/* 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 2.6.6 Sun Mar 5 19:10:03 2000 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 when the request size is treaded as a long will return null. 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. 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. WIN32 (default: undefined) Define this on MS win (95, nt) platforms to compile in sbrk emulation. LACKS_UNISTD_H (default: undefined if not WIN32) Define this if your system does not have a <unistd.h>. LACKS_SYS_PARAM_H (default: undefined if not WIN32) Define this if your system does not have a <sys/param.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. USE_DL_PREFIX (default: undefined) Prefix all public routines with the string 'dl'. Useful to quickly avoid procedure declaration conflicts and linker symbol conflicts with existing memory allocation routines. */ /* 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 || defined(WIN32)) #define Void_t void #else #define Void_t char #endif #endif /*Void_t*/ #if __STD_C #include <linux/stddef.h> /* for size_t */ #else #include <sys/types.h> #endif /* __STD_C */ #ifdef __cplusplus extern "C" { #endif #if 0 /* not for U-Boot */ #include <stdio.h> /* needed for malloc_stats */ #endif /* Compile-time options */ /* 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. */ #ifdef DEBUG /* #include <assert.h> */ #define assert(x) ((void)0) #else #define assert(x) ((void)0) #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 /* 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 #define LACKS_UNISTD_H #define LACKS_SYS_PARAM_H /* Include 'windows.h' to get the necessary declarations for the Microsoft Visual C++ data structures and routines used in the 'sbrk' emulation. Define WIN32_LEAN_AND_MEAN so that only the essential Microsoft Visual C++ header files are included. */ #define WIN32_LEAN_AND_MEAN #include <windows.h> #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 #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); #else #ifdef WIN32 /* On Win32 platforms, 'memset()' and 'memcpy()' are already declared in */ /* 'windows.h' */ #else Void_t* memset(); Void_t* memcpy(); #endif #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 memcpy(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 ***/ #undef HAVE_MMAP /* Not available for U-Boot */ /* 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 ***/ #undef HAVE_MREMAP /* Not available for U-Boot */ #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 */ #define LACKS_UNISTD_H /* Shortcut for U-Boot */ #define malloc_getpagesize 4096 #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 # ifdef WIN32 # define malloc_getpagesize (4096) /* TBD: Use 'GetSystemInfo' instead */ # else # ifndef LACKS_SYS_PARAM_H # include <sys/param.h> # endif # 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 #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 (128 * 1024) #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. */ /* USE_DL_PREFIX will prefix all public routines with the string 'dl'. Useful to quickly avoid procedure declaration conflicts and linker symbol conflicts with existing memory allocation routines. */ /* #define USE_DL_PREFIX */ /* 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 */ #if __STD_C extern Void_t* sbrk(ptrdiff_t); #else extern Void_t* sbrk(); #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 USE_DL_PREFIX #define cALLOc dlcalloc #define fREe dlfree #define mALLOc dlmalloc #define mEMALIGn dlmemalign #define rEALLOc dlrealloc #define vALLOc dlvalloc #define pvALLOc dlpvalloc #define mALLINFo dlmallinfo #define mALLOPt dlmallopt #else /* USE_DL_PREFIX */ #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 /* USE_DL_PREFIX */ #endif /* Public routines */ #if __STD_C Void_t* mALLOc(size_t); void fREe(Void_t*); Void_t* rEALLOc(Void_t*, size_t); Void_t* mEMALIGn(size_t, size_t); Void_t* vALLOc(size_t); Void_t* pvALLOc(size_t); Void_t* cALLOc(size_t, size_t); void cfree(Void_t*); int malloc_trim(size_t); size_t malloc_usable_size(Void_t*); void malloc_stats(void); int mALLOPt(int, int); struct mallinfo mALLINFo(void); #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