malloc.h

linux下bash的源码

/* Declarations for `malloc' and friends.
   Copyright 1990, 1991, 1992, 1993 Free Software Foundation, Inc.
		  Written May 1989 by Mike Haertel.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with this library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.

   The author may be reached (Email) at the address [e-mail],
   or (US mail) as Mike Haertel c/o Free Software Foundation.  */

#ifndef _MALLOC_H

#define _MALLOC_H	1

#ifdef _MALLOC_INTERNAL
/* Harmless, gets __GNU_LIBRARY__ defined.
   We must do this before #defining size_t and ptrdiff_t
   because <stdio.h> tries to typedef them on some systems.  */
#include <stdio.h>
#endif

#ifdef	__cplusplus
extern "C"
{
#endif

#if defined (__cplusplus) || (defined (__STDC__) && __STDC__)
#undef	__P
#define	__P(args)	args
#undef	__ptr_t
#define	__ptr_t		void *
#else /* Not C++ or ANSI C.  */
#undef	__P
#define	__P(args)	()
#undef	const
#define	const
#undef	__ptr_t
#define	__ptr_t		char *
#endif /* C++ or ANSI C.  */

#ifndef	NULL
#define	NULL	0
#endif

#ifdef	__STDC__
#include <stddef.h>
#else
#undef	size_t
#define	size_t		unsigned int
#undef	ptrdiff_t
#define	ptrdiff_t	int
#endif


/* Allocate SIZE bytes of memory.  */
extern __ptr_t malloc __P ((size_t __size));
/* Re-allocate the previously allocated block
   in __ptr_t, making the new block SIZE bytes long.  */
extern __ptr_t realloc __P ((__ptr_t __ptr, size_t __size));
/* Allocate NMEMB elements of SIZE bytes each, all initialized to 0.  */
extern __ptr_t calloc __P ((size_t __nmemb, size_t __size));
/* Free a block allocated by `malloc', `realloc' or `calloc'.  */
extern void free __P ((__ptr_t __ptr));

/* Allocate SIZE bytes allocated to ALIGNMENT bytes.  */
extern __ptr_t memalign __P ((size_t __alignment, size_t __size));

/* Allocate SIZE bytes on a page boundary.  */
extern __ptr_t valloc __P ((size_t __size));


#ifdef _MALLOC_INTERNAL

#ifdef	HAVE_CONFIG_H
#include "config.h"
#endif

#if	defined(__GNU_LIBRARY__) || defined(STDC_HEADERS) || defined(USG)
#include <string.h>
#else
#ifndef memset
#define	memset(s, zero, n)	bzero ((s), (n))
#endif
#ifndef memcpy
#define	memcpy(d, s, n)		bcopy ((s), (d), (n))
#endif
#ifndef memmove
#define	memmove(d, s, n)	bcopy ((s), (d), (n))
#endif
#endif


#if	defined(__GNU_LIBRARY__) || defined(__STDC__)
#include <limits.h>
#else
#define	CHAR_BIT	8
#endif

/* The allocator divides the heap into blocks of fixed size; large
   requests receive one or more whole blocks, and small requests
   receive a fragment of a block.  Fragment sizes are powers of two,
   and all fragments of a block are the same size.  When all the
   fragments in a block have been freed, the block itself is freed.  */
#define INT_BIT		(CHAR_BIT * sizeof(int))
#define BLOCKLOG	(INT_BIT > 16 ? 12 : 9)
#define BLOCKSIZE	(1 << BLOCKLOG)
#define BLOCKIFY(SIZE)	(((SIZE) + BLOCKSIZE - 1) / BLOCKSIZE)

/* Determine the amount of memory spanned by the initial heap table
   (not an absolute limit).  */
#define HEAP		(INT_BIT > 16 ? 4194304 : 65536)

/* Number of contiguous free blocks allowed to build up at the end of
   memory before they will be returned to the system.  */
#define FINAL_FREE_BLOCKS	8

