned int;\n\
l:long; L:unsigned long; f:float; d:double.\n\
Special cases (preceding decimal count indicates length):\n\
s:string (array of char); p: pascal string (with count byte).\n\
Special case (only available in native format):\n\
P:an integer type that is wide enough to hold a pointer.\n\
Special case (not in native mode unless 'long long' in platform C):\n\
q:long long; Q:unsigned long long\n\
Whitespace between formats is ignored.\n\
\n\
The variable struct.error is an exception raised on errors.");
/* Exception */
static PyObject *StructError;
/* Define various structs to figure out the alignments of types */
typedef struct { char c; short x; } st_short;
typedef struct { char c; int x; } st_int;
typedef struct { char c; long x; } st_long;
typedef struct { char c; float x; } st_float;
typedef struct { char c; double x; } st_double;
typedef struct { char c; void *x; } st_void_p;
#define SHORT_ALIGN (sizeof(st_short) - sizeof(short))
#define INT_ALIGN (sizeof(st_int) - sizeof(int))
#define LONG_ALIGN (sizeof(st_long) - sizeof(long))
#define FLOAT_ALIGN (sizeof(st_float) - sizeof(float))
#define DOUBLE_ALIGN (sizeof(st_double) - sizeof(double))
#define VOID_P_ALIGN (sizeof(st_void_p) - sizeof(void *))
/* We can't support q and Q in native mode unless the compiler does;
in std mode, they're 8 bytes on all platforms. */
#ifdef HAVE_LONG_LONG
typedef struct { char c; PY_LONG_LONG x; } s_long_long;
#define LONG_LONG_ALIGN (sizeof(s_long_long) - sizeof(PY_LONG_LONG))
#endif
#define STRINGIFY(x) #x
#ifdef __powerc
#pragma options align=reset
#endif
/* Helper to get a PyLongObject by hook or by crook. Caller should decref. */
static PyObject *
get_pylong(PyObject *v)
{
PyNumberMethods *m;
assert(v != NULL);
if (PyInt_Check(v))
return PyLong_FromLong(PyInt_AS_LONG(v));
if (PyLong_Check(v)) {
Py_INCREF(v);
return v;
}
m = v->ob_type->tp_as_number;
if (m != NULL && m->nb_long != NULL) {
v = m->nb_long(v);
if (v == NULL)
return NULL;
if (PyLong_Check(v))
return v;
Py_DECREF(v);
}
PyErr_SetString(StructError,
"cannot convert argument to long");
return NULL;
}
/* Helper routine to get a Python integer and raise the appropriate error
if it isn't one */
static int
get_long(PyObject *v, long *p)
{
long x = PyInt_AsLong(v);
if (x == -1 && PyErr_Occurred()) {
if (PyErr_ExceptionMatches(PyExc_TypeError))
PyErr_SetString(StructError,
"required argument is not an integer");
return -1;
}
*p = x;
return 0;
}
/* Same, but handling unsigned long */
static int
get_ulong(PyObject *v, unsigned long *p)
{
if (PyLong_Check(v)) {
unsigned long x = PyLong_AsUnsignedLong(v);
if (x == (unsigned long)(-1) && PyErr_Occurred())
return -1;
*p = x;
return 0;
}
else {
return get_long(v, (long *)p);
}
}
#ifdef HAVE_LONG_LONG
/* Same, but handling native long long. */
static int
get_longlong(PyObject *v, PY_LONG_LONG *p)
{
PY_LONG_LONG x;
v = get_pylong(v);
if (v == NULL)
return -1;
assert(PyLong_Check(v));
x = PyLong_AsLongLong(v);
Py_DECREF(v);
if (x == (PY_LONG_LONG)-1 && PyErr_Occurred())
return -1;
*p = x;
return 0;
}
/* Same, but handling native unsigned long long. */
static int
get_ulonglong(PyObject *v, unsigned PY_LONG_LONG *p)
{
unsigned PY_LONG_LONG x;
v = get_pylong(v);
if (v == NULL)
return -1;
assert(PyLong_Check(v));
x = PyLong_AsUnsignedLongLong(v);
Py_DECREF(v);
if (x == (unsigned PY_LONG_LONG)-1 && PyErr_Occurred())
return -1;
*p = x;
return 0;
}
#endif
/* Floating point helpers */
static PyObject *
unpack_float(const char *p, /* start of 4-byte string */
int le) /* true for little-endian, false for big-endian */
{
double x;
x = _PyFloat_Unpack4((unsigned char *)p, le);
if (x == -1.0 && PyErr_Occurred())
return NULL;
return PyFloat_FromDouble(x);
}
static PyObject *
unpack_double(const char *p, /* start of 8-byte string */
int le) /* true for little-endian, false for big-endian */
{
double x;
x = _PyFloat_Unpack8((unsigned char *)p, le);
if (x == -1.0 && PyErr_Occurred())
return NULL;
return PyFloat_FromDouble(x);
}
/* The translation function for each format character is table driven */
typedef struct _formatdef {
char format;
int size;
int alignment;
PyObject* (*unpack)(const char *,
const struct _formatdef *);
int (*pack)(char *, PyObject *,
const struct _formatdef *);
} formatdef;
/* A large number of small routines follow, with names of the form
[bln][up]_TYPE
[bln] distiguishes among big-endian, little-endian and native.
