From d0bd16da2f913417de3b1bd797e9f498d6341f76 Mon Sep 17 00:00:00 2001
From: Guillem George <guillem.george@epita.fr>
Date: Tue, 4 Nov 2025 14:38:36 +0100
Subject: [PATCH] '

---
 .gitignore                        |  3 +++
 beware_overflow/beware_overflow.c | 11 +++++++++++
 beware_overflow/beware_overflow.h |  8 ++++++++
 beware_overflow/main.c            | 21 +++++++++++++++++++++
 my_recycler/my_recycler.c         |  1 +
 my_recycler/my_recycler.h         | 24 ++++++++++++++++++++++++
 page_begin/main.c                 | 21 +++++++++++++++++++++
 page_begin/page_begin.c           |  0
 page_begin/page_begin.h           |  8 ++++++++
 9 files changed, 97 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 beware_overflow/beware_overflow.c
 create mode 100644 beware_overflow/beware_overflow.h
 create mode 100644 beware_overflow/main.c
 create mode 100644 my_recycler/my_recycler.c
 create mode 100644 my_recycler/my_recycler.h
 create mode 100644 page_begin/main.c
 create mode 100644 page_begin/page_begin.c
 create mode 100644 page_begin/page_begin.h

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..7d45161
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+a.out
+*.o
+*.a
diff --git a/beware_overflow/beware_overflow.c b/beware_overflow/beware_overflow.c
new file mode 100644
index 0000000..a97ef7e
--- /dev/null
+++ b/beware_overflow/beware_overflow.c
@@ -0,0 +1,11 @@
+#include "beware_overflow.h"
+
+void *beware_overflow(void *ptr, size_t nmemb, size_t size)
+{
+    size_t c;
+    if (__builtin_mul_overflow(nmemb, size, &c))
+        return NULL;
+
+    char *byte_ptr = ptr;
+    return c + byte_ptr;
+}
diff --git a/beware_overflow/beware_overflow.h b/beware_overflow/beware_overflow.h
new file mode 100644
index 0000000..821e81e
--- /dev/null
+++ b/beware_overflow/beware_overflow.h
@@ -0,0 +1,8 @@
+#ifndef BEWARE_OVERFLOW_H
+#define BEWARE_OVERFLOW_H
+
+#include <stddef.h>
+
+void *beware_overflow(void *ptr, size_t nmemb, size_t size);
+
+#endif /* BEWARE_OVERFLOW_H */
diff --git a/beware_overflow/main.c b/beware_overflow/main.c
new file mode 100644
index 0000000..42fd689
--- /dev/null
+++ b/beware_overflow/main.c
@@ -0,0 +1,21 @@
+#include <stddef.h>
+#include <stdio.h>
+
+#include "beware_overflow.h"
+
+void print_overflow(void *ptr, size_t nmemb, size_t size)
+{
+    void *begin = ptr;
+    void *res = beware_overflow(ptr, nmemb, size);
+    if (res)
+        printf("Pointer was incremented from %p to %p.\n", begin, res);
+    else
+        printf("Overflow detected between %ld and %ld.\n", nmemb, size);
+}
+
+int main(void)
+{
+    print_overflow((void *)0x1000, 25, 6);
+    print_overflow((void *)0x40000, 12345678904, 12345678904);
+    return 0;
+}
diff --git a/my_recycler/my_recycler.c b/my_recycler/my_recycler.c
new file mode 100644
index 0000000..e84f090
--- /dev/null
+++ b/my_recycler/my_recycler.c
@@ -0,0 +1 @@
+#include "my_recycler.h"
diff --git a/my_recycler/my_recycler.h b/my_recycler/my_recycler.h
new file mode 100644
index 0000000..36418dd
--- /dev/null
+++ b/my_recycler/my_recycler.h
@@ -0,0 +1,24 @@
+#ifndef MY_RECYCLER_H
+#define MY_RECYCLER_H
+
+#include <stddef.h>
+
+struct recycler
+{
+    size_t block_size; // size of a block
+    size_t capacity; // number of blocks in the chunk
+    void *chunk; // memory chunk containing all blocks
+    void *free; // address of the first free block of the free list
+};
+
+struct free_list
+{
+    struct free_list *next; // next free block
+};
+
+struct recycler *recycler_create(size_t block_size, size_t total_size);
+void recycler_destroy(struct recycler *r);
+void *recycler_allocate(struct recycler *r);
+void recycler_free(struct recycler *r, void *block);
+
+#endif /* ! MY_RECYCLER_H */
diff --git a/page_begin/main.c b/page_begin/main.c
new file mode 100644
index 0000000..8fc931e
--- /dev/null
+++ b/page_begin/main.c
@@ -0,0 +1,21 @@
+#include <stdio.h>
+
+#include "page_begin.h"
+
+static void display_result(void *ptr, size_t page_size, void *expected_result)
+{
+    void *res = page_begin(ptr, page_size);
+
+    printf("ptr: %p\n", ptr);
+    printf("page_size: %lu\n", page_size);
+    printf("expected_result: %p\n", expected_result);
+    printf("result: %p\n", res);
+
+    printf(expected_result == res ? "OK\n" : "KO\n");
+}
+
+int main(void)
+{
+    display_result((void *)0x1234ffea, 4096, (void *)0x1234f000);
+    display_result((void *)0x1234ffea, 256, (void *)0x1234ff00);
+}
diff --git a/page_begin/page_begin.c b/page_begin/page_begin.c
new file mode 100644
index 0000000..e69de29
diff --git a/page_begin/page_begin.h b/page_begin/page_begin.h
new file mode 100644
index 0000000..ba467d5
--- /dev/null
+++ b/page_begin/page_begin.h
@@ -0,0 +1,8 @@
+#ifndef PAGE_BEGIN_H
+#define PAGE_BEGIN_H
+
+#include <stddef.h>
+
+void *page_begin(void *ptr, size_t page_size);
+
+#endif /* !PAGE_BEGIN_H */