Operating System Utilities

PyObject *PyOS_FSPath(PyObject *path)

Return value: New reference. Part of the Stable ABI since version 3.6.

Return the file system representation for path. If the object is a str or bytes object, then a new strong reference is returned. If the object implements the os.PathLike interface, then __fspath__() is returned as long as it is a str or bytes object. Otherwise TypeError is raised and NULL is returned.

Added in version 3.6.

int Py_FdIsInteractive(FILE *fp, const char *filename)

Return true (nonzero) if the standard I/O file fp with name filename is deemed interactive. This is the case for files for which isatty(fileno(fp)) is true. If the PyConfig.interactive is non-zero, this function also returns true if the filename pointer is NULL or if the name is equal to one of the strings '<stdin>' or '???'.

This function must not be called before Python is initialized.

void PyOS_BeforeFork()

Part of the Stable ABI on platforms with fork() since version 3.7.

Function to prepare some internal state before a process fork. This should be called before calling fork() or any similar function that clones the current process. Only available on systems where fork() is defined.

Warning

The C fork() call should only be made from the “main” thread (of the “main” interpreter). The same is true for PyOS_BeforeFork().

Added in version 3.7.

void PyOS_AfterFork_Parent()

Part of the Stable ABI on platforms with fork() since version 3.7.

Function to update some internal state after a process fork. This should be called from the parent process after calling fork() or any similar function that clones the current process, regardless of whether process cloning was successful. Only available on systems where fork() is defined.

Warning

The C fork() call should only be made from the “main” thread (of the “main” interpreter). The same is true for PyOS_AfterFork_Parent().

Added in version 3.7.

void PyOS_AfterFork_Child()

Part of the Stable ABI on platforms with fork() since version 3.7.

Function to update internal interpreter state after a process fork. This must be called from the child process after calling fork(), or any similar function that clones the current process, if there is any chance the process will call back into the Python interpreter. Only available on systems where fork() is defined.

Warning

The C fork() call should only be made from the “main” thread (of the “main” interpreter). The same is true for PyOS_AfterFork_Child().

Added in version 3.7.

See also

os.register_at_fork() allows registering custom Python functions to be called by PyOS_BeforeFork(), PyOS_AfterFork_Parent() and PyOS_AfterFork_Child().

void PyOS_AfterFork()

Part of the Stable ABI on platforms with fork().

Function to update some internal state after a process fork; this should be called in the new process if the Python interpreter will continue to be used. If a new executable is loaded into the new process, this function does not need to be called.

Deprecated since version 3.7: This function is superseded by PyOS_AfterFork_Child().

int PyOS_CheckStack()

Part of the Stable ABI on platforms with USE_STACKCHECK since version 3.7.

Return true when the interpreter runs out of stack space. This is a reliable check, but is only available when USE_STACKCHECK is defined (currently on certain versions of Windows using the Microsoft Visual C++ compiler). USE_STACKCHECK will be defined automatically; you should never change the definition in your own code.

typedef void (*PyOS_sighandler_t)(int)

Part of the Stable ABI.

PyOS_sighandler_t PyOS_getsig(int i)

Part of the Stable ABI.

Return the current signal handler for signal i. This is a thin wrapper around either sigaction() or signal(). Do not call those functions directly!

PyOS_sighandler_t PyOS_setsig(int i, PyOS_sighandler_t h)

Part of the Stable ABI.

Set the signal handler for signal i to be h; return the old signal handler. This is a thin wrapper around either sigaction() or signal(). Do not call those functions directly!

wchar_t *Py_DecodeLocale(const char *arg, size_t *size)

Part of the Stable ABI since version 3.7.

Warning

This function should not be called directly: use the PyConfig API with the PyConfig_SetBytesString() function which ensures that Python is preinitialized.

This function must not be called before Python is preinitialized and so that the LC_CTYPE locale is properly configured: see the Py_PreInitialize() function.

Decode a byte string from the filesystem encoding and error handler. If the error handler is surrogateescape error handler, undecodable bytes are decoded as characters in range U+DC80..U+DCFF; and if a byte sequence can be decoded as a surrogate character, the bytes are escaped using the surrogateescape error handler instead of decoding them.

