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Diffstat (limited to 'lib/libc/stdlib/malloc.c')
| -rw-r--r-- | lib/libc/stdlib/malloc.c | 1127 |
1 files changed, 1127 insertions, 0 deletions
diff --git a/lib/libc/stdlib/malloc.c b/lib/libc/stdlib/malloc.c new file mode 100644 index 0000000..5d33a58 --- /dev/null +++ b/lib/libc/stdlib/malloc.c @@ -0,0 +1,1127 @@ +/* + * ---------------------------------------------------------------------------- + * "THE BEER-WARE LICENSE" (Revision 42): + * <phk@FreeBSD.ORG> 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 + * ---------------------------------------------------------------------------- + * + * $Id: malloc.c,v 1.4 1995/09/22 14:11:00 phk Exp $ + * + */ + +/* + * Defining EXTRA_SANITY will enable some checks which are related + * to internal conditions and consistency in malloc.c + */ +#define EXTRA_SANITY + +/* + * What to use for Junk + */ +#define SOME_JUNK 0xd0 /* as in "Duh" :-) */ + +/* + * If these weren't defined here, they would be calculated on the fly, + * at a considerable cost in performance. + */ +#if defined(__i386__) && defined(__FreeBSD__) +# define malloc_pagesize 4096U +# define malloc_pageshift 12U +# define malloc_minsize 16U +# define malloc_maxsize ((malloc_pagesize)>>1) +#endif /* __i386__ && __FreeBSD__ */ + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <memory.h> +#include <errno.h> +#include <err.h> +#include <sys/types.h> +#include <sys/mman.h> + +/* + * 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_long 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 */ + u_long size; /* number of bytes free */ +}; + +/* + * How many bits per u_long in the bitmap. + * Change only if not 8 bits/byte + */ +#define MALLOC_BITS (8*sizeof(u_long)) + +/* + * 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) + +/* + * The i386 architecture has some very convenient instructions. + * We might as well use them. There are C-language backups, but + * they are considerably slower. + */ +#ifdef __i386__ +#define ffs _ffs +static __inline int +_ffs(unsigned input) +{ + int result; + asm("bsfl %1,%0" : "=r" (result) : "r" (input)); + return result+1; +} + +#define fls _fls +static __inline int +_fls(unsigned input) +{ + int result; + asm("bsrl %1,%0" : "=r" (result) : "r" (input)); + return result+1; +} + +#define set_bit _set_bit +static __inline void +_set_bit(struct pginfo *pi, int bit) +{ + asm("btsl %0,(%1)" : + : "r" (bit & (MALLOC_BITS-1)), "r" (pi->bits+(bit/MALLOC_BITS))); +} + +#define clr_bit _clr_bit +static __inline void +_clr_bit(struct pginfo *pi, int bit) +{ + asm("btcl %0,(%1)" : + : "r" (bit & (MALLOC_BITS-1)), "r" (pi->bits+(bit/MALLOC_BITS))); +} + +#endif /* __i386__ */ + +/* + * Set to one when malloc_init has been called + */ +static unsigned initialized; + +/* + * The size of a page. + * Must be a integral multiplum of the granularity of mmap(2). + * Your toes will curl if it isn't a power of two + */ +#ifndef malloc_pagesize +static unsigned malloc_pagesize; +#endif /* malloc_pagesize */ + +/* + * 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) + +/* + * malloc_pagesize == 1 << malloc_pageshift + */ +#ifndef malloc_pageshift +static unsigned malloc_pageshift; +#endif /* malloc_pageshift */ + +/* + * The smallest allocation we bother about. + * Must be power of two + */ +#ifndef malloc_minsize +static unsigned malloc_minsize; +#endif /* malloc_minsize */ + +/* + * The largest chunk we care about. + * Must be smaller than pagesize + * Must be power of two + */ +#ifndef malloc_maxsize +static unsigned malloc_maxsize; +#endif /* malloc_maxsize */ + +/* + * The minimum size (in bytes) of the free page cache. + */ +#ifndef malloc_cache +static unsigned malloc_cache; +#endif /* malloc_cache */ + +/* + * 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() if we fail to get VM ? + */ +static int malloc_abort; + +/* + * Are we trying to die ? + */ +static int suicide; + +#ifdef EXTRA_SANITY +/* + * dump statistics + */ +static int malloc_stats; +#endif /* EXTRA_SANITY */ + +/* + * always realloc ? + */ +static int malloc_realloc; + +/* + * zero fill ? + */ +static int malloc_zero; + +/* + * junk