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cpython/Modules/_struct.c
Antoine Pitrou 45d9c91d4b Issue #3163: The struct module gets new format characters 'n' and 'N' 
supporting C integer types `ssize_t` and `size_t`, respectively.
2011-10-06 15:27:40 +02:00

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/* struct module -- pack values into and (out of) bytes objects */
/* New version supporting byte order, alignment and size options,
character strings, and unsigned numbers */
#define PY_SSIZE_T_CLEAN
#include "Python.h"
#include "structmember.h"
#include <ctype.h>
static PyTypeObject PyStructType;
/* The translation function for each format character is table driven */
typedef struct _formatdef {
char format;
Py_ssize_t size;
Py_ssize_t alignment;
PyObject* (*unpack)(const char *,
const struct _formatdef *);
int (*pack)(char *, PyObject *,
const struct _formatdef *);
} formatdef;
typedef struct _formatcode {
const struct _formatdef *fmtdef;
Py_ssize_t offset;
Py_ssize_t size;
} formatcode;
/* Struct object interface */
typedef struct {
PyObject_HEAD
Py_ssize_t s_size;
Py_ssize_t s_len;
formatcode *s_codes;
PyObject *s_format;
PyObject *weakreflist; /* List of weak references */
} PyStructObject;
#define PyStruct_Check(op) PyObject_TypeCheck(op, &PyStructType)
#define PyStruct_CheckExact(op) (Py_TYPE(op) == &PyStructType)
/* 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;
typedef struct { char c; size_t x; } st_size_t;
#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 *))
#define SIZE_T_ALIGN (sizeof(st_size_t) - sizeof(size_t))
/* 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
#ifdef HAVE_C99_BOOL
#define BOOL_TYPE _Bool
typedef struct { char c; _Bool x; } s_bool;
#define BOOL_ALIGN (sizeof(s_bool) - sizeof(BOOL_TYPE))
#else
#define BOOL_TYPE char
#define BOOL_ALIGN 0
#endif
#define STRINGIFY(x) #x
#ifdef __powerc
#pragma options align=reset
#endif
/* Helper for integer format codes: converts an arbitrary Python object to a
PyLongObject if possible, otherwise fails. Caller should decref. */
static PyObject *
get_pylong(PyObject *v)
{
assert(v != NULL);
if (!PyLong_Check(v)) {
/* Not an integer; try to use __index__ to convert. */
if (PyIndex_Check(v)) {
v = PyNumber_Index(v);
if (v == NULL)
return NULL;
}
else {
PyErr_SetString(StructError,
"required argument is not an integer");
return NULL;
}
}
else
Py_INCREF(v);
assert(PyLong_Check(v));
return v;
}
/* Helper routine to get a C long and raise the appropriate error if it isn't
one */
static int
get_long(PyObject *v, long *p)
{
long x;
v = get_pylong(v);
if (v == NULL)
return -1;
assert(PyLong_Check(v));
x = PyLong_AsLong(v);
Py_DECREF(v);
if (x == (long)-1 && PyErr_Occurred()) {
if (PyErr_ExceptionMatches(PyExc_OverflowError))
PyErr_SetString(StructError,
"argument out of range");
return -1;
}
*p = x;
return 0;
}
/* Same, but handling unsigned long */
static int
get_ulong(PyObject *v, unsigned long *p)
{
unsigned long x;
v = get_pylong(v);
if (v == NULL)
return -1;
assert(PyLong_Check(v));
x = PyLong_AsUnsignedLong(v);
Py_DECREF(v);
if (x == (unsigned long)-1 && PyErr_Occurred()) {
if (PyErr_ExceptionMatches(PyExc_OverflowError))
PyErr_SetString(StructError,
"argument out of range");
return -1;
}
*p = x;
return 0;
}
#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()) {
if (PyErr_ExceptionMatches(PyExc_OverflowError))
PyErr_SetString(StructError,
"argument out of range");
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()) {
if (PyErr_ExceptionMatches(PyExc_OverflowError))
PyErr_SetString(StructError,
"argument out of range");
return -1;
}
*p = x;
return 0;
}
#endif
/* Same, but handling Py_ssize_t */
static int
get_ssize_t(PyObject *v, Py_ssize_t *p)
{
Py_ssize_t x;
v = get_pylong(v);
if (v == NULL)
return -1;
assert(PyLong_Check(v));
x = PyLong_AsSsize_t(v);
Py_DECREF(v);
if (x == (Py_ssize_t)-1 && PyErr_Occurred()) {
if (PyErr_ExceptionMatches(PyExc_OverflowError))
PyErr_SetString(StructError,
"argument out of range");
return -1;
}
*p = x;
return 0;
}
/* Same, but handling size_t */
static int
get_size_t(PyObject *v, size_t *p)
{
size_t x;
v = get_pylong(v);
if (v == NULL)
return -1;
assert(PyLong_Check(v));
x = PyLong_AsSize_t(v);
Py_DECREF(v);
if (x == (size_t)-1 && PyErr_Occurred()) {
if (PyErr_ExceptionMatches(PyExc_OverflowError))
PyErr_SetString(StructError,
"argument out of range");
return -1;
}
*p = x;
return 0;
}
#define RANGE_ERROR(x, f, flag, mask) return _range_error(f, flag)
/* 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);
}
/* Helper to format the range error exceptions */
static int
_range_error(const formatdef *f, int is_unsigned)
{
/* ulargest is the largest unsigned value with f->size bytes.
