blob: 9588ffd8308a662d2fca08a5d52f60712429f16f [file] [log] [blame]
#ifdef MALLOC_PROVIDED
int _dummy_mallocr = 1;
#else
/* ---------- To make a malloc.h, start cutting here ------------ */
/*
A version of malloc/free/realloc written by Doug Lea and released to the
public domain. Send questions/comments/complaints/performance data
to dl@cs.oswego.edu
* VERSION 2.6.4 Thu Nov 28 07:54:55 1996 Doug Lea (dl at gee)
Note: There may be an updated version of this malloc obtainable at
ftp://g.oswego.edu/pub/misc/malloc.c
Check before installing!
* Why use this malloc?
This is not the fastest, most space-conserving, most portable, or
most tunable malloc ever written. However it is among the fastest
while also being among the most space-conserving, portable and tunable.
Consistent balance across these factors results in a good general-purpose
allocator. For a high-level description, see
http://g.oswego.edu/dl/html/malloc.html
* Synopsis of public routines
(Much fuller descriptions are contained in the program documentation below.)
malloc(size_t n);
Return a pointer to a newly allocated chunk of at least n bytes, or null
if no space is available.
free(Void_t* p);
Release the chunk of memory pointed to by p, or no effect if p is null.
realloc(Void_t* p, size_t n);
Return a pointer to a chunk of size n that contains the same data
as does chunk p up to the minimum of (n, p's size) bytes, or null
if no space is available. The returned pointer may or may not be
the same as p. If p is null, equivalent to malloc. Unless the
#define REALLOC_ZERO_BYTES_FREES below is set, realloc with a
size argument of zero (re)allocates a minimum-sized chunk.
memalign(size_t alignment, size_t n);
Return a pointer to a newly allocated chunk of n bytes, aligned
in accord with the alignment argument, which must be a power of
two.
valloc(size_t n);
Equivalent to memalign(pagesize, n), where pagesize is the page
size of the system (or as near to this as can be figured out from
all the includes/defines below.)
pvalloc(size_t n);
Equivalent to valloc(minimum-page-that-holds(n)), that is,
round up n to nearest pagesize.
calloc(size_t unit, size_t quantity);
Returns a pointer to quantity * unit bytes, with all locations
set to zero.
cfree(Void_t* p);
Equivalent to free(p).
malloc_trim(size_t pad);
Release all but pad bytes of freed top-most memory back
to the system. Return 1 if successful, else 0.
malloc_usable_size(Void_t* p);
Report the number usable allocated bytes associated with allocated
chunk p. This may or may not report more bytes than were requested,
due to alignment and minimum size constraints.
malloc_stats();
Prints brief summary statistics on stderr.
mallinfo()
Returns (by copy) a struct containing various summary statistics.
mallopt(int parameter_number, int parameter_value)
Changes one of the tunable parameters described below. Returns
1 if successful in changing the parameter, else 0.
* Vital statistics:
Alignment: 8-byte
8 byte alignment is currently hardwired into the design. This
seems to suffice for all current machines and C compilers.
Assumed pointer representation: 4 or 8 bytes
Code for 8-byte pointers is untested by me but has worked
reliably by Wolfram Gloger, who contributed most of the
changes supporting this.
Assumed size_t representation: 4 or 8 bytes
Note that size_t is allowed to be 4 bytes even if pointers are 8.
Minimum overhead per allocated chunk: 4 or 8 bytes
Each malloced chunk has a hidden overhead of 4 bytes holding size
and status information.
Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)
8-byte ptrs: 24/32 bytes (including, 4/8 overhead)
When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
needed; 4 (8) for a trailing size field
and 8 (16) bytes for free list pointers. Thus, the minimum
allocatable size is 16/24/32 bytes.
Even a request for zero bytes (i.e., malloc(0)) returns a
pointer to something of the minimum allocatable size.
Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes
8-byte size_t: 2^63 - 16 bytes
It is assumed that (possibly signed) size_t bit values suffice to
represent chunk sizes. `Possibly signed' is due to the fact
that `size_t' may be defined on a system as either a signed or
an unsigned type. To be conservative, values that would appear
as negative numbers are avoided.
Requests for sizes with a negative sign bit will return a
minimum-sized chunk.
Maximum overhead wastage per allocated chunk: normally 15 bytes
Alignnment demands, plus the minimum allocatable size restriction
make the normal worst-case wastage 15 bytes (i.e., up to 15
more bytes will be allocated than were requested in malloc), with
two exceptions:
1. Because requests for zero bytes allocate non-zero space,
the worst case wastage for a request of zero bytes is 24 bytes.
2. For requests >= mmap_threshold that are serviced via
mmap(), the worst case wastage is 8 bytes plus the remainder
from a system page (the minimal mmap unit); typically 4096 bytes.
* Limitations
Here are some features that are NOT currently supported
* No user-definable hooks for callbacks and the like.
* No automated mechanism for fully checking that all accesses
to malloced memory stay within their bounds.
* No support for compaction.
* Synopsis of compile-time options:
People have reported using previous versions of this malloc on all
versions of Unix, sometimes by tweaking some of the defines
below. It has been tested most extensively on Solaris and
Linux. It is also reported to work on WIN32 platforms.
People have also reported adapting this malloc for use in
stand-alone embedded systems.
The implementation is in straight, hand-tuned ANSI C. Among other
consequences, it uses a lot of macros. Because of this, to be at
all usable, this code should be compiled using an optimizing compiler
(for example gcc -O2) that can simplify expressions and control
paths.
__STD_C (default: derived from C compiler defines)
Nonzero if using ANSI-standard C compiler, a C++ compiler, or
a C compiler sufficiently close to ANSI to get away with it.
DEBUG (default: NOT defined)
Define to enable debugging. Adds fairly extensive assertion-based
checking to help track down memory errors, but noticeably slows down
execution.
SEPARATE_OBJECTS (default: NOT defined)
Define this to compile into separate .o files. You must then
compile malloc.c several times, defining a DEFINE_* macro each
time. The list of DEFINE_* macros appears below.
MALLOC_LOCK (default: NOT defined)
MALLOC_UNLOCK (default: NOT defined)
Define these to C expressions which are run to lock and unlock
the malloc data structures. Calls may be nested; that is,
MALLOC_LOCK may be called more than once before the corresponding
MALLOC_UNLOCK calls. MALLOC_LOCK must avoid waiting for a lock
that it already holds.
MALLOC_ALIGNMENT (default: NOT defined)
Define this to 16 if you need 16 byte alignment instead of 8 byte alignment
which is the normal default.
REALLOC_ZERO_BYTES_FREES (default: NOT defined)
Define this if you think that realloc(p, 0) should be equivalent
to free(p). Otherwise, since malloc returns a unique pointer for
malloc(0), so does realloc(p, 0).
HAVE_MEMCPY (default: defined)
Define if you are not otherwise using ANSI STD C, but still
have memcpy and memset in your C library and want to use them.
Otherwise, simple internal versions are supplied.
USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise)
Define as 1 if you want the C library versions of memset and
memcpy called in realloc and calloc (otherwise macro versions are used).
At least on some platforms, the simple macro versions usually
outperform libc versions.
HAVE_MMAP (default: defined as 1)
Define to non-zero to optionally make malloc() use mmap() to
allocate very large blocks.
HAVE_MREMAP (default: defined as 0 unless Linux libc set)
Define to non-zero to optionally make realloc() use mremap() to
reallocate very large blocks.
malloc_getpagesize (default: derived from system #includes)
Either a constant or routine call returning the system page size.
HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined)
Optionally define if you are on a system with a /usr/include/malloc.h
that declares struct mallinfo. It is not at all necessary to
define this even if you do, but will ensure consistency.
INTERNAL_SIZE_T (default: size_t)
Define to a 32-bit type (probably `unsigned int') if you are on a
64-bit machine, yet do not want or need to allow malloc requests of
greater than 2^31 to be handled. This saves space, especially for
very small chunks.
INTERNAL_LINUX_C_LIB (default: NOT defined)
Defined only when compiled as part of Linux libc.
Also note that there is some odd internal name-mangling via defines
(for example, internally, `malloc' is named `mALLOc') needed
when compiling in this case. These look funny but don't otherwise
affect anything.
INTERNAL_NEWLIB (default: NOT defined)
Defined only when compiled as part of the Cygnus newlib
distribution.
WIN32 (default: undefined)
Define this on MS win (95, nt) platforms to compile in sbrk emulation.
LACKS_UNISTD_H (default: undefined)
Define this if your system does not have a <unistd.h>.
MORECORE (default: sbrk)
The name of the routine to call to obtain more memory from the system.
MORECORE_FAILURE (default: -1)
The value returned upon failure of MORECORE.
MORECORE_CLEARS (default 1)
True (1) if the routine mapped to MORECORE zeroes out memory (which
holds for sbrk).
DEFAULT_TRIM_THRESHOLD
DEFAULT_TOP_PAD
DEFAULT_MMAP_THRESHOLD
DEFAULT_MMAP_MAX
Default values of tunable parameters (described in detail below)
controlling interaction with host system routines (sbrk, mmap, etc).
These values may also be changed dynamically via mallopt(). The
preset defaults are those that give best performance for typical
programs/systems.
*/
/* Preliminaries */
#ifndef __STD_C
#ifdef __STDC__
#define __STD_C 1
#else
#if __cplusplus
#define __STD_C 1
#else
#define __STD_C 0
#endif /*__cplusplus*/
#endif /*__STDC__*/
#endif /*__STD_C*/
#ifndef Void_t
#if __STD_C
#define Void_t void
#else
#define Void_t char
#endif
#endif /*Void_t*/
#if __STD_C
#include <stddef.h> /* for size_t */
#else
#include <sys/types.h>
#endif
#ifdef __cplusplus
extern "C" {
#endif
#include <stdio.h> /* needed for malloc_stats */
#include <limits.h> /* needed for overflow checks */
#include <errno.h> /* needed to set errno to ENOMEM */
#ifdef WIN32
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#endif
/*
Compile-time options
*/
/*
Special defines for Cygnus newlib distribution.
*/
#ifdef INTERNAL_NEWLIB
#include <sys/config.h>
/*
In newlib, all the publically visible routines take a reentrancy
pointer. We don't currently do anything much with it, but we do
pass it to the lock routine.
