/* * ---------------------------------------------------------------------------- * "THE BEER-WARE LICENSE" (Revision 42): * wrote this file. As long as you retain this notice you * can do whatever you want with this stuff. If we meet some day, and you think * this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp * ---------------------------------------------------------------------------- * * $FreeBSD: src/lib/libc/stdlib/malloc.c,v 1.49.2.4 2001/12/29 08:10:14 knu Exp $ * $DragonFly: src/lib/libc/stdlib/malloc.c,v 1.5 2004/02/03 07:34:10 dillon Exp $ * */ /* * Defining EXTRA_SANITY will enable extra checks which are related * to internal conditions and consistency in malloc.c. This has a * noticeable runtime performance hit, and generally will not do you * any good unless you fiddle with the internals of malloc or want * to catch random pointer corruption as early as possible. */ #ifndef MALLOC_EXTRA_SANITY #undef MALLOC_EXTRA_SANITY #endif /* * What to use for Junk. This is the byte value we use to fill with * when the 'J' option is enabled. */ #define SOME_JUNK 0xd0 /* as in "Duh" :-) */ /* * The basic parameters you can tweak. * * malloc_pageshift pagesize = 1 << malloc_pageshift * It's probably best if this is the native * page size, but it doesn't have to be. * * malloc_minsize minimum size of an allocation in bytes. * If this is too small it's too much work * to manage them. This is also the smallest * unit of alignment used for the storage * returned by malloc/realloc. * */ #if defined(__FreeBSD__) || defined(__DragonFly__) # if defined(__i386__) # define malloc_pageshift 12U # define malloc_minsize 16U # endif # if defined(__alpha__) # define malloc_pageshift 13U # define malloc_minsize 16U # endif # if !defined(__NETBSD_SYSCALLS) # define HAS_UTRACE # endif /* * Make malloc/free/realloc thread-safe in libc for use with * kernel threads. */ # include "libc_private.h" # include "spinlock.h" static spinlock_t thread_lock = _SPINLOCK_INITIALIZER; # define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock); # define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock); #endif /* __FreeBSD__ || __DragonFly__ */ #if defined(__sparc__) && defined(sun) # define malloc_pageshift 12U # define malloc_minsize 16U # define MAP_ANON (0) static int fdzero; # define MMAP_FD fdzero # define INIT_MMAP() \ { if ((fdzero = _open(_PATH_DEVZERO, O_RDWR, 0000)) == -1) \ wrterror("open of /dev/zero"); } # define MADV_FREE MADV_DONTNEED #endif /* __sparc__ */ /* Insert your combination here... */ #if defined(__FOOCPU__) && defined(__BAROS__) # define malloc_pageshift 12U # define malloc_minsize 16U #endif /* __FOOCPU__ && __BAROS__ */ /* * No user serviceable parts behind this point. */ #include #include #include #include #include #include #include #include #include #include /* * This structure describes a page worth of chunks. */ struct pginfo { struct pginfo *next; /* next on the free list */ void *page; /* Pointer to the page */ u_short size; /* size of this page's chunks */ u_short shift; /* How far to shift for this size chunks */ u_short free; /* How many free chunks */ u_short total; /* How many chunk */ u_int bits[1]; /* Which chunks are free */ }; /* * This structure describes a number of free pages. */ struct pgfree { struct pgfree *next; /* next run of free pages */ struct pgfree *prev; /* prev run of free pages */ void *page; /* pointer to free pages */ void *end; /* pointer to end of free pages */ size_t size; /* number of bytes free */ }; /* * How many bits per u_int in the bitmap. * Change only if not 8 bits/byte */ #define MALLOC_BITS (8*sizeof(u_int)) /* * Magic values to put in the page_directory */ #define MALLOC_NOT_MINE ((struct pginfo*) 