libc.obj: Add allocator

just add allocator instead of `_ksys_alloc`, `_ksys_free` and `_ksys_realloc`.

programs/develop/ktcc/trunk/libc.obj/.gitignore

@@ -0,0 +1,4 @@
+.tup
+*.o
+*.obj
+*.kex

programs/develop/ktcc/trunk/libc.obj/samples/Makefile

@@ -27,7 +27,8 @@ BIN = \
 	libc_test.kex \
 	pipe.kex \
 	defgen.kex \
-	futex.kex
+	futex.kek \
+	malloc_test.kex
 	
 all: $(BIN)
 	

programs/develop/ktcc/trunk/libc.obj/samples/build_all.sh

@@ -23,5 +23,6 @@ cp     clayer/logo.png /tmp0/1/tcc_samples/logo.png
 ../tcc defgen.c -o /tmp0/1/tcc_samples/defgen
 ../tcc pipe.c -o /tmp0/1/tcc_samples/pipe
 ../tcc futex.c -o /tmp0/1/tcc_samples/futex
+../tcc malloc_test.c -o /tmp0/1/tcc_samples/malloc_test
 "/sys/File managers/Eolite" /tmp0/1/tcc_samples
 exit

programs/develop/ktcc/trunk/libc.obj/samples/malloc_test.c

@@ -0,0 +1,292 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdbool.h>
+#include "../source/stdlib/_mem.h"
+
+#define RUN_TEST(func)                                  \
+    printf("---\tRUN TEST: %s\t---\n", #func);          \
+    if (func()) {                                       \
+        printf("[SUCCESS]\tTest %s is ok.\n\n", #func); \
+    } else {                                            \
+        printf("[FAIL]\tTest %s failed.\n\n", #func);   \
+        exit(EXIT_FAILURE);                             \
+    }
+
+// c between a and b
+#define IN_RANGE(a, b, c, len) ((a > c && c > b) || ((a > c + len && c + len > b)))
+
+bool test_malloc_basic_allocation()
+{
+    void* ptr = malloc(sizeof(int));
+
+    if (ptr)
+        free(ptr);
+
+    return ptr;
+}
+bool test_malloc_zero_bytes()
+{
+    return malloc(0) == NULL;
+}
+
+bool test_malloc_multiple_allocations()
+{
+    void* ptr[512];
+
+    for (int i = 1; i < sizeof(ptr) / sizeof(*ptr); i++) {
+        ptr[i] = malloc(i);
+        if (ptr[i] == NULL) {
+            return false;
+        }
+    }
+    for (int i = 1; i < sizeof(ptr) / sizeof(*ptr); i++) {
+        for (int j = 1; j < sizeof(ptr) / sizeof(*ptr); j++) {
+            if (i != j) {
+                if (ptr[i] == ptr[j]) {
+                    printf("ptrs[%d] == ptrs[%d].\n", i, j);
+                    return false;
+                } else if (IN_RANGE(
+                               (char*)GET_MEM_NODE_HEADER(ptr[i]) + GET_MEM_NODE_HEADER(ptr[i])->size,
+                               (char*)GET_MEM_NODE_HEADER(ptr[i]),
+                               (char*)GET_MEM_NODE_HEADER(ptr[j]),
+                               GET_MEM_NODE_HEADER(ptr[j])->size)) {
+                    printf("node %p in node %p", GET_MEM_NODE_HEADER(ptr[i]), GET_MEM_NODE_HEADER(ptr[j]));
+                    // additional info, may help with debug
+                    printf("node %p\n size:%p\n free:%p\n next: %p\n last: %p\n", GET_MEM_NODE_HEADER(ptr[i]), GET_MEM_NODE_HEADER(ptr[i])->size, GET_MEM_NODE_HEADER(ptr[i])->free, GET_MEM_NODE_HEADER(ptr[i])->next, GET_MEM_NODE_HEADER(ptr[i])->last);
+                    printf("node %p\n size:%p\n free:%p\n next: %p\n last: %p\n", GET_MEM_NODE_HEADER(ptr[j]), GET_MEM_NODE_HEADER(ptr[j])->size, GET_MEM_NODE_HEADER(ptr[j])->free, GET_MEM_NODE_HEADER(ptr[j])->next, GET_MEM_NODE_HEADER(ptr[j])->last);
+                    exit(EXIT_FAILURE);
+                }
+            }
+        }
+    }
+
+    for (int i = 1; i < sizeof(ptr) / sizeof(*ptr); i++) {
+        free(ptr[i]);
+    }
+
+    return true;
+}
+bool test_malloc_data_integrity()
+{
+    const char* As = "AAA";
+    const char* Cs = "CCC";
+
+    char* A = (char*)malloc(10);
+    char* B = (char*)malloc(10);
+    char* C = (char*)malloc(10);
+
+    if (!A || !B || !C) {
+        printf("can't alloc\n");
+        free(A);
+        free(B);
+        free(C);
+        return false;
+    }
+
+    strcpy(A, As);
+    strcpy(C, Cs);
+
+    free(B);
+
+    if (strcmp(A, As) != 0) {
+        printf("A data is broken after free(B). A = '%s'\n", A);
+        free(A);
+        free(C);
+        return false;
+    }
+    if (strcmp(C, Cs) != 0) {
+        printf("C data is broken after free(B). C = '%s'\n", C);
+        free(A);
+        free(C);
+        return false;