*/
#include <reent.h>
#define POINTER_UINT unsigned _POINTER_INT
#define SEPARATE_OBJECTS
#define HAVE_MMAP 0
#define MORECORE(size) _sbrk_r(reent_ptr, (size))
#define MORECORE_CLEARS 0
#define MALLOC_LOCK __malloc_lock(reent_ptr)
#define MALLOC_UNLOCK __malloc_unlock(reent_ptr)
#ifdef __CYGWIN__
# undef _WIN32
# undef WIN32
#endif
#ifndef _WIN32
#ifdef SMALL_MEMORY
#define malloc_getpagesize (128)
#else
#define malloc_getpagesize (4096)
#endif
#endif
#if __STD_C
extern void __malloc_lock(struct _reent *);
extern void __malloc_unlock(struct _reent *);
#else
extern void __malloc_lock();
extern void __malloc_unlock();
#endif
#if __STD_C
#define RARG struct _reent *reent_ptr,
#define RONEARG struct _reent *reent_ptr
#else
#define RARG reent_ptr
#define RONEARG reent_ptr
#define RDECL struct _reent *reent_ptr;
#endif
#define RERRNO reent_ptr->_errno
#define RCALL reent_ptr,
#define RONECALL reent_ptr
#else /* ! INTERNAL_NEWLIB */
#define POINTER_UINT unsigned long
#define RARG
#define RONEARG
#define RDECL
#define RERRNO errno
#define RCALL
#define RONECALL
#endif /* ! INTERNAL_NEWLIB */
/*
Debugging:
Because freed chunks may be overwritten with link fields, this
malloc will often die when freed memory is overwritten by user
programs. This can be very effective (albeit in an annoying way)
in helping track down dangling pointers.
If you compile with -DDEBUG, a number of assertion checks are
enabled that will catch more memory errors. You probably won't be
able to make much sense of the actual assertion errors, but they
should help you locate incorrectly overwritten memory. The
checking is fairly extensive, and will slow down execution
noticeably. Calling malloc_stats or mallinfo with DEBUG set will
attempt to check every non-mmapped allocated and free chunk in the
course of computing the summmaries. (By nature, mmapped regions
cannot be checked very much automatically.)
Setting DEBUG may also be helpful if you are trying to modify
this code. The assertions in the check routines spell out in more
detail the assumptions and invariants underlying the algorithms.
*/
#if DEBUG
#include <assert.h>
#else
#define assert(x) ((void)0)
#endif
/*
SEPARATE_OBJECTS should be defined if you want each function to go
into a separate .o file. You must then compile malloc.c once per
function, defining the appropriate DEFINE_ macro. See below for the
list of macros.
*/
#ifndef SEPARATE_OBJECTS
#define DEFINE_MALLOC
#define DEFINE_FREE
#define DEFINE_REALLOC
#define DEFINE_CALLOC
#define DEFINE_CFREE
#define DEFINE_MEMALIGN
#define DEFINE_VALLOC
#define DEFINE_PVALLOC
#define DEFINE_MALLINFO
#define DEFINE_MALLOC_STATS
#define DEFINE_MALLOC_USABLE_SIZE
#define DEFINE_MALLOPT
#define STATIC static
#else
#define STATIC
#endif
/*
Define MALLOC_LOCK and MALLOC_UNLOCK to C expressions to run to
lock and unlock the malloc data structures. MALLOC_LOCK may be
called recursively.
*/
#ifndef MALLOC_LOCK
#define MALLOC_LOCK
#endif
#ifndef MALLOC_UNLOCK
#define MALLOC_UNLOCK
#endif
/*
INTERNAL_SIZE_T is the word-size used for internal bookkeeping
of chunk sizes. On a 64-bit machine, you can reduce malloc
overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int'
at the expense of not being able to handle requests greater than
2^31. This limitation is hardly ever a concern; you are encouraged
to set this. However, the default version is the same as size_t.
*/
#ifndef INTERNAL_SIZE_T
#define INTERNAL_SIZE_T size_t
#endif
/*
Following is needed on implementations whereby long > size_t.
The problem is caused because the code performs subtractions of
size_t values and stores the result in long values. In the case
where long > size_t and the first value is actually less than
the second value, the resultant value is positive. For example,
(long)(x - y) where x = 0 and y is 1 ends up being 0x00000000FFFFFFFF
which is 2*31 - 1 instead of 0xFFFFFFFFFFFFFFFF. This is due to the
fact that assignment from unsigned to signed won't sign extend.
*/
#define long_sub_size_t(x, y) \
(sizeof (long) > sizeof (INTERNAL_SIZE_T) && x < y \
? -(long) (y - x) \
: (long) (x - y))
/*
REALLOC_ZERO_BYTES_FREES should be set if a call to
realloc with zero bytes should be the same as a call to free.
Some people think it should. Otherwise, since this malloc
returns a unique pointer for malloc(0), so does realloc(p, 0).
*/
/* #define REALLOC_ZERO_BYTES_FREES */
/*
WIN32 causes an emulation of sbrk to be compiled in
mmap-based options are not currently supported in WIN32.
*/
/* #define WIN32 */
#ifdef WIN32
#define MORECORE wsbrk
#define HAVE_MMAP 0
#endif
/*
HAVE_MEMCPY should be defined if you are not otherwise using
ANSI STD C, but still have memcpy and memset in your C library
and want to use them in calloc and realloc. Otherwise simple
macro versions are defined here.
USE_MEMCPY should be defined as 1 if you actually want to
have memset and memcpy called. People report that the macro
versions are often enough faster than libc versions on many
systems that it is better to use them.
*/
#define HAVE_MEMCPY
/* Although the original macro is called USE_MEMCPY, newlib actually
uses memmove to handle cases whereby a platform's memcpy implementation
copies backwards and thus destructive overlap may occur in realloc
whereby we are reclaiming free memory prior to the old allocation. */
#ifndef USE_MEMCPY
#ifdef HAVE_MEMCPY
#define USE_MEMCPY 1
#else
#define USE_MEMCPY 0
#endif
#endif
#if (__STD_C || defined(HAVE_MEMCPY))
#if __STD_C
void* memset(void*, int, size_t);
void* memcpy(void*, const void*, size_t);
void* memmove(void*, const void*, size_t);
#else
Void_t* memset();
Void_t* memcpy();
Void_t* memmove();
#endif
#endif
#if USE_MEMCPY
/* The following macros are only invoked with (2n+1)-multiples of
INTERNAL_SIZE_T units, with a positive integer n. This is exploited
for fast inline execution when n is small. */
#define MALLOC_ZERO(charp, nbytes) \
do { \
INTERNAL_SIZE_T mzsz = (nbytes); \
if(mzsz <= 9*sizeof(mzsz)) { \
INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \
if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \
*mz++ = 0; \
if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \
*mz++ = 0; \
if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \
*mz++ = 0; }}} \
*mz++ = 0; \
*mz++ = 0; \
*mz = 0; \
} else memset((charp), 0, mzsz); \
} while(0)
#define MALLOC_COPY(dest,src,nbytes) \
do { \
INTERNAL_SIZE_T mcsz = (nbytes); \
if(mcsz <= 9*sizeof(mcsz)) { \
INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \
INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \
if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; \
if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; \
if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; }}} \
*mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; \
*mcdst = *mcsrc ; \
} else memmove(dest, src, mcsz); \
} while(0)
#else /* !USE_MEMCPY */
/* Use Duff's device for good zeroing/copying performance. */
#define MALLOC_ZERO(charp, nbytes) \
do { \
INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \
long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
switch (mctmp) { \
case 0: for(;;) { *mzp++ = 0; \
case 7: *mzp++ = 0; \
case 6: *mzp++ = 0; \
case 5: *mzp++ = 0; \
case 4: *mzp++ = 0; \
case 3: *mzp++ = 0; \
case 2: *mzp++ = 0; \
case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \
} \
} while(0)
#define MALLOC_COPY(dest,src,nbytes) \
do { \
INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \
INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \
long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
switch (mctmp) { \
case 0: for(;;) { *mcdst++ = *mcsrc++; \
case 7: *mcdst++ = *mcsrc++; \
case 6: *mcdst++ = *mcsrc++; \
case 5: *mcdst++ = *mcsrc++; \
case 4: *mcdst++ = *mcsrc++; \
case 3: *mcdst++ = *mcsrc++; \
case 2: *mcdst++ = *mcsrc++; \
case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \
} \
} while(0)
#endif
/*
Define HAVE_MMAP to optionally make malloc() use mmap() to
allocate very large blocks. These will be returned to the
operating system immediately after a free().
*/
#ifndef HAVE_MMAP
#define HAVE_MMAP 1
#endif
/*
Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
large blocks. This is currently only possible on Linux with
kernel versions newer than 1.3.77.
*/
#ifndef HAVE_MREMAP
#ifdef INTERNAL_LINUX_C_LIB
#define HAVE_MREMAP 1
#else
#define HAVE_MREMAP 0
#endif
#endif
#if HAVE_MMAP
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
#define MAP_ANONYMOUS MAP_ANON
#endif
#endif /* HAVE_MMAP */
/*
Access to system page size. To the extent possible, this malloc
manages memory from the system in page-size units.
The following mechanics for getpagesize were adapted from
bsd/gnu getpagesize.h
*/
#ifndef LACKS_UNISTD_H
# include <unistd.h>
#endif
#ifndef malloc_getpagesize
# ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */
# ifndef _SC_PAGE_SIZE
# define _SC_PAGE_SIZE _SC_PAGESIZE
# endif
# endif
# ifdef _SC_PAGE_SIZE
# define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
# else
# if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
extern size_t getpagesize();
# define malloc_getpagesize getpagesize()
# else
# include <sys/param.h>
# ifdef EXEC_PAGESIZE
# define malloc_getpagesize EXEC_PAGESIZE
# else
# ifdef NBPG
# ifndef CLSIZE
# define malloc_getpagesize NBPG
# else
# define malloc_getpagesize (NBPG * CLSIZE)
# endif
# else
# ifdef NBPC
# define malloc_getpagesize NBPC
# else
# ifdef PAGESIZE
# define malloc_getpagesize PAGESIZE
# else
# define malloc_getpagesize (4096) /* just guess */
# endif
# endif
# endif
# endif
# endif
# endif
#endif
/*
This version of malloc supports the standard SVID/XPG mallinfo
routine that returns a struct containing the same kind of
information you can get from malloc_stats. It should work on
any SVID/XPG compliant system that has a /usr/include/malloc.h
defining struct mallinfo. (If you'd like to install such a thing
yourself, cut out the preliminary declarations as described above
and below and save them in a malloc.h file. But there's no
compelling reason to bother to do this.)
The main declaration needed is the mallinfo struct that is returned
(by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a
bunch of fields, most of which are not even meaningful in this
version of malloc. Some of these fields are are instead filled by
mallinfo() with other numbers that might possibly be of interest.
HAVE_USR_INCLUDE_MALLOC_H should be set if you have a
/usr/include/malloc.h file that includes a declaration of struct
mallinfo. If so, it is included; else an SVID2/XPG2 compliant
version is declared below. These must be precisely the same for
mallinfo() to work.