* Note that the simpler:
* ((size_t)1 << (f->size * 8)) - 1
* doesn't work when f->size == sizeof(size_t) because C doesn't
* define what happens when a left shift count is >= the number of
* bits in the integer being shifted; e.g., on some boxes it doesn't
* shift at all when they're equal.
*/
const size_t ulargest = (size_t)-1 >> ((SIZEOF_SIZE_T - f->size)*8);
assert(f->size >= 1 && f->size <= SIZEOF_SIZE_T);
if (is_unsigned)
PyErr_Format(StructError,
"'%c' format requires 0 <= number <= %zu",
f->format,
ulargest);
else {
const Py_ssize_t largest = (Py_ssize_t)(ulargest >> 1);
PyErr_Format(StructError,
"'%c' format requires %zd <= number <= %zd",
f->format,
~ largest,
largest);
}
return -1;
}
/* 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 PyBytes_FromStringAndSize(p, 1);
}
static PyObject *
nu_byte(const char *p, const formatdef *f)
{
return PyLong_FromLong((long) *(signed char *)p);
}
static PyObject *
nu_ubyte(const char *p, const formatdef *f)
{
return PyLong_FromLong((long) *(unsigned char *)p);
}
static PyObject *
nu_short(const char *p, const formatdef *f)
{
short x;
memcpy((char *)&x, p, sizeof x);
return PyLong_FromLong((long)x);
}
static PyObject *
nu_ushort(const char *p, const formatdef *f)
{
unsigned short x;
memcpy((char *)&x, p, sizeof x);
return PyLong_FromLong((long)x);
}
static PyObject *
nu_int(const char *p, const formatdef *f)
{
int x;
memcpy((char *)&x, p, sizeof x);
return PyLong_FromLong((long)x);
}
static PyObject *
nu_uint(const char *p, const formatdef *f)
{
unsigned int x;
memcpy((char *)&x, p, sizeof x);
#if (SIZEOF_LONG > SIZEOF_INT)
return PyLong_FromLong((long)x);
#else
if (x <= ((unsigned int)LONG_MAX))
return PyLong_FromLong((long)x);
return PyLong_FromUnsignedLong((unsigned long)x);
#endif
}
static PyObject *
nu_long(const char *p, const formatdef *f)
{
long x;
memcpy((char *)&x, p, sizeof x);
return PyLong_FromLong(x);
}
static PyObject *
nu_ulong(const char *p, const formatdef *f)
{
unsigned long x;
memcpy((char *)&x, p, sizeof x);
if (x <= LONG_MAX)
return PyLong_FromLong((long)x);
return PyLong_FromUnsignedLong(x);
}
static PyObject *
nu_ssize_t(const char *p, const formatdef *f)
{
Py_ssize_t x;
memcpy((char *)&x, p, sizeof x);
return PyLong_FromSsize_t(x);
}
static PyObject *
nu_size_t(const char *p, const formatdef *f)
{
size_t x;
memcpy((char *)&x, p, sizeof x);
return PyLong_FromSize_t(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);
if (x >= LONG_MIN && x <= LONG_MAX)
return PyLong_FromLong(Py_SAFE_DOWNCAST(x, PY_LONG_LONG, long));
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);
if (x <= LONG_MAX)
return PyLong_FromLong(Py_SAFE_DOWNCAST(x, unsigned PY_LONG_LONG, long));
return PyLong_FromUnsignedLongLong(x);
}
#endif
static PyObject *
nu_bool(const char *p, const formatdef *f)
{
BOOL_TYPE x;
memcpy((char *)&x, p, sizeof x);
return PyBool_FromLong(x != 0);
}
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 (!PyBytes_Check(v) || PyBytes_Size(v) != 1) {
PyErr_SetString(StructError,
"char format requires a bytes object of length 1");
return -1;
}
*p = *PyBytes_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,
"ushort 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;
#if (SIZEOF_LONG > SIZEOF_INT)
if ((x < ((long)INT_MIN)) || (x > ((long)INT_MAX)))
RANGE_ERROR(x, f, 0, -1);
#endif
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;
#if (SIZEOF_LONG > SIZEOF_INT)
if (x > ((unsigned long)UINT_MAX))
RANGE_ERROR(y, f, 1, -1);
#endif
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;
}
static int
np_ssize_t(char *p, PyObject *v, const formatdef *f)
{
Py_ssize_t x;
if (get_ssize_t(v, &x) < 0)
return -1;
memcpy(p, (char *)&x, sizeof x);
return 0;
}
static int
np_size_t(char *p, PyObject *v, const formatdef *f)
{
size_t x;
if (get_size_t(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_bool(char *p, PyObject *v, const formatdef *f)
{
int y;
BOOL_TYPE x;
y = PyObject_IsTrue(v);
if (y < 0)
return -1;
x = y;
memcpy(p, (char *)&x, sizeof x);
return 0;
}
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},
{'n', sizeof(size_t), SIZE_T_ALIGN, nu_ssize_t, np_ssize_t},
{'N', sizeof(size_t), SIZE_T_ALIGN, nu_size_t, np_size_t},
