Reformat prior to editing.

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Jeroen Ruigrok van der Werven 2009-04-25 20:40:10 +00:00
parent 9e03cee97c
commit a4c03abb9e
1 changed files with 34 additions and 32 deletions

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@ -5,25 +5,26 @@
Data marshalling support Data marshalling support
======================== ========================
These routines allow C code to work with serialized objects using the same data These routines allow C code to work with serialized objects using the same
format as the :mod:`marshal` module. There are functions to write data into the data format as the :mod:`marshal` module. There are functions to write data
serialization format, and additional functions that can be used to read the data into the serialization format, and additional functions that can be used to
back. Files used to store marshalled data must be opened in binary mode. read the data back. Files used to store marshalled data must be opened in
binary mode.
Numeric values are stored with the least significant byte first. Numeric values are stored with the least significant byte first.
The module supports two versions of the data format: version 0 is the historical The module supports two versions of the data format: version 0 is the
version, version 1 (new in Python 2.4) shares interned strings in the file, and historical version, version 1 (new in Python 2.4) shares interned strings in
upon unmarshalling. Version 2 (new in Python 2.5) uses a binary format for the file, and upon unmarshalling. Version 2 (new in Python 2.5) uses a binary
floating point numbers. format for floating point numbers. *Py_MARSHAL_VERSION* indicates the current
*Py_MARSHAL_VERSION* indicates the current file format (currently 2). file format (currently 2).
.. cfunction:: void PyMarshal_WriteLongToFile(long value, FILE *file, int version) .. cfunction:: void PyMarshal_WriteLongToFile(long value, FILE *file, int version)
Marshal a :ctype:`long` integer, *value*, to *file*. This will only write the Marshal a :ctype:`long` integer, *value*, to *file*. This will only write
least-significant 32 bits of *value*; regardless of the size of the native the least-significant 32 bits of *value*; regardless of the size of the
:ctype:`long` type. native :ctype:`long` type.
.. versionchanged:: 2.4 .. versionchanged:: 2.4
*version* indicates the file format. *version* indicates the file format.
@ -48,24 +49,24 @@ floating point numbers.
The following functions allow marshalled values to be read back in. The following functions allow marshalled values to be read back in.
XXX What about error detection? It appears that reading past the end of the XXX What about error detection? It appears that reading past the end of the
file will always result in a negative numeric value (where that's relevant), but file will always result in a negative numeric value (where that's relevant),
it's not clear that negative values won't be handled properly when there's no but it's not clear that negative values won't be handled properly when there's
error. What's the right way to tell? Should only non-negative values be written no error. What's the right way to tell? Should only non-negative values be
using these routines? written using these routines?
.. cfunction:: long PyMarshal_ReadLongFromFile(FILE *file) .. cfunction:: long PyMarshal_ReadLongFromFile(FILE *file)
Return a C :ctype:`long` from the data stream in a :ctype:`FILE\*` opened for Return a C :ctype:`long` from the data stream in a :ctype:`FILE\*` opened
reading. Only a 32-bit value can be read in using this function, regardless of for reading. Only a 32-bit value can be read in using this function,
the native size of :ctype:`long`. regardless of the native size of :ctype:`long`.
.. cfunction:: int PyMarshal_ReadShortFromFile(FILE *file) .. cfunction:: int PyMarshal_ReadShortFromFile(FILE *file)
Return a C :ctype:`short` from the data stream in a :ctype:`FILE\*` opened for Return a C :ctype:`short` from the data stream in a :ctype:`FILE\*` opened
reading. Only a 16-bit value can be read in using this function, regardless of for reading. Only a 16-bit value can be read in using this function,
the native size of :ctype:`short`. regardless of the native size of :ctype:`short`.
.. cfunction:: PyObject* PyMarshal_ReadObjectFromFile(FILE *file) .. cfunction:: PyObject* PyMarshal_ReadObjectFromFile(FILE *file)
@ -78,17 +79,18 @@ using these routines?
.. cfunction:: PyObject* PyMarshal_ReadLastObjectFromFile(FILE *file) .. cfunction:: PyObject* PyMarshal_ReadLastObjectFromFile(FILE *file)
Return a Python object from the data stream in a :ctype:`FILE\*` opened for Return a Python object from the data stream in a :ctype:`FILE\*` opened for
reading. Unlike :cfunc:`PyMarshal_ReadObjectFromFile`, this function assumes reading. Unlike :cfunc:`PyMarshal_ReadObjectFromFile`, this function
that no further objects will be read from the file, allowing it to aggressively assumes that no further objects will be read from the file, allowing it to
load file data into memory so that the de-serialization can operate from data in aggressively load file data into memory so that the de-serialization can
memory rather than reading a byte at a time from the file. Only use these operate from data in memory rather than reading a byte at a time from the
variant if you are certain that you won't be reading anything else from the file. Only use these variant if you are certain that you won't be reading
file. On error, sets the appropriate exception (:exc:`EOFError` or anything else from the file. On error, sets the appropriate exception
:exc:`TypeError`) and returns *NULL*. (:exc:`EOFError` or :exc:`TypeError`) and returns *NULL*.
.. cfunction:: PyObject* PyMarshal_ReadObjectFromString(char *string, Py_ssize_t len) .. cfunction:: PyObject* PyMarshal_ReadObjectFromString(char *string, Py_ssize_t len)
Return a Python object from the data stream in a character buffer containing Return a Python object from the data stream in a character buffer
*len* bytes pointed to by *string*. On error, sets the appropriate exception containing *len* bytes pointed to by *string*. On error, sets the
(:exc:`EOFError` or :exc:`TypeError`) and returns *NULL*. appropriate exception (:exc:`EOFError` or :exc:`TypeError`) and returns
*NULL*.