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123 lines
4.6 KiB
C
123 lines
4.6 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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*/
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#ifndef Py_PYMEM_H
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#define Py_PYMEM_H
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#include "pyport.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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PYMALLOC_DEBUG mode, Python wraps all calls to all PyMem_ and PyObject_
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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);
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PyAPI_FUNC(void *) PyMem_Realloc(void *, size_t);
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PyAPI_FUNC(void) PyMem_Free(void *);
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/* Starting from Python 1.6, the wrappers Py_{Malloc,Realloc,Free} are
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no longer supported. They used to call PyErr_NoMemory() on failure. */
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/* Macros. */
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#ifdef PYMALLOC_DEBUG
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/* Redirect all memory operations to Python's debugging allocator. */
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#define PyMem_MALLOC _PyMem_DebugMalloc
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#define PyMem_REALLOC _PyMem_DebugRealloc
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#define PyMem_FREE _PyMem_DebugFree
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#else /* ! PYMALLOC_DEBUG */
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/* PyMem_MALLOC(0) means malloc(1). Some systems would return NULL
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for malloc(0), which would be treated as an error. Some platforms
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would return a pointer with no memory behind it, which would break
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pymalloc. To solve these problems, allocate an extra byte. */
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/* Returns NULL to indicate error if a negative size or size larger than
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Py_ssize_t can represent is supplied. Helps prevents security holes. */
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#define PyMem_MALLOC(n) ((size_t)(n) > (size_t)PY_SSIZE_T_MAX ? NULL \
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: malloc(((n) != 0) ? (n) : 1))
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#define PyMem_REALLOC(p, n) ((size_t)(n) > (size_t)PY_SSIZE_T_MAX ? NULL \
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: realloc((p), ((n) != 0) ? (n) : 1))
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#define PyMem_FREE free
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#endif /* PYMALLOC_DEBUG */
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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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#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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#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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/* PyMem{Del,DEL} are left over from ancient days, and shouldn't be used
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* anymore. They're just confusing aliases for PyMem_{Free,FREE} now.
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*/
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#define PyMem_Del PyMem_Free
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#define PyMem_DEL PyMem_FREE
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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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