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cpython/Modules/_io/stringio.c

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#define PY_SSIZE_T_CLEAN
#include "Python.h"
#include "structmember.h"
#include "_iomodule.h"
/* Implementation note: the buffer is always at least one character longer
than the enclosed string, for proper functioning of _PyIO_find_line_ending.
*/
typedef struct {
PyObject_HEAD
Py_UNICODE *buf;
Py_ssize_t pos;
Py_ssize_t string_size;
size_t buf_size;
char ok; /* initialized? */
char closed;
char readuniversal;
char readtranslate;
PyObject *decoder;
PyObject *readnl;
PyObject *writenl;
PyObject *dict;
PyObject *weakreflist;
} StringIOObject;
#define CHECK_INITIALIZED(self) \
if (self->ok <= 0) { \
PyErr_SetString(PyExc_ValueError, \
"I/O operation on uninitialized object"); \
return NULL; \
}
#define CHECK_CLOSED(self) \
if (self->closed) { \
PyErr_SetString(PyExc_ValueError, \
"I/O operation on closed file"); \
return NULL; \
}
PyDoc_STRVAR(stringio_doc,
"Text I/O implementation using an in-memory buffer.\n"
"\n"
"The initial_value argument sets the value of object. The newline\n"
"argument is like the one of TextIOWrapper's constructor.");
/* Internal routine for changing the size, in terms of characters, of the
buffer of StringIO objects. The caller should ensure that the 'size'
argument is non-negative. Returns 0 on success, -1 otherwise. */
static int
resize_buffer(StringIOObject *self, size_t size)
{
/* Here, unsigned types are used to avoid dealing with signed integer
overflow, which is undefined in C. */
size_t alloc = self->buf_size;
Py_UNICODE *new_buf = NULL;
assert(self->buf != NULL);
/* Reserve one more char for line ending detection. */
size = size + 1;
/* For simplicity, stay in the range of the signed type. Anyway, Python
doesn't allow strings to be longer than this. */
if (size > PY_SSIZE_T_MAX)
goto overflow;
if (size < alloc / 2) {
/* Major downsize; resize down to exact size. */
alloc = size + 1;
}
else if (size < alloc) {
/* Within allocated size; quick exit */
return 0;
}
else if (size <= alloc * 1.125) {
/* Moderate upsize; overallocate similar to list_resize() */
alloc = size + (size >> 3) + (size < 9 ? 3 : 6);
}
else {
/* Major upsize; resize up to exact size */
alloc = size + 1;
}
if (alloc > ((size_t)-1) / sizeof(Py_UNICODE))
goto overflow;
new_buf = (Py_UNICODE *)PyMem_Realloc(self->buf,
alloc * sizeof(Py_UNICODE));
if (new_buf == NULL) {
PyErr_NoMemory();
return -1;
}
self->buf_size = alloc;
self->buf = new_buf;
return 0;
overflow:
PyErr_SetString(PyExc_OverflowError,
"new buffer size too large");
return -1;
}
/* Internal routine for writing a whole PyUnicode object to the buffer of a
StringIO object. Returns 0 on success, or -1 on error. */
static Py_ssize_t
write_str(StringIOObject *self, PyObject *obj)
{
Py_UNICODE *str;
Py_ssize_t len;
PyObject *decoded = NULL;
assert(self->buf != NULL);
assert(self->pos >= 0);
if (self->decoder != NULL) {
decoded = _PyIncrementalNewlineDecoder_decode(
self->decoder, obj, 1 /* always final */);
}
else {
decoded = obj;
Py_INCREF(decoded);
}
if (self->writenl) {
PyObject *translated = PyUnicode_Replace(
decoded, _PyIO_str_nl, self->writenl, -1);
Py_DECREF(decoded);
decoded = translated;
}
if (decoded == NULL)
return -1;
assert(PyUnicode_Check(decoded));
str = PyUnicode_AS_UNICODE(decoded);
len = PyUnicode_GET_SIZE(decoded);
assert(len >= 0);
/* This overflow check is not strictly necessary. However, it avoids us to
deal with funky things like comparing an unsigned and a signed
integer. */
if (self->pos > PY_SSIZE_T_MAX - len) {
PyErr_SetString(PyExc_OverflowError,
"new position too large");
goto fail;
}
if (self->pos + len > self->string_size) {
if (resize_buffer(self, self->pos + len) < 0)
goto fail;
}
if (self->pos > self->string_size) {
/* In case of overseek, pad with null bytes the buffer region between
the end of stream and the current position.
