mirror of https://github.com/python/cpython
255 lines
7.0 KiB
ReStructuredText
255 lines
7.0 KiB
ReStructuredText
:mod:`msvcrt` --- Useful routines from the MS VC++ runtime
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==========================================================
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.. module:: msvcrt
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:platform: Windows
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:synopsis: Miscellaneous useful routines from the MS VC++ runtime.
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.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
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--------------
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These functions provide access to some useful capabilities on Windows platforms.
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Some higher-level modules use these functions to build the Windows
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implementations of their services. For example, the :mod:`getpass` module uses
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this in the implementation of the :func:`getpass` function.
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Further documentation on these functions can be found in the Platform API
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documentation.
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The module implements both the normal and wide char variants of the console I/O
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api. The normal API deals only with ASCII characters and is of limited use
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for internationalized applications. The wide char API should be used where
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ever possible.
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.. versionchanged:: 3.3
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Operations in this module now raise :exc:`OSError` where :exc:`IOError`
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was raised.
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.. _msvcrt-files:
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File Operations
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---------------
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.. function:: locking(fd, mode, nbytes)
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Lock part of a file based on file descriptor *fd* from the C runtime. Raises
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:exc:`OSError` on failure. The locked region of the file extends from the
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current file position for *nbytes* bytes, and may continue beyond the end of the
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file. *mode* must be one of the :const:`!LK_\*` constants listed below. Multiple
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regions in a file may be locked at the same time, but may not overlap. Adjacent
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regions are not merged; they must be unlocked individually.
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.. audit-event:: msvcrt.locking fd,mode,nbytes msvcrt.locking
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.. data:: LK_LOCK
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LK_RLCK
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Locks the specified bytes. If the bytes cannot be locked, the program
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immediately tries again after 1 second. If, after 10 attempts, the bytes cannot
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be locked, :exc:`OSError` is raised.
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.. data:: LK_NBLCK
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LK_NBRLCK
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Locks the specified bytes. If the bytes cannot be locked, :exc:`OSError` is
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raised.
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.. data:: LK_UNLCK
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Unlocks the specified bytes, which must have been previously locked.
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.. function:: setmode(fd, flags)
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Set the line-end translation mode for the file descriptor *fd*. To set it to
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text mode, *flags* should be :const:`os.O_TEXT`; for binary, it should be
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:const:`os.O_BINARY`.
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.. function:: open_osfhandle(handle, flags)
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Create a C runtime file descriptor from the file handle *handle*. The *flags*
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parameter should be a bitwise OR of :const:`os.O_APPEND`,
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:const:`os.O_RDONLY`, :const:`os.O_TEXT` and :const:`os.O_NOINHERIT`.
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The returned file descriptor may be used as a parameter
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to :func:`os.fdopen` to create a file object.
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The file descriptor is inheritable by default. Pass :const:`os.O_NOINHERIT`
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flag to make it non inheritable.
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.. audit-event:: msvcrt.open_osfhandle handle,flags msvcrt.open_osfhandle
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.. function:: get_osfhandle(fd)
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Return the file handle for the file descriptor *fd*. Raises :exc:`OSError` if
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*fd* is not recognized.
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.. audit-event:: msvcrt.get_osfhandle fd msvcrt.get_osfhandle
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.. _msvcrt-console:
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Console I/O
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-----------
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.. function:: kbhit()
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Returns a nonzero value if a keypress is waiting to be read. Otherwise,
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return 0.
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.. function:: getch()
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Read a keypress and return the resulting character as a byte string.
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Nothing is echoed to the console. This call will block if a keypress
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is not already available, but will not wait for :kbd:`Enter` to be
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pressed. If the pressed key was a special function key, this will
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return ``'\000'`` or ``'\xe0'``; the next call will return the keycode.
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The :kbd:`Control-C` keypress cannot be read with this function.
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.. function:: getwch()
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Wide char variant of :func:`getch`, returning a Unicode value.
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.. function:: getche()
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Similar to :func:`getch`, but the keypress will be echoed if it represents a
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printable character.
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.. function:: getwche()
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Wide char variant of :func:`getche`, returning a Unicode value.
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.. function:: putch(char)
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Print the byte string *char* to the console without buffering.
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.. function:: putwch(unicode_char)
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Wide char variant of :func:`putch`, accepting a Unicode value.
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.. function:: ungetch(char)
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Cause the byte string *char* to be "pushed back" into the console buffer;
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it will be the next character read by :func:`getch` or :func:`getche`.
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.. function:: ungetwch(unicode_char)
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Wide char variant of :func:`ungetch`, accepting a Unicode value.
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.. _msvcrt-other:
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Other Functions
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---------------
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.. function:: heapmin()
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Force the :c:func:`malloc` heap to clean itself up and return unused blocks to
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the operating system. On failure, this raises :exc:`OSError`.
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.. function:: set_error_mode(mode)
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Changes the location where the C runtime writes an error message for an error
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that might end the program. *mode* must be one of the :const:`!OUT_\*`
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constants listed below or :const:`REPORT_ERRMODE`. Returns the old setting
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or -1 if an error occurs. Only available in
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:ref:`debug build of Python <debug-build>`.
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.. data:: OUT_TO_DEFAULT
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Error sink is determined by the app's type. Only available in
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:ref:`debug build of Python <debug-build>`.
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.. data:: OUT_TO_STDERR
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Error sink is a standard error. Only available in
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:ref:`debug build of Python <debug-build>`.
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.. data:: OUT_TO_MSGBOX
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Error sink is a message box. Only available in
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:ref:`debug build of Python <debug-build>`.
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.. data:: REPORT_ERRMODE
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Report the current error mode value. Only available in
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:ref:`debug build of Python <debug-build>`.
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.. function:: CrtSetReportMode(type, mode)
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Specifies the destination or destinations for a specific report type
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generated by :c:func:`!_CrtDbgReport` in the MS VC++ runtime. *type* must be
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one of the :const:`!CRT_\*` constants listed below. *mode* must be one of the
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:const:`!CRTDBG_\*` constants listed below. Only available in
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:ref:`debug build of Python <debug-build>`.
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.. function:: CrtSetReportFile(type, file)
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After you use :func:`CrtSetReportMode` to specify :const:`CRTDBG_MODE_FILE`,
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you can specify the file handle to receive the message text. *type* must be
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one of the :const:`!CRT_\*` constants listed below. *file* shuld be the file
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handle your want specified. Only available in
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:ref:`debug build of Python <debug-build>`.
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.. data:: CRT_WARN
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Warnings, messages, and information that doesn't need immediate attention.
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.. data:: CRT_ERROR
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Errors, unrecoverable problems, and issues that require immediate attention.
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.. data:: CRT_ASSERT
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Assertion failures.
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.. data:: CRTDBG_MODE_DEBUG
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Writes the message to the debugger's output window.
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.. data:: CRTDBG_MODE_FILE
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Writes the message to a user-supplied file handle. :func:`CrtSetReportFile`
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should be called to define the specific file or stream to use as
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the destination.
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.. data:: CRTDBG_MODE_WNDW
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Creates a message box to display the message along with the ``Abort``,
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``Retry``, and ``Ignore`` buttons.
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.. data:: CRTDBG_REPORT_MODE
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Returns current *mode* for the specified *type*.
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