[pu] distiguishes between pack (to struct) and unpack (from struct).
TYPE is one of char, byte, ubyte, etc.
*/
/* Native mode routines. ****************************************************/
/* NOTE:
In all n[up]_<type> routines handling types larger than 1 byte, there is
*no* guarantee that the p pointer is properly aligned for each type,
therefore memcpy is called. An intermediate variable is used to
compensate for big-endian architectures.
Normally both the intermediate variable and the memcpy call will be
skipped by C optimisation in little-endian architectures (gcc >= 2.91
does this). */
static PyObject *
nu_char(const char *p, const formatdef *f)
{
return PyString_FromStringAndSize(p, 1);
}
static PyObject *
nu_byte(const char *p, const formatdef *f)
{
return PyInt_FromLong((long) *(signed char *)p);
}
static PyObject *
nu_ubyte(const char *p, const formatdef *f)
{
return PyInt_FromLong((long) *(unsigned char *)p);
}
static PyObject *
nu_short(const char *p, const formatdef *f)
{
short x;
memcpy((char *)&x, p, sizeof x);
return PyInt_FromLong((long)x);
}
static PyObject *
nu_ushort(const char *p, const formatdef *f)
{
unsigned short x;
memcpy((char *)&x, p, sizeof x);
return PyInt_FromLong((long)x);
}
static PyObject *
nu_int(const char *p, const formatdef *f)
{
int x;
memcpy((char *)&x, p, sizeof x);
return PyInt_FromLong((long)x);
}
static PyObject *
nu_uint(const char *p, const formatdef *f)
{
unsigned int x;
memcpy((char *)&x, p, sizeof x);
return PyLong_FromUnsignedLong((unsigned long)x);
}
static PyObject *
nu_long(const char *p, const formatdef *f)
{
long x;
memcpy((char *)&x, p, sizeof x);
return PyInt_FromLong(x);
}
static PyObject *
nu_ulong(const char *p, const formatdef *f)
{
unsigned long x;
memcpy((char *)&x, p, sizeof x);
return PyLong_FromUnsignedLong(x);
}
/* Native mode doesn't support q or Q unless the platform C supports
long long (or, on Windows, __int64). */
#ifdef HAVE_LONG_LONG
static PyObject *
nu_longlong(const char *p, const formatdef *f)
{
PY_LONG_LONG x;
memcpy((char *)&x, p, sizeof x);
return PyLong_FromLongLong(x);
}
static PyObject *
nu_ulonglong(const char *p, const formatdef *f)
{
unsigned PY_LONG_LONG x;
memcpy((char *)&x, p, sizeof x);
return PyLong_FromUnsignedLongLong(x);
}
#endif
static PyObject *
nu_float(const char *p, const formatdef *f)
{
float x;
memcpy((char *)&x, p, sizeof x);
return PyFloat_FromDouble((double)x);
}
static PyObject *
nu_double(const char *p, const formatdef *f)
{
double x;
memcpy((char *)&x, p, sizeof x);
return PyFloat_FromDouble(x);
}
static PyObject *
nu_void_p(const char *p, const formatdef *f)
{
void *x;
memcpy((char *)&x, p, sizeof x);
return PyLong_FromVoidPtr(x);
}
static int
np_byte(char *p, PyObject *v, const formatdef *f)
{
long x;
if (get_long(v, &x) < 0)
return -1;
if (x < -128 || x > 127){
PyErr_SetString(StructError,
"byte format requires -128<=number<=127");
return -1;
}
*p = (char)x;
return 0;
}
static int
