'

.gitignore

@@ -0,0 +1,3 @@
+a.out
+*.o
+*.a

beware_overflow/beware_overflow.c

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+#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;
+}

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 */

beware_overflow/main.c

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+#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;
+}

my_recycler/my_recycler.c

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+#include "my_recycler.h"

my_recycler/my_recycler.h

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+#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 */

page_begin/main.c

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+#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);
+}

page_begin/page_begin.h

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+#ifndef PAGE_BEGIN_H
+#define PAGE_BEGIN_H
+
+#include <stddef.h>
+
+void *page_begin(void *ptr, size_t page_size);
+
+#endif /* !PAGE_BEGIN_H */