#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
{'?', sizeof(BOOL_TYPE), BOOL_ALIGN, nu_bool, np_bool},
{'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},
{0}
};
/* Big-endian routines. *****************************************************/
static PyObject *
bu_int(const char *p, const formatdef *f)
{
long x = 0;
Py_ssize_t i = f->size;
const unsigned char *bytes = (const unsigned char *)p;
do {
x = (x<<8) | *bytes++;
} while (--i > 0);
/* Extend the sign bit. */
if (SIZEOF_LONG > f->size)
x |= -(x & (1L << ((8 * f->size) - 1)));
return PyLong_FromLong(x);
}
static PyObject *
bu_uint(const char *p, const formatdef *f)
{
unsigned long x = 0;
Py_ssize_t i = f->size;
const unsigned char *bytes = (const unsigned char *)p;
do {
x = (x<<8) | *bytes++;
} while (--i > 0);
if (x <= LONG_MAX)
return PyLong_FromLong((long)x);
return PyLong_FromUnsignedLong(x);
}
static PyObject *
bu_longlong(const char *p, const formatdef *f)
{
#ifdef HAVE_LONG_LONG
PY_LONG_LONG x = 0;
Py_ssize_t i = f->size;
const unsigned char *bytes = (const unsigned char *)p;
do {
x = (x<<8) | *bytes++;
} while (--i > 0);
/* Extend the sign bit. */
if (SIZEOF_LONG_LONG > f->size)
x |= -(x & ((PY_LONG_LONG)1 << ((8 * f->size) - 1)));
if (x >= LONG_MIN && x <= LONG_MAX)
return PyLong_FromLong(Py_SAFE_DOWNCAST(x, PY_LONG_LONG, long));
return PyLong_FromLongLong(x);
#else
return _PyLong_FromByteArray((const unsigned char *)p,
8,
0, /* little-endian */
1 /* signed */);
#endif
}
static PyObject *
bu_ulonglong(const char *p, const formatdef *f)
{
#ifdef HAVE_LONG_LONG
unsigned PY_LONG_LONG x = 0;
Py_ssize_t i = f->size;
const unsigned char *bytes = (const unsigned char *)p;
do {
x = (x<<8) | *bytes++;
} while (--i > 0);
if (x <= LONG_MAX)
return PyLong_FromLong(Py_SAFE_DOWNCAST(x, unsigned PY_LONG_LONG, long));
return PyLong_FromUnsignedLongLong(x);
#else
return _PyLong_FromByteArray((const unsigned char *)p,
8,
0, /* little-endian */
0 /* signed */);
#endif
}
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 PyObject *
bu_bool(const char *p, const formatdef *f)
{
char x;
memcpy((char *)&x, p, sizeof x);
return PyBool_FromLong(x != 0);
}
static int
bp_int(char *p, PyObject *v, const formatdef *f)
{
long x;
Py_ssize_t i;
if (get_long(v, &x) < 0)
return -1;
i = f->size;
if (i != SIZEOF_LONG) {
if ((i == 2) && (x < -32768 || x > 32767))
RANGE_ERROR(x, f, 0, 0xffffL);
#if (SIZEOF_LONG != 4)
else if ((i == 4) && (x < -2147483648L || x > 2147483647L))
RANGE_ERROR(x, f, 0, 0xffffffffL);
#endif
}
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;
Py_ssize_t i;
if (get_ulong(v, &x) < 0)
return -1;
i = f->size;
if (i != SIZEOF_LONG) {
unsigned long maxint = 1;
maxint <<= (unsigned long)(i * 8);
if (x >= maxint)
RANGE_ERROR(x, f, 1, maxint - 1);
}
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 int
bp_bool(char *p, PyObject *v, const formatdef *f)
{
int y;
y = PyObject_IsTrue(v);
if (y < 0)
return -1;
*p = (char)y;
return 0;
}
static formatdef bigendian_table[] = {
{'x', 1, 0, NULL},
{'b', 1, 0, nu_byte, np_byte},
{'B', 1, 0, nu_ubyte, np_ubyte},
{'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},
{'?', 1, 0, bu_bool, bp_bool},
{'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;
Py_ssize_t i = f->size;
const unsigned char *bytes = (const unsigned char *)p;
do {
x = (x<<8) | bytes[--i];
} while (i > 0);
/* Extend the sign bit. */
if (SIZEOF_LONG > f->size)
x |= -(x & (1L << ((8 * f->size) - 1)));
return PyLong_FromLong(x);
}
static PyObject *
lu_uint(const char *p, const formatdef *f)
{
unsigned long x = 0;
Py_ssize_t i = f->size;
const unsigned char *bytes = (const unsigned char *)p;
do {
x = (x<<8) | bytes[--i];
} while (i > 0);
if (x <= LONG_MAX)
return PyLong_FromLong((long)x);
return PyLong_FromUnsignedLong((long)x);
}
static PyObject *
lu_longlong(const char *p, const formatdef *f)
{
#ifdef HAVE_LONG_LONG
PY_LONG_LONG x = 0;
Py_ssize_t i = f->size;
const unsigned char *bytes = (const unsigned char *)p;
do {
x = (x<<8) | bytes[--i];
} while (i > 0);
/* Extend the sign bit. */
if (SIZEOF_LONG_LONG > f->size)
x |= -(x & ((PY_LONG_LONG)1 << ((8 * f->size) - 1)));