np_ubyte(char *p, PyObject *v, const formatdef *f)
{
long x;
if (get_long(v, &x) < 0)
return -1;
if (x < 0 || x > 255){
PyErr_SetString(StructError,
"ubyte format requires 0<=number<=255");
return -1;
}
*p = (char)x;
return 0;
}
static int
np_char(char *p, PyObject *v, const formatdef *f)
{
if (!PyString_Check(v) || PyString_Size(v) != 1) {
PyErr_SetString(StructError,
"char format require string of length 1");
return -1;
}
*p = *PyString_AsString(v);
return 0;
}
static int
np_short(char *p, PyObject *v, const formatdef *f)
{
long x;
short y;
if (get_long(v, &x) < 0)
return -1;
if (x < SHRT_MIN || x > SHRT_MAX){
PyErr_SetString(StructError,
"short format requires " STRINGIFY(SHRT_MIN)
"<=number<=" STRINGIFY(SHRT_MAX));
return -1;
}
y = (short)x;
memcpy(p, (char *)&y, sizeof y);
return 0;
}
static int
np_ushort(char *p, PyObject *v, const formatdef *f)
{
long x;
unsigned short y;
if (get_long(v, &x) < 0)
return -1;
if (x < 0 || x > USHRT_MAX){
PyErr_SetString(StructError,
"short format requires 0<=number<=" STRINGIFY(USHRT_MAX));
return -1;
}
y = (unsigned short)x;
memcpy(p, (char *)&y, sizeof y);
return 0;
}
static int
np_int(char *p, PyObject *v, const formatdef *f)
{
long x;
int y;
if (get_long(v, &x) < 0)
return -1;
y = (int)x;
memcpy(p, (char *)&y, sizeof y);
return 0;
}
static int
np_uint(char *p, PyObject *v, const formatdef *f)
{
unsigned long x;
unsigned int y;
if (get_ulong(v, &x) < 0)
return -1;
y = (unsigned int)x;
memcpy(p, (char *)&y, sizeof y);
return 0;
}
static int
np_long(char *p, PyObject *v, const formatdef *f)
{
long x;
if (get_long(v, &x) < 0)
return -1;
memcpy(p, (char *)&x, sizeof x);
return 0;
}
static int
np_ulong(char *p, PyObject *v, const formatdef *f)
{
unsigned long x;
if (get_ulong(v, &x) < 0)
return -1;
memcpy(p, (char *)&x, sizeof x);
return 0;
}
#ifdef HAVE_LONG_LONG
static int
np_longlong(char *p, PyObject *v, const formatdef *f)
{
PY_LONG_LONG x;
if (get_longlong(v, &x) < 0)
return -1;
memcpy(p, (char *)&x, sizeof x);
return 0;
}
static int
np_ulonglong(char *p, PyObject *v, const formatdef *f)
{
unsigned PY_LONG_LONG x;
if (get_ulonglong(v, &x) < 0)
return -1;
memcpy(p, (char *)&x, sizeof x);
return 0;
}
#endif
static int
np_float(char *p, PyObject *v, const formatdef *f)
{
float x = (float)PyFloat_AsDouble(v);
if (x == -1 && PyErr_Occurred()) {
PyErr_SetString(StructError,
"required argument is not a float");
return -1;
}
memcpy(p, (char *)&x, sizeof x);
return 0;
}
static int
np_double(char *p, PyObject *v, const formatdef *f)
{
double x = PyFloat_AsDouble(v);
if (x == -1 && PyErr_Occurred()) {
PyErr_SetString(StructError,
"required argument is not a float");
return -1;
}
memcpy(p, (char *)&x, sizeof(double));
return 0;
}
static int
np_void_p(char *p, PyObject *v, const formatdef *f)
{
void *x;
v = get_pylong(v);
if (v == NULL)
return -1;
assert(PyLong_Check(v));
x = PyLong_AsVoidPtr(v);
Py_DECREF(v);
if (x == NULL && PyErr_Occurred())
return -1;