*/
/* #define HAVE_USR_INCLUDE_MALLOC_H */
#if HAVE_USR_INCLUDE_MALLOC_H
#include "/usr/include/malloc.h"
#else
/* SVID2/XPG mallinfo structure */
struct mallinfo {
int arena; /* total space allocated from system */
int ordblks; /* number of non-inuse chunks */
int smblks; /* unused -- always zero */
int hblks; /* number of mmapped regions */
int hblkhd; /* total space in mmapped regions */
int usmblks; /* unused -- always zero */
int fsmblks; /* unused -- always zero */
int uordblks; /* total allocated space */
int fordblks; /* total non-inuse space */
int keepcost; /* top-most, releasable (via malloc_trim) space */
};
/* SVID2/XPG mallopt options */
#define M_MXFAST 1 /* UNUSED in this malloc */
#define M_NLBLKS 2 /* UNUSED in this malloc */
#define M_GRAIN 3 /* UNUSED in this malloc */
#define M_KEEP 4 /* UNUSED in this malloc */
#endif
/* mallopt options that actually do something */
#define M_TRIM_THRESHOLD -1
#define M_TOP_PAD -2
#define M_MMAP_THRESHOLD -3
#define M_MMAP_MAX -4
#ifndef DEFAULT_TRIM_THRESHOLD
#define DEFAULT_TRIM_THRESHOLD (128L * 1024L)
#endif
/*
M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
to keep before releasing via malloc_trim in free().
Automatic trimming is mainly useful in long-lived programs.
Because trimming via sbrk can be slow on some systems, and can
sometimes be wasteful (in cases where programs immediately
afterward allocate more large chunks) the value should be high
enough so that your overall system performance would improve by
releasing.
The trim threshold and the mmap control parameters (see below)
can be traded off with one another. Trimming and mmapping are
two different ways of releasing unused memory back to the
system. Between these two, it is often possible to keep
system-level demands of a long-lived program down to a bare
minimum. For example, in one test suite of sessions measuring
the XF86 X server on Linux, using a trim threshold of 128K and a
mmap threshold of 192K led to near-minimal long term resource
consumption.
If you are using this malloc in a long-lived program, it should
pay to experiment with these values. As a rough guide, you
might set to a value close to the average size of a process
(program) running on your system. Releasing this much memory
would allow such a process to run in memory. Generally, it's
worth it to tune for trimming rather tham memory mapping when a
program undergoes phases where several large chunks are
allocated and released in ways that can reuse each other's
storage, perhaps mixed with phases where there are no such
chunks at all. And in well-behaved long-lived programs,
controlling release of large blocks via trimming versus mapping
is usually faster.
However, in most programs, these parameters serve mainly as
protection against the system-level effects of carrying around
massive amounts of unneeded memory. Since frequent calls to
sbrk, mmap, and munmap otherwise degrade performance, the default
parameters are set to relatively high values that serve only as
safeguards.
The default trim value is high enough to cause trimming only in
fairly extreme (by current memory consumption standards) cases.
It must be greater than page size to have any useful effect. To
disable trimming completely, you can set to (unsigned long)(-1);
*/
#ifndef DEFAULT_TOP_PAD
#define DEFAULT_TOP_PAD (0)
#endif
/*
M_TOP_PAD is the amount of extra `padding' space to allocate or
retain whenever sbrk is called. It is used in two ways internally:
* When sbrk is called to extend the top of the arena to satisfy
a new malloc request, this much padding is added to the sbrk
request.
* When malloc_trim is called automatically from free(),
it is used as the `pad' argument.
In both cases, the actual amount of padding is rounded
so that the end of the arena is always a system page boundary.
The main reason for using padding is to avoid calling sbrk so
often. Having even a small pad greatly reduces the likelihood
that nearly every malloc request during program start-up (or
after trimming) will invoke sbrk, which needlessly wastes
time.
Automatic rounding-up to page-size units is normally sufficient
to avoid measurable overhead, so the default is 0. However, in
systems where sbrk is relatively slow, it can pay to increase
this value, at the expense of carrying around more memory than
the program needs.
*/
#ifndef DEFAULT_MMAP_THRESHOLD
#define DEFAULT_MMAP_THRESHOLD (128 * 1024)
#endif
/*
M_MMAP_THRESHOLD is the request size threshold for using mmap()
to service a request. Requests of at least this size that cannot
be allocated using already-existing space will be serviced via mmap.
(If enough normal freed space already exists it is used instead.)
Using mmap segregates relatively large chunks of memory so that
they can be individually obtained and released from the host
system. A request serviced through mmap is never reused by any
other request (at least not directly; the system may just so
happen to remap successive requests to the same locations).
Segregating space in this way has the benefit that mmapped space
can ALWAYS be individually released back to the system, which
helps keep the system level memory demands of a long-lived
program low. Mapped memory can never become `locked' between
other chunks, as can happen with normally allocated chunks, which
menas that even trimming via malloc_trim would not release them.
However, it has the disadvantages that:
1. The space cannot be reclaimed, consolidated, and then
used to service later requests, as happens with normal chunks.
2. It can lead to more wastage because of mmap page alignment
requirements
3. It causes malloc performance to be more dependent on host
system memory management support routines which may vary in
implementation quality and may impose arbitrary
limitations. Generally, servicing a request via normal
malloc steps is faster than going through a system's mmap.
All together, these considerations should lead you to use mmap
only for relatively large requests.
*/
#ifndef DEFAULT_MMAP_MAX
#if HAVE_MMAP
#define DEFAULT_MMAP_MAX (64)
#else
#define DEFAULT_MMAP_MAX (0)
#endif
#endif
/*
M_MMAP_MAX is the maximum number of requests to simultaneously
service using mmap. This parameter exists because:
1. Some systems have a limited number of internal tables for
use by mmap.
2. In most systems, overreliance on mmap can degrade overall
performance.
3. If a program allocates many large regions, it is probably
better off using normal sbrk-based allocation routines that
can reclaim and reallocate normal heap memory. Using a
small value allows transition into this mode after the
first few allocations.
Setting to 0 disables all use of mmap. If HAVE_MMAP is not set,
the default value is 0, and attempts to set it to non-zero values
in mallopt will fail.
*/
/*
Special defines for linux libc
Except when compiled using these special defines for Linux libc
using weak aliases, this malloc is NOT designed to work in
multithreaded applications. No semaphores or other concurrency
control are provided to ensure that multiple malloc or free calls
don't run at the same time, which could be disasterous. A single
semaphore could be used across malloc, realloc, and free (which is
essentially the effect of the linux weak alias approach). It would
be hard to obtain finer granularity.
*/
#ifdef INTERNAL_LINUX_C_LIB
#if __STD_C
Void_t * __default_morecore_init (ptrdiff_t);
Void_t *(*__morecore)(ptrdiff_t) = __default_morecore_init;
#else
Void_t * __default_morecore_init ();
Void_t *(*__morecore)() = __default_morecore_init;
#endif
#define MORECORE (*__morecore)
#define MORECORE_FAILURE 0
#define MORECORE_CLEARS 1
#else /* INTERNAL_LINUX_C_LIB */
#ifndef INTERNAL_NEWLIB
#if __STD_C
extern Void_t* sbrk(ptrdiff_t);
#else
extern Void_t* sbrk();
#endif
#endif
#ifndef MORECORE
#define MORECORE sbrk
#endif
#ifndef MORECORE_FAILURE
#define MORECORE_FAILURE -1
#endif
#ifndef MORECORE_CLEARS
#define MORECORE_CLEARS 1
#endif
#endif /* INTERNAL_LINUX_C_LIB */
#if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__)
#define cALLOc __libc_calloc
#define fREe __libc_free
#define mALLOc __libc_malloc
#define mEMALIGn __libc_memalign
#define rEALLOc __libc_realloc
#define vALLOc __libc_valloc
#define pvALLOc __libc_pvalloc
#define mALLINFo __libc_mallinfo
#define mALLOPt __libc_mallopt
#pragma weak calloc = __libc_calloc
#pragma weak free = __libc_free
#pragma weak cfree = __libc_free
#pragma weak malloc = __libc_malloc
#pragma weak memalign = __libc_memalign
#pragma weak realloc = __libc_realloc
#pragma weak valloc = __libc_valloc
#pragma weak pvalloc = __libc_pvalloc
#pragma weak mallinfo = __libc_mallinfo
#pragma weak mallopt = __libc_mallopt
#else
#ifdef INTERNAL_NEWLIB
#define cALLOc _calloc_r
#define fREe _free_r
#define mALLOc _malloc_r
#define mEMALIGn _memalign_r
#define rEALLOc _realloc_r
#define vALLOc _valloc_r
#define pvALLOc _pvalloc_r
#define mALLINFo _mallinfo_r
#define mALLOPt _mallopt_r
#define malloc_stats _malloc_stats_r
#define malloc_trim _malloc_trim_r
#define malloc_usable_size _malloc_usable_size_r
#define malloc_update_mallinfo __malloc_update_mallinfo
#define malloc_av_ __malloc_av_
#define malloc_current_mallinfo __malloc_current_mallinfo
#define malloc_max_sbrked_mem __malloc_max_sbrked_mem
#define malloc_max_total_mem __malloc_max_total_mem
#define malloc_sbrk_base __malloc_sbrk_base
#define malloc_top_pad __malloc_top_pad
#define malloc_trim_threshold __malloc_trim_threshold
#else /* ! INTERNAL_NEWLIB */
#define cALLOc calloc
#define fREe free
#define mALLOc malloc
#define mEMALIGn memalign
#define rEALLOc realloc
#define vALLOc valloc
#define pvALLOc pvalloc
#define mALLINFo mallinfo
#define mALLOPt mallopt
#endif /* ! INTERNAL_NEWLIB */
#endif
/* Public routines */
#if __STD_C
Void_t* mALLOc(RARG size_t);
void fREe(RARG Void_t*);
Void_t* rEALLOc(RARG Void_t*, size_t);
Void_t* mEMALIGn(RARG size_t, size_t);
Void_t* vALLOc(RARG size_t);
Void_t* pvALLOc(RARG size_t);
Void_t* cALLOc(RARG size_t, size_t);
void cfree(Void_t*);
int malloc_trim(RARG size_t);
size_t malloc_usable_size(RARG Void_t*);
void malloc_stats(RONEARG);
int mALLOPt(RARG int, int);
struct mallinfo mALLINFo(RONEARG);
#else
Void_t* mALLOc();
void fREe();
Void_t* rEALLOc();
Void_t* mEMALIGn();
Void_t* vALLOc();
Void_t* pvALLOc();
Void_t* cALLOc();
void cfree();
int malloc_trim();
size_t malloc_usable_size();
void malloc_stats();
int mALLOPt();
struct mallinfo mALLINFo();
#endif
#ifdef __cplusplus
}; /* end of extern "C" */
#endif
/* ---------- To make a malloc.h, end cutting here ------------ */
/*
Emulation of sbrk for WIN32
All code within the ifdef WIN32 is untested by me.
