| .. highlight:: c |
| |
| .. _bytesobjects: |
| |
| Bytes Objects |
| ------------- |
| |
| These functions raise :exc:`TypeError` when expecting a bytes parameter and |
| called with a non-bytes parameter. |
| |
| .. index:: pair: object; bytes |
| |
| |
| .. c:type:: PyBytesObject |
| |
| This subtype of :c:type:`PyObject` represents a Python bytes object. |
| |
| |
| .. c:var:: PyTypeObject PyBytes_Type |
| |
| This instance of :c:type:`PyTypeObject` represents the Python bytes type; it |
| is the same object as :class:`bytes` in the Python layer. |
| |
| |
| .. c:function:: int PyBytes_Check(PyObject *o) |
| |
| Return true if the object *o* is a bytes object or an instance of a subtype |
| of the bytes type. This function always succeeds. |
| |
| |
| .. c:function:: int PyBytes_CheckExact(PyObject *o) |
| |
| Return true if the object *o* is a bytes object, but not an instance of a |
| subtype of the bytes type. This function always succeeds. |
| |
| |
| .. c:function:: PyObject* PyBytes_FromString(const char *v) |
| |
| Return a new bytes object with a copy of the string *v* as value on success, |
| and ``NULL`` on failure. The parameter *v* must not be ``NULL``; it will not be |
| checked. |
| |
| |
| .. c:function:: PyObject* PyBytes_FromStringAndSize(const char *v, Py_ssize_t len) |
| |
| Return a new bytes object with a copy of the string *v* as value and length |
| *len* on success, and ``NULL`` on failure. If *v* is ``NULL``, the contents of |
| the bytes object are uninitialized. |
| |
| .. deprecated:: 3.15 |
| ``PyBytes_FromStringAndSize(NULL, len)`` is :term:`soft deprecated`, |
| use the :c:type:`PyBytesWriter` API instead. |
| |
| |
| .. c:function:: PyObject* PyBytes_FromFormat(const char *format, ...) |
| |
| Take a C :c:func:`printf`\ -style *format* string and a variable number of |
| arguments, calculate the size of the resulting Python bytes object and return |
| a bytes object with the values formatted into it. The variable arguments |
| must be C types and must correspond exactly to the format characters in the |
| *format* string. The following format characters are allowed: |
| |
| .. % XXX: This should be exactly the same as the table in PyErr_Format. |
| .. % One should just refer to the other. |
| |
| .. tabularcolumns:: |l|l|L| |
| |
| +-------------------+---------------+--------------------------------+ |
| | Format Characters | Type | Comment | |
| +===================+===============+================================+ |
| | ``%%`` | *n/a* | The literal % character. | |
| +-------------------+---------------+--------------------------------+ |
| | ``%c`` | int | A single byte, | |
| | | | represented as a C int. | |
| +-------------------+---------------+--------------------------------+ |
| | ``%d`` | int | Equivalent to | |
| | | | ``printf("%d")``. [1]_ | |
| +-------------------+---------------+--------------------------------+ |
| | ``%u`` | unsigned int | Equivalent to | |
| | | | ``printf("%u")``. [1]_ | |
| +-------------------+---------------+--------------------------------+ |
| | ``%ld`` | long | Equivalent to | |
| | | | ``printf("%ld")``. [1]_ | |
| +-------------------+---------------+--------------------------------+ |
| | ``%lu`` | unsigned long | Equivalent to | |
| | | | ``printf("%lu")``. [1]_ | |
| +-------------------+---------------+--------------------------------+ |
| | ``%zd`` | :c:type:`\ | Equivalent to | |
| | | Py_ssize_t` | ``printf("%zd")``. [1]_ | |
| +-------------------+---------------+--------------------------------+ |
| | ``%zu`` | size_t | Equivalent to | |
| | | | ``printf("%zu")``. [1]_ | |
| +-------------------+---------------+--------------------------------+ |
| | ``%i`` | int | Equivalent to | |
| | | | ``printf("%i")``. [1]_ | |
| +-------------------+---------------+--------------------------------+ |
| | ``%x`` | int | Equivalent to | |
| | | | ``printf("%x")``. [1]_ | |
| +-------------------+---------------+--------------------------------+ |
| | ``%s`` | const char\* | A null-terminated C character | |
| | | | array. | |
| +-------------------+---------------+--------------------------------+ |