0 lo string_size hi
| |<---used--->|<----------available----------->|
| | <--to pad-->|<---to write---> |
0 buf positon
*/
memset(self->buf + self->string_size, '\0',
(self->pos - self->string_size) * sizeof(Py_UNICODE));
}
/* Copy the data to the internal buffer, overwriting some of the
existing data if self->pos < self->string_size. */
memcpy(self->buf + self->pos, str, len * sizeof(Py_UNICODE));
self->pos += len;
/* Set the new length of the internal string if it has changed. */
if (self->string_size < self->pos) {
self->string_size = self->pos;
}
Py_DECREF(decoded);
return 0;
fail:
Py_XDECREF(decoded);
return -1;
}
PyDoc_STRVAR(stringio_getvalue_doc,
"Retrieve the entire contents of the object.");
static PyObject *
stringio_getvalue(StringIOObject *self)
{
CHECK_INITIALIZED(self);
CHECK_CLOSED(self);
return PyUnicode_FromUnicode(self->buf, self->string_size);
}
PyDoc_STRVAR(stringio_tell_doc,
"Tell the current file position.");
static PyObject *
stringio_tell(StringIOObject *self)
{
CHECK_INITIALIZED(self);
CHECK_CLOSED(self);
return PyLong_FromSsize_t(self->pos);
}
PyDoc_STRVAR(stringio_read_doc,
"Read at most n characters, returned as a string.\n"
"\n"
"If the argument is negative or omitted, read until EOF\n"
"is reached. Return an empty string at EOF.\n");
static PyObject *
stringio_read(StringIOObject *self, PyObject *args)
{
Py_ssize_t size, n;
Py_UNICODE *output;
PyObject *arg = Py_None;
CHECK_INITIALIZED(self);
if (!PyArg_ParseTuple(args, "|O:read", &arg))
return NULL;
CHECK_CLOSED(self);
if (PyNumber_Check(arg)) {
size = PyNumber_AsSsize_t(arg, PyExc_OverflowError);
if (size == -1 && PyErr_Occurred())
return NULL;
}
else if (arg == Py_None) {
/* Read until EOF is reached, by default. */
size = -1;
}
else {
PyErr_Format(PyExc_TypeError, "integer argument expected, got '%s'",
Py_TYPE(arg)->tp_name);
return NULL;
}
/* adjust invalid sizes */
n = self->string_size - self->pos;
if (size < 0 || size > n) {
size = n;
if (size < 0)
size = 0;
}
output = self->buf + self->pos;
self->pos += size;
return PyUnicode_FromUnicode(output, size);
}
/* Internal helper, used by stringio_readline and stringio_iternext */
static PyObject *
_stringio_readline(StringIOObject *self, Py_ssize_t limit)
{
Py_UNICODE *start, *end, old_char;
Py_ssize_t len, consumed;
/* In case of overseek, return the empty string */
if (self->pos >= self->string_size)
return PyUnicode_FromString("");
start = self->buf + self->pos;
if (limit < 0 || limit > self->string_size - self->pos)
limit = self->string_size - self->pos;
end = start + limit;
old_char = *end;
*end = '\0';
len = _PyIO_find_line_ending(
self->readtranslate, self->readuniversal, self->readnl,
start, end, &consumed);
*end = old_char;
/* If we haven't found any line ending, we just return everything
(`consumed` is ignored). */
if (len < 0)
len = limit;
self->pos += len;
return PyUnicode_FromUnicode(start, len);
}
PyDoc_STRVAR(stringio_readline_doc,
"Read until newline or EOF.\n"
"\n"
"Returns an empty string if EOF is hit immediately.\n");
static PyObject *
stringio_readline(StringIOObject *self, PyObject *args)
{
PyObject *arg = Py_None;
Py_ssize_t limit = -1;
CHECK_INITIALIZED(self);