*/
#ifdef WIN32
#define AlignPage(add) (((add) + (malloc_getpagesize-1)) & \
~(malloc_getpagesize-1))
/* resrve 64MB to insure large contiguous space */
#define RESERVED_SIZE (1024*1024*64)
#define NEXT_SIZE (2048*1024)
#define TOP_MEMORY ((unsigned long)2*1024*1024*1024)
struct GmListElement;
typedef struct GmListElement GmListElement;
struct GmListElement
{
GmListElement* next;
void* base;
};
static GmListElement* head = 0;
static unsigned int gNextAddress = 0;
static unsigned int gAddressBase = 0;
static unsigned int gAllocatedSize = 0;
static
GmListElement* makeGmListElement (void* bas)
{
GmListElement* this;
this = (GmListElement*)(void*)LocalAlloc (0, sizeof (GmListElement));
ASSERT (this);
if (this)
{
this->base = bas;
this->next = head;
head = this;
}
return this;
}
void gcleanup ()
{
BOOL rval;
ASSERT ( (head == NULL) || (head->base == (void*)gAddressBase));
if (gAddressBase && (gNextAddress - gAddressBase))
{
rval = VirtualFree ((void*)gAddressBase,
gNextAddress - gAddressBase,
MEM_DECOMMIT);
ASSERT (rval);
}
while (head)
{
GmListElement* next = head->next;
rval = VirtualFree (head->base, 0, MEM_RELEASE);
ASSERT (rval);
LocalFree (head);
head = next;
}
}
static
void* findRegion (void* start_address, unsigned long size)
{
MEMORY_BASIC_INFORMATION info;
while ((unsigned long)start_address < TOP_MEMORY)
{
VirtualQuery (start_address, &info, sizeof (info));
if (info.State != MEM_FREE)
start_address = (char*)info.BaseAddress + info.RegionSize;
else if (info.RegionSize >= size)
return start_address;
else
start_address = (char*)info.BaseAddress + info.RegionSize;
}
return NULL;
}
void* wsbrk (long size)
{
void* tmp;
if (size > 0)
{
if (gAddressBase == 0)
{
gAllocatedSize = max (RESERVED_SIZE, AlignPage (size));
gNextAddress = gAddressBase =
(unsigned int)VirtualAlloc (NULL, gAllocatedSize,
MEM_RESERVE, PAGE_NOACCESS);
} else if (AlignPage (gNextAddress + size) > (gAddressBase +
gAllocatedSize))
{
long new_size = max (NEXT_SIZE, AlignPage (size));
void* new_address = (void*)(gAddressBase+gAllocatedSize);
do
{
new_address = findRegion (new_address, new_size);
if (new_address == 0)
return (void*)-1;
gAddressBase = gNextAddress =
(unsigned int)VirtualAlloc (new_address, new_size,
MEM_RESERVE, PAGE_NOACCESS);
// repeat in case of race condition
// The region that we found has been snagged
// by another thread
}
while (gAddressBase == 0);
ASSERT (new_address == (void*)gAddressBase);
gAllocatedSize = new_size;
if (!makeGmListElement ((void*)gAddressBase))
return (void*)-1;
}
if ((size + gNextAddress) > AlignPage (gNextAddress))
{
void* res;
res = VirtualAlloc ((void*)AlignPage (gNextAddress),
(size + gNextAddress -
AlignPage (gNextAddress)),
MEM_COMMIT, PAGE_READWRITE);
if (res == 0)
return (void*)-1;
}
tmp = (void*)gNextAddress;
gNextAddress = (unsigned int)tmp + size;
return tmp;
}
else if (size < 0)
{
unsigned int alignedGoal = AlignPage (gNextAddress + size);
/* Trim by releasing the virtual memory */
if (alignedGoal >= gAddressBase)
{
VirtualFree ((void*)alignedGoal, gNextAddress - alignedGoal,
MEM_DECOMMIT);
gNextAddress = gNextAddress + size;
return (void*)gNextAddress;
}
else
{
VirtualFree ((void*)gAddressBase, gNextAddress - gAddressBase,
MEM_DECOMMIT);
gNextAddress = gAddressBase;
return (void*)-1;
}
}
else
{
return (void*)gNextAddress;
}
}
#endif
/*
Type declarations
*/
struct malloc_chunk
{
INTERNAL_SIZE_T prev_size; /* Size of previous chunk (if free). */
INTERNAL_SIZE_T size; /* Size in bytes, including overhead. */
struct malloc_chunk* fd; /* double links -- used only if free. */
struct malloc_chunk* bk;
};
typedef struct malloc_chunk* mchunkptr;
/*
malloc_chunk details:
(The following includes lightly edited explanations by Colin Plumb.)
Chunks of memory are maintained using a `boundary tag' method as
described in e.g., Knuth or Standish. (See the paper by Paul
Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
survey of such techniques.) Sizes of free chunks are stored both
in the front of each chunk and at the end. This makes
consolidating fragmented chunks into bigger chunks very fast. The
size fields also hold bits representing whether chunks are free or
in use.
An allocated chunk looks like this:
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of previous chunk, if allocated | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of chunk, in bytes |P|
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| User data starts here... .
. .
. (malloc_usable_space() bytes) .
. |
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of chunk |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where "chunk" is the front of the chunk for the purpose of most of
the malloc code, but "mem" is the pointer that is returned to the
user. "Nextchunk" is the beginning of the next contiguous chunk.
Chunks always begin on even word boundries, so the mem portion
(which is returned to the user) is also on an even word boundary, and
thus double-word aligned.
Free chunks are stored in circular doubly-linked lists, and look like this:
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of previous chunk |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
`head:' | Size of chunk, in bytes |P|
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Forward pointer to next chunk in list |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Back pointer to previous chunk in list |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unused space (may be 0 bytes long) .
. .
. |
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
`foot:' | Size of chunk, in bytes |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The P (PREV_INUSE) bit, stored in the unused low-order bit of the
chunk size (which is always a multiple of two words), is an in-use
bit for the *previous* chunk. If that bit is *clear*, then the
word before the current chunk size contains the previous chunk
size, and can be used to find the front of the previous chunk.
(The very first chunk allocated always has this bit set,
preventing access to non-existent (or non-owned) memory.)
Note that the `foot' of the current chunk is actually represented
as the prev_size of the NEXT chunk. (This makes it easier to
deal with alignments etc).
The two exceptions to all this are
1. The special chunk `top', which doesn't bother using the
trailing size field since there is no
next contiguous chunk that would have to index off it. (After
initialization, `top' is forced to always exist. If it would
become less than MINSIZE bytes long, it is replenished via
malloc_extend_top.)
2. Chunks allocated via mmap, which have the second-lowest-order
bit (IS_MMAPPED) set in their size fields. Because they are
never merged or traversed from any other chunk, they have no
foot size or inuse information.
Available chunks are kept in any of several places (all declared below):
* `av': An array of chunks serving as bin headers for consolidated
chunks. Each bin is doubly linked. The bins are approximately
proportionally (log) spaced. There are a lot of these bins
(128). This may look excessive, but works very well in
practice. All procedures maintain the invariant that no
consolidated chunk physically borders another one. Chunks in
bins are kept in size order, with ties going to the
approximately least recently used chunk.
The chunks in each bin are maintained in decreasing sorted order by
size. This is irrelevant for the small bins, which all contain
the same-sized chunks, but facilitates best-fit allocation for
larger chunks. (These lists are just sequential. Keeping them in
order almost never requires enough traversal to warrant using
fancier ordered data structures.) Chunks of the same size are
linked with the most recently freed at the front, and allocations
are taken from the back. This results in LRU or FIFO allocation
order, which tends to give each chunk an equal opportunity to be
consolidated with adjacent freed chunks, resulting in larger free
chunks and less fragmentation.
* `top': The top-most available chunk (i.e., the one bordering the
end of available memory) is treated specially. It is never
included in any bin, is used only if no other chunk is
available, and is released back to the system if it is very
large (see M_TRIM_THRESHOLD).
* `last_remainder': A bin holding only the remainder of the
most recently split (non-top) chunk. This bin is checked
before other non-fitting chunks, so as to provide better
locality for runs of sequentially allocated chunks.
* Implicitly, through the host system's memory mapping tables.
If supported, requests greater than a threshold are usually
serviced via calls to mmap, and then later released via munmap.
*/
/* sizes, alignments */
#define SIZE_SZ (sizeof(INTERNAL_SIZE_T))
#ifndef MALLOC_ALIGNMENT
#define MALLOC_ALIGN 8
#define MALLOC_ALIGNMENT (SIZE_SZ < 4 ? 8 : (SIZE_SZ + SIZE_SZ))
#else
#define MALLOC_ALIGN MALLOC_ALIGNMENT
#endif
#define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1)
#define MINSIZE (sizeof(struct malloc_chunk))
/* conversion from malloc headers to user pointers, and back */
#define chunk2mem(p) ((Void_t*)((char*)(p) + 2*SIZE_SZ))
#define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ))
/* pad request bytes into a usable size */
#define request2size(req) \
(((unsigned long)((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) < \
(unsigned long)(MINSIZE + MALLOC_ALIGN_MASK)) ? ((MINSIZE + MALLOC_ALIGN_MASK) & ~(MALLOC_ALIGN_MASK)) : \
(((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) & ~(MALLOC_ALIGN_MASK)))
/* Check if m has acceptable alignment */
#define aligned_OK(m) (((unsigned long)((m)) & (MALLOC_ALIGN_MASK)) == 0)
/*
Physical chunk operations
*/
/* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */
#define PREV_INUSE 0x1
/* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */
#define IS_MMAPPED 0x2
/* Bits to mask off when extracting size */
#define SIZE_BITS (PREV_INUSE|IS_MMAPPED)
/* Ptr to next physical malloc_chunk. */
#define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->size & ~PREV_INUSE) ))
/* Ptr to previous physical malloc_chunk */
#define prev_chunk(p)\
((mchunkptr)( ((char*)(p)) - ((p)->prev_size) ))
/* Treat space at ptr + offset as a chunk */
#define chunk_at_offset(p, s) ((mchunkptr)(((char*)(p)) + (s)))
/*
Dealing with use bits
*/
/* extract p's inuse bit */
#define inuse(p)\
((((mchunkptr)(((char*)(p))+((p)->size & ~PREV_INUSE)))->size) & PREV_INUSE)
/* extract inuse bit of previous chunk */
#define prev_inuse(p) ((p)->size & PREV_INUSE)
/* check for mmap()'ed chunk */
#define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED)
/* set/clear chunk as in use without otherwise disturbing */
#define set_inuse(p)\
((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size |= PREV_INUSE
#define clear_inuse(p)\
((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size &= ~(PREV_INUSE)
/* check/set/clear inuse bits in known places */
#define inuse_bit_at_offset(p, s)\
(((mchunkptr)(((char*)(p)) + (s)))->size & PREV_INUSE)
#define set_inuse_bit_at_offset(p, s)\
(((mchunkptr)(((char*)(p)) + (s)))->size |= PREV_INUSE)
#define clear_inuse_bit_at_offset(p, s)\
(((mchunkptr)(((char*)(p)) + (s)))->size &= ~(PREV_INUSE))
/*
Dealing with size fields
*/
/* Get size, ignoring use bits */
#define chunksize(p) ((p)->size & ~(SIZE_BITS))
/* Set size at head, without disturbing its use bit */
#define set_head_size(p, s) ((p)->size = (((p)->size & PREV_INUSE) | (s)))
/* Set size/use ignoring previous bits in header */
#define set_head(p, s) ((p)->size = (s))
/* Set size at footer (only when chunk is not in use) */
#define set_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_size = (s))
/*
Bins
The bins, `av_' are an array of pairs of pointers serving as the
heads of (initially empty) doubly-linked lists of chunks, laid out
in a way so that each pair can be treated as if it were in a
malloc_chunk. (This way, the fd/bk offsets for linking bin heads
and chunks are the same).
