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| #include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#define CHECK(x, code, message, ...) if(!(x)) {fprintf(stderr, "%s:%d, error: %s\t----\t", __FILE__, __LINE__, strerror(errno)); fprintf(stderr, (const char*)message, ##__VA_ARGS__); exit(code); }
#define ERR(code, format, ...) fprintf(stderr, (const char*)format, ##__VA_ARGS__); exit(code)
#define UNUSED 0
#define USED 1
#define EXIT_SBRK_FAIL 1
#define UNKNOWN_FAIL 2
#define UNKNOWN_MEM_ERROR 3
#define FREE_TWICE 4
#define MAXALLOC 100000
void *freeMem = NULL;
unsigned long getBlockSize(void *mem) {
return *((unsigned long *)mem - 1);
}
void setBlockSize(void *mem, size_t size) {
*((unsigned long *)mem - 1) = size;
}
void *getNextFreeBlock(void *__free) {
return (unsigned long*) *((unsigned long *)__free + 1);
}
void setNextFreeBlock(void *__free, void *__ptr) {
*((unsigned long *)__free + 1) = (unsigned long)__ptr;
}
void *getPrevFreeBlock(void *__free) {
return (unsigned long*) *(unsigned long *)__free;
}
void setPrevFreeBlock(void *__free, void *__ptr) {
*(unsigned long *)__free = (unsigned long)__ptr;
}
char getUsed(void *__ptr) {
return *((char *)__ptr - 1 - sizeof(void *));
}
void setUsed(void *__ptr, char used) {
*((char *)__ptr - 1 - sizeof(void *)) = used;
}
void memInit(char used, void *__ptr, void *prev, void *next, size_t size) {
setUsed(__ptr, used);
setBlockSize(__ptr, size);
setPrevFreeBlock(__ptr, prev);
setNextFreeBlock(__ptr, next);
}
void *firstFit(size_t size) {
void *move = freeMem;
void *next = getNextFreeBlock(freeMem);
while(next != NULL) {
if(getBlockSize(next) >= size) {
break;
}
move = next;
next = getNextFreeBlock(next);
}
return move;
}
void *__malloc(size_t size) {
if(freeMem == NULL) {
freeMem = sbrk(sizeof(void *) * 3 + 1);
CHECK(freeMem != (void*)-1, EXIT_SBRK_FAIL, "sbrk fail\n");
freeMem += sizeof(void *) + 1;
memInit(UNUSED, freeMem, NULL, NULL, sizeof(void *) * 2);
}
void *__free = firstFit(size);
void *newMem = NULL;
CHECK(__free != NULL, UNKNOWN_FAIL, "unknown error\n");
if(getNextFreeBlock(__free) == NULL) {
size = size > 2 * sizeof(void *) ? size : 2 * sizeof(void *);
newMem = sbrk(1 + sizeof(void *) + size);
CHECK(newMem != (void*)-1, EXIT_SBRK_FAIL, "sbrk fail\n");
newMem += 1 + sizeof(void *);
memInit(USED, newMem, NULL, NULL, size);
} else {
newMem = getNextFreeBlock(__free);
setUsed(newMem, USED);
setNextFreeBlock(__free, getNextFreeBlock(newMem));
}
return newMem;
}
void __free(void * __ptr) {
CHECK(freeMem != NULL, UNKNOWN_MEM_ERROR,"memory: %p is not allocated by __mallo\n", __ptr);
CHECK(getUsed(__ptr) == USED, FREE_TWICE, "trying to free memory %p twice\n", __ptr);
setUsed(__ptr, UNUSED);
void *move = freeMem;
void *next = getNextFreeBlock(freeMem);
void *front = (char *)__ptr - 1 - sizeof(void *), *back = (char *)__ptr + getBlockSize(__ptr);
while(next != NULL) {
if((char *)next - 1 - sizeof(void *) >= (char *)back) {
break;
}
move = next;
next = getNextFreeBlock(next);
}
if(front == (char *)move + getBlockSize(move)) {
setBlockSize(move, (char *)back - (char *)move);
__ptr = move;
} else {
setNextFreeBlock(__ptr, getNextFreeBlock(move));
setNextFreeBlock(move, __ptr);
setPrevFreeBlock(__ptr, move);
}
if(next == NULL) return;
if(back == (char *)next - 1 - sizeof(void *)) {
setBlockSize(__ptr, (char *)next + getBlockSize(next) - (char *)__ptr);
} else {
setPrevFreeBlock(next, __ptr);
}
return;
}
void __printMemblock(void* ptr) {
printf("------------Memory Block %p---------------\n", ptr);
printf("front = %p, back = %p\n", (char *)ptr - 1 - sizeof(void *), (char *)ptr + getBlockSize(ptr));
int used = *((char *)ptr - 1 - sizeof(unsigned long));
printf("used\t\t=\t%d\n", used);
printf("blocksize\t=\t%lu\n", *((unsigned long *)ptr - 1));
if(!used) {
printf("last free block\t=\t%p\n", (unsigned long*) *(unsigned long *)ptr);
printf("next free block\t=\t%p\n", (unsigned long*) *((unsigned long *)ptr + 1));
}
printf("Current brk = %p\n", sbrk(0));
}
void __showFreeBlocks() {
printf("show free blocks\n");
void *move = freeMem;
while(move) {
__printMemblock(move);
move = getNextFreeBlock(move);
}
}
int main(int argc, char *argv[]) {
if(argc < 3) {
ERR(1, "Usage: %s numalloc blocksize [freestep] [freemin] [freemax]\n", argv[0]);
}
int numalloc = atoi(argv[1]);
size_t blocksize = atoi(argv[2]);
int freestep = argc > 3 ? atoi(argv[3]) : 1;
int freemin = argc > 4 ? atoi(argv[4]) : 1;
int freemax = argc > 5 ? atoi(argv[5]) : numalloc;
void *ptr[MAXALLOC];
if(numalloc > MAXALLOC) {
ERR(2, "constraint: numalloc <= %d\n", MAXALLOC);
}
printf("sizeof(void *) = %lu\n", sizeof(void *));
printf("Start to allocate mem, Current program break: %p\n", sbrk(0));
for(int i = 0; i < numalloc; i++) {
ptr[i] = __malloc(blocksize);
if(ptr[i] == NULL) {
ERR(3, "fail to __malloc loc: %d\n", i);
}
printf("Current program break: %p\n", sbrk(0));
__printMemblock(ptr[i]);
}
for(int i = 0; i < numalloc; i++) {
__printMemblock(ptr[i]);
}
__showFreeBlocks();
printf("Allocation finished, Current program break: %p\n", sbrk(0));
for(int i = freemin-1; i < freemax; i += freestep) {
__free(ptr[i]);
printf("Current program break: %p\n", sbrk(0));
__printMemblock(ptr[i]);
}
printf("Mem __free finished, Current program break: %p\n", sbrk(0));
for(int i = freemin-1; i < freemax; i += freestep) {
__printMemblock(ptr[i]);
}
__showFreeBlocks();
return 0;
}
|