| | ``%p`` | const void\* | The hex representation of a C | |
| | | | pointer. Mostly equivalent to | |
| | | | ``printf("%p")`` except that | |
| | | | it is guaranteed to start with | |
| | | | the literal ``0x`` regardless | |
| | | | of what the platform's | |
| | | | ``printf`` yields. | |
| +-------------------+---------------+--------------------------------+ |
| |
| An unrecognized format character causes all the rest of the format string to be |
| copied as-is to the result object, and any extra arguments discarded. |
| |
| .. [1] For integer specifiers (d, u, ld, lu, zd, zu, i, x): the 0-conversion |
| flag has effect even when a precision is given. |
| |
| |
| .. c:function:: PyObject* PyBytes_FromFormatV(const char *format, va_list vargs) |
| |
| Identical to :c:func:`PyBytes_FromFormat` except that it takes exactly two |
| arguments. |
| |
| |
| .. c:function:: PyObject* PyBytes_FromObject(PyObject *o) |
| |
| Return the bytes representation of object *o* that implements the buffer |
| protocol. |
| |
| |
| .. c:function:: Py_ssize_t PyBytes_Size(PyObject *o) |
| |
| Return the length of the bytes in bytes object *o*. |
| |
| |
| .. c:function:: Py_ssize_t PyBytes_GET_SIZE(PyObject *o) |
| |
| Similar to :c:func:`PyBytes_Size`, but without error checking. |
| |
| |
| .. c:function:: char* PyBytes_AsString(PyObject *o) |
| |
| Return a pointer to the contents of *o*. The pointer |
| refers to the internal buffer of *o*, which consists of ``len(o) + 1`` |
| bytes. The last byte in the buffer is always null, regardless of |
| whether there are any other null bytes. The data must not be |
| modified in any way, unless the object was just created using |
| ``PyBytes_FromStringAndSize(NULL, size)``. It must not be deallocated. If |
| *o* is not a bytes object at all, :c:func:`PyBytes_AsString` returns ``NULL`` |
| and raises :exc:`TypeError`. |
| |
| |
| .. c:function:: char* PyBytes_AS_STRING(PyObject *string) |
| |
| Similar to :c:func:`PyBytes_AsString`, but without error checking. |
| |
| |
| .. c:function:: int PyBytes_AsStringAndSize(PyObject *obj, char **buffer, Py_ssize_t *length) |
| |
| Return the null-terminated contents of the object *obj* |
| through the output variables *buffer* and *length*. |
| Returns ``0`` on success. |
| |
| If *length* is ``NULL``, the bytes object |
| may not contain embedded null bytes; |
| if it does, the function returns ``-1`` and a :exc:`ValueError` is raised. |
| |
| The buffer refers to an internal buffer of *obj*, which includes an |
| additional null byte at the end (not counted in *length*). The data |
| must not be modified in any way, unless the object was just created using |
| ``PyBytes_FromStringAndSize(NULL, size)``. It must not be deallocated. If |
| *obj* is not a bytes object at all, :c:func:`PyBytes_AsStringAndSize` |
| returns ``-1`` and raises :exc:`TypeError`. |
| |
| .. versionchanged:: 3.5 |
| Previously, :exc:`TypeError` was raised when embedded null bytes were |
| encountered in the bytes object. |
| |
| |
| .. c:function:: void PyBytes_Concat(PyObject **bytes, PyObject *newpart) |
| |
| Create a new bytes object in *\*bytes* containing the contents of *newpart* |
| appended to *bytes*; the caller will own the new reference. The reference to |
| the old value of *bytes* will be stolen. If the new object cannot be |
| created, the old reference to *bytes* will still be discarded and the value |
| of *\*bytes* will be set to ``NULL``; the appropriate exception will be set. |
| |
| |
| .. c:function:: void PyBytes_ConcatAndDel(PyObject **bytes, PyObject *newpart) |
| |
| Create a new bytes object in *\*bytes* containing the contents of *newpart* |
| appended to *bytes*. This version releases the :term:`strong reference` |
| to *newpart* (i.e. decrements its reference count). |
| |
| |
| .. c:function:: PyObject* PyBytes_Join(PyObject *sep, PyObject *iterable) |
| |
| Similar to ``sep.join(iterable)`` in Python. |
| |
| *sep* must be Python :class:`bytes` object. |
| (Note that :c:func:`PyUnicode_Join` accepts ``NULL`` separator and treats |