Return a pointer to a newly allocated wide character string, use PyMem_RawFree() to free the memory. If size is not NULL, write the number of wide characters excluding the null character into *size

Return NULL on decoding error or memory allocation error. If size is not NULL, *size is set to (size_t)-1 on memory error or set to (size_t)-2 on decoding error.

The filesystem encoding and error handler are selected by PyConfig_Read(): see filesystem_encoding and filesystem_errors members of PyConfig.

Decoding errors should never happen, unless there is a bug in the C library.

Use the Py_EncodeLocale() function to encode the character string back to a byte string.

See also

The PyUnicode_DecodeFSDefaultAndSize() and PyUnicode_DecodeLocaleAndSize() functions.

Added in version 3.5.

Changed in version 3.7: The function now uses the UTF-8 encoding in the Python UTF-8 Mode.

Changed in version 3.8: The function now uses the UTF-8 encoding on Windows if PyPreConfig.legacy_windows_fs_encoding is zero;

char *Py_EncodeLocale(const wchar_t *text, size_t *error_pos)

Part of the Stable ABI since version 3.7.

Encode a wide character string to the filesystem encoding and error handler. If the error handler is surrogateescape error handler, surrogate characters in the range U+DC80..U+DCFF are converted to bytes 0x80..0xFF.

Return a pointer to a newly allocated byte string, use PyMem_Free() to free the memory. Return NULL on encoding error or memory allocation error.

If error_pos is not NULL, *error_pos is set to (size_t)-1 on success, or set to the index of the invalid character on encoding error.

The filesystem encoding and error handler are selected by PyConfig_Read(): see filesystem_encoding and filesystem_errors members of PyConfig.

Use the Py_DecodeLocale() function to decode the bytes string back to a wide character string.

Warning

This function must not be called before Python is preinitialized and so that the LC_CTYPE locale is properly configured: see the Py_PreInitialize() function.

See also

The PyUnicode_EncodeFSDefault() and PyUnicode_EncodeLocale() functions.

Added in version 3.5.

Changed in version 3.7: The function now uses the UTF-8 encoding in the Python UTF-8 Mode.

Changed in version 3.8: The function now uses the UTF-8 encoding on Windows if PyPreConfig.legacy_windows_fs_encoding is zero.

System Functions

These are utility functions that make functionality from the sys module accessible to C code. They all work with the current interpreter thread’s sys module’s dict, which is contained in the internal thread state structure.

PyObject *PySys_GetObject(const char *name)

Return value: Borrowed reference. Part of the Stable ABI.

Return the object name from the sys module or NULL if it does not exist, without setting an exception.

int PySys_SetObject(const char *name, PyObject *v)

Part of the Stable ABI.

Set name in the sys module to v unless v is NULL, in which case name is deleted from the sys module. Returns 0 on success, -1 on error.

void PySys_ResetWarnOptions()

Part of the Stable ABI.

Reset sys.warnoptions to an empty list. This function may be called prior to Py_Initialize().

Deprecated since version 3.13, will be removed in version 3.15: Clear sys.warnoptions and warnings.filters instead.

void PySys_WriteStdout(const char *format, ...)

Part of the Stable ABI.

Write the output string described by format to sys.stdout. No exceptions are raised, even if truncation occurs (see below).

format should limit the total size of the formatted output string to 1000 bytes or less – after 1000 bytes, the output string is truncated. In particular, this means that no unrestricted “%s” formats should occur; these should be limited using “%.<N>s” where <N> is a decimal number calculated so that <N> plus the maximum size of other formatted text does not exceed 1000 bytes. Also watch out for “%f”, which can print hundreds of digits for very large numbers.

If a problem occurs, or sys.stdout is unset, the formatted message is written to the real (C level) stdout.

void PySys_WriteStderr(const char *format, ...)

Part of the Stable ABI.

As PySys_WriteStdout(), but write to sys.stderr or stderr instead.

void PySys_FormatStdout(const char *format, ...)

Part of the Stable ABI.

Function similar to PySys_WriteStdout() but format the message using PyUnicode_FromFormatV() and don’t truncate the message to an arbitrary length.

Added in version 3.2.

void PySys_FormatStderr(const char *format, ...)

Part of the Stable ABI.