if (!PyArg_ParseTuple(args, "|O:readline", &arg))
return NULL;
CHECK_CLOSED(self);
if (PyNumber_Check(arg)) {
limit = PyNumber_AsSsize_t(arg, PyExc_OverflowError);
if (limit == -1 && PyErr_Occurred())
return NULL;
}
else if (arg != Py_None) {
PyErr_Format(PyExc_TypeError, "integer argument expected, got '%s'",
Py_TYPE(arg)->tp_name);
return NULL;
}
return _stringio_readline(self, limit);
}
static PyObject *
stringio_iternext(StringIOObject *self)
{
PyObject *line;
CHECK_INITIALIZED(self);
CHECK_CLOSED(self);
if (Py_TYPE(self) == &PyStringIO_Type) {
/* Skip method call overhead for speed */
line = _stringio_readline(self, -1);
}
else {
/* XXX is subclassing StringIO really supported? */
line = PyObject_CallMethodObjArgs((PyObject *)self,
_PyIO_str_readline, NULL);
if (line && !PyUnicode_Check(line)) {
PyErr_Format(PyExc_IOError,
"readline() should have returned an str object, "
"not '%.200s'", Py_TYPE(line)->tp_name);
Py_DECREF(line);
return NULL;
}
}
if (line == NULL)
return NULL;
if (PyUnicode_GET_SIZE(line) == 0) {
/* Reached EOF */
Py_DECREF(line);
return NULL;
}
return line;
}
PyDoc_STRVAR(stringio_truncate_doc,
"Truncate size to pos.\n"
"\n"
"The pos argument defaults to the current file position, as\n"
"returned by tell(). Imply an absolute seek to pos.\n"
"Returns the new absolute position.\n");
static PyObject *
stringio_truncate(StringIOObject *self, PyObject *args)
{
Py_ssize_t size;
PyObject *arg = Py_None;
CHECK_INITIALIZED(self);
if (!PyArg_ParseTuple(args, "|O:truncate", &arg))
return NULL;
CHECK_CLOSED(self);
if (PyNumber_Check(arg)) {
size = PyNumber_AsSsize_t(arg, PyExc_OverflowError);
if (size == -1 && PyErr_Occurred())
return NULL;
}
else if (arg == Py_None) {
/* Truncate to current position if no argument is passed. */
size = self->pos;
}
else {
PyErr_Format(PyExc_TypeError, "integer argument expected, got '%s'",
Py_TYPE(arg)->tp_name);
return NULL;
}
if (size < 0) {
PyErr_Format(PyExc_ValueError,
"Negative size value %zd", size);
return NULL;
}
if (size < self->string_size) {
if (resize_buffer(self, size) < 0)
return NULL;
self->string_size = size;
}
self->pos = size;
return PyLong_FromSsize_t(size);
}
PyDoc_STRVAR(stringio_seek_doc,
"Change stream position.\n"
"\n"
"Seek to character offset pos relative to position indicated by whence:\n"
" 0 Start of stream (the default). pos should be >= 0;\n"
" 1 Current position - pos must be 0;\n"
" 2 End of stream - pos must be 0.\n"
"Returns the new absolute position.\n");
static PyObject *
stringio_seek(StringIOObject *self, PyObject *args)
{
Py_ssize_t pos;
int mode = 0;
CHECK_INITIALIZED(self);
if (!PyArg_ParseTuple(args, "n|i:seek", &pos, &mode))
return NULL;
CHECK_CLOSED(self);
if (mode != 0 && mode != 1 && mode != 2) {
PyErr_Format(PyExc_ValueError,
"Invalid whence (%i, should be 0, 1 or 2)", mode);
return NULL;
}
else if (pos < 0 && mode == 0) {
PyErr_Format(PyExc_ValueError,
"Negative seek position %zd", pos);
return NULL;
}
else if (mode != 0 && pos != 0) {
PyErr_SetString(PyExc_IOError,
"Can't do nonzero cur-relative seeks");
return NULL;
}
/* mode 0: offset relative to beginning of the string.
mode 1: no change to current position.