0) #define MALLOC_FREE ((struct pginfo*) 1) #define MALLOC_FIRST ((struct pginfo*) 2) #define MALLOC_FOLLOW ((struct pginfo*) 3) #define MALLOC_MAGIC ((struct pginfo*) 4) #ifndef malloc_pageshift #define malloc_pageshift 12U #endif #ifndef malloc_minsize #define malloc_minsize 16U #endif #if !defined(malloc_pagesize) #define malloc_pagesize (1UL<>1) #endif /* A mask for the offset inside a page. */ #define malloc_pagemask ((malloc_pagesize)-1) #define pageround(foo) (((foo) + (malloc_pagemask))&(~(malloc_pagemask))) #define ptr2index(foo) (((u_long)(foo) >> malloc_pageshift)-malloc_origo) #ifndef THREAD_LOCK #define THREAD_LOCK() #endif #ifndef THREAD_UNLOCK #define THREAD_UNLOCK() #endif #ifndef MMAP_FD #define MMAP_FD (-1) #endif #ifndef INIT_MMAP #define INIT_MMAP() #endif /* Set when initialization has been done */ static unsigned malloc_started; /* Recusion flag for public interface. */ static int malloc_active; /* Number of free pages we cache */ static unsigned malloc_cache = 16; /* The offset from pagenumber to index into the page directory */ static u_long malloc_origo; /* The last index in the page directory we care about */ static u_long last_index; /* Pointer to page directory. Allocated "as if with" malloc */ static struct pginfo **page_dir; /* How many slots in the page directory */ static unsigned malloc_ninfo; /* Free pages line up here */ static struct pgfree free_list; /* Abort(), user doesn't handle problems. */ static int malloc_abort; /* Are we trying to die ? */ static int suicide; /* always realloc ? */ static int malloc_realloc; /* pass the kernel a hint on free pages ? */ static int malloc_hint = 0; /* xmalloc behaviour ? */ static int malloc_xmalloc; /* sysv behaviour for malloc(0) ? */ static int malloc_sysv; /* zero fill ? */ static int malloc_zero; /* junk fill ? */ static int malloc_junk; #ifdef HAS_UTRACE /* utrace ? */ static int malloc_utrace; struct ut { void *p; size_t s; void *r; }; void utrace (struct ut *, int); #define UTRACE(a, b, c) \ if (malloc_utrace) \ {struct ut u; u.p=a; u.s = b; u.r=c; utrace(&u, sizeof u);} #else /* !HAS_UTRACE */ #define UTRACE(a,b,c) #endif /* HAS_UTRACE */ /* my last break. */ static void *malloc_brk; /* one location cache for free-list holders */ static struct pgfree *px; /* compile-time options */ char *malloc_options; /* Name of the current public function */ static char *malloc_func; /* Macro for mmap */ #define MMAP(size) \ mmap(0, (size), PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, \ MMAP_FD, 0); /* * Necessary function declarations */ static int extend_pgdir(u_long index); static void *imalloc(size_t size); static void ifree(void *ptr); static void *irealloc(void *ptr, size_t size); extern char *__progname; static void wrterror(char *p) { char *q = " error: "; _write(STDERR_FILENO, __progname, strlen(__progname)); _write(STDERR_FILENO, malloc_func, strlen(malloc_func)); _write(STDERR_FILENO, q, strlen(q)); _write(STDERR_FILENO, p, strlen(p)); suicide = 1; abort(); } static void wrtwarning(char *p) { char *q = " warning: "; if (malloc_abort) wrterror(p); _write(STDERR_FILENO, __progname, strlen(__progname)); _write(STDERR_FILENO, malloc_func, strlen(malloc_func)); _write(STDERR_FILENO, q, strlen(q)); _write(STDERR_FILENO, p, strlen(p)); } /* * Allocate a number of pages from the OS */ static void * map_pages(size_t pages) { caddr_t result, tail; result = (caddr_t)pageround((u_long)sbrk(0)); tail = result + (pages << malloc_pageshift); if (brk(tail)) { #ifdef EXTRA_SANITY wrterror("(ES): map_pages fails\n"); #endif /* EXTRA_SANITY */ return 0; } last_index = ptr2index(tail) - 1; malloc_brk = tail; if ((last_index+1) >= malloc_ninfo && !extend_pgdir(last_index)) return 