/* 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
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;
Py_ssize_t repeat;
} 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
#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 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 format,
ulargest);
else {
const Py_ssize_t largest = (Py_ssize_t)(ulargest >> 1);
PyErr_Format(StructError,
"'%c' format requires %zd (v1, v2, ...)\n\
\n\
Return a tuple containing values unpacked according to the format\n\
string S.format. The buffer's size in bytes must be S.size. See\n\
help(struct) 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. The buffer's size in bytes, minus offset, must be at\n\
least S.size. See 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;
}
/* Unpack iterator type */
typedef struct {
PyObject_HEAD
PyStructObject *so;
Py_buffer buf;
Py_ssize_t index;
} unpackiterobject;
static void
unpackiter_dealloc(unpackiterobject *self)
{
/* bpo-31095: UnTrack is needed before calling any callbacks */
PyObject_GC_UnTrack(self);
Py_XDECREF(self->so);
PyBuffer_Release(&self->buf);
PyObject_GC_Del(self);
}
static int
unpackiter_traverse(unpackiterobject *self, visitproc visit, void *arg)
{
Py_VISIT(self->so);
Py_VISIT(self->buf.obj);
return 0;
}
static PyObject *
unpackiter_len(unpackiterobject *self)
{
Py_ssize_t len;
if (self->so == NULL)
len = 0;
else
len = (self->buf.len - self->index) / self->so->s_size;
return PyLong_FromSsize_t(len);
}
static PyMethodDef unpackiter_methods[] = {
{"__length_hint__", (PyCFunction) unpackiter_len, METH_NOARGS, NULL},
{NULL, NULL} /* sentinel */
};
static PyObject *
unpackiter_iternext(unpackiterobject *self)
{
PyObject *result;
if (self->so == NULL)
return NULL;
if (self->index >= self->buf.len) {
/* Iterator exhausted */
Py_CLEAR(self->so);
PyBuffer_Release(&self->buf);
return NULL;
}
assert(self->index + self->so->s_size buf.len);
result = s_unpack_internal(self->so,
(char*) self->buf.buf + self->index);
self->index += self->so->s_size;
return result;
}
static PyTypeObject unpackiter_type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"unpack_iterator", /* tp_name */
sizeof(unpackiterobject), /* tp_basicsize */
0, /* tp_itemsize */
(destructor)unpackiter_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 */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
0, /* tp_doc */
(traverseproc)unpackiter_traverse, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)unpackiter_iternext, /* tp_iternext */
unpackiter_methods /* tp_methods */
};
PyDoc_STRVAR(s_iter_unpack__doc__,
"S.iter_unpack(buffer) -> iterator(v1, v2, ...)\n\
\n\
Return an iterator yielding tuples unpacked from the given bytes\n\
source, like a repeated invocation of unpack_from(). Requires\n\
that the bytes length be a multiple of the struct size.");
static PyObject *
s_iter_unpack(PyObject *_so, PyObject *input)
{
PyStructObject *so = (PyStructObject *) _so;
unpackiterobject *self;
assert(PyStruct_Check(_so));
assert(so->s_codes != NULL);
if (so->s_size == 0) {
PyErr_Format(StructError,
"cannot iteratively unpack with a struct of length 0");
return NULL;
}
self = (unpackiterobject *) PyType_GenericAlloc(&unpackiter_type, 0);
if (self == NULL)
return NULL;
if (PyObject_GetBuffer(input, &self->buf, PyBUF_SIMPLE) < 0) {
Py_DECREF(self);
return NULL;
}
if (self->buf.len % so->s_size != 0) {
PyErr_Format(StructError,
"iterative unpacking requires a bytes length "
"multiple of %zd",
so->s_size);
Py_DECREF(self);
return NULL;
}
Py_INCREF(so);
self->so = so;
self->index = 0;
return (PyObject *) self;
}
/*
* 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++) {
const formatdef *e = code->fmtdef;
char *res = buf + code->offset;
Py_ssize_t j = code->repeat;
while (j--) {
PyObject *v = PyTuple_GET_ITEM(args, i++);
if (e->format == 's') {
Py_ssize_t n;
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') {
Py_ssize_t n;
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,
"int too large to convert");
return -1;
}
}
res += code->size;
}
}
/* 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 expected %zd items for packing (got %zd)", soself->s_len, PyTuple_GET_SIZE(args));
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;
Py_buffer buffer;
Py_ssize_t 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))
{
if (PyTuple_GET_SIZE(args) == 0) {
PyErr_Format(StructError,
"pack_into expected buffer argument");
}
else if (PyTuple_GET_SIZE(args) == 1) {
PyErr_Format(StructError,
"pack_into expected offset argument");
}
else {
PyErr_Format(StructError,
"pack_into expected %zd items for packing (got %zd)",
soself->s_len, (PyTuple_GET_SIZE(args) - 2));
}
return NULL;
}
/* Extract a writable memory buffer from the first argument */
if (!PyArg_Parse(PyTuple_GET_ITEM(args, 0), "w*", &buffer))
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()) {
PyBuffer_Release(&buffer);
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);
PyBuffer_Release(&buffer);
return NULL;
}
/* Call the guts */
if (s_pack_internal(soself, args, 2, (char*)buffer.buf + offset) != 0) {
PyBuffer_Release(&buffer);
return NULL;
}
PyBuffer_Release(&buffer);
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);
}
PyDoc_STRVAR(s_sizeof__doc__,
"S.__sizeof__() -> size of S in memory, in bytes");
static PyObject *
s_sizeof(PyStructObject *self, void *unused)
{
Py_ssize_t size;
formatcode *code;
size = _PyObject_SIZE(Py_TYPE(self)) + sizeof(formatcode);
for (code = self->s_codes; code->fmtdef != NULL; code++)
size += sizeof(formatcode);
return PyLong_FromSsize_t(size);
}
/* List of functions */
static struct PyMethodDef s_methods[] = {
{"iter_unpack", s_iter_unpack, METH_O, s_iter_unpack__doc__},
{"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__},
{"__sizeof__", (PyCFunction)s_sizeof, METH_NOARGS, s_sizeof__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. The buffer's size in bytes must be calcsize(fmt). See help(struct)\n\
for more 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. The buffer's size, minus offset, must be at least calcsize(fmt).\n\
See help(struct) 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;
}
PyDoc_STRVAR(iter_unpack_doc,
"iter_unpack(fmt, buffer) -> iterator(v1, v2, ...)\n\
\n\
Return an iterator yielding tuples unpacked from the given bytes\n\
source according to the format string, like a repeated invocation of\n\
unpack_from(). Requires that the bytes length be a multiple of the\n\
format struct size.");
static PyObject *
iter_unpack(PyObject *self, PyObject *args)
{
PyObject *s_object, *fmt, *input, *result;
if (!PyArg_ParseTuple(args, "OO:iter_unpack", &fmt, &input))
return NULL;
s_object = cache_struct(fmt);
if (s_object == NULL)
return NULL;
result = s_iter_unpack(s_object, input);
Py_DECREF(s_object);
return result;
}
static struct PyMethodDef module_functions[] = {
{"_clearcache", (PyCFunction)clearcache, METH_NOARGS, clearcache_doc},
{"calcsize", calcsize, METH_O, calcsize_doc},
{"iter_unpack", iter_unpack, METH_VARARGS, iter_unpack_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\
: 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 */
{
formatdef *native = native_table;
formatdef *other, *ptr;
#if PY_LITTLE_ENDIAN
other = lilendian_table;
#else
other = bigendian_table;
#endif
/* 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;
}