Bins for sizes < 512 bytes contain chunks of all the same size, spaced
8 bytes apart. Larger bins are approximately logarithmically
spaced. (See the table below.) The `av_' array is never mentioned
directly in the code, but instead via bin access macros.
Bin layout:
64 bins of size 8
32 bins of size 64
16 bins of size 512
8 bins of size 4096
4 bins of size 32768
2 bins of size 262144
1 bin of size what's left
There is actually a little bit of slop in the numbers in bin_index
for the sake of speed. This makes no difference elsewhere.
The special chunks `top' and `last_remainder' get their own bins,
(this is implemented via yet more trickery with the av_ array),
although `top' is never properly linked to its bin since it is
always handled specially.
*/
#ifdef SEPARATE_OBJECTS
#define av_ malloc_av_
#endif
#define NAV 128 /* number of bins */
typedef struct malloc_chunk* mbinptr;
/* access macros */
#define bin_at(i) ((mbinptr)((char*)&(av_[2*(i) + 2]) - 2*SIZE_SZ))
#define next_bin(b) ((mbinptr)((char*)(b) + 2 * sizeof(mbinptr)))
#define prev_bin(b) ((mbinptr)((char*)(b) - 2 * sizeof(mbinptr)))
/*
The first 2 bins are never indexed. The corresponding av_ cells are instead
used for bookkeeping. This is not to save space, but to simplify
indexing, maintain locality, and avoid some initialization tests.
*/
#define top (bin_at(0)->fd) /* The topmost chunk */
#define last_remainder (bin_at(1)) /* remainder from last split */
/*
Because top initially points to its own bin with initial
zero size, thus forcing extension on the first malloc request,
we avoid having any special code in malloc to check whether
it even exists yet. But we still need to in malloc_extend_top.
*/
#define initial_top ((mchunkptr)(bin_at(0)))
/* Helper macro to initialize bins */
#define IAV(i) bin_at(i), bin_at(i)
#ifdef DEFINE_MALLOC
STATIC mbinptr av_[NAV * 2 + 2] = {
0, 0,
IAV(0), IAV(1), IAV(2), IAV(3), IAV(4), IAV(5), IAV(6), IAV(7),
IAV(8), IAV(9), IAV(10), IAV(11), IAV(12), IAV(13), IAV(14), IAV(15),
IAV(16), IAV(17), IAV(18), IAV(19), IAV(20), IAV(21), IAV(22), IAV(23),
IAV(24), IAV(25), IAV(26), IAV(27), IAV(28), IAV(29), IAV(30), IAV(31),
IAV(32), IAV(33), IAV(34), IAV(35), IAV(36), IAV(37), IAV(38), IAV(39),
IAV(40), IAV(41), IAV(42), IAV(43), IAV(44), IAV(45), IAV(46), IAV(47),
IAV(48), IAV(49), IAV(50), IAV(51), IAV(52), IAV(53), IAV(54), IAV(55),
IAV(56), IAV(57), IAV(58), IAV(59), IAV(60), IAV(61), IAV(62), IAV(63),
IAV(64), IAV(65), IAV(66), IAV(67), IAV(68), IAV(69), IAV(70), IAV(71),
IAV(72), IAV(73), IAV(74), IAV(75), IAV(76), IAV(77), IAV(78), IAV(79),
IAV(80), IAV(81), IAV(82), IAV(83), IAV(84), IAV(85), IAV(86), IAV(87),
IAV(88), IAV(89), IAV(90), IAV(91), IAV(92), IAV(93), IAV(94), IAV(95),
IAV(96), IAV(97), IAV(98), IAV(99), IAV(100), IAV(101), IAV(102), IAV(103),
IAV(104), IAV(105), IAV(106), IAV(107), IAV(108), IAV(109), IAV(110), IAV(111),
IAV(112), IAV(113), IAV(114), IAV(115), IAV(116), IAV(117), IAV(118), IAV(119),
IAV(120), IAV(121), IAV(122), IAV(123), IAV(124), IAV(125), IAV(126), IAV(127)
};
#else
extern mbinptr av_[NAV * 2 + 2];
#endif
/* field-extraction macros */
#define first(b) ((b)->fd)
#define last(b) ((b)->bk)
/*
Indexing into bins
*/
#define bin_index(sz) \
(((((unsigned long)(sz)) >> 9) == 0) ? (((unsigned long)(sz)) >> 3): \
((((unsigned long)(sz)) >> 9) <= 4) ? 56 + (((unsigned long)(sz)) >> 6): \
((((unsigned long)(sz)) >> 9) <= 20) ? 91 + (((unsigned long)(sz)) >> 9): \
((((unsigned long)(sz)) >> 9) <= 84) ? 110 + (((unsigned long)(sz)) >> 12): \
((((unsigned long)(sz)) >> 9) <= 340) ? 119 + (((unsigned long)(sz)) >> 15): \
((((unsigned long)(sz)) >> 9) <= 1364) ? 124 + (((unsigned long)(sz)) >> 18): \
126)
/*
bins for chunks < 512 are all spaced SMALLBIN_WIDTH bytes apart, and hold
identically sized chunks. This is exploited in malloc.
*/
#define MAX_SMALLBIN_SIZE 512
#define SMALLBIN_WIDTH 8
#define SMALLBIN_WIDTH_BITS 3
#define MAX_SMALLBIN (MAX_SMALLBIN_SIZE / SMALLBIN_WIDTH) - 1
#define smallbin_index(sz) (((unsigned long)(sz)) >> SMALLBIN_WIDTH_BITS)
/*
Requests are `small' if both the corresponding and the next bin are small
*/
#define is_small_request(nb) (nb < MAX_SMALLBIN_SIZE - SMALLBIN_WIDTH)
/*
To help compensate for the large number of bins, a one-level index
structure is used for bin-by-bin searching. `binblocks' is a
one-word bitvector recording whether groups of BINBLOCKWIDTH bins
have any (possibly) non-empty bins, so they can be skipped over
all at once during during traversals. The bits are NOT always
cleared as soon as all bins in a block are empty, but instead only
when all are noticed to be empty during traversal in malloc.
*/
#define BINBLOCKWIDTH 4 /* bins per block */
#define binblocks (bin_at(0)->size) /* bitvector of nonempty blocks */
/* bin<->block macros */
#define idx2binblock(ix) ((unsigned long)1 << (ix / BINBLOCKWIDTH))
#define mark_binblock(ii) (binblocks |= idx2binblock(ii))
#define clear_binblock(ii) (binblocks &= ~(idx2binblock(ii)))
/* Other static bookkeeping data */
#ifdef SEPARATE_OBJECTS
#define trim_threshold malloc_trim_threshold
#define top_pad malloc_top_pad
#define n_mmaps_max malloc_n_mmaps_max
#define mmap_threshold malloc_mmap_threshold
#define sbrk_base malloc_sbrk_base
#define max_sbrked_mem malloc_max_sbrked_mem
#define max_total_mem malloc_max_total_mem
#define current_mallinfo malloc_current_mallinfo
#define n_mmaps malloc_n_mmaps
#define max_n_mmaps malloc_max_n_mmaps
#define mmapped_mem malloc_mmapped_mem
#define max_mmapped_mem malloc_max_mmapped_mem
#endif
/* variables holding tunable values */
#ifdef DEFINE_MALLOC
STATIC unsigned long trim_threshold = DEFAULT_TRIM_THRESHOLD;
STATIC unsigned long top_pad = DEFAULT_TOP_PAD;
#if HAVE_MMAP
STATIC unsigned int n_mmaps_max = DEFAULT_MMAP_MAX;
STATIC unsigned long mmap_threshold = DEFAULT_MMAP_THRESHOLD;
#endif
/* The first value returned from sbrk */
STATIC char* sbrk_base = (char*)(-1);
/* The maximum memory obtained from system via sbrk */
STATIC unsigned long max_sbrked_mem = 0;
/* The maximum via either sbrk or mmap */
STATIC unsigned long max_total_mem = 0;
/* internal working copy of mallinfo */
STATIC struct mallinfo current_mallinfo = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
#if HAVE_MMAP
/* Tracking mmaps */
STATIC unsigned int n_mmaps = 0;
STATIC unsigned int max_n_mmaps = 0;
STATIC unsigned long mmapped_mem = 0;
STATIC unsigned long max_mmapped_mem = 0;
#endif
#else /* ! DEFINE_MALLOC */
extern unsigned long trim_threshold;
extern unsigned long top_pad;
#if HAVE_MMAP
extern unsigned int n_mmaps_max;
extern unsigned long mmap_threshold;
#endif
extern char* sbrk_base;
extern unsigned long max_sbrked_mem;
extern unsigned long max_total_mem;
extern struct mallinfo current_mallinfo;
#if HAVE_MMAP
extern unsigned int n_mmaps;
extern unsigned int max_n_mmaps;
extern unsigned long mmapped_mem;
extern unsigned long max_mmapped_mem;
#endif
#endif /* ! DEFINE_MALLOC */
/* The total memory obtained from system via sbrk */
#define sbrked_mem (current_mallinfo.arena)
/*
Debugging support
*/
#if DEBUG
/*
These routines make a number of assertions about the states
of data structures that should be true at all times. If any
are not true, it's very likely that a user program has somehow
trashed memory. (It's also possible that there is a coding error
in malloc. In which case, please report it!)
*/
#if __STD_C
static void do_check_chunk(mchunkptr p)
#else
static void do_check_chunk(p) mchunkptr p;
#endif
{
INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
/* No checkable chunk is mmapped */
assert(!chunk_is_mmapped(p));
/* Check for legal address ... */
assert((char*)p >= sbrk_base);
if (p != top)
assert((char*)p + sz <= (char*)top);
else
assert((char*)p + sz <= sbrk_base + sbrked_mem);
}
#if __STD_C
static void do_check_free_chunk(mchunkptr p)
#else
static void do_check_free_chunk(p) mchunkptr p;
#endif
{
INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
mchunkptr next = chunk_at_offset(p, sz);
do_check_chunk(p);
/* Check whether it claims to be free ... */
assert(!inuse(p));
/* Unless a special marker, must have OK fields */
if ((long)sz >= (long)MINSIZE)
{
assert((sz & MALLOC_ALIGN_MASK) == 0);
assert(aligned_OK(chunk2mem(p)));
/* ... matching footer field */
assert(next->prev_size == sz);
/* ... and is fully consolidated */
assert(prev_inuse(p));
assert (next == top || inuse(next));
/* ... and has minimally sane links */
assert(p->fd->bk == p);
assert(p->bk->fd == p);
}
else /* markers are always of size SIZE_SZ */
assert(sz == SIZE_SZ);
}
#if __STD_C
static void do_check_inuse_chunk(mchunkptr p)
#else
static void do_check_inuse_chunk(p) mchunkptr p;
#endif
{
mchunkptr next = next_chunk(p);
do_check_chunk(p);
/* Check whether it claims to be in use ... */
assert(inuse(p));
/* ... and is surrounded by OK chunks.
