backup

malloc/Makefile

@@ -1,10 +1,10 @@
 CC=gcc
 CFLAGS=-std=c99 -pedantic -Werror -Wall -Wextra -Wvla -fvisibility=hidden -fPIC
-CPPFLAGS=D_DEFAULT_SOURCE
+CPPFLAGS= -D_DEFAULT_SOURCE
 LDFLAGS= -shared -Wl --no-undefined
 
-SRCS=
-OBJS=${SRC:.c=.o}
+SRCS=src/malloc.c src/helpers/helpers.c src/helpers/allocate.c
+OBJS=${SRCS:.c=.o}
 TARGET=libmalloc.so
 
 library: $(OBJS)

malloc/src/helpers/allocate.c

@@ -0,0 +1,70 @@
+#include "allocate.h"
+
+#include <string.h>
+#include <sys/mman.h>
+
+#include "helpers.h"
+
+void *allocate_block(struct bucket *biquette, int block_number)
+{
+    if (block_number == -1)
+        return NULL;
+
+    // Update header
+    unsigned char byte_mask = 1 << ((block_number % 8) - 1);
+    biquette->alloc_blk_cnt++;
+    biquette->free_map[block_number / 8] &= byte_mask;
+
+    // Compute block address
+    return get_block(biquette, block_number);
+}
+
+struct bucket *create_bucket(size_t min_alloc_size)
+{
+    // Round up
+    size_t alloc_size;
+    if (min_alloc_size > PAGE_SIZE - sizeof(struct bucket))
+        // Huge page
+        alloc_size = min_alloc_size;
+    else
+        // Regular page
+        alloc_size = s2p(min_alloc_size);
+
+    // Get page
+    void *page =
+        mmap(NULL, alloc_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, -1, 0);
+
+    if (page == NULL)
+        return NULL;
+
+    // Init bucket
+    struct bucket *header = page;
+    header->block_size = alloc_size;
+    header->alloc_blk_cnt = 0;
+    memset(header->free_map, 0, FREE_LIST_SIZE);
+
+    return header;
+}
+
+void free_block(void *ptr, struct bucket **list)
+{
+    // Compute header location and block number
+    struct bucket *header = get_page_begin(ptr);
+
+    // free in map and update size
+    int block_number; // ...
+    unsigned char byte_mask = 1 << ((block_number % 8) - 1);
+    header->free_map[block_number / 8] &= ~byte_mask;
+
+    // Huge page
+    if (header->block_size > BUCKET_SIZE)
+        // Delete bucket
+        header->alloc_blk_cnt = 0;
+
+    // free bucket if necessary
+    if (header->alloc_blk_cnt == 0)
+    {
+        bucket_list_remove(list, header);
+        munmap(ptr, 1);
+    }
+}

malloc/src/helpers/allocate.h

@@ -0,0 +1,13 @@
+#ifndef ALLOCATE_H
+#define ALLOCATE_H
+
+#include "helpers.h"
+
+#include <stddef.h>
+
+void *allocate_block(struct bucket *biquette, int block_number);
+struct bucket *create_bucket(size_t min_alloc_size);
+void bucket_append(struct bucket **head, struct bucket *elt);
+void free_block(void *ptr, struct bucket **list);
+
+#endif // ! ALLOCATE_H

malloc/src/helpers/helpers.c

@@ -1,8 +1,5 @@
 #include "helpers.h"
 
-#include <string.h>
-#include <sys/mman.h>
-
 // Returns the smallest power of 2 greater or equal to s
 size_t s2p(size_t s)
 {
@@ -33,44 +30,47 @@ size_t s2p(size_t s)
     return n;
 }
 
-void *find_free_block(struct bucket *buck)
+int find_free_block(struct bucket *buck)
 {
-    unsigned maplength = buck->block_size / 8;
+    unsigned maplength = PAGE_SIZE / buck->block_size / 8;
     // for each block
     for (unsigned i = 0; i < maplength; i++)
     {
-        unsigned char map_byte = buck->free_list[i];
+        unsigned char map_byte = buck->free_map[i];
         unsigned char bit = 1;
         // Test byte
         for (unsigned j = 0; j < 8; j <<= 1)
         {
             if (map_byte & bit) // Test if free
-                return get_data_begin(buck) + (buck->block_size * (i * 8 + j));
+                return i * 8 + j;
 
             bit <<= 1;
         }
     }
 
-    return NULL;
+    return -1;
 }
 
-struct bucket *create_bucket(size_t min_alloc_size)
+void *get_block(struct bucket *biquette, int block_number)
 {
-    // Round up
-    size_t alloc_size = s2p(min_alloc_size);
-    // Get page
-    void *page =
-        mmap(NULL, alloc_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, -1, 0);
-
-    if (page == NULL)
+    if (block_number == -1)
         return NULL;
 
-    // Init bucket
-    struct bucket *header = page;
-    header->block_size = alloc_size;
-    memset(header->free_list, 0, FREE_LIST_SIZE);
+    char *data_begin = get_data_begin(biquette);
+    return data_begin + (biquette->block_size * (block_number));
+}
 