+    }
+
+    free(A);
+    free(C);
+    return true;
+}
+bool test_malloc_large_allocation()
+{
+    void* ptr = malloc(1024 * 1024 * 16); // alloc 16mb
+
+    if (ptr)
+        free(ptr);
+
+    return ptr;
+}
+bool test_malloc_allocation_and_free()
+{
+    free(malloc(sizeof(int)));
+    return true;
+}
+
+void fill_buffer(void* ptr, size_t size, unsigned char pattern)
+{
+    if (ptr) {
+        memset(ptr, pattern, size);
+    }
+}
+
+bool check_buffer(void* ptr, size_t size, unsigned char pattern)
+{
+    if (!ptr) {
+        return false; // Нельзя проверить NULL
+    }
+    unsigned char* byte_ptr = (unsigned char*)ptr;
+    for (size_t i = 0; i < size; ++i) {
+        if (byte_ptr[i] != pattern) {
+            fprintf(stderr, "Ошибка: Байт %zu не соответствует паттерну. Ожидалось %02X, получено %02X\n",
+                i, pattern, byte_ptr[i]);
+            return false;
+        }
+    }
+    return true;
+}
+
+bool test_realloc_basic_grow()
+{
+    size_t old_size = 10;
+    size_t new_size = 20;
+    int* ptr = (int*)malloc(old_size * sizeof(int));
+
+    if (ptr == NULL) {
+        return false;
+    }
+    fill_buffer(ptr, old_size * sizeof(int), 0xAA);
+
+    int* new_ptr = (int*)realloc(ptr, new_size * sizeof(int));
+
+    if (new_ptr == NULL) {
+        free(ptr);
+        return false;
+    }
+
+    if (!check_buffer(new_ptr, old_size * sizeof(int), 0xAA)) {
+        free(new_ptr);
+        return false;
+    }
+
+    fill_buffer(new_ptr + old_size, (new_size - old_size) * sizeof(int), 0xBB);
+    if (!check_buffer(new_ptr + old_size, (new_size - old_size) * sizeof(int), 0xBB)) {
+        free(new_ptr);
+        return false;
+    }
+
+    free(new_ptr);
+    return true;
+}
+
+bool test_realloc_basic_shrink()
+{
+    size_t old_size = 20;
+    size_t new_size = 10;
+    int* ptr = (int*)malloc(old_size * sizeof(int));
+
+    if (ptr == NULL) {
+        return false;
+    }
+    fill_buffer(ptr, old_size * sizeof(int), 0xCC);
+
+    int* new_ptr = (int*)realloc(ptr, new_size * sizeof(int));
+
+    if (new_ptr == NULL) {
+        free(ptr);
+        return false;
+    }
+
+    if (!check_buffer(new_ptr, new_size * sizeof(int), 0xCC)) {
+        free(new_ptr);
+        return false;
+    }
+
+    free(new_ptr);
+    return true;
+}
+
+bool test_realloc_same_size()
+{
+    size_t size = 15;
+    int* ptr = (int*)malloc(size * sizeof(int));
+
+    if (ptr == NULL) {
+        return false;
+    }
+    fill_buffer(ptr, size * sizeof(int), 0xDD);
+
+    int* new_ptr = (int*)realloc(ptr, size * sizeof(int));
+
+    if (new_ptr == NULL) {
+        free(ptr);
+        return false;
+    }
+
+    if (!check_buffer(new_ptr, size * sizeof(int), 0xDD)) {
+        free(new_ptr);
+        return false;
+    }
+
+    free(new_ptr);
+
+    return true;
+}
+
+bool test_realloc_null_ptr()
+{
+    size_t size = 25;
+    void* ptr = realloc(NULL, size);
+
+    if (ptr == NULL) {
+        return false;
+    }
+
+    fill_buffer(ptr, size, 0xEE);
+    if (!check_buffer(ptr, size, 0xEE)) {
+        free(ptr);
+        return false;
+    }
+
+    free(ptr);
+
+    return true;
+}
+
+bool test_realloc_to_zero_size()
+{
+    size_t old_size = 30;
+    void* ptr = malloc(old_size);
+
+    if (ptr == NULL) {
+        return false;
+    }
+    fill_buffer(ptr, old_size, 0xFF);
+
+    void* new_ptr = realloc(ptr, 0);
+
+    if (new_ptr == NULL) {
+        printf("realloc(ptr, 0) return NULL.\n");
+        free(ptr);
+    } else {
+        printf("realloc(ptr, 0) return: %p.\n", new_ptr);
+        free(new_ptr);
+    }
+    return true;
+}
+
+int main()
+{
+    RUN_TEST(test_malloc_basic_allocation);
+    RUN_TEST(test_malloc_zero_bytes);
+    RUN_TEST(test_malloc_multiple_allocations);
+    RUN_TEST(test_malloc_data_integrity);
+    RUN_TEST(test_malloc_large_allocation);
+    RUN_TEST(test_malloc_basic_allocation);
+    RUN_TEST(test_malloc_allocation_and_free);
+    RUN_TEST(test_realloc_basic_grow);
+    RUN_TEST(test_realloc_basic_shrink);
+    RUN_TEST(test_realloc_same_size);
+    RUN_TEST(test_realloc_null_ptr);
+    RUN_TEST(test_realloc_to_zero_size);
+
+    return 0;
+}