0;; return result; } /* * Extend page directory */ static int extend_pgdir(u_long index) { struct pginfo **new, **old; u_long i, oldlen; /* Make it this many pages */ i = index * sizeof *page_dir; i /= malloc_pagesize; i += 2; /* remember the old mapping size */ oldlen = malloc_ninfo * sizeof *page_dir; /* * NOTE: we allocate new pages and copy the directory rather than tempt * fate by trying to "grow" the region.. There is nothing to prevent * us from accidently re-mapping space that's been allocated by our caller * via dlopen() or other mmap(). * * The copy problem is not too bad, as there is 4K of page index per * 4MB of malloc arena. * * We can totally avoid the copy if we open a file descriptor to associate * the anon mappings with. Then, when we remap the pages at the new * address, the old pages will be "magically" remapped.. But this means * keeping open a "secret" file descriptor..... */ /* Get new pages */ new = (struct pginfo**) MMAP(i * malloc_pagesize); if (new == (struct pginfo **)-1) return 0; /* Copy the old stuff */ memcpy(new, page_dir, malloc_ninfo * sizeof *page_dir); /* register the new size */ malloc_ninfo = i * malloc_pagesize / sizeof *page_dir; /* swap the pointers */ old = page_dir; page_dir = new; /* Now free the old stuff */ munmap(old, oldlen); return 1; } /* * Initialize the world */ static void malloc_init () { char *p, b[64]; int i, j; int errnosave; INIT_MMAP(); #ifdef EXTRA_SANITY malloc_junk = 1; #endif /* EXTRA_SANITY */ for (i = 0; i < 3; i++) { if (i == 0) { errnosave = errno; j = readlink("/etc/malloc.conf", b, sizeof b - 1); errno = errnosave; if (j <= 0) continue; b[j] = '\0'; p = b; } else if (i == 1) { p = getenv("MALLOC_OPTIONS"); } else { p = malloc_options; } for (; p && *p; p++) { switch (*p) { case '>': malloc_cache <<= 1; break; case '<': malloc_cache >>= 1; break; case 'a': malloc_abort = 0; break; case 'A': malloc_abort = 1; break; case 'h': malloc_hint = 0; break; case 'H': malloc_hint = 1; break; case 'r': malloc_realloc = 0; break; case 'R': malloc_realloc = 1; break; case 'j': malloc_junk = 0; break; case 'J': malloc_junk = 1; break; #ifdef HAS_UTRACE case 'u': malloc_utrace = 0; break; case 'U': malloc_utrace = 1; break; #endif case 'v': malloc_sysv = 0; break; case 'V': malloc_sysv = 1; break; case 'x': malloc_xmalloc = 0; break; case 'X': malloc_xmalloc = 1; break; case 'z': malloc_zero = 0; break; case 'Z': malloc_zero = 1; break; default: j = malloc_abort; malloc_abort = 0; wrtwarning("unknown char in MALLOC_OPTIONS\n"); malloc_abort = j; break; } } } UTRACE(0, 0, 0); /* * We want junk in the entire allocation, and zero only in the part * the user asked for. */ if (malloc_zero) malloc_junk=1; /* * If we run with junk (or implicitly from above: zero), we want to * force realloc() to get new storage, so we can DTRT with it. */ if (malloc_junk) malloc_realloc=1; /* Allocate one page for the page directory */ page_dir = (struct pginfo **) MMAP(malloc_pagesize); if (page_dir == (struct pginfo **) -1) wrterror("mmap(2) failed, check limits\n"); /* * We need a maximum of malloc_pageshift buckets, steal these from the * front of the page_directory; */ malloc_origo = ((u_long)pageround((u_long)sbrk(0))) >> malloc_pageshift; malloc_origo -= malloc_pageshift; malloc_ninfo = malloc_pagesize / sizeof *page_dir; /* Recalculate the cache size in bytes, and make sure it's nonzero */ if (!malloc_cache) malloc_cache++; malloc_cache <<= malloc_pageshift; /* * This is a nice hack from Kaleb Keithly (kaleb@x.org). * We can sbrk(2) further back when we keep this on a low address. */ px = (struct pgfree *) imalloc (sizeof *px); /* Been here, done that */ malloc_started++; } /* * Allocate a number of complete pages */ static