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cpython/Modules/_struct.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 "structseq.h"
#include "structmember.h"
#include <ctype.h>
static PyTypeObject PyStructType;
/* compatibility macros */
#if (PY_VERSION_HEX < 0x02050000)
typedef int Py_ssize_t;
#endif
/* PY_USE_INT_WHEN_POSSIBLE is an experimental flag that changes the
struct API to return int instead of long when possible. This is
often a significant performance improvement. */
/*
#define PY_USE_INT_WHEN_POSSIBLE 1
*/
/* 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;
typedef struct _formatcode {
const struct _formatdef *fmtdef;
int offset;
int size;
} formatcode;
/* Struct object interface */
typedef struct {
PyObject_HEAD
int s_size;
int 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) ((op)->ob_type == &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;
#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);
}
/* 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);
#ifdef PY_USE_INT_WHEN_POSSIBLE
if (x <= LONG_MAX)
return PyInt_FromLong((long)x);
#endif
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);
#ifdef PY_USE_INT_WHEN_POSSIBLE
if (x <= LONG_MAX)
return PyInt_FromLong((long)x);
#endif
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);
#ifdef PY_USE_INT_WHEN_POSSIBLE
if (x >= LONG_MIN && x <= LONG_MAX)
return PyInt_FromLong(Py_SAFE_DOWNCAST(x, PY_LONG_LONG, long));
#endif
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);
#ifdef PY_USE_INT_WHEN_POSSIBLE
if (x <= LONG_MAX)
return PyInt_FromLong(Py_SAFE_DOWNCAST(x, unsigned PY_LONG_LONG, long));
#endif
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},
#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
{'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;
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);
#ifdef PY_USE_INT_WHEN_POSSIBLE
if (x <= LONG_MAX)
return PyInt_FromLong((long)x);
#else
if (SIZEOF_LONG > f->size)
return PyInt_FromLong((long)x);
#endif
return PyLong_FromUnsignedLong(x);
}
static PyObject *
bu_longlong(const char *p, const formatdef *f)
{
#if HAVE_LONG_LONG
PY_LONG_LONG x = 0;
int i = f->size;
do {
x = (x<<8) | (*p++ & 0xFF);
} while (--i > 0);
/* Extend the sign bit. */
if (SIZEOF_LONG_LONG > f->size)
x |= -(x & (1L << (8 * f->size - 1)));
#ifdef PY_USE_INT_WHEN_POSSIBLE
if (x >= LONG_MIN && x <= LONG_MAX)
return PyInt_FromLong(Py_SAFE_DOWNCAST(x, PY_LONG_LONG, long));
#endif
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)
{
#if HAVE_LONG_LONG
unsigned PY_LONG_LONG x = 0;
int i = f->size;
do {
x = (x<<8) | (*p++ & 0xFF);
} while (--i > 0);
#ifdef PY_USE_INT_WHEN_POSSIBLE
if (x <= LONG_MAX)
return PyInt_FromLong(Py_SAFE_DOWNCAST(x, unsigned PY_LONG_LONG, long));
#endif
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 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);
#ifdef PY_USE_INT_WHEN_POSSIBLE
if (x <= LONG_MAX)
return PyInt_FromLong((long)x);
#else
if (SIZEOF_LONG > f->size)
return PyInt_FromLong((long)x);
#endif
return PyLong_FromUnsignedLong((long)x);
}
static PyObject *
lu_longlong(const char *p, const formatdef *f)
{
#if HAVE_LONG_LONG
PY_LONG_LONG x = 0;
int i = f->size;
do {
x = (x<<8) | (p[--i] & 0xFF);
} while (i > 0);
/* Extend the sign bit. */
if (SIZEOF_LONG_LONG > f->size)
x |= -(x & (1L << (8 * f->size - 1)));
#ifdef PY_USE_INT_WHEN_POSSIBLE
if (x >= LONG_MIN && x <= LONG_MAX)
return PyInt_FromLong(Py_SAFE_DOWNCAST(x, PY_LONG_LONG, long));
#endif
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)
{
#if HAVE_LONG_LONG
unsigned PY_LONG_LONG x = 0;
int i = f->size;
do {
x = (x<<8) | (p[--i] & 0xFF);