if (x >= LONG_MIN && x <= LONG_MAX)
return PyLong_FromLong(Py_SAFE_DOWNCAST(x, PY_LONG_LONG, long));
return PyLong_FromLongLong(x);
#else
return _PyLong_FromByteArray((const unsigned char *)p,
8,
1, /* little-endian */
1 /* signed */);
#endif
}
static PyObject *
lu_ulonglong(const char *p, const formatdef *f)
{
#ifdef HAVE_LONG_LONG
unsigned PY_LONG_LONG x = 0;
Py_ssize_t i = f->size;
const unsigned char *bytes = (const unsigned char *)p;
do {
x = (x<<8) | bytes[--i];
} while (i > 0);
if (x <= LONG_MAX)
return PyLong_FromLong(Py_SAFE_DOWNCAST(x, unsigned PY_LONG_LONG, long));
return PyLong_FromUnsignedLongLong(x);
#else
return _PyLong_FromByteArray((const unsigned char *)p,
8,
1, /* little-endian */
0 /* signed */);
#endif
}
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;
Py_ssize_t i;
if (get_long(v, &x) < 0)
return -1;
i = f->size;
if (i != SIZEOF_LONG) {
if ((i == 2) && (x < -32768 || x > 32767))
RANGE_ERROR(x, f, 0, 0xffffL);
#if (SIZEOF_LONG != 4)
else if ((i == 4) && (x < -2147483648L || x > 2147483647L))
RANGE_ERROR(x, f, 0, 0xffffffffL);
#endif
}
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;
Py_ssize_t i;
if (get_ulong(v, &x) < 0)
return -1;
i = f->size;
if (i != SIZEOF_LONG) {
unsigned long maxint = 1;
maxint <<= (unsigned long)(i * 8);
if (x >= maxint)
RANGE_ERROR(x, f, 1, maxint - 1);
}
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, nu_byte, np_byte},
{'B', 1, 0, nu_ubyte, np_ubyte},
{'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},
{'?', 1, 0, bu_bool, bp_bool}, /* Std rep not endian dep,
but potentially different from native rep -- reuse bx_bool funcs. */
{'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 alignment! */
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. Return -1 on overflow. */
static Py_ssize_t
align(Py_ssize_t size, char c, const formatdef *e)
{
Py_ssize_t extra;
if (e->format == c) {
if (e->alignment && size > 0) {
extra = (e->alignment - 1) - (size - 1) % (e->alignment);
if (extra > PY_SSIZE_T_MAX - size)
return -1;
size += extra;
}
}
return size;
}
/* calculate the size of a format string */
static int
prepare_s(PyStructObject *self)
{
const formatdef *f;
const formatdef *e;
formatcode *codes;
const char *s;
const char *fmt;
char c;
Py_ssize_t size, len, num, itemsize;
fmt = PyBytes_AS_STRING(self->s_format);
f = whichtable((char **)&fmt);
s = fmt;
size = 0;
len = 0;
while ((c = *s++) != '\0') {
if (isspace(Py_CHARMASK(c)))
continue;
if ('0' <= c && c <= '9') {
num = c - '0';
while ('0' <= (c = *s++) && c <= '9') {
/* overflow-safe version of
if (num*10 + (c - '0') > PY_SSIZE_T_MAX) { ... } */
if (num >= PY_SSIZE_T_MAX / 10 && (
num > PY_SSIZE_T_MAX / 10 ||
(c - '0') > PY_SSIZE_T_MAX % 10))
goto overflow;
num = num*10 + (c - '0');
}
if (c == '\0') {
PyErr_SetString(StructError,
"repeat count given without format specifier");
return -1;
}
}
else
num = 1;
e = getentry(c, f);
if (e == NULL)
return -1;
switch (c) {
case 's': /* fall through */
case 'p': len++; break;
case 'x': break;
default: len += num; break;
}
itemsize = e->size;
size = align(size, c, e);
if (size == -1)
goto overflow;
/* if (size + num * itemsize > PY_SSIZE_T_MAX) { ... } */
if (num > (PY_SSIZE_T_MAX - size) / itemsize)
goto overflow;
size += num * itemsize;
}
/* check for overflow */
if ((len + 1) > (PY_SSIZE_T_MAX / sizeof(formatcode))) {
PyErr_NoMemory();
return -1;
}
self->s_size = size;
self->s_len = len;
codes = PyMem_MALLOC((len + 1) * sizeof(formatcode));
if (codes == NULL) {
PyErr_NoMemory();
return -1;
}
/* Free any s_codes value left over from a previous initialization. */
if (self->s_codes != NULL)
PyMem_FREE(self->s_codes);
self->s_codes = codes;
s = fmt;
size = 0;
while ((c = *s++) != '\0') {
if (isspace(Py_CHARMASK(c)))
continue;
if ('0' <= c && c <= '9') {
num = c - '0';
while ('0' <= (c = *s++) && c <= '9')
num = num*10 + (c - '0');
if (c == '\0')
break;
}
else
num = 1;
e = getentry(c, f);
size = align(size, c, e);
if (c == 's' || c == 'p') {
codes->offset = size;
codes->size = num;
codes->fmtdef = e;
codes++;
size += num;
} else if (c == 'x') {
size += num;
} else {
while (--num >= 0) {
codes->offset = size;
codes->size = e->size;