void * malloc_pages(size_t size) { void *p, *delay_free = 0; size_t i; struct pgfree *pf; u_long index; size = pageround(size); p = 0; /* Look for free pages before asking for more */ for(pf = free_list.next; pf; pf = pf->next) { #ifdef EXTRA_SANITY if (pf->size & malloc_pagemask) wrterror("(ES): junk length entry on free_list\n"); if (!pf->size) wrterror("(ES): zero length entry on free_list\n"); if (pf->page == pf->end) wrterror("(ES): zero entry on free_list\n"); if (pf->page > pf->end) wrterror("(ES): sick entry on free_list\n"); if ((void*)pf->page >= (void*)sbrk(0)) wrterror("(ES): entry on free_list past brk\n"); if (page_dir[ptr2index(pf->page)] != MALLOC_FREE) wrterror("(ES): non-free first page on free-list\n"); if (page_dir[ptr2index(pf->end)-1] != MALLOC_FREE) wrterror("(ES): non-free last page on free-list\n"); #endif /* EXTRA_SANITY */ if (pf->size < size) continue; if (pf->size == size) { p = pf->page; if (pf->next) pf->next->prev = pf->prev; pf->prev->next = pf->next; delay_free = pf; break; } p = pf->page; pf->page = (char *)pf->page + size; pf->size -= size; break; } #ifdef EXTRA_SANITY if (p && page_dir[ptr2index(p)] != MALLOC_FREE) wrterror("(ES): allocated non-free page on free-list\n"); #endif /* EXTRA_SANITY */ size >>= malloc_pageshift; /* Map new pages */ if (!p) p = map_pages(size); if (p) { index = ptr2index(p); page_dir[index] = MALLOC_FIRST; for (i=1;ibits[0] * (((malloc_pagesize >> bits)+MALLOC_BITS-1) / MALLOC_BITS); /* Don't waste more than two chunks on this */ if ((1<<(bits)) <= l+l) { bp = (struct pginfo *)pp; } else { bp = (struct pginfo *)imalloc(l); if (!bp) { ifree(pp); return 0; } } bp->size = (1<shift = bits; bp->total = bp->free = malloc_pagesize >> bits; bp->page = pp; /* set all valid bits in the bitmap */ k = bp->total; i = 0; /* Do a bunch at a time */ for(;k-i >= MALLOC_BITS; i += MALLOC_BITS) bp->bits[i / MALLOC_BITS] = ~0; for(; i < k; i++) bp->bits[i/MALLOC_BITS] |= 1<<(i%MALLOC_BITS); if (bp == bp->page) { /* Mark the ones we stole for ourselves */ for(i=0;l > 0;i++) { bp->bits[i/MALLOC_BITS] &= ~(1<<(i%MALLOC_BITS)); bp->free--; bp->total--; l -= (1 << bits); } } /* MALLOC_LOCK */ page_dir[ptr2index(pp)] = bp; bp->next = page_dir[bits]; page_dir[bits] = bp; /* MALLOC_UNLOCK */ return 1; } /* * Allocate a fragment */ static void * malloc_bytes(size_t size) { int i,j; u_int u; struct pginfo *bp; int k; u_int *lp; /* Don't bother with anything less than this */ if (size < malloc_minsize) size = malloc_minsize; /* Find the right bucket */ j = 1; i = size-1; while (i >>= 1) j++; /* If it's empty, make a page more of that size chunks */ if (!page_dir[j] && !malloc_make_chunks(j)) return 0; bp = page_dir[j]; /* Find first word of bitmap which isn't empty */ for (lp = bp->bits; !*lp; lp++) ; /* Find that bit, and tweak it */ u = 1; k = 0; while (!(*lp & u)) { u += u; k++; } *lp ^= u; /* If there are no more free, remove from free-list */ if (!--bp->free) { page_dir[j] = bp->next; bp->next = 0; } /* Adjust to the real offset of that chunk */ k += (lp-bp->bits)*MALLOC_BITS; k <<= bp->shift; if (malloc_junk) memset((u_char*)bp->page + k, SOME_JUNK, bp->size); return (u_char *)bp->page + k; } /* * Allocate a piece of memory */ static void * imalloc(size_t size) { void *result; if (suicide) abort(); if ((size + malloc_pagesize) < size) /* Check for overflow */ result = 0; else if (size <= malloc_maxsize) result = malloc_bytes(size); else result = malloc_pages(size); if (malloc_zero && result) memset(result, 0, size); return result; } /* * Change the size of an allocation. */ static void * irealloc(void *ptr, size_t size) { void *p; u_long osize, index; struct pginfo **mp; int i; if (suicide) abort(); index = ptr2index(ptr); if (index < malloc_pageshift) { wrtwarning("junk pointer, too low to make sense\n"); return 0; } if (index > last_index) { wrtwarning("junk pointer, too high to make sense\n"); return 0; } mp = &page_dir[index]; if (*mp == MALLOC_FIRST) { /* Page allocation */ /* Check the pointer */ if ((u_long)ptr & malloc_pagemask) { wrtwarning("modified (page-) pointer\n"); return 0; } /* Find the size in bytes */ for (osize = malloc_pagesize; *++mp == MALLOC_FOLLOW;) osize += malloc_pagesize; if (!malloc_realloc && /* unless we have to, */ size <= osize && /* .. or are too small, */ size > (osize - malloc_pagesize)) { /* .. or can free a page, */ return ptr; /* don't do anything. */ } } else if (*mp >= MALLOC_MAGIC) { /* Chunk allocation */ /* Check the pointer for sane values */ if (((u_long)ptr & ((*mp)->size-1))) { wrtwarning("modified (chunk-) pointer\n"); return 0; } /* Find the chunk index in the page */ i = ((u_long)ptr & malloc_pagemask) >> (*mp)->shift; /* Verify that it isn't a free chunk already */ if ((*mp)->bits[i/MALLOC_BITS] & (1<<(i%MALLOC_BITS))) { wrtwarning("chunk is already free\n"); return 0; } osize = (*mp)->size; if (!malloc_realloc && /* Unless we have to, */ size < osize && /* ..or are too small, */ (size > osize/2 || /* ..or could use a smaller size, */ osize == malloc_minsize)) { /* ..(if there is one) */ return ptr; /* ..Don't do anything */ } } else { wrtwarning("pointer to wrong page\n"); return 0; } p = imalloc(size); if (p) { /* copy the lesser of the two sizes, and free the old one */ if (!size || !osize) ; else if (osize < size) memcpy(p, ptr, osize); else memcpy(p, ptr, size); ifree(ptr); } return p; } /* * Free a sequence of pages */ static __inline__ void free_pages(void *ptr, u_long index, struct pginfo *info) { u_long i; struct pgfree *pf, *pt=0; u_long l; void *tail; if (info == MALLOC_FREE) { wrtwarning("page is already free\n"); return; } if (info != MALLOC_FIRST) { wrtwarning("pointer to wrong page\n"); return; } if ((u_long)ptr & malloc_pagemask) { wrtwarning("modified (page-) pointer\n"); return; } /* Count how many pages and mark them free at the same time */ page_dir[index] = MALLOC_FREE; for (i = 1; page_dir[index+i] == MALLOC_FOLLOW; i++) page_dir[index + i] = MALLOC_FREE; l = i << malloc_pageshift; if (malloc_junk) memset(ptr, SOME_JUNK, l); if (malloc_hint) madvise(ptr, l, MADV_FREE); tail = (char *)ptr+l; /* add to free-list */ if (!px) px = imalloc(sizeof *pt); /* This cannot fail... */ px->page = ptr; px->end = tail; px->size = l; if (!free_list.next) { /* Nothing on free list, put this at head */ px->next = free_list.next; px->prev = &free_list; free_list.next = px; pf = px; px = 0; } else { /* Find the right spot, leave pf pointing to the modified entry. */ tail = (char *)ptr+l; for(pf = free_list.next; pf->end < ptr && pf->next; pf = pf->next) ; /* Race ahead here */ if (pf->page > tail) { /* Insert before entry */ px->next = pf; px->prev = pf->prev; pf->prev = px; px->prev->next = px; pf = px; px = 0; } else if (pf->end == ptr ) { /* Append to the previous entry */ pf->end = (char *)pf->end + l; pf->size += l; if (pf->next && pf->end == pf->next->page ) { /* And collapse the next too. */ pt = pf->next; pf->end = pt->end; pf->size += pt->size; pf->next = pt->next; if (pf->next) pf->next->prev = pf; } } else if (pf->page == tail) { /* Prepend to entry */ pf->size += l; pf->page = ptr; } else if (!pf->next) { /* Append at tail of chain */ px->next = 0; px->prev = pf; pf->next = px; pf = px; px = 0; } else { wrterror("freelist is destroyed\n"); } } /* Return something to OS ? */ if (!pf->next && /* If we're the last one, */ pf->size > malloc_cache && /* ..and the cache is full, */ pf->end == malloc_brk && /* ..and