} while (i > 0);
#ifdef PY_USE_INT_WHEN_POSSIBLE
if (x <= LONG_MAX)
return PyInt_FromLong(Py_SAFE_DOWNCAST(x, unsigned PY_LONG_LONG, long));
#endif
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;
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
prepare_s(PyStructObject *self)
{
const formatdef *f;
const formatdef *e;
formatcode *codes;
const char *s;
const char *fmt;
char c;
int size, len, num, itemsize, x;
fmt = PyString_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') {
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;
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);
x = num * itemsize;
size += x;
if (x/itemsize != num || size < 0) {
PyErr_SetString(StructError,
"total struct size too long");
return -1;
}
}
self->s_size = size;
self->s_len = len;
codes = PyMem_MALLOC((len + 1) * sizeof(formatcode));
if (codes == NULL) {
PyErr_NoMemory();
return -1;
}
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;
}
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, "S:Struct", kwlist,
&o_format))
return -1;
Py_INCREF(o_format);
Py_XDECREF(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);
s->ob_type->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 = PyString_FromStringAndSize(res, code->size);
if (v == NULL)
goto fail;
PyTuple_SET_ITEM(result, i++, v);
} else if (e->format == 'p') {
Py_ssize_t n = *(unsigned char*)res;
if (n >= code->size)
n = code->size - 1;
v = PyString_FromStringAndSize(res + 1, n);
if (v == NULL)
goto fail;
PyTuple_SET_ITEM(result, i++, v);
} 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__,
"unpack(str) -> (v1, v2, ...)\n\
\n\
Return tuple containing values unpacked according to this Struct's format.\n\
Requires len(str) == self.size. See struct.__doc__ for more on format\n\
strings.");
static PyObject *
s_unpack(PyObject *self, PyObject *inputstr)
{
PyStructObject *soself = (PyStructObject *)self;
assert(PyStruct_Check(self));
assert(soself->s_codes != NULL);
if (inputstr == NULL || !PyString_Check(inputstr) ||
PyString_GET_SIZE(inputstr) != soself->s_size) {
PyErr_Format(StructError,
"unpack requires a string argument of length %d", soself->s_size);
return NULL;
}
return s_unpack_internal(soself, PyString_AS_STRING(inputstr));
}
PyDoc_STRVAR(s_unpack_from__doc__,
"unpack_from(buffer[, offset]) -> (v1, v2, ...)\n\
\n\
Return tuple containing values unpacked according to this Struct's format.\n\
Unlike unpack, unpack_from can unpack values from any object supporting\n\
the buffer API, not just str. Requires len(buffer[offset:]) >= self.size.\n\
See struct.__doc__ for more on format strings.");
static PyObject *
s_unpack_from(PyObject *self, PyObject *args, PyObject *kwds)
{
static char *kwlist[] = {"buffer", "offset", 0};
#if (PY_VERSION_HEX < 0x02050000)
static char *fmt = "z#|i:unpack_from";
#else
static char *fmt = "z#|n:unpack_from";
#endif
Py_ssize_t buffer_len = 0, offset = 0;
char *buffer = NULL;
PyStructObject *soself = (PyStructObject *)self;
assert(PyStruct_Check(self));
assert(soself->s_codes != NULL);
if (!PyArg_ParseTupleAndKeywords(args, kwds, fmt, kwlist,
&buffer, &buffer_len, &offset))
return NULL;
if (buffer == NULL) {
PyErr_Format(StructError,
"unpack_from requires a buffer argument");
return NULL;
}
if (offset < 0)
offset += buffer_len;
if (offset < 0 || (buffer_len - offset) < soself->s_size) {
PyErr_Format(StructError,
"unpack_from requires a buffer of at least %d bytes",
soself->s_size);
return NULL;
}
return s_unpack_internal(soself, buffer + offset);
}
PyDoc_STRVAR(s_pack__doc__,
"pack(v1, v2, ...) -> string\n\
\n\
Return a string containing values v1, v2, ... packed according to this\n\
