mirror of https://github.com/python/cpython
111 lines
4.3 KiB
C
111 lines
4.3 KiB
C
// The PyMem_ family: low-level memory allocation interfaces.
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// See objimpl.h for the PyObject_ memory family.
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#ifndef Py_PYMEM_H
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#define Py_PYMEM_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* BEWARE:
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Each interface exports both functions and macros. Extension modules should
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use the functions, to ensure binary compatibility across Python versions.
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Because the Python implementation is free to change internal details, and
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the macros may (or may not) expose details for speed, if you do use the
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macros you must recompile your extensions with each Python release.
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Never mix calls to PyMem_ with calls to the platform malloc/realloc/
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calloc/free. For example, on Windows different DLLs may end up using
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different heaps, and if you use PyMem_Malloc you'll get the memory from the
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heap used by the Python DLL; it could be a disaster if you free()'ed that
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directly in your own extension. Using PyMem_Free instead ensures Python
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can return the memory to the proper heap. As another example, in
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a debug build (Py_DEBUG macro), Python wraps all calls to all PyMem_ and
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PyObject_ memory functions in special debugging wrappers that add additional
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debugging info to dynamic memory blocks. The system routines have no idea
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what to do with that stuff, and the Python wrappers have no idea what to do
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with raw blocks obtained directly by the system routines then.
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The GIL must be held when using these APIs.
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*/
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/*
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* Raw memory interface
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* ====================
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*/
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/* Functions
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Functions supplying platform-independent semantics for malloc/realloc/
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free. These functions make sure that allocating 0 bytes returns a distinct
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non-NULL pointer (whenever possible -- if we're flat out of memory, NULL
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may be returned), even if the platform malloc and realloc don't.
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Returned pointers must be checked for NULL explicitly. No action is
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performed on failure (no exception is set, no warning is printed, etc).
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*/
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PyAPI_FUNC(void *) PyMem_Malloc(size_t size);
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PyAPI_FUNC(void *) PyMem_Calloc(size_t nelem, size_t elsize);
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PyAPI_FUNC(void *) PyMem_Realloc(void *ptr, size_t new_size);
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PyAPI_FUNC(void) PyMem_Free(void *ptr);
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/*
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* Type-oriented memory interface
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* ==============================
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*
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* Allocate memory for n objects of the given type. Returns a new pointer
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* or NULL if the request was too large or memory allocation failed. Use
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* these macros rather than doing the multiplication yourself so that proper
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* overflow checking is always done.
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*/
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#define PyMem_New(type, n) \
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( ((size_t)(n) > PY_SSIZE_T_MAX / sizeof(type)) ? NULL : \
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( (type *) PyMem_Malloc((n) * sizeof(type)) ) )
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/*
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* The value of (p) is always clobbered by this macro regardless of success.
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* The caller MUST check if (p) is NULL afterwards and deal with the memory
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* error if so. This means the original value of (p) MUST be saved for the
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* caller's memory error handler to not lose track of it.
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*/
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#define PyMem_Resize(p, type, n) \
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( (p) = ((size_t)(n) > PY_SSIZE_T_MAX / sizeof(type)) ? NULL : \
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(type *) PyMem_Realloc((p), (n) * sizeof(type)) )
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// Deprecated aliases only kept for backward compatibility.
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// PyMem_Del and PyMem_DEL are defined with no parameter to be able to use
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// them as function pointers (ex: dealloc = PyMem_Del).
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#define PyMem_MALLOC(n) PyMem_Malloc((n))
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#define PyMem_NEW(type, n) PyMem_New(type, (n))
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#define PyMem_REALLOC(p, n) PyMem_Realloc((p), (n))
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#define PyMem_RESIZE(p, type, n) PyMem_Resize((p), type, (n))
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#define PyMem_FREE(p) PyMem_Free((p))
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#define PyMem_Del(p) PyMem_Free((p))
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#define PyMem_DEL(p) PyMem_Free((p))
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#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030d0000
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// Memory allocator which doesn't require the GIL to be held.
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// Usually, it's just a thin wrapper to functions of the standard C library:
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// malloc(), calloc(), realloc() and free(). The difference is that
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// tracemalloc can track these memory allocations.
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PyAPI_FUNC(void *) PyMem_RawMalloc(size_t size);
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PyAPI_FUNC(void *) PyMem_RawCalloc(size_t nelem, size_t elsize);
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PyAPI_FUNC(void *) PyMem_RawRealloc(void *ptr, size_t new_size);
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PyAPI_FUNC(void) PyMem_RawFree(void *ptr);
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#endif
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#ifndef Py_LIMITED_API
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# define Py_CPYTHON_PYMEM_H
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# include "cpython/pymem.h"
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# undef Py_CPYTHON_PYMEM_H
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#endif
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#ifdef __cplusplus
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}
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#endif
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#endif // !Py_PYMEM_H
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