mode 2: change position to end of file. */
if (mode == 1) {
pos = self->pos;
}
else if (mode == 2) {
pos = self->string_size;
}
self->pos = pos;
return PyLong_FromSsize_t(self->pos);
}
PyDoc_STRVAR(stringio_write_doc,
"Write string to file.\n"
"\n"
"Returns the number of characters written, which is always equal to\n"
"the length of the string.\n");
static PyObject *
stringio_write(StringIOObject *self, PyObject *obj)
{
Py_ssize_t size;
CHECK_INITIALIZED(self);
if (!PyUnicode_Check(obj)) {
PyErr_Format(PyExc_TypeError, "string argument expected, got '%s'",
Py_TYPE(obj)->tp_name);
return NULL;
}
CHECK_CLOSED(self);
size = PyUnicode_GET_SIZE(obj);
if (size > 0 && write_str(self, obj) < 0)
return NULL;
return PyLong_FromSsize_t(size);
}
PyDoc_STRVAR(stringio_close_doc,
"Close the IO object. Attempting any further operation after the\n"
"object is closed will raise a ValueError.\n"
"\n"
"This method has no effect if the file is already closed.\n");
static PyObject *
stringio_close(StringIOObject *self)
{
self->closed = 1;
/* Free up some memory */
if (resize_buffer(self, 0) < 0)
return NULL;
Py_CLEAR(self->readnl);
Py_CLEAR(self->writenl);
Py_CLEAR(self->decoder);
Py_RETURN_NONE;
}
static int
stringio_traverse(StringIOObject *self, visitproc visit, void *arg)
{
Py_VISIT(self->dict);
return 0;
}
static int
stringio_clear(StringIOObject *self)
{
Py_CLEAR(self->dict);
return 0;
}
static void
stringio_dealloc(StringIOObject *self)
{
_PyObject_GC_UNTRACK(self);
Py_CLEAR(self->readnl);
Py_CLEAR(self->writenl);
Py_CLEAR(self->decoder);
if (self->buf)
PyMem_Free(self->buf);
if (self->weakreflist != NULL)
PyObject_ClearWeakRefs((PyObject *) self);
Py_TYPE(self)->tp_free(self);
}
static PyObject *
stringio_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
StringIOObject *self;
assert(type != NULL && type->tp_alloc != NULL);
self = (StringIOObject *)type->tp_alloc(type, 0);
if (self == NULL)
return NULL;
self->string_size = 0;
self->pos = 0;
self->buf_size = 0;
self->buf = (Py_UNICODE *)PyMem_Malloc(0);
if (self->buf == NULL) {
Py_DECREF(self);
return PyErr_NoMemory();
}
return (PyObject *)self;
}
static int
stringio_init(StringIOObject *self, PyObject *args, PyObject *kwds)
{
char *kwlist[] = {"initial_value", "newline", NULL};
PyObject *value = NULL;
char *newline = "\n";
if (!PyArg_ParseTupleAndKeywords(args, kwds, "|Oz:__init__", kwlist,
&value, &newline))
return -1;
if (newline && newline[0] != '\0'
&& !(newline[0] == '\n' && newline[1] == '\0')
&& !(newline[0] == '\r' && newline[1] == '\0')
&& !(newline[0] == '\r' && newline[1] == '\n' && newline[2] == '\0')) {
PyErr_Format(PyExc_ValueError,
"illegal newline value: %s", newline);
return -1;
}
if (value && value != Py_None && !PyUnicode_Check(value)) {
PyErr_Format(PyExc_ValueError,
"initial_value must be str or None, not %.200s",
Py_TYPE(value)->tp_name);
return -1;
}
self->ok = 0;
Py_CLEAR(self->readnl);
Py_CLEAR(self->writenl);
Py_CLEAR(self->decoder);
if (newline) {
self->readnl = PyUnicode_FromString(newline);
if (self->readnl == NULL)
return -1;
}
self->readuniversal = (newline == NULL || newline[0] == '\0');
self->readtranslate = (newline == NULL);
/* If newline == "", we don't translate anything.
If newline == "\n" or newline == None, we translate to "\n", which is
a no-op.
(for newline == None, TextIOWrapper translates to os.sepline, but it
is pointless for StringIO)
*/
if (newline != NULL && newline[0] == '\r') {
self->writenl = self->readnl;
Py_INCREF(self->writenl);
}
if (self->readuniversal) {
self->decoder = PyObject_CallFunction(
(PyObject *)&PyIncrementalNewlineDecoder_Type,
"Oi", Py_None, (int) self->readtranslate);
if (self->decoder == NULL)
return -1;
}
/* Now everything is set up, resize buffer to size of initial value,
and copy it */
self->string_size = 0;
if (value && value != Py_None) {
Py_ssize_t len = PyUnicode_GetSize(value);
/* This is a heuristic, for newline translation might change
the string length. */
if (resize_buffer(self, len) < 0)
return -1;