Struct's format. See struct.__doc__ for more on format strings.");
static PyObject *
s_pack(PyObject *self, PyObject *args)
{
PyStructObject *soself;
PyObject *result;
char *restart;
formatcode *code;
Py_ssize_t i;
soself = (PyStructObject *)self;
assert(PyStruct_Check(self));
assert(soself->s_codes != NULL);
if (args == NULL || !PyTuple_Check(args) ||
PyTuple_GET_SIZE(args) != soself->s_len)
{
PyErr_Format(StructError,
"pack requires exactly %d arguments", soself->s_len);
return NULL;
}
result = PyString_FromStringAndSize((char *)NULL, soself->s_size);
if (result == NULL)
return NULL;
restart = PyString_AS_STRING(result);
memset(restart, '\0', soself->s_size);
i = 0;
for (code = soself->s_codes; code->fmtdef != NULL; code++) {
Py_ssize_t n;
PyObject *v;
const formatdef *e = code->fmtdef;
char *res = restart + code->offset;
if (e->format == 's') {
v = PyTuple_GET_ITEM(args, i++);
if (!PyString_Check(v)) {
PyErr_SetString(StructError,
"argument for 's' must be a string");
goto fail;
}
n = PyString_GET_SIZE(v);
if (n > code->size)
n = code->size;
if (n > 0)
memcpy(res, PyString_AS_STRING(v), n);
} else if (e->format == 'p') {
v = PyTuple_GET_ITEM(args, i++);
if (!PyString_Check(v)) {
PyErr_SetString(StructError,
"argument for 'p' must be a string");
goto fail;
}
n = PyString_GET_SIZE(v);
if (n > (code->size - 1))
n = code->size - 1;
if (n > 0)
memcpy(res + 1, PyString_AS_STRING(v), n);
if (n > 255)
n = 255;
*res = Py_SAFE_DOWNCAST(n, Py_ssize_t, unsigned char);
} else {
v = PyTuple_GET_ITEM(args, i++);
if (e->pack(res, v, e) < 0)
goto fail;
}
}
return result;
fail:
Py_DECREF(result);
return NULL;
}
/* List of functions */
static struct PyMethodDef s_methods[] = {
{"pack", (PyCFunction)s_pack, METH_VARARGS, s_pack__doc__},
{"unpack", (PyCFunction)s_unpack, METH_O, s_unpack__doc__},
{"unpack_from", (PyCFunction)s_unpack_from, METH_KEYWORDS, s_unpack_from__doc__},
{NULL, NULL} /* sentinel */
};
PyDoc_STRVAR(s__doc__, "Compiled struct object");
#define OFF(x) offsetof(PyStructObject, x)
static PyMemberDef s_memberlist[] = {
{"format", T_OBJECT, OFF(s_format), RO,
"struct format string"},
{"size", T_INT, OFF(s_size), RO,
"struct size in bytes"},
{"_len", T_INT, OFF(s_len), RO,
"number of items expected in tuple"},
{NULL} /* Sentinel */
};
static
PyTypeObject PyStructType = {
PyObject_HEAD_INIT(NULL)
0,
"Struct",
sizeof(PyStructObject),
0,
(destructor)s_dealloc, /* tp_dealloc */
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_compare */
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 | Py_TPFLAGS_HAVE_WEAKREFS, /* 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 */
s_memberlist, /* tp_members */
0, /* 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 */
};
/* Module initialization */
PyMODINIT_FUNC
init_struct(void)
{
PyObject *m = Py_InitModule("_struct", NULL);
if (m == NULL)
return;
PyStructType.ob_type = &PyType_Type;
if (PyType_Ready(&PyStructType) < 0)
return;
/* 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;
while (native->format != '\0' && other->format != '\0') {
ptr = other;
while (ptr->format != '\0') {
if (ptr->format == native->format) {
ptr->pack = native->pack;
ptr->unpack = native->unpack;
if (ptr == other)
other++;
break;
}
ptr++;
}
native++;
}
}
/* Add some symbolic constants to the module */
if (StructError == NULL) {
StructError = PyErr_NewException("struct.error", NULL, NULL);
if (StructError == NULL)
return;
}
Py_INCREF(StructError);
PyModule_AddObject(m, "error", StructError);
Py_INCREF((PyObject*)&PyStructType);
PyModule_AddObject(m, "Struct", (PyObject*)&PyStructType);
}
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