programs/develop/ktcc/trunk/libc.obj/source/stdlib/_mem.h

@@ -0,0 +1,81 @@
+#ifndef _LIBC_STDLIB__MEM_
+#define _LIBC_STDLIB__MEM_
+
+#include <stddef.h>
+
+struct mem_node {
+    size_t free; // Amount of free space in this node.  When equal to size, the entire node is free.
+
+    size_t size; // Total size of this memory node.
+
+    struct mem_node* last; // Pointer to the previous memory node in the linked list.
+    struct mem_node* next; // Pointer to the next memory node in the linked list.
+};
+
+struct mem_block {
+    size_t size; // Size of the allocated memory block.
+
+    size_t a; // align to 8bytes
+};
+
+// Size of the blocks allocated by `_ksys_alloc`
+#define ALLOC_BLOCK_SIZE 4096
+
+// Macro to get a pointer to the user data area from a mem_node pointer.
+// This is done by adding the size of the mem_node structure to the mem_node pointer.
+#define GET_MEM_NODE_PTR(node) (char*)((char*)(node) + sizeof(struct mem_node))
+
+// Macro to check if a memory node is completely free.
+#define MEM_NODE_IS_FREE(node) (node->free == node->size)
+
+// Macro to get the amount of used memory in a memory node.
+#define GET_MEM_NODE_USED_MEM(node) (node->size - node->free)
+
+// Macro to get a pointer to the mem_node structure from a user data pointer.
+// This is done by subtracting the size of the mem_node structure from the user data pointer.
+#define GET_MEM_NODE_HEADER(ptr) ((struct mem_node*)(((char*)ptr) - sizeof(struct mem_node)))
+
+// Macro to check if two adjacent memory nodes are in the same block.
+// Checks if the end of the left node's allocated space is the start of the right node.
+#define MEM_NODES_ARE_IN_ONE_BLOCK(left, right) (GET_MEM_NODE_PTR(left) + ((struct mem_node*)left)->size == (char*)right)
+
+// Macro to merge two adjacent memory nodes.
+#define CHECK_SIDE_IN_OTHER_BLOCK(node, side) (side == NULL || ((side != NULL) && !MEM_NODES_ARE_IN_ONE_BLOCK(node, side)))
+
+// align a value to a specified alignment.
+// Ensures that the allocated memory is aligned to a certain boundary
+inline size_t __mem_align(size_t value, size_t align)
+{
+    return ((value + align - 1) & ~(align - 1));
+}
+
+#define __mem_default_align(value) __mem_align(value, 8)
+
+inline struct mem_node* __mem_MERGE_MEM_NODES(struct mem_node* base, struct mem_node* addition)
+{
+    // addition is free && nodes base and addition both in one block, else merge is impossible
+    if (MEM_NODE_IS_FREE(addition) && MEM_NODES_ARE_IN_ONE_BLOCK(base, addition)) {
+        // just change size
+        const size_t s = addition->size + sizeof(struct mem_node);
+        base->size += s;
+        base->free += s;
+
+        // and delete addition from list
+        if (addition->next != NULL) {
+            addition->next->last = base;
+            base->next = addition->next;
+        } else {
+            base->next = NULL;
+        }
+        return base;
+    }
+    return NULL;
+}
+
+// Static pointer to the first memory node in the linked list.
+// This acts as the head of the memory pool.
+static struct mem_node* __mem_node = NULL;
+
+static struct mem_node* __last_biggest_mem_node = NULL;
+
+#endif // _LIBC_STDLIB_MEM_

