Issue #22832: Tweaked parameter names for fcntl module to better match

official POSIX documentation.  Updated the documenttion for Python 3.
Patch by Alex Shkop.

Doc/library/fcntl.rst

@@ -28,41 +28,41 @@ descriptor.
 The module defines the following functions:
 
 
-.. function:: fcntl(fd, op[, arg])
+.. function:: fcntl(fd, cmd, arg=0)
 
-   Perform the operation *op* on file descriptor *fd* (file objects providing
+   Perform the operation *cmd* on file descriptor *fd* (file objects providing
    a :meth:`~io.IOBase.fileno` method are accepted as well).  The values used
-   for *op* are operating system dependent, and are available as constants
+   for *cmd* are operating system dependent, and are available as constants
    in the :mod:`fcntl` module, using the same names as used in the relevant C
-   header files.  The argument *arg* is optional, and defaults to the integer
-   value ``0``.  When present, it can either be an integer value, or a string.
-   With the argument missing or an integer value, the return value of this function
-   is the integer return value of the C :c:func:`fcntl` call.  When the argument is
-   a string it represents a binary structure, e.g. created by :func:`struct.pack`.
-   The binary data is copied to a buffer whose address is passed to the C
-   :c:func:`fcntl` call.  The return value after a successful call is the contents
-   of the buffer, converted to a string object.  The length of the returned string
-   will be the same as the length of the *arg* argument.  This is limited to 1024
-   bytes.  If the information returned in the buffer by the operating system is
-   larger than 1024 bytes, this is most likely to result in a segmentation
-   violation or a more subtle data corruption.
+   header files. The argument *arg* can either be an integer value, or a
+   :class:`bytes` object. With an integer value, the return value of this
+   function is the integer return value of the C :c:func:`fcntl` call.  When
+   the argument is bytes it represents a binary structure, e.g. created by
+   :func:`struct.pack`. The binary data is copied to a buffer whose address is
+   passed to the C :c:func:`fcntl` call.  The return value after a successful
+   call is the contents of the buffer, converted to a :class:`bytes` object.
+   The length of the returned object will be the same as the length of the
+   *arg* argument. This is limited to 1024 bytes. If the information returned
+   in the buffer by the operating system is larger than 1024 bytes, this is
+   most likely to result in a segmentation violation or a more subtle data
+   corruption.
 
    If the :c:func:`fcntl` fails, an :exc:`OSError` is raised.
 
 
-.. function:: ioctl(fd, op[, arg[, mutate_flag]])
+.. function:: ioctl(fd, request, arg=0, mutate_flag=True)
 
    This function is identical to the :func:`~fcntl.fcntl` function, except
    that the argument handling is even more complicated.
 
-   The op parameter is limited to values that can fit in 32-bits.
-   Additional constants of interest for use as the *op* argument can be
+   The *request* parameter is limited to values that can fit in 32-bits.
+   Additional constants of interest for use as the *request* argument can be
    found in the :mod:`termios` module, under the same names as used in
    the relevant C header files.
 
-   The parameter *arg* can be one of an integer, absent (treated identically to the
-   integer ``0``), an object supporting the read-only buffer interface (most likely
-   a plain Python string) or an object supporting the read-write buffer interface.
+   The parameter *arg* can be one of an integer, an object supporting the
+   read-only buffer interface (like :class:`bytes`) or an object supporting
+   the read-write buffer interface (like :class:`bytearray`).
 
    In all but the last case, behaviour is as for the :func:`~fcntl.fcntl`
    function.
@@ -72,7 +72,7 @@ The module defines the following functions:
 
    If it is false, the buffer's mutability is ignored and behaviour is as for a
    read-only buffer, except that the 1024 byte limit mentioned above is avoided --
-   so long as the buffer you pass is as least as long as what the operating system
+   so long as the buffer you pass is at least as long as what the operating system
    wants to put there, things should work.
 
    If *mutate_flag* is true (the default), then the buffer is (in effect) passed
@@ -97,25 +97,25 @@ The module defines the following functions:
       array('h', [13341])
 
 
-.. function:: flock(fd, op)
+.. function:: flock(fd, operation)
 
-   Perform the lock operation *op* on file descriptor *fd* (file objects providing
+   Perform the lock operation *operation* on file descriptor *fd* (file objects providing
    a :meth:`~io.IOBase.fileno` method are accepted as well). See the Unix manual
    :manpage:`flock(2)` for details.  (On some systems, this function is emulated
    using :c:func:`fcntl`.)
 