Since more things can be checked with free chunks than inuse ones,
if an inuse chunk borders them and debug is on, it's worth doing them.
*/
if (!prev_inuse(p))
{
mchunkptr prv = prev_chunk(p);
assert(next_chunk(prv) == p);
do_check_free_chunk(prv);
}
if (next == top)
{
assert(prev_inuse(next));
assert(chunksize(next) >= MINSIZE);
}
else if (!inuse(next))
do_check_free_chunk(next);
}
#if __STD_C
static void do_check_malloced_chunk(mchunkptr p, INTERNAL_SIZE_T s)
#else
static void do_check_malloced_chunk(p, s) mchunkptr p; INTERNAL_SIZE_T s;
#endif
{
INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
long room = long_sub_size_t(sz, s);
do_check_inuse_chunk(p);
/* Legal size ... */
assert((long)sz >= (long)MINSIZE);
assert((sz & MALLOC_ALIGN_MASK) == 0);
assert(room >= 0);
assert(room < (long)MINSIZE);
/* ... and alignment */
assert(aligned_OK(chunk2mem(p)));
/* ... and was allocated at front of an available chunk */
assert(prev_inuse(p));
}
#define check_free_chunk(P) do_check_free_chunk(P)
#define check_inuse_chunk(P) do_check_inuse_chunk(P)
#define check_chunk(P) do_check_chunk(P)
#define check_malloced_chunk(P,N) do_check_malloced_chunk(P,N)
#else
#define check_free_chunk(P)
#define check_inuse_chunk(P)
#define check_chunk(P)
#define check_malloced_chunk(P,N)
#endif
/*
Macro-based internal utilities
*/
/*
Linking chunks in bin lists.
Call these only with variables, not arbitrary expressions, as arguments.
*/
/*
Place chunk p of size s in its bin, in size order,
putting it ahead of others of same size.
*/
#define frontlink(P, S, IDX, BK, FD) \
{ \
if (S < MAX_SMALLBIN_SIZE) \
{ \
IDX = smallbin_index(S); \
mark_binblock(IDX); \
BK = bin_at(IDX); \
FD = BK->fd; \
P->bk = BK; \
P->fd = FD; \
FD->bk = BK->fd = P; \
} \
else \
{ \
IDX = bin_index(S); \
BK = bin_at(IDX); \
FD = BK->fd; \
if (FD == BK) mark_binblock(IDX); \
else \
{ \
while (FD != BK && S < chunksize(FD)) FD = FD->fd; \
BK = FD->bk; \
} \
P->bk = BK; \
P->fd = FD; \
FD->bk = BK->fd = P; \
} \
}
/* take a chunk off a list */
#define unlink(P, BK, FD) \
{ \
BK = P->bk; \
FD = P->fd; \
FD->bk = BK; \
BK->fd = FD; \
} \
/* Place p as the last remainder */
#define link_last_remainder(P) \
{ \
last_remainder->fd = last_remainder->bk = P; \
P->fd = P->bk = last_remainder; \
}
/* Clear the last_remainder bin */
#define clear_last_remainder \
(last_remainder->fd = last_remainder->bk = last_remainder)
/* Routines dealing with mmap(). */
#if HAVE_MMAP
#ifdef DEFINE_MALLOC
#if __STD_C
static mchunkptr mmap_chunk(size_t size)
#else
static mchunkptr mmap_chunk(size) size_t size;
#endif
{
size_t page_mask = malloc_getpagesize - 1;
mchunkptr p;
#ifndef MAP_ANONYMOUS
static int fd = -1;
#endif
if(n_mmaps >= n_mmaps_max) return 0; /* too many regions */
/* For mmapped chunks, the overhead is one SIZE_SZ unit larger, because
* there is no following chunk whose prev_size field could be used.
*/
size = (size + SIZE_SZ + page_mask) & ~page_mask;
#ifdef MAP_ANONYMOUS
p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
#else /* !MAP_ANONYMOUS */
if (fd < 0)
{
fd = open("/dev/zero", O_RDWR);
if(fd < 0) return 0;
}
p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
#endif
if(p == (mchunkptr)-1) return 0;
n_mmaps++;
if (n_mmaps > max_n_mmaps) max_n_mmaps = n_mmaps;
/* We demand that eight bytes into a page must be 8-byte aligned. */
assert(aligned_OK(chunk2mem(p)));
/* The offset to the start of the mmapped region is stored
* in the prev_size field of the chunk; normally it is zero,
* but that can be changed in memalign().
*/
p->prev_size = 0;
set_head(p, size|IS_MMAPPED);
mmapped_mem += size;
if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)
max_mmapped_mem = mmapped_mem;
if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
max_total_mem = mmapped_mem + sbrked_mem;
return p;
}
#endif /* DEFINE_MALLOC */
#ifdef SEPARATE_OBJECTS
#define munmap_chunk malloc_munmap_chunk
#endif
#ifdef DEFINE_FREE
#if __STD_C
STATIC void munmap_chunk(mchunkptr p)
#else
STATIC void munmap_chunk(p) mchunkptr p;
#endif
{
INTERNAL_SIZE_T size = chunksize(p);
int ret;
assert (chunk_is_mmapped(p));
assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
assert((n_mmaps > 0));
assert(((p->prev_size + size) & (malloc_getpagesize-1)) == 0);
n_mmaps--;
mmapped_mem -= (size + p->prev_size);
ret = munmap((char *)p - p->prev_size, size + p->prev_size);
/* munmap returns non-zero on failure */
assert(ret == 0);
}
#else /* ! DEFINE_FREE */
#if __STD_C
extern void munmap_chunk(mchunkptr);
#else
extern void munmap_chunk();
#endif
#endif /* ! DEFINE_FREE */
#if HAVE_MREMAP
#ifdef DEFINE_REALLOC
#if __STD_C
static mchunkptr mremap_chunk(mchunkptr p, size_t new_size)
#else
static mchunkptr mremap_chunk(p, new_size) mchunkptr p; size_t new_size;
#endif
{
size_t page_mask = malloc_getpagesize - 1;
INTERNAL_SIZE_T offset = p->prev_size;
INTERNAL_SIZE_T size = chunksize(p);
char *cp;
assert (chunk_is_mmapped(p));
assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
assert((n_mmaps > 0));
assert(((size + offset) & (malloc_getpagesize-1)) == 0);
/* Note the extra SIZE_SZ overhead as in mmap_chunk(). */
new_size = (new_size + offset + SIZE_SZ + page_mask) & ~page_mask;
cp = (char *)mremap((char *)p - offset, size + offset, new_size, 1);
if (cp == (char *)-1) return 0;
p = (mchunkptr)(cp + offset);
assert(aligned_OK(chunk2mem(p)));
assert((p->prev_size == offset));
set_head(p, (new_size - offset)|IS_MMAPPED);
mmapped_mem -= size + offset;
mmapped_mem += new_size;
if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)
max_mmapped_mem = mmapped_mem;
if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
max_total_mem = mmapped_mem + sbrked_mem;
return p;
}
#endif /* DEFINE_REALLOC */
#endif /* HAVE_MREMAP */
#endif /* HAVE_MMAP */
#ifdef DEFINE_MALLOC
/*
Extend the top-most chunk by obtaining memory from system.
Main interface to sbrk (but see also malloc_trim).
*/
#if __STD_C
static void malloc_extend_top(RARG INTERNAL_SIZE_T nb)
#else
static void malloc_extend_top(RARG nb) RDECL INTERNAL_SIZE_T nb;
#endif
{
char* brk; /* return value from sbrk */
INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of sbrked space */
INTERNAL_SIZE_T correction; /* bytes for 2nd sbrk call */
int correction_failed = 0; /* whether we should relax the assertion */
char* new_brk; /* return of 2nd sbrk call */
INTERNAL_SIZE_T top_size; /* new size of top chunk */
mchunkptr old_top = top; /* Record state of old top */
INTERNAL_SIZE_T old_top_size = chunksize(old_top);
char* old_end = (char*)(chunk_at_offset(old_top, old_top_size));
/* Pad request with top_pad plus minimal overhead */
INTERNAL_SIZE_T sbrk_size = nb + top_pad + MINSIZE;
unsigned long pagesz = malloc_getpagesize;
/* If not the first time through, round to preserve page boundary */
/* Otherwise, we need to correct to a page size below anyway. */
/* (We also correct below if an intervening foreign sbrk call.) */
if (sbrk_base != (char*)(-1))
sbrk_size = (sbrk_size + (pagesz - 1)) & ~(pagesz - 1);
brk = (char*)(MORECORE (sbrk_size));
/* Fail if sbrk failed or if a foreign sbrk call killed our space */
if (brk == (char*)(MORECORE_FAILURE) ||
(brk < old_end && old_top != initial_top))
return;
sbrked_mem += sbrk_size;
if (brk == old_end /* can just add bytes to current top, unless
previous correction failed */
&& ((POINTER_UINT)old_end & (pagesz - 1)) == 0)
{
top_size = sbrk_size + old_top_size;
set_head(top, top_size | PREV_INUSE);
}
else
{
if (sbrk_base == (char*)(-1)) /* First time through. Record base */
sbrk_base = brk;
else /* Someone else called sbrk(). Count those bytes as sbrked_mem. */
sbrked_mem += brk - (char*)old_end;
/* Guarantee alignment of first new chunk made from this space */
front_misalign = (POINTER_UINT)chunk2mem(brk) & MALLOC_ALIGN_MASK;
if (front_misalign > 0)
{
correction = (MALLOC_ALIGNMENT) - front_misalign;
brk += correction;
}
else
correction = 0;
/* Guarantee the next brk will be at a page boundary */
correction += pagesz - ((POINTER_UINT)(brk + sbrk_size) & (pagesz - 1));
/* Allocate correction */
new_brk = (char*)(MORECORE (correction));
if (new_brk == (char*)(MORECORE_FAILURE))
{
correction = 0;
correction_failed = 1;
new_brk = brk;
}
sbrked_mem += correction;
top = (mchunkptr)brk;
top_size = new_brk - brk + correction;
set_head(top, top_size | PREV_INUSE);
if (old_top != initial_top)
{
/* There must have been an intervening foreign sbrk call. */
/* A double fencepost is necessary to prevent consolidation */
/* If not enough space to do this, then user did something very wrong */
if (old_top_size < MINSIZE)
{
set_head(top, PREV_INUSE); /* will force null return from malloc */
return;
}
/* Also keep size a multiple of MALLOC_ALIGNMENT */
old_top_size = (old_top_size - 3*SIZE_SZ) & ~MALLOC_ALIGN_MASK;
chunk_at_offset(old_top, old_top_size )->size =
SIZE_SZ|PREV_INUSE;
chunk_at_offset(old_top, old_top_size + SIZE_SZ)->size =
SIZE_SZ|PREV_INUSE;
set_head_size(old_top, old_top_size);
/* If possible, release the rest. */
if (old_top_size >= MINSIZE)
fREe(RCALL chunk2mem(old_top));
}
}
if ((unsigned long)sbrked_mem > (unsigned long)max_sbrked_mem)
max_sbrked_mem = sbrked_mem;
#if HAVE_MMAP
if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
max_total_mem = mmapped_mem + sbrked_mem;
#else
if ((unsigned long)(sbrked_mem) > (unsigned long)max_total_mem)
max_total_mem = sbrked_mem;
#endif
/* We always land on a page boundary */
assert(((unsigned long)((char*)top + top_size) & (pagesz - 1)) == 0
|| correction_failed);
}
#endif /* DEFINE_MALLOC */
/* Main public routines */
#ifdef DEFINE_MALLOC
/*
Malloc Algorthim:
The requested size is first converted into a usable form, `nb'.