codes->fmtdef = e;
codes++;
size += e->size;
}
}
}
codes->fmtdef = NULL;
codes->offset = size;
codes->size = 0;
return 0;
overflow:
PyErr_SetString(StructError,
"total struct size too long");
return -1;
}
static PyObject *
s_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
PyObject *self;
assert(type != NULL && type->tp_alloc != NULL);
self = type->tp_alloc(type, 0);
if (self != NULL) {
PyStructObject *s = (PyStructObject*)self;
Py_INCREF(Py_None);
s->s_format = Py_None;
s->s_codes = NULL;
s->s_size = -1;
s->s_len = -1;
}
return self;
}
static int
s_init(PyObject *self, PyObject *args, PyObject *kwds)
{
PyStructObject *soself = (PyStructObject *)self;
PyObject *o_format = NULL;
int ret = 0;
static char *kwlist[] = {"format", 0};
assert(PyStruct_Check(self));
if (!PyArg_ParseTupleAndKeywords(args, kwds, "O:Struct", kwlist,
&o_format))
return -1;
if (PyUnicode_Check(o_format)) {
o_format = PyUnicode_AsASCIIString(o_format);
if (o_format == NULL)
return -1;
}
/* XXX support buffer interface, too */
else {
Py_INCREF(o_format);
}
if (!PyBytes_Check(o_format)) {
Py_DECREF(o_format);
PyErr_Format(PyExc_TypeError,
"Struct() argument 1 must be a bytes object, not %.200s",
Py_TYPE(o_format)->tp_name);
return -1;
}
Py_CLEAR(soself->s_format);
soself->s_format = o_format;
ret = prepare_s(soself);
return ret;
}
static void
s_dealloc(PyStructObject *s)
{
if (s->weakreflist != NULL)
PyObject_ClearWeakRefs((PyObject *)s);
if (s->s_codes != NULL) {
PyMem_FREE(s->s_codes);
}
Py_XDECREF(s->s_format);
Py_TYPE(s)->tp_free((PyObject *)s);
}
static PyObject *
s_unpack_internal(PyStructObject *soself, char *startfrom) {
formatcode *code;
Py_ssize_t i = 0;
PyObject *result = PyTuple_New(soself->s_len);
if (result == NULL)
return NULL;
for (code = soself->s_codes; code->fmtdef != NULL; code++) {
PyObject *v;
const formatdef *e = code->fmtdef;
const char *res = startfrom + code->offset;
if (e->format == 's') {
v = PyBytes_FromStringAndSize(res, code->size);
} else if (e->format == 'p') {
Py_ssize_t n = *(unsigned char*)res;
if (n >= code->size)
n = code->size - 1;
v = PyBytes_FromStringAndSize(res + 1, n);
} else {
v = e->unpack(res, e);
}
if (v == NULL)
goto fail;
PyTuple_SET_ITEM(result, i++, v);
}
return result;
fail:
Py_DECREF(result);
return NULL;
}
PyDoc_STRVAR(s_unpack__doc__,
"S.unpack(buffer) -> (v1, v2, ...)\n\
\n\
Return a tuple containing values unpacked according to the format\n\
string S.format. Requires len(buffer) == S.size. See help(struct)\n\
for more on format strings.");
static PyObject *
s_unpack(PyObject *self, PyObject *input)
{
Py_buffer vbuf;
PyObject *result;
PyStructObject *soself = (PyStructObject *)self;
assert(PyStruct_Check(self));
assert(soself->s_codes != NULL);
if (PyObject_GetBuffer(input, &vbuf, PyBUF_SIMPLE) < 0)
return NULL;
if (vbuf.len != soself->s_size) {
PyErr_Format(StructError,
"unpack requires a bytes object of length %zd",
soself->s_size);
PyBuffer_Release(&vbuf);
return NULL;
}
result = s_unpack_internal(soself, vbuf.buf);
PyBuffer_Release(&vbuf);
return result;
}
PyDoc_STRVAR(s_unpack_from__doc__,
"S.unpack_from(buffer, offset=0) -> (v1, v2, ...)\n\
\n\
Return a tuple containing values unpacked according to the format\n\
string S.format. Requires len(buffer[offset:]) >= S.size. See\n\
help(struct) for more on format strings.");
static PyObject *
s_unpack_from(PyObject *self, PyObject *args, PyObject *kwds)
{
static char *kwlist[] = {"buffer", "offset", 0};
PyObject *input;
Py_ssize_t offset = 0;
Py_buffer vbuf;
PyObject *result;
PyStructObject *soself = (PyStructObject *)self;
assert(PyStruct_Check(self));
assert(soself->s_codes != NULL);
if (!PyArg_ParseTupleAndKeywords(args, kwds,
"O|n:unpack_from", kwlist,
&input, &offset))
return NULL;
if (PyObject_GetBuffer(input, &vbuf, PyBUF_SIMPLE) < 0)
return NULL;
if (offset < 0)
offset += vbuf.len;
if (offset < 0 || vbuf.len - offset < soself->s_size) {
PyErr_Format(StructError,
"unpack_from requires a buffer of at least %zd bytes",
soself->s_size);
PyBuffer_Release(&vbuf);
return NULL;
}
result = s_unpack_internal(soself, (char*)vbuf.buf + offset);
PyBuffer_Release(&vbuf);
return result;
}
/*
* Guts of the pack function.