 
-.. function:: lockf(fd, operation, [length, [start, [whence]]])
+.. function:: lockf(fd, cmd, len=0, start=0, whence=0)
 
    This is essentially a wrapper around the :func:`~fcntl.fcntl` locking calls.
-   *fd* is the file descriptor of the file to lock or unlock, and *operation*
+   *fd* is the file descriptor of the file to lock or unlock, and *cmd*
    is one of the following values:
 
    * :const:`LOCK_UN` -- unlock
    * :const:`LOCK_SH` -- acquire a shared lock
    * :const:`LOCK_EX` -- acquire an exclusive lock
 
-   When *operation* is :const:`LOCK_SH` or :const:`LOCK_EX`, it can also be
+   When *cmd* is :const:`LOCK_SH` or :const:`LOCK_EX`, it can also be
    bitwise ORed with :const:`LOCK_NB` to avoid blocking on lock acquisition.
    If :const:`LOCK_NB` is used and the lock cannot be acquired, an
    :exc:`OSError` will be raised and the exception will have an *errno*
@@ -124,7 +124,7 @@ The module defines the following functions:
    systems, :const:`LOCK_EX` can only be used if the file descriptor refers to a
    file opened for writing.
 
-   *length* is the number of bytes to lock, *start* is the byte offset at
+   *len* is the number of bytes to lock, *start* is the byte offset at
    which the lock starts, relative to *whence*, and *whence* is as with
    :func:`io.IOBase.seek`, specifically:
 
@@ -133,7 +133,7 @@ The module defines the following functions:
    * :const:`2` -- relative to the end of the file (:data:`os.SEEK_END`)
 
    The default for *start* is 0, which means to start at the beginning of the file.
-   The default for *length* is 0 which means to lock to the end of the file.  The
+   The default for *len* is 0 which means to lock to the end of the file.  The
    default for *whence* is also 0.
 
 Examples (all on a SVR4 compliant system)::
@@ -147,9 +147,9 @@ Examples (all on a SVR4 compliant system)::
    rv = fcntl.fcntl(f, fcntl.F_SETLKW, lockdata)
 
 Note that in the first example the return value variable *rv* will hold an
-integer value; in the second example it will hold a string value.  The structure
-lay-out for the *lockdata* variable is system dependent --- therefore using the
-:func:`flock` call may be better.
+integer value; in the second example it will hold a :class:`bytes` object.  The
+structure lay-out for the *lockdata* variable is system dependent --- therefore
+using the :func:`flock` call may be better.
 
 
 .. seealso::

Modules/clinic/fcntlmodule.c.h

@@ -3,12 +3,12 @@ preserve
 [clinic start generated code]*/
 
 PyDoc_STRVAR(fcntl_fcntl__doc__,
-"fcntl($module, fd, code, arg=None, /)\n"
+"fcntl($module, fd, cmd, arg=0, /)\n"
 "--\n"
 "\n"
-"Perform the operation `code` on file descriptor fd.\n"
+"Perform the operation `cmd` on file descriptor fd.\n"
 "\n"
-"The values used for `code` are operating system dependent, and are available\n"
+"The values used for `cmd` are operating system dependent, and are available\n"
 "as constants in the fcntl module, using the same names as used in\n"
 "the relevant C header files.  The argument arg is optional, and\n"
 "defaults to 0; it may be an int or a string.  If arg is given as a string,\n"
@@ -43,13 +43,13 @@ exit:
 }
 
 PyDoc_STRVAR(fcntl_ioctl__doc__,
-"ioctl($module, fd, op, arg=None, mutate_flag=True, /)\n"
+"ioctl($module, fd, request, arg=0, mutate_flag=True, /)\n"
 "--\n"
 "\n"
-"Perform the operation op on file descriptor fd.\n"
+"Perform the operation `request` on file descriptor `fd`.\n"
 "\n"
-"The values used for op are operating system dependent, and are available as\n"
-"constants in the fcntl or termios library modules, using the same names as\n"
+"The values used for `request` are operating system dependent, and are available\n"
+"as constants in the fcntl or termios library modules, using the same names as\n"
 "used in the relevant C header files.\n"
 "\n"
 "The argument `arg` is optional, and defaults to 0; it may be an int or a\n"
@@ -62,9 +62,8 @@ PyDoc_STRVAR(fcntl_ioctl__doc__,
 "returned.  The return value is the integer returned by the ioctl system\n"
 "call.\n"
 "\n"
-"If the argument is a mutable buffer and the mutable_flag argument is not\n"
-"passed or is false, the behavior is as if a string had been passed.  This\n"
-"behavior will change in future releases of Python.\n"
+"If the argument is a mutable buffer and the mutable_flag argument is false,\n"
+"the behavior is as if a string had been passed.\n"
 "\n"
 "If the argument is an immutable buffer (most likely a string) then a copy\n"
 "of the buffer is passed to the operating system and the return value is a\n"
@@ -102,10 +101,10 @@ exit:
 }
 