memcpy(p, (char *)&x, sizeof x);
return 0;
}
static formatdef native_table[] = {
{'x', sizeof(char), 0, NULL},
{'b', sizeof(char), 0, nu_byte, np_byte},
{'B', sizeof(char), 0, nu_ubyte, np_ubyte},
{'c', sizeof(char), 0, nu_char, np_char},
{'s', sizeof(char), 0, NULL},
{'p', sizeof(char), 0, NULL},
{'h', sizeof(short), SHORT_ALIGN, nu_short, np_short},
{'H', sizeof(short), SHORT_ALIGN, nu_ushort, np_ushort},
{'i', sizeof(int), INT_ALIGN, nu_int, np_int},
{'I', sizeof(int), INT_ALIGN, nu_uint, np_uint},
{'l', sizeof(long), LONG_ALIGN, nu_long, np_long},
{'L', sizeof(long), LONG_ALIGN, nu_ulong, np_ulong},
{'f', sizeof(float), FLOAT_ALIGN, nu_float, np_float},
{'d', sizeof(double), DOUBLE_ALIGN, nu_double, np_double},
{'P', sizeof(void *), VOID_P_ALIGN, nu_void_p, np_void_p},
#ifdef HAVE_LONG_LONG
{'q', sizeof(PY_LONG_LONG), LONG_LONG_ALIGN, nu_longlong, np_longlong},
{'Q', sizeof(PY_LONG_LONG), LONG_LONG_ALIGN, nu_ulonglong,np_ulonglong},
#endif
{0}
};
/* Big-endian routines. *****************************************************/
static PyObject *
bu_int(const char *p, const formatdef *f)
{
long x = 0;
int i = f->size;
do {
x = (x<<8) | (*p++ & 0xFF);
} while (--i > 0);
/* Extend the sign bit. */
if (SIZEOF_LONG > f->size)
x |= -(x & (1L << (8*f->size - 1)));
return PyInt_FromLong(x);
}
static PyObject *
bu_uint(const char *p, const formatdef *f)
{
unsigned long x = 0;
int i = f->size;
do {
x = (x<<8) | (*p++ & 0xFF);
} while (--i > 0);
if (f->size >= 4)
return PyLong_FromUnsignedLong(x);
else
return PyInt_FromLong((long)x);
}
static PyObject *
bu_longlong(const char *p, const formatdef *f)
{
return _PyLong_FromByteArray((const unsigned char *)p,
8,
0, /* little-endian */
1 /* signed */);
}
static PyObject *
bu_ulonglong(const char *p, const formatdef *f)
{
return _PyLong_FromByteArray((const unsigned char *)p,
8,
0, /* little-endian */
0 /* signed */);
}
static PyObject *
bu_float(const char *p, const formatdef *f)
{
return unpack_float(p, 0);
}
static PyObject *
bu_double(const char *p, const formatdef *f)
{
return unpack_double(p, 0);
}
static int
bp_int(char *p, PyObject *v, const formatdef *f)
{
long x;
int i;
if (get_long(v, &x) < 0)
return -1;
i = f->size;
do {
p[--i] = (char)x;
x >>= 8;
} while (i > 0);
return 0;
}
static int
bp_uint(char *p, PyObject *v, const formatdef *f)
{
unsigned long x;
int i;
if (get_ulong(v, &x) < 0)
return -1;
i = f->size;
do {
p[--i] = (char)x;
x >>= 8;
} while (i > 0);
return 0;
}
static int
bp_longlong(char *p, PyObject *v, const formatdef *f)
{
int res;
v = get_pylong(v);
if (v == NULL)
return -1;
res = _PyLong_AsByteArray((PyLongObject *)v,
(unsigned char *)p,
8,
0, /* little_endian */
1 /* signed */);
Py_DECREF(v);
return res;
}
static int
bp_ulonglong(char *p, PyObject *v, const formatdef *f)
{
int res;
v = get_pylong(v);
if (v == NULL)
return -1;
res = _PyLong_AsByteArray((PyLongObject *)v,
(unsigned char *)p,
8,
0, /* little_endian */
0 /* signed */);
Py_DECREF(v);