fill ? + */ +static int malloc_junk; + +/* + * my last break. + */ +static void *malloc_brk; + +/* + * one location cache for free-list holders + */ +static struct pgfree *px; + +/* + * Necessary function declarations + */ +static int extend_pgdir(u_long index); + +#ifdef EXTRA_SANITY +void +malloc_dump(FILE *fd) +{ + struct pginfo **pd; + struct pgfree *pf; + int j; + + pd = page_dir; + + /* print out all the pages */ + for(j=0;j<=last_index;j++) { + fprintf(fd,"%08lx %5d ",(j+malloc_origo) << malloc_pageshift,j); + if (pd[j] == MALLOC_NOT_MINE) { + for(j++;j<=last_index && pd[j] == MALLOC_NOT_MINE;j++) + ; + j--; + fprintf(fd,".. %5d not mine\n", j); + } else if (pd[j] == MALLOC_FREE) { + for(j++;j<=last_index && pd[j] == MALLOC_FREE;j++) + ; + j--; + fprintf(fd,".. %5d free\n", j); + } else if (pd[j] == MALLOC_FIRST) { + for(j++;j<=last_index && pd[j] == MALLOC_FOLLOW;j++) + ; + j--; + fprintf(fd,".. %5d in use\n", j); + } else if (pd[j] < MALLOC_MAGIC) { + fprintf(fd,"(%p)\n", pd[j]); + } else { + fprintf(fd,"%p %d (of %d) x %d @ %p --> %p\n", + pd[j],pd[j]->free, pd[j]->total, + pd[j]->size, pd[j]->page, pd[j]->next); + } + } + + for(pf=free_list.next; pf; pf=pf->next) { + fprintf(fd,"Free: @%p [%p...%p[ %ld ->%p <-%p\n", + pf,pf->page,pf->end,pf->size,pf->prev,pf->next); + if (pf == pf->next) { + fprintf(fd,"Free_list loops.\n"); + break; + } + } + + /* print out various info */ + fprintf(fd,"Minsize\t%d\n",malloc_minsize); + fprintf(fd,"Maxsize\t%d\n",malloc_maxsize); + fprintf(fd,"Pagesize\t%d\n",malloc_pagesize); + fprintf(fd,"Pageshift\t%d\n",malloc_pageshift); + fprintf(fd,"FirstPage\t%ld\n",malloc_origo); + fprintf(fd,"LastPage\t%ld %lx\n",last_index+malloc_pageshift, + (last_index + malloc_pageshift) << malloc_pageshift); + fprintf(fd,"Break\t%ld\n",(u_long)sbrk(0) >> malloc_pageshift); +} +#endif /* EXTRA_SANITY */ + +static void +wrterror(char *p) +{ + char *q = "Malloc error: "; + suicide = 1; + write(2,q,strlen(q)); + write(2,p,strlen(p)); +#ifdef EXTRA_SANITY + if (malloc_stats) + malloc_dump(stderr); +#endif /* EXTRA_SANITY */ + abort(); +} + +static void +wrtwarning(char *p) +{ + char *q = "Malloc warning: "; + if (malloc_abort) + wrterror(p); + write(2,q,strlen(q)); + write(2,p,strlen(p)); +} + +#ifdef EXTRA_SANITY +static void +malloc_exit() +{ + FILE *fd = fopen("malloc.out","a"); + char *q = "malloc() warning: Couldn't dump stats.\n"; + if (fd) { + malloc_dump(fd); + fclose(fd); + } else + write(2,q,strlen(q)); +} +#endif /* EXTRA_SANITY */ + + +/* + * Allocate a number of pages from the OS + */ +static caddr_t +map_pages(int pages, int update) +{ + caddr_t result,tail; + + result = (caddr_t)pageround((u_long)sbrk(0)); + tail = result + (pages << malloc_pageshift); + + if (brk(tail)) { +#ifdef EXTRA_SANITY + wrterror("(internal): map_pages fails\n"); +#endif /* EXTRA_SANITY */ + return 0; + } + + last_index = ptr2index(tail) - 1; + malloc_brk = tail; + + if (update && last_index >= malloc_ninfo && !extend_pgdir(last_index)) + return 0;; + + return result; +} + +/* + * Set a bit in the bitmap + */ +#ifndef set_bit +static __inline void +set_bit(struct pginfo *pi, int bit) +{ + pi->bits[bit/MALLOC_BITS] |= 1<<(bit%MALLOC_BITS); +} +#endif /* set_bit */ + +/* + * Clear a bit in the bitmap + */ +#ifndef clr_bit +static __inline void +clr_bit(struct pginfo *pi, int bit) +{ + pi->bits[bit/MALLOC_BITS] &= ~(1<<(bit%MALLOC_BITS)); +} +#endif /* clr_bit */ + +#ifndef tst_bit +/* + * Test a bit in the bitmap + */ +static __inline int +tst_bit(struct pginfo *pi, int bit) +{ + return pi->bits[bit/MALLOC_BITS] & (1<<(bit%MALLOC_BITS)); +} +#endif /* tst_bit */ + +/* + * Find last bit + */ +#ifndef fls +static __inline int +fls(int size) +{ + int i = 1; + while (size >>= 1) + i++; + return i; +} +#endif /* fls */ + +/* + * Extend page directory + */ +static int +extend_pgdir(u_long index) +{ + struct pginfo **new,**old; + int i; + + /* Make it this many pages */ + i = index * sizeof *page_dir; + i /= malloc_pagesize; + i += 2; + + /* Get new pages */ + new = (struct pginfo**) map_pages(i,0); + if (!new) + return 0; + + /* Copy the old stuff */ + memset(new, 0, i * malloc_pagesize); + 