 PyDoc_STRVAR(fcntl_flock__doc__,
-"flock($module, fd, code, /)\n"
+"flock($module, fd, operation, /)\n"
 "--\n"
 "\n"
-"Perform the lock operation op on file descriptor fd.\n"
+"Perform the lock operation `operation` on file descriptor `fd`.\n"
 "\n"
 "See the Unix manual page for flock(2) for details (On some systems, this\n"
 "function is emulated using fcntl()).");
@@ -134,12 +133,12 @@ exit:
 }
 
 PyDoc_STRVAR(fcntl_lockf__doc__,
-"lockf($module, fd, code, lenobj=None, startobj=None, whence=0, /)\n"
+"lockf($module, fd, cmd, len=0, start=0, whence=0, /)\n"
 "--\n"
 "\n"
 "A wrapper around the fcntl() locking calls.\n"
 "\n"
-"fd is the file descriptor of the file to lock or unlock, and operation is one\n"
+"`fd` is the file descriptor of the file to lock or unlock, and operation is one\n"
 "of the following values:\n"
 "\n"
 "    LOCK_UN - unlock\n"
@@ -152,9 +151,9 @@ PyDoc_STRVAR(fcntl_lockf__doc__,
 "have an errno attribute set to EACCES or EAGAIN (depending on the operating\n"
 "system -- for portability, check for either value).\n"
 "\n"
-"length is the number of bytes to lock, with the default meaning to lock to\n"
-"EOF.  start is the byte offset, relative to whence, to that the lock\n"
-"starts.  whence is as with fileobj.seek(), specifically:\n"
+"`len` is the number of bytes to lock, with the default meaning to lock to\n"
+"EOF.  `start` is the byte offset, relative to `whence`, to that the lock\n"
+"starts.  `whence` is as with fileobj.seek(), specifically:\n"
 "\n"
 "    0 - relative to the start of the file (SEEK_SET)\n"
 "    1 - relative to the current buffer position (SEEK_CUR)\n"
@@ -185,4 +184,4 @@ fcntl_lockf(PyModuleDef *module, PyObject *args)
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=84bdde73a92f7c61 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=ec482672292aab0c input=a9049054013a1b77]*/

Modules/fcntlmodule.c

@@ -39,13 +39,13 @@ conv_descriptor(PyObject *object, int *target)
 fcntl.fcntl
 
     fd: object(type='int', converter='conv_descriptor')
-    code: int
-    arg: object = NULL
+    cmd as code: int
+    arg: object(c_default='NULL') = 0
     /
 
-Perform the operation `code` on file descriptor fd.
+Perform the operation `cmd` on file descriptor fd.
 
-The values used for `code` are operating system dependent, and are available
+The values used for `cmd` are operating system dependent, and are available
 as constants in the fcntl module, using the same names as used in
 the relevant C header files.  The argument arg is optional, and
 defaults to 0; it may be an int or a string.  If arg is given as a string,
@@ -58,7 +58,7 @@ corresponding to the return value of the fcntl call in the C code.
 
 static PyObject *
 fcntl_fcntl_impl(PyModuleDef *module, int fd, int code, PyObject *arg)
-/*[clinic end generated code: output=afc5bfa74a03ef0d input=4850c13a41e86930]*/
+/*[clinic end generated code: output=afc5bfa74a03ef0d input=8cefbe59b29efbe2]*/
 {
     unsigned int int_arg = 0;
     int ret;
@@ -111,15 +111,15 @@ fcntl_fcntl_impl(PyModuleDef *module, int fd, int code, PyObject *arg)
 fcntl.ioctl
 
     fd: object(type='int', converter='conv_descriptor')
-    op as code: unsigned_int(bitwise=True)
-    arg as ob_arg: object = NULL
+    request as code: unsigned_int(bitwise=True)
+    arg as ob_arg: object(c_default='NULL') = 0
     mutate_flag as mutate_arg: bool = True
     /
 
-Perform the operation op on file descriptor fd.
+Perform the operation `request` on file descriptor `fd`.
 