*
* Takes a struct object, a tuple of arguments, and offset in that tuple of
* argument for where to start processing the arguments for packing, and a
* character buffer for writing the packed string. The caller must insure
* that the buffer may contain the required length for packing the arguments.
* 0 is returned on success, 1 is returned if there is an error.
*
*/
static int
s_pack_internal(PyStructObject *soself, PyObject *args, int offset, char* buf)
{
formatcode *code;
/* XXX(nnorwitz): why does i need to be a local? can we use
the offset parameter or do we need the wider width? */
Py_ssize_t i;
memset(buf, '\0', soself->s_size);
i = offset;
for (code = soself->s_codes; code->fmtdef != NULL; code++) {
Py_ssize_t n;
PyObject *v = PyTuple_GET_ITEM(args, i++);
const formatdef *e = code->fmtdef;
char *res = buf + code->offset;
if (e->format == 's') {
int isstring;
void *p;
isstring = PyBytes_Check(v);
if (!isstring && !PyByteArray_Check(v)) {
PyErr_SetString(StructError,
"argument for 's' must be a bytes object");
return -1;
}
if (isstring) {
n = PyBytes_GET_SIZE(v);
p = PyBytes_AS_STRING(v);
}
else {
n = PyByteArray_GET_SIZE(v);
p = PyByteArray_AS_STRING(v);
}
if (n > code->size)
n = code->size;
if (n > 0)
memcpy(res, p, n);
} else if (e->format == 'p') {
int isstring;
void *p;
isstring = PyBytes_Check(v);
if (!isstring && !PyByteArray_Check(v)) {
PyErr_SetString(StructError,
"argument for 'p' must be a bytes object");
return -1;
}
if (isstring) {
n = PyBytes_GET_SIZE(v);
p = PyBytes_AS_STRING(v);
}
else {
n = PyByteArray_GET_SIZE(v);
p = PyByteArray_AS_STRING(v);
}
if (n > (code->size - 1))
n = code->size - 1;
if (n > 0)
memcpy(res + 1, p, n);
if (n > 255)
n = 255;
*res = Py_SAFE_DOWNCAST(n, Py_ssize_t, unsigned char);
} else {
if (e->pack(res, v, e) < 0) {
if (PyLong_Check(v) && PyErr_ExceptionMatches(PyExc_OverflowError))
PyErr_SetString(StructError,
"long too large to convert to int");
return -1;
}
}
}
/* Success */
return 0;
}
PyDoc_STRVAR(s_pack__doc__,
"S.pack(v1, v2, ...) -> bytes\n\
\n\
Return a bytes object containing values v1, v2, ... packed according\n\
to the format string S.format. See help(struct) for more on format\n\
strings.");
static PyObject *
s_pack(PyObject *self, PyObject *args)
{
PyStructObject *soself;
PyObject *result;
/* Validate arguments. */
soself = (PyStructObject *)self;
assert(PyStruct_Check(self));
assert(soself->s_codes != NULL);
if (PyTuple_GET_SIZE(args) != soself->s_len)
{
PyErr_Format(StructError,
"pack requires exactly %zd arguments", soself->s_len);
return NULL;
}
/* Allocate a new string */
result = PyBytes_FromStringAndSize((char *)NULL, soself->s_size);
if (result == NULL)
return NULL;
/* Call the guts */
if ( s_pack_internal(soself, args, 0, PyBytes_AS_STRING(result)) != 0 ) {
Py_DECREF(result);
return NULL;
}
return result;
}
PyDoc_STRVAR(s_pack_into__doc__,
"S.pack_into(buffer, offset, v1, v2, ...)\n\
\n\
Pack the values v1, v2, ... according to the format string S.format\n\
and write the packed bytes into the writable buffer buf starting at\n\
offset. Note that the offset is a required argument. See\n\
help(struct) for more on format strings.");
static PyObject *
s_pack_into(PyObject *self, PyObject *args)
{
PyStructObject *soself;
char *buffer;
Py_ssize_t buffer_len, offset;
/* Validate arguments. +1 is for the first arg as buffer. */
soself = (PyStructObject *)self;
assert(PyStruct_Check(self));
assert(soself->s_codes != NULL);
if (PyTuple_GET_SIZE(args) != (soself->s_len + 2))
{
PyErr_Format(StructError,
"pack_into requires exactly %zd arguments",
(soself->s_len + 2));
return NULL;
}
/* Extract a writable memory buffer from the first argument */
if ( PyObject_AsWriteBuffer(PyTuple_GET_ITEM(args, 0),
(void**)&buffer, &buffer_len) == -1 ) {
return NULL;
}
assert( buffer_len >= 0 );
/* Extract the offset from the first argument */
offset = PyNumber_AsSsize_t(PyTuple_GET_ITEM(args, 1), PyExc_IndexError);
if (offset == -1 && PyErr_Occurred())
return NULL;
/* Support negative offsets. */
if (offset < 0)
offset += buffer_len;
/* Check boundaries */
if (offset < 0 || (buffer_len - offset) < soself->s_size) {
PyErr_Format(StructError,
"pack_into requires a buffer of at least %zd bytes",
soself->s_size);
return NULL;
}
/* Call the guts */
if ( s_pack_internal(soself, args, 2, buffer + offset) != 0 ) {