programs/develop/ktcc/trunk/libc.obj/source/stdlib/calloc.c

@@ -1,14 +1,10 @@
-#include <errno.h>
 #include <stdlib.h>
-#include <sys/ksys.h>
 
 void* calloc(size_t num, size_t size)
 {
-    void* ptr = _ksys_alloc(num * size);
-    if (!ptr) {
-        __errno = ENOMEM;
-        return NULL;
+    void* ptr = malloc(num * size);
+    if (ptr) {
+        memset(ptr, 0, num * size);
     }
-    memset(ptr, 0, num * size);
     return ptr;
 }

programs/develop/ktcc/trunk/libc.obj/source/stdlib/free.c

@@ -1,7 +1,97 @@
 #include <stdlib.h>
+#include <stdbool.h>
 #include <sys/ksys.h>
+#include "_mem.h"
 
 void free(void* ptr)
 {
-    _ksys_free(ptr);
-}
+    // Handle NULL pointer.
+    if (ptr == NULL)
+        return;
+
+    // Get a pointer to the mem_node header from the user data pointer.
+    struct mem_node* node = GET_MEM_NODE_HEADER(ptr);
+
+    // Mark the memory node as free.
+    node->free = node->size;
+
+    if (__last_biggest_mem_node == node) {
+        if (node->last) {
+            __last_biggest_mem_node = node->last; // anyway node will be merged with next
+                                                  // and last and last will have size = last + node + next(if its free too)
+        }
+    }
+
+    // Merge with the next node if possible.
+    if (node->next != NULL)
+        __mem_MERGE_MEM_NODES(node, node->next);
+
+    // Merge with the previous node if possible.
+    if (node->last != NULL)
+        node = __mem_MERGE_MEM_NODES(node->last, node);
+
+    if (node) {
+
+        // If the current node is not adjacent to either the next or previous node,
+        // it might be a separate block that can be freed.
+        if (MEM_NODE_IS_FREE(node) // check it because node maybe was merged with last
+            && (node->last == NULL || !MEM_NODES_ARE_IN_ONE_BLOCK(node, node->next))
+            && (node->next == NULL || !MEM_NODES_ARE_IN_ONE_BLOCK(node->last, node))) {
+
+            // Get a pointer to the mem_block header from the mem_node header.
+            struct mem_block* block = (struct mem_block*)(((char*)node) - sizeof(struct mem_block));
+
+            // Check if the block size matches the node size.
+            if (block->size == node->size + sizeof(struct mem_block) + sizeof(struct mem_node)) {
+
+                // Update the linked list pointers to remove the current node.
+                if (node->last != NULL)
+                    node->last->next = node->next;
+
+                if (node->next != NULL)
+                    node->next->last = node->last;
+
+                // Update the head of the linked list if necessary.
+                if (__mem_node == node) {
+                    if (node->last != NULL) {
+                        __mem_node = node->last;
+                    } else if (node->next != NULL) {
+                        __mem_node = node->next;
+                    } else {
+                        __mem_node = NULL;
+                    }
+                }
+
+                struct mem_node* a = node->next;
+                struct mem_node* b = node->last;
+
+                if (!a && !b) {
+                    __last_biggest_mem_node = NULL;
+                } else if (a && !b) {
+                    __last_biggest_mem_node = a;
+                } else if (!a && b) {
+                    __last_biggest_mem_node = b;
+                } else if (a && b) {
+                    __last_biggest_mem_node = (a->free > b->free) ? a : b;
+                }
+
+                if (__last_biggest_mem_node == node) {
+                    if (node->next && !(node->last)) {
+                        __last_biggest_mem_node = node->next;
+                    } else if (node->last && !(node->next)) {
+                        __last_biggest_mem_node = node->last;
+                    } else if (node->next && node->last) {
+                        if (node->last->free > node->next->free) {
+                            __last_biggest_mem_node = node->last;
+                        } else {
+                            __last_biggest_mem_node = node->next;
+                        }
+                    }
+                }
+
+                // Free the memory block using the ksys_free function.
+                _ksys_free(block);
+            }
+        }
+    }
+}