| it as a space, whereas :c:func:`PyBytes_Join` doesn't accept ``NULL`` |
| separator.) |
| |
| *iterable* must be an iterable object yielding objects that implement the |
| :ref:`buffer protocol <bufferobjects>`. |
| |
| On success, return a new :class:`bytes` object. |
| On error, set an exception and return ``NULL``. |
| |
| .. versionadded:: 3.14 |
| |
| |
| .. c:function:: int _PyBytes_Resize(PyObject **bytes, Py_ssize_t newsize) |
| |
| Resize a bytes object. *newsize* will be the new length of the bytes object. |
| You can think of it as creating a new bytes object and destroying the old |
| one, only more efficiently. |
| Pass the address of an |
| existing bytes object as an lvalue (it may be written into), and the new size |
| desired. On success, *\*bytes* holds the resized bytes object and ``0`` is |
| returned; the address in *\*bytes* may differ from its input value. If the |
| reallocation fails, the original bytes object at *\*bytes* is deallocated, |
| *\*bytes* is set to ``NULL``, :exc:`MemoryError` is set, and ``-1`` is |
| returned. |
| |
| .. deprecated:: 3.15 |
| The function is :term:`soft deprecated`, |
| use the :c:type:`PyBytesWriter` API instead. |
| |
| |
| .. c:function:: PyObject *PyBytes_Repr(PyObject *bytes, int smartquotes) |
| |
| Get the string representation of *bytes*. This function is currently used to |
| implement :meth:`!bytes.__repr__` in Python. |
| |
| This function does not do type checking; it is undefined behavior to pass |
| *bytes* as a non-bytes object or ``NULL``. |
| |
| If *smartquotes* is true, the representation will use a double-quoted string |
| instead of single-quoted string when single-quotes are present in *bytes*. |
| For example, the byte string ``'Python'`` would be represented as |
| ``b"'Python'"`` when *smartquotes* is true, or ``b'\'Python\''`` when it is |
| false. |
| |
| On success, this function returns a :term:`strong reference` to a |
| :class:`str` object containing the representation. On failure, this |
| returns ``NULL`` with an exception set. |
| |
| |
| .. c:function:: PyObject *PyBytes_DecodeEscape(const char *s, Py_ssize_t len, const char *errors, Py_ssize_t unicode, const char *recode_encoding) |
| |
| Unescape a backslash-escaped string *s*. *s* must not be ``NULL``. |
| *len* must be the size of *s*. |
| |
| *errors* must be one of ``"strict"``, ``"replace"``, or ``"ignore"``. If |
| *errors* is ``NULL``, then ``"strict"`` is used by default. |
| |
| On success, this function returns a :term:`strong reference` to a Python |
| :class:`bytes` object containing the unescaped string. On failure, this |
| function returns ``NULL`` with an exception set. |
| |
| .. versionchanged:: 3.9 |
| *unicode* and *recode_encoding* are now unused. |
| |
| |
| .. _pybyteswriter: |
| |
| PyBytesWriter |
| ------------- |
| |
| The :c:type:`PyBytesWriter` API can be used to create a Python :class:`bytes` |
| object. |
| |
| .. versionadded:: 3.15 |
| |
| .. c:type:: PyBytesWriter |
| |
| A bytes writer instance. |
| |
| The API is **not thread safe**: a writer should only be used by a single |
| thread at the same time. |
| |
| The instance must be destroyed by :c:func:`PyBytesWriter_Finish` on |
| success, or :c:func:`PyBytesWriter_Discard` on error. |
| |
| |
| Create, Finish, Discard |
| ^^^^^^^^^^^^^^^^^^^^^^^ |
| |
| .. c:function:: PyBytesWriter* PyBytesWriter_Create(Py_ssize_t size) |
| |
| Create a :c:type:`PyBytesWriter` to write *size* bytes. |
| |
| If *size* is greater than zero, allocate *size* bytes, and set the |
| writer size to *size*. The caller is responsible to write *size* |
| bytes using :c:func:`PyBytesWriter_GetData`. |
| This function does not overallocate. |
| |
| On error, set an exception and return ``NULL``. |
| |
| *size* must be positive or zero. |
| |
| .. c:function:: PyObject* PyBytesWriter_Finish(PyBytesWriter *writer) |
| |
| Finish a :c:type:`PyBytesWriter` created by |
| :c:func:`PyBytesWriter_Create`. |
| |
| On success, return a Python :class:`bytes` object. |
| On error, set an exception and return ``NULL``. |
| |
| The writer instance is invalid after the call in any case. |