return NULL;
}
Py_RETURN_NONE;
}
static PyObject *
s_get_format(PyStructObject *self, void *unused)
{
Py_INCREF(self->s_format);
return self->s_format;
}
static PyObject *
s_get_size(PyStructObject *self, void *unused)
{
return PyLong_FromSsize_t(self->s_size);
}
/* List of functions */
static struct PyMethodDef s_methods[] = {
{"pack", s_pack, METH_VARARGS, s_pack__doc__},
{"pack_into", s_pack_into, METH_VARARGS, s_pack_into__doc__},
{"unpack", s_unpack, METH_O, s_unpack__doc__},
{"unpack_from", (PyCFunction)s_unpack_from, METH_VARARGS|METH_KEYWORDS,
s_unpack_from__doc__},
{NULL, NULL} /* sentinel */
};
PyDoc_STRVAR(s__doc__,
"Struct(fmt) --> compiled struct object\n"
"\n"
"Return a new Struct object which writes and reads binary data according to\n"
"the format string fmt. See help(struct) for more on format strings.");
#define OFF(x) offsetof(PyStructObject, x)
static PyGetSetDef s_getsetlist[] = {
{"format", (getter)s_get_format, (setter)NULL, "struct format string", NULL},
{"size", (getter)s_get_size, (setter)NULL, "struct size in bytes", NULL},
{NULL} /* sentinel */
};
static
PyTypeObject PyStructType = {
PyVarObject_HEAD_INIT(NULL, 0)
"Struct",
sizeof(PyStructObject),
0,
(destructor)s_dealloc, /* tp_dealloc */
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_reserved */
0, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
PyObject_GenericSetAttr, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
s__doc__, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
offsetof(PyStructObject, weakreflist), /* tp_weaklistoffset */
0, /* tp_iter */
0, /* tp_iternext */
s_methods, /* tp_methods */
NULL, /* tp_members */
s_getsetlist, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
0, /* tp_dictoffset */
s_init, /* tp_init */
PyType_GenericAlloc,/* tp_alloc */
s_new, /* tp_new */
PyObject_Del, /* tp_free */
};
/* ---- Standalone functions ---- */
#define MAXCACHE 100
static PyObject *cache = NULL;
static PyObject *
cache_struct(PyObject *fmt)
{
PyObject * s_object;
if (cache == NULL) {
cache = PyDict_New();
if (cache == NULL)
return NULL;
}
s_object = PyDict_GetItem(cache, fmt);
if (s_object != NULL) {
Py_INCREF(s_object);
return s_object;
}
s_object = PyObject_CallFunctionObjArgs((PyObject *)(&PyStructType), fmt, NULL);
if (s_object != NULL) {
if (PyDict_Size(cache) >= MAXCACHE)
PyDict_Clear(cache);
/* Attempt to cache the result */
if (PyDict_SetItem(cache, fmt, s_object) == -1)
PyErr_Clear();
}
return s_object;
}
PyDoc_STRVAR(clearcache_doc,
"Clear the internal cache.");
static PyObject *
clearcache(PyObject *self)
{
Py_CLEAR(cache);
Py_RETURN_NONE;
}
PyDoc_STRVAR(calcsize_doc,
"calcsize(fmt) -> integer\n\
\n\
Return size in bytes of the struct described by the format string fmt.");
static PyObject *
calcsize(PyObject *self, PyObject *fmt)
{
Py_ssize_t n;
PyObject *s_object = cache_struct(fmt);
if (s_object == NULL)
return NULL;
n = ((PyStructObject *)s_object)->s_size;
Py_DECREF(s_object);
return PyLong_FromSsize_t(n);
}
PyDoc_STRVAR(pack_doc,
"pack(fmt, v1, v2, ...) -> bytes\n\
\n\
Return a bytes object containing the values v1, v2, ... packed according\n\
to the format string fmt. See help(struct) for more on format strings.");
static PyObject *
pack(PyObject *self, PyObject *args)
{
PyObject *s_object, *fmt, *newargs, *result;
Py_ssize_t n = PyTuple_GET_SIZE(args);
if (n == 0) {
PyErr_SetString(PyExc_TypeError, "missing format argument");
return NULL;
}
fmt = PyTuple_GET_ITEM(args, 0);
newargs = PyTuple_GetSlice(args, 1, n);
if (newargs == NULL)
return NULL;
s_object = cache_struct(fmt);
if (s_object == NULL) {
Py_DECREF(newargs);
return NULL;
}
result = s_pack(s_object, newargs);
Py_DECREF(newargs);
Py_DECREF(s_object);
return result;
}
PyDoc_STRVAR(pack_into_doc,
"pack_into(fmt, buffer, offset, v1, v2, ...)\n\
\n\
Pack the values v1, v2, ... according to the format string fmt and write\n\
the packed bytes into the writable buffer buf starting at offset. Note\n\
that the offset is a required argument. See help(struct) for more\n\
on format strings.");
static PyObject *
pack_into(PyObject *self, PyObject *args)
{
PyObject *s_object, *fmt, *newargs, *result;
Py_ssize_t n = PyTuple_GET_SIZE(args);
if (n == 0) {
PyErr_SetString(PyExc_TypeError, "missing format argument");
return NULL;
}
fmt = PyTuple_GET_ITEM(args, 0);