programs/develop/ktcc/trunk/libc.obj/source/stdlib/malloc.c

@@ -1,7 +1,128 @@
+#include <string.h>
 #include <stdlib.h>
+#include <errno.h>
 #include <sys/ksys.h>
+#include <stdbool.h>
+#include "_mem.h"
+
+static struct mem_node* __new_mem_node_from_exist(struct mem_node* current_node, size_t size, bool* from_empty_node)
+{
+    struct mem_node* new_node = NULL;
+    // Check if the current node has enough free space for the requested size.
+    if (size + sizeof(struct mem_node) <= current_node->free) {
+
+        *from_empty_node = MEM_NODE_IS_FREE(current_node);
+        if (*from_empty_node) {
+            new_node = current_node;
+        } else {
+            // Calculate the used memory in current node
+            const size_t s = GET_MEM_NODE_USED_MEM(current_node);
+
+            // Create a new memory node after the current node's used space.
+            new_node = (struct mem_node*)(GET_MEM_NODE_PTR(current_node) + s);
+
+            // Update current node's size
+            current_node->size = s;
+
+            // Set the size of the new node.
+            // for new node give all free space in current node
+            new_node->size = current_node->free - sizeof(struct mem_node);
+
+            // Mark current node as used.
+            current_node->free = 0;
+        }
+    }
+    return new_node;
+}
 
 void* malloc(size_t size)
 {
-    return _ksys_alloc(size);
-}
+    char b[32];
+
+    // Handle zero-size allocation.
+    if (size == 0) {
+        return NULL;
+    }
+
+    // Align the size to 8 bytes.
+    size = __mem_default_align(size);
+
+    struct mem_node* current_node = __mem_node;
+    struct mem_node* new_node = NULL; // Pointer to the new node that will be created.
+    bool from_empty_node = false;
+
+    if (__last_biggest_mem_node != NULL)
+        new_node = __new_mem_node_from_exist(__last_biggest_mem_node, size, &from_empty_node); // try find free space in last created node
+
+    // if cant find in __last_biggest_mem_node
+    if (new_node == NULL) {
+        // Iterate through the linked list of memory nodes.
+        while (current_node != NULL) {
+            new_node = __new_mem_node_from_exist(current_node, size, &from_empty_node);
+            if (new_node)
+                break; // Found a suitable node, exit the loop.
+
+            current_node = current_node->next; // Move to the next node in the list.
+        }
+    }
+
+    // If no suitable node was found in the existing list:
+    if (new_node == NULL) {
+        // Calculate the size of the new block, including the mem_block header, mem_node header and alignment.
+        const size_t s = __mem_align(size + sizeof(struct mem_block) + sizeof(struct mem_node), ALLOC_BLOCK_SIZE);
+
+        // Allocate a new block of memory using the ksys_alloc function (presumably a kernel-level allocation function).
+        struct mem_block* block = (struct mem_block*)_ksys_alloc(s);
+
+        // Check if the allocation was successful.
+        if (block == NULL) {
+            __errno = ENOMEM; // Set the error number to indicate memory allocation failure.
+            return NULL;      // Return NULL to indicate allocation failure.
+        }
+
+        block->size = s;
+
+        // Create a new memory node after the mem_block header.
+        new_node = (struct mem_node*)(((char*)block) + sizeof(struct mem_block));
+
+        // Set the size of the new node.
+        new_node->size = s - sizeof(struct mem_block) - sizeof(struct mem_node);
+    }
+
+    // Set the free space in the new node.
+    new_node->free = new_node->size - size;
+
+    if (!from_empty_node) {
+        // Set the last pointer of the new node to the current node.
+        new_node->last = current_node;
+
+        // Link the new node into the linked list.
+        if (current_node != NULL) {
+            // Set the next pointer of the current node to the new node.
+            new_node->next = current_node->next;
+
+            // Update the last pointer of the next node, if it exists.
+            if (current_node->next != NULL) {
+                current_node->next->last = new_node;
+            }
+            current_node->next = new_node;
+        } else {
+            // If the current node is NULL, the new node is the first node in the list.
+            new_node->next = NULL;
+        }
+    }
+
+    // If the linked list was empty, set the head to the new node.
+    if (__mem_node == NULL) {
+        __mem_node = new_node;
+    }
+
+    if (__last_biggest_mem_node == NULL || new_node->free > __last_biggest_mem_node->free) {
+        __last_biggest_mem_node = new_node;
+    }
+
+    // Return a pointer to the user data area of the new node.
+    return GET_MEM_NODE_PTR(new_node);
+}
+
+#undef __mem_align