This currently means to add 4 bytes overhead plus possibly more to
obtain 8-byte alignment and/or to obtain a size of at least
MINSIZE (currently 16 bytes), the smallest allocatable size.
(All fits are considered `exact' if they are within MINSIZE bytes.)
From there, the first successful of the following steps is taken:
1. The bin corresponding to the request size is scanned, and if
a chunk of exactly the right size is found, it is taken.
2. The most recently remaindered chunk is used if it is big
enough. This is a form of (roving) first fit, used only in
the absence of exact fits. Runs of consecutive requests use
the remainder of the chunk used for the previous such request
whenever possible. This limited use of a first-fit style
allocation strategy tends to give contiguous chunks
coextensive lifetimes, which improves locality and can reduce
fragmentation in the long run.
3. Other bins are scanned in increasing size order, using a
chunk big enough to fulfill the request, and splitting off
any remainder. This search is strictly by best-fit; i.e.,
the smallest (with ties going to approximately the least
recently used) chunk that fits is selected.
4. If large enough, the chunk bordering the end of memory
(`top') is split off. (This use of `top' is in accord with
the best-fit search rule. In effect, `top' is treated as
larger (and thus less well fitting) than any other available
chunk since it can be extended to be as large as necessary
(up to system limitations).
5. If the request size meets the mmap threshold and the
system supports mmap, and there are few enough currently
allocated mmapped regions, and a call to mmap succeeds,
the request is allocated via direct memory mapping.
6. Otherwise, the top of memory is extended by
obtaining more space from the system (normally using sbrk,
but definable to anything else via the MORECORE macro).
Memory is gathered from the system (in system page-sized
units) in a way that allows chunks obtained across different
sbrk calls to be consolidated, but does not require
contiguous memory. Thus, it should be safe to intersperse
mallocs with other sbrk calls.
All allocations are made from the the `lowest' part of any found
chunk. (The implementation invariant is that prev_inuse is
always true of any allocated chunk; i.e., that each allocated
chunk borders either a previously allocated and still in-use chunk,
or the base of its memory arena.)
*/
#if __STD_C
Void_t* mALLOc(RARG size_t bytes)
#else
Void_t* mALLOc(RARG bytes) RDECL size_t bytes;
#endif
{
#ifdef MALLOC_PROVIDED
return malloc (bytes); // Make sure that the pointer returned by malloc is returned back.
#else
mchunkptr victim; /* inspected/selected chunk */
INTERNAL_SIZE_T victim_size; /* its size */
int idx; /* index for bin traversal */
mbinptr bin; /* associated bin */
mchunkptr remainder; /* remainder from a split */
long remainder_size; /* its size */
int remainder_index; /* its bin index */
unsigned long block; /* block traverser bit */
int startidx; /* first bin of a traversed block */
mchunkptr fwd; /* misc temp for linking */
mchunkptr bck; /* misc temp for linking */
mbinptr q; /* misc temp */
INTERNAL_SIZE_T nb = request2size(bytes); /* padded request size; */
/* Check for overflow and just fail, if so. */
if (nb > INT_MAX || nb < bytes)
{
RERRNO = ENOMEM;
return 0;
}
MALLOC_LOCK;
/* Check for exact match in a bin */
if (is_small_request(nb)) /* Faster version for small requests */
{
idx = smallbin_index(nb);
/* No traversal or size check necessary for small bins. */
q = bin_at(idx);
victim = last(q);
#if MALLOC_ALIGN != 16
/* Also scan the next one, since it would have a remainder < MINSIZE */
if (victim == q)
{
q = next_bin(q);
victim = last(q);
}
#endif
if (victim != q)
{
victim_size = chunksize(victim);
unlink(victim, bck, fwd);
set_inuse_bit_at_offset(victim, victim_size);
check_malloced_chunk(victim, nb);
MALLOC_UNLOCK;
return chunk2mem(victim);
}
idx += 2; /* Set for bin scan below. We've already scanned 2 bins. */
}
else
{
idx = bin_index(nb);
bin = bin_at(idx);
for (victim = last(bin); victim != bin; victim = victim->bk)
{
victim_size = chunksize(victim);
remainder_size = long_sub_size_t(victim_size, nb);
if (remainder_size >= (long)MINSIZE) /* too big */
{
--idx; /* adjust to rescan below after checking last remainder */
break;
}
else if (remainder_size >= 0) /* exact fit */
{
unlink(victim, bck, fwd);
set_inuse_bit_at_offset(victim, victim_size);
check_malloced_chunk(victim, nb);
MALLOC_UNLOCK;
return chunk2mem(victim);
}
}
++idx;
}
/* Try to use the last split-off remainder */
if ( (victim = last_remainder->fd) != last_remainder)
{
victim_size = chunksize(victim);
remainder_size = long_sub_size_t(victim_size, nb);
if (remainder_size >= (long)MINSIZE) /* re-split */
{
remainder = chunk_at_offset(victim, nb);
set_head(victim, nb | PREV_INUSE);
link_last_remainder(remainder);
set_head(remainder, remainder_size | PREV_INUSE);
set_foot(remainder, remainder_size);
check_malloced_chunk(victim, nb);
MALLOC_UNLOCK;
return chunk2mem(victim);
}
clear_last_remainder;
if (remainder_size >= 0) /* exhaust */
{
set_inuse_bit_at_offset(victim, victim_size);
check_malloced_chunk(victim, nb);
MALLOC_UNLOCK;
return chunk2mem(victim);
}
/* Else place in bin */
frontlink(victim, victim_size, remainder_index, bck, fwd);
}
/*
If there are any possibly nonempty big-enough blocks,
search for best fitting chunk by scanning bins in blockwidth units.
*/
if ( (block = idx2binblock(idx)) <= binblocks)
{
/* Get to the first marked block */
if ( (block & binblocks) == 0)
{
/* force to an even block boundary */
idx = (idx & ~(BINBLOCKWIDTH - 1)) + BINBLOCKWIDTH;
block <<= 1;
while ((block & binblocks) == 0)
{
idx += BINBLOCKWIDTH;
block <<= 1;
}
}
/* For each possibly nonempty block ... */
for (;;)
{
startidx = idx; /* (track incomplete blocks) */
q = bin = bin_at(idx);
/* For each bin in this block ... */
do
{
/* Find and use first big enough chunk ... */
for (victim = last(bin); victim != bin; victim = victim->bk)
{
victim_size = chunksize(victim);
remainder_size = long_sub_size_t(victim_size, nb);
if (remainder_size >= (long)MINSIZE) /* split */
{
remainder = chunk_at_offset(victim, nb);
set_head(victim, nb | PREV_INUSE);
unlink(victim, bck, fwd);
link_last_remainder(remainder);
set_head(remainder, remainder_size | PREV_INUSE);
set_foot(remainder, remainder_size);
check_malloced_chunk(victim, nb);
MALLOC_UNLOCK;
return chunk2mem(victim);
}
else if (remainder_size >= 0) /* take */
{
set_inuse_bit_at_offset(victim, victim_size);
unlink(victim, bck, fwd);
check_malloced_chunk(victim, nb);
MALLOC_UNLOCK;
return chunk2mem(victim);
}
}
bin = next_bin(bin);
#if MALLOC_ALIGN == 16
if (idx < MAX_SMALLBIN)
{
bin = next_bin(bin);
++idx;
}
#endif
} while ((++idx & (BINBLOCKWIDTH - 1)) != 0);
/* Clear out the block bit. */
do /* Possibly backtrack to try to clear a partial block */
{
if ((startidx & (BINBLOCKWIDTH - 1)) == 0)
{
binblocks &= ~block;
break;
}
--startidx;
q = prev_bin(q);
} while (first(q) == q);
/* Get to the next possibly nonempty block */
if ( (block <<= 1) <= binblocks && (block != 0) )
{
while ((block & binblocks) == 0)
{
idx += BINBLOCKWIDTH;
block <<= 1;
}
}
else
break;
}
}
/* Try to use top chunk */
/* Require that there be a remainder, ensuring top always exists */
remainder_size = long_sub_size_t(chunksize(top), nb);
if (chunksize(top) < nb || remainder_size < (long)MINSIZE)
{
#if HAVE_MMAP
/* If big and would otherwise need to extend, try to use mmap instead */
if ((unsigned long)nb >= (unsigned long)mmap_threshold &&
(victim = mmap_chunk(nb)) != 0)
{
MALLOC_UNLOCK;
return chunk2mem(victim);
}
#endif
/* Try to extend */
malloc_extend_top(RCALL nb);
remainder_size = long_sub_size_t(chunksize(top), nb);
if (chunksize(top) < nb || remainder_size < (long)MINSIZE)
{
MALLOC_UNLOCK;
return 0; /* propagate failure */
}
}
victim = top;
set_head(victim, nb | PREV_INUSE);
top = chunk_at_offset(victim, nb);
set_head(top, remainder_size | PREV_INUSE);
check_malloced_chunk(victim, nb);
MALLOC_UNLOCK;
return chunk2mem(victim);
#endif /* MALLOC_PROVIDED */
}
#endif /* DEFINE_MALLOC */
#ifdef DEFINE_FREE
/*
free() algorithm :
cases:
1. free(0) has no effect.
2. If the chunk was allocated via mmap, it is release via munmap().
3. If a returned chunk borders the current high end of memory,
it is consolidated into the top, and if the total unused
topmost memory exceeds the trim threshold, malloc_trim is
called.
4. Other chunks are consolidated as they arrive, and
placed in corresponding bins. (This includes the case of
consolidating with the current `last_remainder').