none behind us, */ malloc_brk == sbrk(0)) { /* ..and it's OK to do... */ /* * Keep the cache intact. Notice that the '>' above guarantees that * the pf will always have at least one page afterwards. */ pf->end = (char *)pf->page + malloc_cache; pf->size = malloc_cache; brk(pf->end); malloc_brk = pf->end; index = ptr2index(pf->end); last_index = index - 1; for(i=index;i <= last_index;) page_dir[i++] = MALLOC_NOT_MINE; /* XXX: We could realloc/shrink the pagedir here I guess. */ } if (pt) ifree(pt); } /* * Free a chunk, and possibly the page it's on, if the page becomes empty. */ static __inline__ void free_bytes(void *ptr, u_long index, struct pginfo *info) { int i; struct pginfo **mp; void *vp; /* Find the chunk number on the page */ i = ((u_long)ptr & malloc_pagemask) >> info->shift; if (((u_long)ptr & (info->size-1))) { wrtwarning("modified (chunk-) pointer\n"); return; } if (info->bits[i/MALLOC_BITS] & (1<<(i%MALLOC_BITS))) { wrtwarning("chunk is already free\n"); return; } if (malloc_junk) memset(ptr, SOME_JUNK, info->size); info->bits[i/MALLOC_BITS] |= 1<<(i%MALLOC_BITS); info->free++; mp = page_dir + info->shift; if (info->free == 1) { /* Page became non-full */ mp = page_dir + info->shift; /* Insert in address order */ while (*mp && (*mp)->next && (*mp)->next->page < info->page) mp = &(*mp)->next; info->next = *mp; *mp = info; return; } if (info->free != info->total) return; /* Find & remove this page in the queue */ while (*mp != info) { mp = &((*mp)->next); #ifdef EXTRA_SANITY if (!*mp) wrterror("(ES): Not on queue\n"); #endif /* EXTRA_SANITY */ } *mp = info->next; /* Free the page & the info structure if need be */ page_dir[ptr2index(info->page)] = MALLOC_FIRST; vp = info->page; /* Order is important ! */ if(vp != (void*)info) ifree(info); ifree(vp); } static void ifree(void *ptr) { struct pginfo *info; u_long index; /* This is legal */ if (!ptr) return; if (!malloc_started) { wrtwarning("malloc() has never been called\n"); return; } /* If we're already sinking, don't make matters any worse. */ if (suicide) return; index = ptr2index(ptr); if (index < malloc_pageshift) { wrtwarning("junk pointer, too low to make sense\n"); return; } if (index > last_index) { wrtwarning("junk pointer, too high to make sense\n"); return; } info = page_dir[index]; if (info < MALLOC_MAGIC) free_pages(ptr, index, info); else free_bytes(ptr, index, info); return; } /* * These are the public exported interface routines. */ void * malloc(size_t size) { void *r; THREAD_LOCK(); malloc_func = " in malloc():"; if (malloc_active++) { wrtwarning("recursive call\n"); malloc_active--; THREAD_UNLOCK(); return (0); } if (!malloc_started) malloc_init(); if (malloc_sysv && !size) r = 0; else r = imalloc(size); UTRACE(0, size, r); malloc_active--; THREAD_UNLOCK(); if (malloc_xmalloc && !r) wrterror("out of memory\n"); return (r); } void free(void *ptr) { THREAD_LOCK(); malloc_func = " in free():"; if (malloc_active++) { wrtwarning("recursive call\n"); malloc_active--; THREAD_UNLOCK(); return; } else { ifree(ptr); UTRACE(ptr, 0, 0); } malloc_active--; THREAD_UNLOCK(); return; } void * realloc(void *ptr, size_t size) { void *r; int err = 0; THREAD_LOCK(); malloc_func = " in realloc():"; if (malloc_active++) { wrtwarning("recursive call\n"); malloc_active--; THREAD_UNLOCK(); return (0); } if (ptr && !malloc_started) { wrtwarning("malloc() has never been called\n"); ptr = 0; } if (!malloc_started) malloc_init(); if (malloc_sysv && !size) { ifree(ptr); r = 0; } else if (!ptr) { r = imalloc(size); err = (r == NULL); } else { r = irealloc(ptr, size); err = (r == NULL); } UTRACE(ptr, size, r); malloc_active--; THREAD_UNLOCK(); if (malloc_xmalloc && err) wrterror("out of memory\n"); return (r); }