-The values used for op are operating system dependent, and are available as
-constants in the fcntl or termios library modules, using the same names as
+The values used for `request` are operating system dependent, and are available
+as constants in the fcntl or termios library modules, using the same names as
 used in the relevant C header files.
 
 The argument `arg` is optional, and defaults to 0; it may be an int or a
@@ -132,9 +132,8 @@ the OS will be reflected in the contents of the buffer after the call has
 returned.  The return value is the integer returned by the ioctl system
 call.
 
-If the argument is a mutable buffer and the mutable_flag argument is not
-passed or is false, the behavior is as if a string had been passed.  This
-behavior will change in future releases of Python.
+If the argument is a mutable buffer and the mutable_flag argument is false,
+the behavior is as if a string had been passed.
 
 If the argument is an immutable buffer (most likely a string) then a copy
 of the buffer is passed to the operating system and the return value is a
@@ -149,7 +148,7 @@ code.
 
 static PyObject *
 fcntl_ioctl_impl(PyModuleDef *module, int fd, unsigned int code, PyObject *ob_arg, int mutate_arg)
-/*[clinic end generated code: output=ad47738c118622bf input=a55a6ee8e494c449]*/
+/*[clinic end generated code: output=ad47738c118622bf input=ede70c433cccbbb2]*/
 {
 #define IOCTL_BUFSZ 1024
     /* We use the unsigned non-checked 'I' format for the 'code' parameter
@@ -270,10 +269,10 @@ fcntl_ioctl_impl(PyModuleDef *module, int fd, unsigned int code, PyObject *ob_ar
 fcntl.flock
 
     fd: object(type='int', converter='conv_descriptor')
-    code: int
+    operation as code: int
     /
 
-Perform the lock operation op on file descriptor fd.
+Perform the lock operation `operation` on file descriptor `fd`.
 
 See the Unix manual page for flock(2) for details (On some systems, this
 function is emulated using fcntl()).
@@ -281,7 +280,7 @@ function is emulated using fcntl()).
 
 static PyObject *
 fcntl_flock_impl(PyModuleDef *module, int fd, int code)
-/*[clinic end generated code: output=c9035133a7dbfc96 input=b762aa9448d05e43]*/
+/*[clinic end generated code: output=c9035133a7dbfc96 input=b70a0a41ca22a8a0]*/
 {
     int ret;
 
@@ -328,15 +327,15 @@ fcntl_flock_impl(PyModuleDef *module, int fd, int code)
 fcntl.lockf
 
     fd: object(type='int', converter='conv_descriptor')
-    code: int
-    lenobj: object = NULL
-    startobj: object = NULL
+    cmd as code: int
+    len as lenobj: object(c_default='NULL') = 0
+    start as startobj: object(c_default='NULL') = 0
     whence: int = 0
     /
 
 A wrapper around the fcntl() locking calls.
 
-fd is the file descriptor of the file to lock or unlock, and operation is one
+`fd` is the file descriptor of the file to lock or unlock, and operation is one
 of the following values:
 
     LOCK_UN - unlock
@@ -349,9 +348,9 @@ lock cannot be acquired, an IOError will be raised and the exception will
 have an errno attribute set to EACCES or EAGAIN (depending on the operating
 system -- for portability, check for either value).
 
-length is the number of bytes to lock, with the default meaning to lock to
-EOF.  start is the byte offset, relative to whence, to that the lock
-starts.  whence is as with fileobj.seek(), specifically:
+`len` is the number of bytes to lock, with the default meaning to lock to
+EOF.  `start` is the byte offset, relative to `whence`, to that the lock
+starts.  `whence` is as with fileobj.seek(), specifically:
 
     0 - relative to the start of the file (SEEK_SET)
     1 - relative to the current buffer position (SEEK_CUR)
@@ -360,7 +359,7 @@ starts.  whence is as with fileobj.seek(), specifically:
 
 static PyObject *
 fcntl_lockf_impl(PyModuleDef *module, int fd, int code, PyObject *lenobj, PyObject *startobj, int whence)
-/*[clinic end generated code: output=5536df2892bf3ce9 input=44856fa06db36184]*/
+/*[clinic end generated code: output=5536df2892bf3ce9 input=9c594391de821f24]*/
 {
     int ret;