newargs = PyTuple_GetSlice(args, 1, n);
if (newargs == NULL)
return NULL;
s_object = cache_struct(fmt);
if (s_object == NULL) {
Py_DECREF(newargs);
return NULL;
}
result = s_pack_into(s_object, newargs);
Py_DECREF(newargs);
Py_DECREF(s_object);
return result;
}
PyDoc_STRVAR(unpack_doc,
"unpack(fmt, buffer) -> (v1, v2, ...)\n\
\n\
Return a tuple containing values unpacked according to the format string\n\
fmt. Requires len(buffer) == calcsize(fmt). See help(struct) for more\n\
on format strings.");
static PyObject *
unpack(PyObject *self, PyObject *args)
{
PyObject *s_object, *fmt, *inputstr, *result;
if (!PyArg_UnpackTuple(args, "unpack", 2, 2, &fmt, &inputstr))
return NULL;
s_object = cache_struct(fmt);
if (s_object == NULL)
return NULL;
result = s_unpack(s_object, inputstr);
Py_DECREF(s_object);
return result;
}
PyDoc_STRVAR(unpack_from_doc,
"unpack_from(fmt, buffer, offset=0) -> (v1, v2, ...)\n\
\n\
Return a tuple containing values unpacked according to the format string\n\
fmt. Requires len(buffer[offset:]) >= calcsize(fmt). See help(struct)\n\
for more on format strings.");
static PyObject *
unpack_from(PyObject *self, PyObject *args, PyObject *kwds)
{
PyObject *s_object, *fmt, *newargs, *result;
Py_ssize_t n = PyTuple_GET_SIZE(args);
if (n == 0) {
PyErr_SetString(PyExc_TypeError, "missing format argument");
return NULL;
}
fmt = PyTuple_GET_ITEM(args, 0);
newargs = PyTuple_GetSlice(args, 1, n);
if (newargs == NULL)
return NULL;
s_object = cache_struct(fmt);
if (s_object == NULL) {
Py_DECREF(newargs);
return NULL;
}
result = s_unpack_from(s_object, newargs, kwds);
Py_DECREF(newargs);
Py_DECREF(s_object);
return result;
}
static struct PyMethodDef module_functions[] = {
{"_clearcache", (PyCFunction)clearcache, METH_NOARGS, clearcache_doc},
{"calcsize", calcsize, METH_O, calcsize_doc},
{"pack", pack, METH_VARARGS, pack_doc},
{"pack_into", pack_into, METH_VARARGS, pack_into_doc},
{"unpack", unpack, METH_VARARGS, unpack_doc},
{"unpack_from", (PyCFunction)unpack_from,
METH_VARARGS|METH_KEYWORDS, unpack_from_doc},
{NULL, NULL} /* sentinel */
};
/* Module initialization */
PyDoc_STRVAR(module_doc,
"Functions to convert between Python values and C structs.\n\
Python bytes objects are used to hold the data representing the C struct\n\
and also as format strings (explained below) to describe the layout of data\n\
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\
?: _Bool (requires C99; if not available, char is used instead)\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 cases (only available in native format):\n\
n:ssize_t; N:size_t;\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.\n");
static struct PyModuleDef _structmodule = {
PyModuleDef_HEAD_INIT,
"_struct",
module_doc,
-1,
module_functions,
NULL,
NULL,
NULL,
NULL
};
PyMODINIT_FUNC
PyInit__struct(void)
{
PyObject *m;
m = PyModule_Create(&_structmodule);
if (m == NULL)
return NULL;
Py_TYPE(&PyStructType) = &PyType_Type;
if (PyType_Ready(&PyStructType) < 0)
return NULL;
/* Check endian and swap in faster functions */
{
int one = 1;
formatdef *native = native_table;
formatdef *other, *ptr;
if ((int)*(unsigned char*)&one)
other = lilendian_table;
else
other = bigendian_table;
/* Scan through the native table, find a matching
entry in the endian table and swap in the
native implementations whenever possible
(64-bit platforms may not have "standard" sizes) */
while (native->format != '\0' && other->format != '\0') {
ptr = other;
while (ptr->format != '\0') {
if (ptr->format == native->format) {
/* Match faster when formats are
listed in the same order */
if (ptr == other)
other++;
/* Only use the trick if the
size matches */
if (ptr->size != native->size)
break;
/* Skip float and double, could be
"unknown" float format */
if (ptr->format == 'd' || ptr->format == 'f')
break;
ptr->pack = native->pack;
ptr->unpack = native->unpack;
break;
}
ptr++;
}
native++;
}
}
/* Add some symbolic constants to the module */
if (StructError == NULL) {
StructError = PyErr_NewException("struct.error", NULL, NULL);
if (StructError == NULL)
return NULL;
}
Py_INCREF(StructError);
PyModule_AddObject(m, "error", StructError);
Py_INCREF((PyObject*)&PyStructType);
PyModule_AddObject(m, "Struct", (PyObject*)&PyStructType);
return m;
}
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