programs/develop/ktcc/trunk/libc.obj/source/stdlib/realloc.c

@@ -1,7 +1,76 @@
 #include <stdlib.h>
+#include <string.h>
 #include <sys/ksys.h>
+#include "_mem.h"
+
+// realloc mem. using if other ways not working
+static void* fail_realloc(void* ptr, size_t newsize)
+{
+    // Allocate a new block of memory with the new size.
+    void* new_ptr = malloc(newsize);
+
+    // If both the old pointer and the new pointer are not NULL:
+    if (ptr != NULL && new_ptr != NULL) {
+        // Copy the data from the old block to the new block.
+        memcpy(new_ptr, ptr, min(newsize, GET_MEM_NODE_USED_MEM(GET_MEM_NODE_HEADER(ptr))));
+    }
+
+    if (ptr) {
+        free(ptr); // Free the old block.
+    }
+
+    return new_ptr;
+}
 
 void* realloc(void* ptr, size_t newsize)
 {
-    return _ksys_realloc(ptr, newsize);
-}
+
+    void* new_ptr = NULL;
+    struct mem_node* node = NULL;
+
+    if (ptr && newsize) {
+
+        // Get a pointer to the mem_node header from the user data pointer.
+        node = GET_MEM_NODE_HEADER(ptr);
+
+        newsize = __mem_default_align(newsize);
+
+        if (node->size >= newsize) { // current node have enough mem
+                                     // it work always if newsize is smaller
+            // Update the free space in the current node.
+            node->free = node->size - newsize;
+            // Return the original pointer.
+            new_ptr = ptr;
+        } else if (node->last && MEM_NODE_IS_FREE(node->last) && node->size + node->last->size >= newsize) {
+            // So what happens here is that the node merges with the last node if their volume is sufficient.
+            // And a reallock is called in the hopes that the first condition will be met.
+            // if merge failed realloc anyway return pointer, but it will got from `fail_realloc`
+            struct mem_node* l = node->last;
+
+            l = __mem_MERGE_MEM_NODES(l, node);
+            if (l) {
+                memmove(GET_MEM_NODE_PTR(l), ptr, GET_MEM_NODE_USED_MEM(node));
+                new_ptr = realloc(GET_MEM_NODE_PTR(l), newsize);
+            }
+        }
+    }
+
+    if (new_ptr == NULL) {
+
+        // Allocate a new block of memory with the new size.
+        new_ptr = malloc(newsize);
+
+        // If both the old pointer and the new pointer are not NULL:
+        if (ptr != NULL && new_ptr != NULL) {
+            // Copy the data from the old block to the new block.
+            memcpy(new_ptr, ptr, min(newsize, GET_MEM_NODE_USED_MEM(GET_MEM_NODE_HEADER(ptr))));
+        }
+
+        if (ptr) {
+            free(ptr); // Free the old block.
+        }
+    }
+
+    // Return the new pointer.
+    return new_ptr;
+}