-    return header;
+int get_block_number(struct bucket *biquette, void *block)
+{
+    if (block == NULL || biquette == NULL)
+        return -1;
+
+    char *block_nul = block;
+    void *biquetteounette = biquette;
+    char *biquette_cherie = biquetteounette;
+
+    return (block_nul - biquette_cherie - sizeof(struct bucket))
+        / biquette->block_size;
 }
 
 // Gets a bucket with at least a block_size of size
@@ -99,7 +99,7 @@ void *get_page_begin(void *ptr)
     return pointeur_alacon + quelenfer;
 }
 
-void bucket_append(struct bucket **head, struct bucket *elt)
+void bucket_list_append(struct bucket **head, struct bucket *elt)
 {
     struct bucket *list_elt = *head;
     if (list_elt == NULL)
@@ -114,3 +114,27 @@ void bucket_append(struct bucket **head, struct bucket *elt)
     }
     list_elt->next = elt;
 }
+
+// Removes a bucket from the list pointed by head
+void bucket_list_remove(struct bucket **head, struct bucket *elt)
+{
+    struct bucket *list_elt = *head;
+    if (list_elt == NULL)
+        return;
+
+    if (*head == elt)
+    {
+        *head = NULL;
+        return;
+    }
+
+    while (list_elt->next != NULL)
+    {
+        if (list_elt->next == elt)
+        {
+            list_elt->next = list_elt->next->next;
+            return;
+        }
+        list_elt = list_elt->next;
+    }
+}

malloc/src/helpers/helpers.h

@@ -1,7 +1,7 @@
 #ifndef HELPERS_H
 #define HELPERS_H
 
-// #define PAGE_SIZE (size_t) sysconf(_SC_PAGE_SIZE)
+// #define PAGE_SIZE sysconf(_SC_PAGE_SIZE)
 #define PAGE_SIZE 4096
 #define MIN_BLOCK_SIZE 8
 #define FREE_LIST_SIZE PAGE_SIZE / MIN_BLOCK_SIZE / sizeof(unsigned char)
@@ -13,19 +13,24 @@
 struct bucket
 {
     unsigned block_size;
-    unsigned char free_list[FREE_LIST_SIZE]; // 4096 / MIN_BLOCK_SIZE /
-                                             // sizeof(unsigned char)    
+    unsigned char free_map[FREE_LIST_SIZE]; // Keeps track of allocations   
+                                            // If block_size > MIN_BLOCK_SIZE
+                                            // It will use a consecutive
+                                            // representation
+    unsigned short alloc_blk_cnt; // Counts the number of allocated blocks
     struct bucket *next;
-
     size_t checksum;
 };
 
+#define BUCKET_SIZE PAGE_SIZE - sizeof(struct bucket)
+
 size_t s2p(size_t n);
-void *find_free_block(struct bucket *buck);
-struct bucket *create_bucket(size_t min_alloc_size);
+int find_free_block(struct bucket *buck);
 struct bucket *get_bucket(struct bucket *head, size_t size);
 void *get_data_begin(struct bucket *biquette);
 void *get_page_begin(void *ptr);
-void bucket_append(struct bucket **head, struct bucket *elt);
+void *get_block(struct bucket* biquette, int block_number);
+void bucket_list_append(struct bucket **head, struct bucket *elt);
+void bucket_list_remove(struct bucket **head, struct bucket *elt);
 
 #endif // ! HELPERS_H

malloc/src/malloc.c

@@ -1,5 +1,7 @@
 #include <stddef.h>
+#include <string.h>
 
+#include "helpers/allocate.h"
 #include "helpers/helpers.h"
 
 struct bucket *head = NULL;
@@ -14,14 +16,13 @@ __attribute__((visibility("default"))) void *malloc(size_t size)
     while (buck != NULL)
     {
         // Find adequate block
-        void *block = find_free_block(buck);
-        if (block != NULL)
-            return block;
+        int block_number = find_free_block(buck);
+        if (block_number != -1)
+            return get_block(buck, block_number);
         else
         {
             // No free space -> loop
             buck = get_bucket(buck->next, size);
-            continue;
         }
     }
 
@@ -34,14 +35,38 @@ __attribute__((visibility("default"))) void free(void *ptr)
 {
     if (ptr == NULL)
         return;
+    free_block(ptr, &head);
 }
 
 __attribute__((visibility("default"))) void *realloc(void *ptr, size_t size)
 {
+    if (size == 0)
+        return NULL;
+    if (ptr == NULL)
+        return malloc(size);
+
+    struct bucket *header = get_page_begin(ptr);
+    if (header == NULL)
+        return NULL; // Shouldn't get here
+
+    if (header->block_size >= size)
+    {
+        return ptr;
+    }
+    else
+    {
+        void *new_ptr = malloc(size);
+        memcpy(new_ptr, ptr, header->block_size);
+        free(ptr);
+        return new_ptr;
+    }
+
     return NULL;
 }
 
 __attribute__((visibility("default"))) void *calloc(size_t nmemb, size_t size)
 {
-    return NULL;
+    char *res = malloc(nmemb * size);
+    memset(res, 0, nmemb * size);
+    return res;
 }