self->pos = 0;
if (write_str(self, value) < 0)
return -1;
}
else {
if (resize_buffer(self, 0) < 0)
return -1;
}
self->pos = 0;
self->closed = 0;
self->ok = 1;
return 0;
}
/* Properties and pseudo-properties */
static PyObject *
stringio_seekable(StringIOObject *self, PyObject *args)
{
CHECK_INITIALIZED(self);
Py_RETURN_TRUE;
}
static PyObject *
stringio_readable(StringIOObject *self, PyObject *args)
{
CHECK_INITIALIZED(self);
Py_RETURN_TRUE;
}
static PyObject *
stringio_writable(StringIOObject *self, PyObject *args)
{
CHECK_INITIALIZED(self);
Py_RETURN_TRUE;
}
static PyObject *
stringio_buffer(StringIOObject *self, void *context)
{
PyErr_SetString(IO_STATE->unsupported_operation,
"buffer attribute is unsupported on type StringIO");
return NULL;
}
static PyObject *
stringio_closed(StringIOObject *self, void *context)
{
CHECK_INITIALIZED(self);
return PyBool_FromLong(self->closed);
}
static PyObject *
stringio_encoding(StringIOObject *self, void *context)
{
CHECK_INITIALIZED(self);
CHECK_CLOSED(self);
Py_RETURN_NONE;
}
static PyObject *
stringio_errors(StringIOObject *self, void *context)
{
CHECK_INITIALIZED(self);
CHECK_CLOSED(self);
return PyUnicode_FromString("strict");
}
static PyObject *
stringio_line_buffering(StringIOObject *self, void *context)
{
CHECK_INITIALIZED(self);
CHECK_CLOSED(self);
Py_RETURN_FALSE;
}
static PyObject *
stringio_newlines(StringIOObject *self, void *context)
{
CHECK_INITIALIZED(self);
CHECK_CLOSED(self);
if (self->decoder == NULL)
Py_RETURN_NONE;
return PyObject_GetAttr(self->decoder, _PyIO_str_newlines);
}
static struct PyMethodDef stringio_methods[] = {
{"close", (PyCFunction)stringio_close, METH_NOARGS, stringio_close_doc},
{"getvalue", (PyCFunction)stringio_getvalue, METH_VARARGS, stringio_getvalue_doc},
{"read", (PyCFunction)stringio_read, METH_VARARGS, stringio_read_doc},
{"readline", (PyCFunction)stringio_readline, METH_VARARGS, stringio_readline_doc},
{"tell", (PyCFunction)stringio_tell, METH_NOARGS, stringio_tell_doc},
{"truncate", (PyCFunction)stringio_truncate, METH_VARARGS, stringio_truncate_doc},
{"seek", (PyCFunction)stringio_seek, METH_VARARGS, stringio_seek_doc},
{"write", (PyCFunction)stringio_write, METH_O, stringio_write_doc},
{"seekable", (PyCFunction)stringio_seekable, METH_NOARGS},
{"readable", (PyCFunction)stringio_readable, METH_NOARGS},
{"writable", (PyCFunction)stringio_writable, METH_NOARGS},
{NULL, NULL} /* sentinel */
};
static PyGetSetDef stringio_getset[] = {
{"closed", (getter)stringio_closed, NULL, NULL},
{"newlines", (getter)stringio_newlines, NULL, NULL},
/* (following comments straight off of the original Python wrapper:)
XXX Cruft to support the TextIOWrapper API. This would only
be meaningful if StringIO supported the buffer attribute.
Hopefully, a better solution, than adding these pseudo-attributes,
will be found.
*/
{"buffer", (getter)stringio_buffer, NULL, NULL},
{"encoding", (getter)stringio_encoding, NULL, NULL},
{"errors", (getter)stringio_errors, NULL, NULL},
{"line_buffering", (getter)stringio_line_buffering, NULL, NULL},
{0}
};
PyTypeObject PyStringIO_Type = {
PyVarObject_HEAD_INIT(NULL, 0)
"_io.StringIO", /*tp_name*/
sizeof(StringIOObject), /*tp_basicsize*/
0, /*tp_itemsize*/
(destructor)stringio_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*/
0, /*tp_getattro*/
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
| Py_TPFLAGS_HAVE_GC, /*tp_flags*/
stringio_doc, /*tp_doc*/
(traverseproc)stringio_traverse, /*tp_traverse*/
(inquiry)stringio_clear, /*tp_clear*/
0, /*tp_richcompare*/
offsetof(StringIOObject, weakreflist), /*tp_weaklistoffset*/
0, /*tp_iter*/
(iternextfunc)stringio_iternext, /*tp_iternext*/
stringio_methods, /*tp_methods*/
0, /*tp_members*/
stringio_getset, /*tp_getset*/
0, /*tp_base*/
0, /*tp_dict*/
0, /*tp_descr_get*/
0, /*tp_descr_set*/
offsetof(StringIOObject, dict), /*tp_dictoffset*/
(initproc)stringio_init, /*tp_init*/
0, /*tp_alloc*/
stringio_new, /*tp_new*/
};
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