return res;
}
static int
bp_float(char *p, PyObject *v, const formatdef *f)
{
double x = PyFloat_AsDouble(v);
if (x == -1 && PyErr_Occurred()) {
PyErr_SetString(StructError,
"required argument is not a float");
return -1;
}
return _PyFloat_Pack4(x, (unsigned char *)p, 0);
}
static int
bp_double(char *p, PyObject *v, const formatdef *f)
{
double x = PyFloat_AsDouble(v);
if (x == -1 && PyErr_Occurred()) {
PyErr_SetString(StructError,
"required argument is not a float");
return -1;
}
return _PyFloat_Pack8(x, (unsigned char *)p, 0);
}
static formatdef bigendian_table[] = {
{'x', 1, 0, NULL},
{'b', 1, 0, bu_int, bp_int},
{'B', 1, 0, bu_uint, bp_int},
{'c', 1, 0, nu_char, np_char},
{'s', 1, 0, NULL},
{'p', 1, 0, NULL},
{'h', 2, 0, bu_int, bp_int},
{'H', 2, 0, bu_uint, bp_uint},
{'i', 4, 0, bu_int, bp_int},
{'I', 4, 0, bu_uint, bp_uint},
{'l', 4, 0, bu_int, bp_int},
{'L', 4, 0, bu_uint, bp_uint},
{'q', 8, 0, bu_longlong, bp_longlong},
{'Q', 8, 0, bu_ulonglong, bp_ulonglong},
{'f', 4, 0, bu_float, bp_float},
{'d', 8, 0, bu_double, bp_double},
{0}
};
/* Little-endian routines. *****************************************************/
static PyObject *
lu_int(const char *p, const formatdef *f)
{
long x = 0;
int i = f->size;
do {
x = (x<<8) | (p[--i] & 0xFF);
} while (i > 0);
/* Extend the sign bit. */
if (SIZEOF_LONG > f->size)
x |= -(x & (1L << (8*f->size - 1)));
return PyInt_FromLong(x);
}
static PyObject *
lu_uint(const char *p, const formatdef *f)
{
unsigned long x = 0;
int i = f->size;
do {
x = (x<<8) | (p[--i] & 0xFF);
} while (i > 0);
if (f->size >= 4)
return PyLong_FromUnsignedLong(x);
else
return PyInt_FromLong((long)x);
}
static PyObject *
lu_longlong(const char *p, const formatdef *f)
{
return _PyLong_FromByteArray((const unsigned char *)p,
8,
1, /* little-endian */
1 /* signed */);
}
static PyObject *
lu_ulonglong(const char *p, const formatdef *f)
{
return _PyLong_FromByteArray((const unsigned char *)p,
8,
1, /* little-endian */
0 /* signed */);
}
static PyObject *
lu_float(const char *p, const formatdef *f)
{
return unpack_float(p, 1);
}
static PyObject *
lu_double(const char *p, const formatdef *f)
{
return unpack_double(p, 1);
}
static int
lp_int(char *p, PyObject *v, const formatdef *f)
{
long x;
int i;
if (get_long(v, &x) < 0)
return -1;
i = f->size;
do {
*p++ = (char)x;
x >>= 8;
} while (--i > 0);
return 0;
}
static int
lp_uint(char *p, PyObject *v, const formatdef *f)
{
unsigned long x;
int i;
if (get_ulong(v, &x) < 0)
return -1;
i = f->size;
do {
*p++ = (char)x;
x >>= 8;
} while (--i > 0);
return 0;
}
static int
lp_longlong(char *p, PyObject *v, const formatdef *f)
{
int res;
v = get_pylong(v);
if (v == NULL)
return -1;
res = _PyLong_AsByteArray((PyLongObject*)v,
(unsigned char *)p,
8,
1, /* little_endian */
1 /* signed */);
Py_DECREF(v);
return res;
}
static int
lp_ulonglong(char *p, PyObject *v, const formatdef *f)
{
int res;
v = get_pylong(v);
if (v == NULL)
return -1;