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; + + /* Mark the pages */ + index = ptr2index(new); + page_dir[index] = MALLOC_FIRST; + while (--i) { + page_dir[++index] = MALLOC_FOLLOW; + } + + /* Now free the old stuff */ + free(old); + return 1; +} + +/* + * Initialize the world + */ +static void +malloc_init () +{ + int i; + char *p; + +#ifdef EXTRA_SANITY + malloc_junk = 1; +#endif /* EXTRA_SANITY */ + + for (p=getenv("MALLOC_OPTIONS"); p && *p; p++) { + switch (*p) { + case 'a': malloc_abort = 0; break; + case 'A': malloc_abort = 1; break; +#ifdef EXTRA_SANITY + case 'd': malloc_stats = 0; break; + case 'D': malloc_stats = 1; break; +#endif /* EXTRA_SANITY */ + case 'r': malloc_realloc = 0; break; + case 'R': malloc_realloc = 1; break; + case 'j': malloc_junk = 0; break; + case 'J': malloc_junk = 1; break; + case 'z': malloc_zero = 0; break; + case 'Z': malloc_zero = 1; break; + default: + wrtwarning("(Init): Unknown char in MALLOC_OPTIONS\n"); + p = 0; + break; + } + } + + /* + * We want junk in the entire allocation, and zero only in the part + * the user asked for. + */ + if (malloc_zero) + malloc_junk=1; + +#ifdef EXTRA_SANITY + if (malloc_stats) + atexit(malloc_exit); +#endif /* EXTRA_SANITY */ + +#ifndef malloc_pagesize + /* determine our pagesize */ + malloc_pagesize = getpagesize(); +#endif /* malloc_pagesize */ + +#ifndef malloc_maxsize + malloc_maxsize = malloc_pagesize >> 1; +#endif /* malloc_maxsize */ + +#ifndef malloc_pageshift + /* determine how much we shift by to get there */ + for (i = malloc_pagesize; i > 1; i >>= 1) + malloc_pageshift++; +#endif /* malloc_pageshift */ + +#ifndef malloc_cache + malloc_cache = 100 << malloc_pageshift; +#endif /* malloc_cache */ + +#ifndef malloc_minsize + /* + * find the smallest size allocation we will bother about. + * this is determined as the smallest allocation that can hold + * it's own pginfo; + */ + i = 2; + for(;;) { + int j; + + /* Figure out the size of the bits */ + j = malloc_pagesize/i; + j /= 8; + if (j < sizeof(u_long)) + j = sizeof (u_long); + if (sizeof(struct pginfo) + j - sizeof (u_long) <= i) + break; + i += i; + } + malloc_minsize = i; +#endif /* malloc_minsize */ + + /* Allocate one page for the page directory */ + page_dir = (struct pginfo **) map_pages(1,0); + if (!page_dir) + wrterror("(Init) my first mmap 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) page_dir >> malloc_pageshift; + malloc_origo -= malloc_pageshift; + + memset(page_dir,0,malloc_pagesize); + + malloc_ninfo = malloc_pagesize / sizeof *page_dir; + + /* Plug the page directory into itself */ + page_dir[ptr2index(page_dir)] = MALLOC_FIRST; + + /* Been here, done that */ + initialized++; +} + +/* + * Allocate a number of complete pages + */ +void * +malloc_pages(size_t size) +{ + void *p,*delay_free = 0; + int 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 += 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,1); + + if (p) { + + index = ptr2index(p); + page_dir[index] = MALLOC_FIRST; + for (i=1;i<size;i++) + page_dir[index+i] = MALLOC_FOLLOW; + + if (malloc_junk) + memset(p, SOME_JUNK,size << malloc_pageshift); + } + + if (delay_free) { + if (!px) + px = delay_free; + else + free(delay_free); + } + + return p; +} + +/* + * Allocate a page of fragments + */ + +static __inline int +malloc_make_chunks(int bits) +{ + struct pginfo *bp; + void *pp; + int i,k,l; + + /* Allocate a new bucket */ + pp = malloc_pages(malloc_pagesize); + if (!pp) + return 0; + + /* Find length of admin structure */ + l = sizeof *bp - sizeof(u_long); + l += sizeof(u_long) * + (((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 *)malloc(l); + if (!bp) + return 0; + } + + bp->size = (1<<bits); + bp->shift = bits; + bp->total = bp->free = malloc_pagesize >> bits; + bp->page = pp; + + page_dir[ptr2index(pp)] = bp; + + bp->next = page_dir[bits]; + page_dir[bits] = bp; + + /* set all valid bits in the bits */ + 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++) + set_bit(bp,i); + + if (bp == bp->page) { + /* Mark the ones we stole for ourselves */ + for(i=0;l > 0;i++) { + clr_bit(bp,i); + bp->free--; + bp->total--; + l -= (1 << bits); + } + } + + return 