From fc00c656c96528112d05cf0edf8631bd5eaea446 Mon Sep 17 00:00:00 2001
From: Kacper <kacper@mail.openlinux.dev>
Date: Sun, 7 Dec 2025 20:10:31 +0100
Subject: Add build system scaffolding and libc headers

---
 lib/libc/stdlib/realloc.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 lib/libc/stdlib/realloc.c

(limited to 'lib/libc/stdlib/realloc.c')

diff --git a/lib/libc/stdlib/realloc.c b/lib/libc/stdlib/realloc.c
new file mode 100644
index 00000000..d90af70d
--- /dev/null
+++ b/lib/libc/stdlib/realloc.c
@@ -0,0 +1,47 @@
+#include <errno.h>
+#include <string.h>
+#include <atomic.h>
+#include <libc.h>
+#include <malloc.h>
+#include <linux/errno.h>
+#include <stdlib.h>
+
+void *realloc(void *ptr, size_t size)
+{
+	if (ptr == NULL) {
+		return malloc(size);
+	}
+	if (size == 0) {
+		free(ptr);
+		return NULL;
+	}
+
+	LIBC_LOCK(libc.lock.malloc);
+
+	struct page *p = __malloc_pvec;
+	while (p) {
+		if ((uintptr_t)ptr >= (uintptr_t)p->heap &&
+		    (uintptr_t)ptr < (uintptr_t)(p->heap + (p->block.size *
+							    p->block.count))) {
+			size_t old_size = p->block.size;
+			LIBC_UNLOCK(libc.lock.malloc);
+
+			if (size <= old_size) {
+				return ptr;
+			} else {
+				void *new_ptr = malloc(size);
+				if (new_ptr) {
+					memcpy(new_ptr, ptr, old_size);
+					free(ptr);
+				}
+				return new_ptr;
+			}
+		}
+		p = p->next;
+	}
+
+	LIBC_UNLOCK(libc.lock.malloc);
+
+	errno = EINVAL;
+	return NULL;
+}
-- 
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