res = _PyLong_AsByteArray((PyLongObject*)v,
(unsigned char *)p,
8,
1, /* little_endian */
0 /* signed */);
Py_DECREF(v);
return res;
}
static int
lp_float(char *p, PyObject *v, const formatdef *f)
{
double x = PyFloat_AsDouble(v);
if (x == -1 && PyErr_Occurred()) {
PyErr_SetString(StructError,
"required argument is not a float");
return -1;
}
return _PyFloat_Pack4(x, (unsigned char *)p, 1);
}
static int
lp_double(char *p, PyObject *v, const formatdef *f)
{
double x = PyFloat_AsDouble(v);
if (x == -1 && PyErr_Occurred()) {
PyErr_SetString(StructError,
"required argument is not a float");
return -1;
}
return _PyFloat_Pack8(x, (unsigned char *)p, 1);
}
static formatdef lilendian_table[] = {
{'x', 1, 0, NULL},
{'b', 1, 0, lu_int, lp_int},
{'B', 1, 0, lu_uint, lp_int},
{'c', 1, 0, nu_char, np_char},
{'s', 1, 0, NULL},
{'p', 1, 0, NULL},
{'h', 2, 0, lu_int, lp_int},
{'H', 2, 0, lu_uint, lp_uint},
{'i', 4, 0, lu_int, lp_int},
{'I', 4, 0, lu_uint, lp_uint},
{'l', 4, 0, lu_int, lp_int},
{'L', 4, 0, lu_uint, lp_uint},
{'q', 8, 0, lu_longlong, lp_longlong},
{'Q', 8, 0, lu_ulonglong, lp_ulonglong},
{'f', 4, 0, lu_float, lp_float},
{'d', 8, 0, lu_double, lp_double},
{0}
};
static const formatdef *
whichtable(char **pfmt)
{
const char *fmt = (*pfmt)++; /* May be backed out of later */
switch (*fmt) {
case '<':
return lilendian_table;
case '>':
case '!': /* Network byte order is big-endian */
return bigendian_table;
case '=': { /* Host byte order -- different from native in aligment! */
int n = 1;
char *p = (char *) &n;
if (*p == 1)
return lilendian_table;
else
return bigendian_table;
}
default:
--*pfmt; /* Back out of pointer increment */
/* Fall through */
case '@':
return native_table;
}
}
/* Get the table entry for a format code */
static const formatdef *
getentry(int c, const formatdef *f)
{
for (; f->format != '\0'; f++) {
if (f->format == c) {
return f;
}
}
PyErr_SetString(StructError, "bad char in struct format");
return NULL;
}
/* Align a size according to a format code */
static int
align(int size, int c, const formatdef *e)
{
if (e->format == c) {
if (e->alignment) {
size = ((size + e->alignment - 1)
/ e->alignment)
* e->alignment;
}
}
return size;
}
/* calculate the size of a format string */
static int
calcsize(const char *fmt, const formatdef *f)
{
const formatdef *e;
const char *s;
char c;
int size, num, itemsize, x;
s = fmt;
size = 0;
while ((c = *s++) != '\0') {
if (isspace((int)c))
continue;
if ('0' <= c && c <= '9') {
num = c - '0';
while ('0' <= (c = *s++) && c <= '9') {
x = num*10 + (c - '0');
if (x/10 != num) {
PyErr_SetString(
StructError,
"overflow in item count");
return -1;
}
num = x;
}
if (c == '\0')
break;
}
else
num = 1;
e = getentry(c, f);
if (e == NULL)
return -1;
itemsize = e->size;
size = align(size, c, e);
x = num * itemsize;
size += x;
if (x/itemsize != num || size < 0) {
PyErr_SetString(StructError,
"total struct size too long");
return -1;
}
}
return size;
}
PyDoc_STRVAR(calcsize__doc__,