1; +} + +/* + * Allocate a fragment + */ +static void * +malloc_bytes(size_t size) +{ + int j; + struct pginfo *bp; + int k; + u_long *lp; + + /* Don't bother with anything less than this */ + if (size < malloc_minsize) + size = malloc_minsize; + + /* Find the right bucket */ + j = fls((size)-1); + + /* 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 */ + k = ffs(*lp) - 1; + *lp ^= 1<<k; + + /* 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(bp->page + k, SOME_JUNK, bp->size); + + return bp->page + k; +} + +/* + * Allocate a piece of memory + */ +void * +malloc(size_t size) +{ + void *result; + + if (!initialized) + malloc_init(); + + if (suicide) + abort(); + + if (size <= malloc_maxsize) + result = malloc_bytes(size); + else + result = malloc_pages(size); + + if (malloc_abort && !result) + wrterror("malloc(): returns NULL\n"); + + if (malloc_zero) + memset(result,0,size); + + return result; +} + +/* + * Change the size of an allocation. + */ +void * +realloc(void *ptr, size_t size) +{ + void *p; + u_long osize,index; + struct pginfo **mp; + int i; + + if (suicide) + return 0; + + if (!ptr) /* Bounce to malloc() */ + return malloc(size); + + if (!initialized) { + wrtwarning("realloc(): malloc() never got called.\n"); + return 0; + } + + if (ptr && !size) { /* Bounce to free() */ + free(ptr); + return 0; + } + + index = ptr2index(ptr); + + if (index < malloc_pageshift) { + wrtwarning("realloc(): junk pointer (too low)\n"); + return 0; + } + + if (index > last_index) { + wrtwarning("realloc(): junk pointer (too high)\n"); + return 0; + } + + mp = &page_dir[index]; + + if (*mp == MALLOC_FIRST) { /* Page allocation */ + + /* Check the pointer */ + if ((u_long)ptr & malloc_pagemask) { + wrtwarning("realloc(): 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("realloc(): 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 (tst_bit(*mp,i)) { + wrtwarning("realloc(): already free chunk.\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("realloc(): wrong page pointer.\n"); + return 0; + } + + p = malloc(size); + + if (p) { + /* copy the lesser of the two sizes, and free the old one */ + if (osize < size) + memcpy(p,ptr,osize); + else + memcpy(p,ptr,size); + free(ptr); + } + return p; +} + +/* + * Free a sequence of pages + */ + +static __inline void +free_pages(void *ptr, int index, struct pginfo *info) +{ + int i; + struct pgfree *pf,*pt; + u_long l; + void *tail; + + if (info == MALLOC_FREE) { + wrtwarning("free(): already free page.\n"); + return; + } + + if (info != MALLOC_FIRST) { + wrtwarning("free(): freeing wrong page.\n"); + return; + } + + if ((u_long)ptr & malloc_pagemask) { + wrtwarning("free(): 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; + + tail = ptr+l; + + /* add to free-list */ + if (!px) + px = malloc(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 = 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 previuos entry */ + 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; + free(pt); + } + } 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("messed up free list"); + } + } + + /* 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 = 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. */ + } +} + +/* + * Free a chunk, and possibly the page it's on, if the page becomes empty. + */ + +static __inline void +free_bytes(void *ptr, int 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("free(): modified pointer.\n"); + return; + } + + if (tst_bit(info,i)) { + wrtwarning("free(): already free chunk.\n"); + return; + } + + set_bit(info,i); + 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) + free(info); + free(vp); +} + +void +free(void *ptr) +{ + u_long page; + struct pginfo *info; + int index; + + /* This is legal */ + if (!ptr) + return; + + if (!initialized) { + wrtwarning("free(): malloc() never got 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("free(): junk pointer (too low)\n"); + return; + } + + if (index > last_index) { + wrtwarning("free(): junk pointer (too high)\n"); + return; + } + + info = page_dir[index]; + + if (info < MALLOC_MAGIC) + free_pages(ptr,index,info); + else + free_bytes(ptr,index,info); + return; +} |