*/
#if __STD_C
void fREe(RARG Void_t* mem)
#else
void fREe(RARG mem) RDECL Void_t* mem;
#endif
{
#ifdef MALLOC_PROVIDED
free (mem);
#else
mchunkptr p; /* chunk corresponding to mem */
INTERNAL_SIZE_T hd; /* its head field */
INTERNAL_SIZE_T sz; /* its size */
int idx; /* its bin index */
mchunkptr next; /* next contiguous chunk */
INTERNAL_SIZE_T nextsz; /* its size */
INTERNAL_SIZE_T prevsz; /* size of previous contiguous chunk */
mchunkptr bck; /* misc temp for linking */
mchunkptr fwd; /* misc temp for linking */
int islr; /* track whether merging with last_remainder */
if (mem == 0) /* free(0) has no effect */
return;
MALLOC_LOCK;
p = mem2chunk(mem);
hd = p->size;
#if HAVE_MMAP
if (hd & IS_MMAPPED) /* release mmapped memory. */
{
munmap_chunk(p);
MALLOC_UNLOCK;
return;
}
#endif
check_inuse_chunk(p);
sz = hd & ~PREV_INUSE;
next = chunk_at_offset(p, sz);
nextsz = chunksize(next);
if (next == top) /* merge with top */
{
sz += nextsz;
if (!(hd & PREV_INUSE)) /* consolidate backward */
{
prevsz = p->prev_size;
p = chunk_at_offset(p, -prevsz);
sz += prevsz;
unlink(p, bck, fwd);
}
set_head(p, sz | PREV_INUSE);
top = p;
if ((unsigned long)(sz) >= (unsigned long)trim_threshold)
malloc_trim(RCALL top_pad);
MALLOC_UNLOCK;
return;
}
set_head(next, nextsz); /* clear inuse bit */
islr = 0;
if (!(hd & PREV_INUSE)) /* consolidate backward */
{
prevsz = p->prev_size;
p = chunk_at_offset(p, -prevsz);
sz += prevsz;
if (p->fd == last_remainder) /* keep as last_remainder */
islr = 1;
else
unlink(p, bck, fwd);
}
if (!(inuse_bit_at_offset(next, nextsz))) /* consolidate forward */
{
sz += nextsz;
if (!islr && next->fd == last_remainder) /* re-insert last_remainder */
{
islr = 1;
link_last_remainder(p);
}
else
unlink(next, bck, fwd);
}
set_head(p, sz | PREV_INUSE);
set_foot(p, sz);
if (!islr)
frontlink(p, sz, idx, bck, fwd);
MALLOC_UNLOCK;
#endif /* MALLOC_PROVIDED */
}
#endif /* DEFINE_FREE */
#ifdef DEFINE_REALLOC
/*
Realloc algorithm:
Chunks that were obtained via mmap cannot be extended or shrunk
unless HAVE_MREMAP is defined, in which case mremap is used.
Otherwise, if their reallocation is for additional space, they are
copied. If for less, they are just left alone.
Otherwise, if the reallocation is for additional space, and the
chunk can be extended, it is, else a malloc-copy-free sequence is
taken. There are several different ways that a chunk could be
extended. All are tried:
* Extending forward into following adjacent free chunk.
* Shifting backwards, joining preceding adjacent space
* Both shifting backwards and extending forward.
* Extending into newly sbrked space
Unless the #define REALLOC_ZERO_BYTES_FREES is set, realloc with a
size argument of zero (re)allocates a minimum-sized chunk.
If the reallocation is for less space, and the new request is for
a `small' (<512 bytes) size, then the newly unused space is lopped
off and freed.
The old unix realloc convention of allowing the last-free'd chunk
to be used as an argument to realloc is no longer supported.
I don't know of any programs still relying on this feature,
and allowing it would also allow too many other incorrect
usages of realloc to be sensible.
*/
#if __STD_C
Void_t* rEALLOc(RARG Void_t* oldmem, size_t bytes)
#else
Void_t* rEALLOc(RARG oldmem, bytes) RDECL Void_t* oldmem; size_t bytes;
#endif
{
#ifdef MALLOC_PROVIDED
realloc (oldmem, bytes);
#else
INTERNAL_SIZE_T nb; /* padded request size */
mchunkptr oldp; /* chunk corresponding to oldmem */
INTERNAL_SIZE_T oldsize; /* its size */
mchunkptr newp; /* chunk to return */
INTERNAL_SIZE_T newsize; /* its size */
Void_t* newmem; /* corresponding user mem */
mchunkptr next; /* next contiguous chunk after oldp */
INTERNAL_SIZE_T nextsize; /* its size */
mchunkptr prev; /* previous contiguous chunk before oldp */
INTERNAL_SIZE_T prevsize; /* its size */
mchunkptr remainder; /* holds split off extra space from newp */
INTERNAL_SIZE_T remainder_size; /* its size */
mchunkptr bck; /* misc temp for linking */
mchunkptr fwd; /* misc temp for linking */
#ifdef REALLOC_ZERO_BYTES_FREES
if (bytes == 0) { fREe(RCALL oldmem); return 0; }
#endif
/* realloc of null is supposed to be same as malloc */
if (oldmem == 0) return mALLOc(RCALL bytes);
MALLOC_LOCK;
newp = oldp = mem2chunk(oldmem);
newsize = oldsize = chunksize(oldp);
nb = request2size(bytes);
/* Check for overflow and just fail, if so. */
if (nb > INT_MAX || nb < bytes)
{
RERRNO = ENOMEM;
return 0;
}
#if HAVE_MMAP
if (chunk_is_mmapped(oldp))
{
#if HAVE_MREMAP
newp = mremap_chunk(oldp, nb);
if(newp)
{
MALLOC_UNLOCK;
return chunk2mem(newp);
}
#endif
/* Note the extra SIZE_SZ overhead. */
if(oldsize - SIZE_SZ >= nb)
{
MALLOC_UNLOCK;
return oldmem; /* do nothing */
}
/* Must alloc, copy, free. */
newmem = mALLOc(RCALL bytes);
if (newmem == 0)
{
MALLOC_UNLOCK;
return 0; /* propagate failure */
}
MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ);
munmap_chunk(oldp);
MALLOC_UNLOCK;
return newmem;
}
#endif
check_inuse_chunk(oldp);
if ((long)(oldsize) < (long)(nb))
{
/* Try expanding forward */
next = chunk_at_offset(oldp, oldsize);
if (next == top || !inuse(next))
{
nextsize = chunksize(next);
/* Forward into top only if a remainder */
if (next == top)
{
if ((long)(nextsize + newsize) >= (long)(nb + MINSIZE))
{
newsize += nextsize;
top = chunk_at_offset(oldp, nb);
set_head(top, (newsize - nb) | PREV_INUSE);
set_head_size(oldp, nb);
MALLOC_UNLOCK;
return chunk2mem(oldp);
}
}
/* Forward into next chunk */
else if (((long)(nextsize + newsize) >= (long)(nb)))
{
unlink(next, bck, fwd);
newsize += nextsize;
goto split;
}
}
else
{
next = 0;
nextsize = 0;
}
/* Try shifting backwards. */
if (!prev_inuse(oldp))
{
prev = prev_chunk(oldp);
prevsize = chunksize(prev);
/* try forward + backward first to save a later consolidation */
if (next != 0)
{
/* into top */
if (next == top)
{
if ((long)(nextsize + prevsize + newsize) >= (long)(nb + MINSIZE))
{
unlink(prev, bck, fwd);
newp = prev;
newsize += prevsize + nextsize;
newmem = chunk2mem(newp);
MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
top = chunk_at_offset(newp, nb);
set_head(top, (newsize - nb) | PREV_INUSE);
set_head_size(newp, nb);
MALLOC_UNLOCK;
return newmem;
}
}
/* into next chunk */
else if (((long)(nextsize + prevsize + newsize) >= (long)(nb)))
{
unlink(next, bck, fwd);
unlink(prev, bck, fwd);
newp = prev;
newsize += nextsize + prevsize;
newmem = chunk2mem(newp);
MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
goto split;
}
}
/* backward only */
if (prev != 0 && (long)(prevsize + newsize) >= (long)nb)
{
unlink(prev, bck, fwd);
newp = prev;
newsize += prevsize;
newmem = chunk2mem(newp);
MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
goto split;
}
}
/* Must allocate */
newmem = mALLOc (RCALL bytes);
if (newmem == 0) /* propagate failure */
{
MALLOC_UNLOCK;
return 0;
}
/* Avoid copy if newp is next chunk after oldp. */
/* (This can only happen when new chunk is sbrk'ed.) */
if ( (newp = mem2chunk(newmem)) == next_chunk(oldp))
{
newsize += chunksize(newp);
newp = oldp;
goto split;
}
/* Otherwise copy, free, and exit */
MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
fREe(RCALL oldmem);
MALLOC_UNLOCK;
return newmem;
}
split: /* split off extra room in old or expanded chunk */
remainder_size = long_sub_size_t(newsize, nb);
if (remainder_size >= (long)MINSIZE) /* split off remainder */
{
remainder = chunk_at_offset(newp, nb);
set_head_size(newp, nb);
set_head(remainder, remainder_size | PREV_INUSE);
set_inuse_bit_at_offset(remainder, remainder_size);
fREe(RCALL chunk2mem(remainder)); /* let free() deal with it */
}
else
{
set_head_size(newp, newsize);
set_inuse_bit_at_offset(newp, newsize);
}
check_inuse_chunk(newp);
MALLOC_UNLOCK;
return chunk2mem(newp);
#endif /* MALLOC_PROVIDED */
}
#endif /* DEFINE_REALLOC */
#ifdef DEFINE_MEMALIGN
/*
memalign algorithm:
memalign requests more than enough space from malloc, finds a spot
within that chunk that meets the alignment request, and then
possibly frees the leading and trailing space.
The alignment argument must be a power of two. This property is not
checked by memalign, so misuse may result in random runtime errors.
8-byte alignment is guaranteed by normal malloc calls, so don't
bother calling memalign with an argument of 8 or less.
Overreliance on memalign is a sure way to fragment space.
*/
#if __STD_C
Void_t* mEMALIGn(RARG size_t alignment, size_t bytes)
#else
Void_t* mEMALIGn(RARG alignment, bytes) RDECL size_t alignment; size_t bytes;
#endif
{
INTERNAL_SIZE_T nb; /* padded request size */
char* m; /* memory returned by malloc call */
mchunkptr p; /* corresponding chunk */
char* brk; /* alignment point within p */
mchunkptr newp; /* chunk to return */
INTERNAL_SIZE_T newsize; /* its size */
INTERNAL_SIZE_T leadsize; /* leading space befor alignment point */
mchunkptr remainder; /* spare room at end to split off */
long remainder_size; /* its size */
/* If need less alignment than we give anyway, just relay to malloc */
if (alignment <= MALLOC_ALIGNMENT) return mALLOc(RCALL bytes);
/* Otherwise, ensure that it is at least a minimum chunk size */