/* Data structure giving per-block information.  */
typedef union
  {
    /* Heap information for a busy block.  */
    struct
      {
	/* Zero for a large block, or positive giving the
	   logarithm to the base two of the fragment size.  */
	int type;
	union
	  {
	    struct
	      {
		size_t nfree;	/* Free fragments in a fragmented block.  */
		size_t first;	/* First free fragment of the block.  */
	      } frag;
	    /* Size (in blocks) of a large cluster.  */
	    size_t size;
	  } info;
      } busy;
    /* Heap information for a free block
       (that may be the first of a free cluster).  */
    struct
      {
	size_t size;		/* Size (in blocks) of a free cluster.  */
	size_t next;		/* Index of next free cluster.  */
	size_t prev;		/* Index of previous free cluster.  */
      } free;
  } malloc_info;

/* Pointer to first block of the heap.  */
extern char *_heapbase;

/* Table indexed by block number giving per-block information.  */
extern malloc_info *_heapinfo;

/* Address to block number and vice versa.  */
#define BLOCK(A)	(((char *) (A) - _heapbase) / BLOCKSIZE + 1)
#define ADDRESS(B)	((__ptr_t) (((B) - 1) * BLOCKSIZE + _heapbase))

/* Current search index for the heap table.  */
extern size_t _heapindex;

/* Limit of valid info table indices.  */
extern size_t _heaplimit;

/* Doubly linked lists of free fragments.  */
struct list
  {
    struct list *next;
    struct list *prev;
  };

/* Count of blocks for each fragment size. */
extern int _fragblocks[];

/* Free list headers for each fragment size.  */
extern struct list _fraghead[];

/* List of blocks allocated with `memalign' (or `valloc').  */
struct alignlist
  {
    struct alignlist *next;
    __ptr_t aligned;		/* The address that memaligned returned.  */
    __ptr_t exact;		/* The address that malloc returned.  */
  };
extern struct alignlist *_aligned_blocks;

/* Instrumentation.  */
extern size_t _chunks_used;
extern size_t _bytes_used;
extern size_t _chunks_free;
extern size_t _bytes_free;

/* Internal version of `free' used in `morecore' (malloc.c). */
extern void _free_internal __P ((__ptr_t __ptr));

#endif /* _MALLOC_INTERNAL.  */

/* Underlying allocation function; successive calls should
   return contiguous pieces of memory.  */
extern __ptr_t (*__morecore) __P ((ptrdiff_t __size));

/* Default value of `__morecore'.  */
extern __ptr_t __default_morecore __P ((ptrdiff_t __size));

/* If not NULL, this function is called after each time
   `__morecore' is called to increase the data size.  */
extern void (*__after_morecore_hook) __P ((void));

/* Nonzero if `malloc' has been called and done its initialization.  */
extern int __malloc_initialized;

/* Hooks for debugging versions.  */
extern void (*__free_hook) __P ((__ptr_t __ptr));
extern __ptr_t (*__malloc_hook) __P ((size_t __size));
extern __ptr_t (*__realloc_hook) __P ((__ptr_t __ptr, size_t __size));

/* Activate a standard collection of debugging hooks.  */
extern int mcheck __P ((void (*__bfunc) __P ((char *)),
			void (*__afunc) __P ((void))));

/* Activate a standard collection of tracing hooks.  */
extern void mtrace __P ((void));

/* Statistics available to the user.  */
struct mstats
  {
    size_t bytes_total;		/* Total size of the heap. */
    size_t chunks_used;		/* Chunks allocated by the user. */
    size_t bytes_used;		/* Byte total of user-allocated chunks. */
    size_t chunks_free;		/* Chunks in the free list. */
    size_t bytes_free;		/* Byte total of chunks in the free list. */
  };

/* Pick up the current statistics. */
extern struct mstats mstats __P ((void));

/* Call WARNFUN with a warning message when memory usage is high.  */
extern void memory_warnings __P ((__ptr_t __start,
				  void (*__warnfun) __P ((__const char *))));


/* Relocating allocator.  */

/* Allocate SIZE bytes, and store the address in *HANDLEPTR.  */
extern __ptr_t r_alloc __P ((__ptr_t *__handleptr, size_t __size));

/* Free the storage allocated in HANDLEPTR.  */
extern void r_alloc_free __P ((__ptr_t *__handleptr));

/* Adjust the block at HANDLEPTR to be SIZE bytes long.  */
extern __ptr_t r_re_alloc __P ((__ptr_t *__handleptr, size_t __size));


#ifdef	__cplusplus
}
#endif

#endif /* malloc.h  */