As PySys_FormatStdout(), but write to sys.stderr or stderr instead.

Added in version 3.2.

PyObject *PySys_GetXOptions()

Return value: Borrowed reference. Part of the Stable ABI since version 3.7.

Return the current dictionary of -X options, similarly to sys._xoptions. On error, NULL is returned and an exception is set.

Added in version 3.2.

int PySys_Audit(const char *event, const char *format, ...)

Part of the Stable ABI since version 3.13.

Raise an auditing event with any active hooks. Return zero for success and non-zero with an exception set on failure.

The event string argument must not be NULL.

If any hooks have been added, format and other arguments will be used to construct a tuple to pass. Apart from N, the same format characters as used in Py_BuildValue() are available. If the built value is not a tuple, it will be added into a single-element tuple.

The N format option must not be used. It consumes a reference, but since there is no way to know whether arguments to this function will be consumed, using it may cause reference leaks.

Note that # format characters should always be treated as Py_ssize_t, regardless of whether PY_SSIZE_T_CLEAN was defined.

sys.audit() performs the same function from Python code.

See also PySys_AuditTuple().

Added in version 3.8.

Changed in version 3.8.2: Require Py_ssize_t for # format characters. Previously, an unavoidable deprecation warning was raised.

int PySys_AuditTuple(const char *event, PyObject *args)

Part of the Stable ABI since version 3.13.

Similar to PySys_Audit(), but pass arguments as a Python object. args must be a tuple. To pass no arguments, args can be NULL.

Added in version 3.13.

int PySys_AddAuditHook(Py_AuditHookFunction hook, void *userData)

Append the callable hook to the list of active auditing hooks. Return zero on success and non-zero on failure. If the runtime has been initialized, also set an error on failure. Hooks added through this API are called for all interpreters created by the runtime.

The userData pointer is passed into the hook function. Since hook functions may be called from different runtimes, this pointer should not refer directly to Python state.

This function is safe to call before Py_Initialize(). When called after runtime initialization, existing audit hooks are notified and may silently abort the operation by raising an error subclassed from Exception (other errors will not be silenced).

The hook function is always called with the GIL held by the Python interpreter that raised the event.

See PEP 578 for a detailed description of auditing. Functions in the runtime and standard library that raise events are listed in the audit events table. Details are in each function’s documentation.

If the interpreter is initialized, this function raises an auditing event sys.addaudithook with no arguments. If any existing hooks raise an exception derived from Exception, the new hook will not be added and the exception is cleared. As a result, callers cannot assume that their hook has been added unless they control all existing hooks.

typedef int (*Py_AuditHookFunction)(const char *event, PyObject *args, void *userData)

The type of the hook function. event is the C string event argument passed to PySys_Audit() or PySys_AuditTuple(). args is guaranteed to be a PyTupleObject. userData is the argument passed to PySys_AddAuditHook().

Added in version 3.8.

Process Control

void Py_FatalError(const char *message)

Part of the Stable ABI.

Print a fatal error message and kill the process. No cleanup is performed. This function should only be invoked when a condition is detected that would make it dangerous to continue using the Python interpreter; e.g., when the object administration appears to be corrupted. On Unix, the standard C library function abort() is called which will attempt to produce a core file.

The Py_FatalError() function is replaced with a macro which logs automatically the name of the current function, unless the Py_LIMITED_API macro is defined.

Changed in version 3.9: Log the function name automatically.

void Py_Exit(int status)

Part of the Stable ABI.

Exit the current process. This calls Py_FinalizeEx() and then calls the standard C library function exit(status). If Py_FinalizeEx() indicates an error, the exit status is set to 120.

Changed in version 3.6: Errors from finalization no longer ignored.

int Py_AtExit(void (*func)())

Part of the Stable ABI.

Register a cleanup function to be called by Py_FinalizeEx(). The cleanup function will be called with no arguments and should return no value. At most 32 cleanup functions can be registered. When the registration is successful, Py_AtExit() returns 0; on failure, it returns -1. The cleanup function registered last is called first. Each cleanup function will be called at most once. Since Python’s internal finalization will have completed before the cleanup function, no Python APIs should be called by func.

See also

PyUnstable_AtExit() for passing a void *data argument.