| No API can be called on the writer after :c:func:`PyBytesWriter_Finish`. |
| |
| .. c:function:: PyObject* PyBytesWriter_FinishWithSize(PyBytesWriter *writer, Py_ssize_t size) |
| |
| Similar to :c:func:`PyBytesWriter_Finish`, but resize the writer |
| to *size* bytes before creating the :class:`bytes` object. |
| |
| .. c:function:: PyObject* PyBytesWriter_FinishWithPointer(PyBytesWriter *writer, void *buf) |
| |
| Similar to :c:func:`PyBytesWriter_Finish`, but resize the writer |
| using *buf* pointer before creating the :class:`bytes` object. |
| |
| Set an exception and return ``NULL`` if *buf* pointer is outside the |
| internal buffer bounds. |
| |
| Function pseudo-code:: |
| |
| Py_ssize_t size = (char*)buf - (char*)PyBytesWriter_GetData(writer); |
| return PyBytesWriter_FinishWithSize(writer, size); |
| |
| .. c:function:: void PyBytesWriter_Discard(PyBytesWriter *writer) |
| |
| Discard a :c:type:`PyBytesWriter` created by :c:func:`PyBytesWriter_Create`. |
| |
| Do nothing if *writer* is ``NULL``. |
| |
| The writer instance is invalid after the call. |
| No API can be called on the writer after :c:func:`PyBytesWriter_Discard`. |
| |
| High-level API |
| ^^^^^^^^^^^^^^ |
| |
| .. c:function:: int PyBytesWriter_WriteBytes(PyBytesWriter *writer, const void *bytes, Py_ssize_t size) |
| |
| Grow the *writer* internal buffer by *size* bytes, |
| write *size* bytes of *bytes* at the *writer* end, |
| and add *size* to the *writer* size. |
| |
| If *size* is equal to ``-1``, call ``strlen(bytes)`` to get the |
| string length. |
| |
| On success, return ``0``. |
| On error, set an exception and return ``-1``. |
| |
| .. c:function:: int PyBytesWriter_Format(PyBytesWriter *writer, const char *format, ...) |
| |
| Similar to :c:func:`PyBytes_FromFormat`, but write the output directly at |
| the writer end. Grow the writer internal buffer on demand. Then add the |
| written size to the writer size. |
| |
| On success, return ``0``. |
| On error, set an exception and return ``-1``. |
| |
| |
| Getters |
| ^^^^^^^ |
| |
| .. c:function:: Py_ssize_t PyBytesWriter_GetSize(PyBytesWriter *writer) |
| |
| Get the writer size. |
| |
| .. c:function:: void* PyBytesWriter_GetData(PyBytesWriter *writer) |
| |
| Get the writer data: start of the internal buffer. |
| |
| The pointer is valid until :c:func:`PyBytesWriter_Finish` or |
| :c:func:`PyBytesWriter_Discard` is called on *writer*. |
| |
| |
| Low-level API |
| ^^^^^^^^^^^^^ |
| |
| .. c:function:: int PyBytesWriter_Resize(PyBytesWriter *writer, Py_ssize_t size) |
| |
| Resize the writer to *size* bytes. It can be used to enlarge or to |
| shrink the writer. |
| This function typically overallocates to achieve amortized performance when |
| resizing multiple times. |
| |
| Newly allocated bytes are left uninitialized. |
| |
| On success, return ``0``. |
| On error, set an exception and return ``-1``. |
| |
| *size* must be positive or zero. |
| |
| .. c:function:: int PyBytesWriter_Grow(PyBytesWriter *writer, Py_ssize_t grow) |
| |
| Resize the writer by adding *grow* bytes to the current writer size. |
| This function typically overallocates to achieve amortized performance when |
| resizing multiple times. |
| |
| Newly allocated bytes are left uninitialized. |
| |
| On success, return ``0``. |
| On error, set an exception and return ``-1``. |
| |
| *size* can be negative to shrink the writer. |
| |
| .. c:function:: void* PyBytesWriter_GrowAndUpdatePointer(PyBytesWriter *writer, Py_ssize_t size, void *buf) |
| |
| Similar to :c:func:`PyBytesWriter_Grow`, but update also the *buf* |
| pointer. |
| |
| The *buf* pointer is moved if the internal buffer is moved in memory. |
| The *buf* relative position within the internal buffer is left |
| unchanged. |
| |
| On error, set an exception and return ``NULL``. |
| |
| *buf* must not be ``NULL``. |
| |
| Function pseudo-code:: |
| |
| Py_ssize_t pos = (char*)buf - (char*)PyBytesWriter_GetData(writer); |
| if (PyBytesWriter_Grow(writer, size) < 0) { |
| return NULL; |
| } |
| return (char*)PyBytesWriter_GetData(writer) + pos; |
