From 3ff27507ccbffba7adf09b2322271606717a9164 Mon Sep 17 00:00:00 2001
From: Freya Murphy <freya@freyacat.org>
Date: Mon, 28 Apr 2025 13:21:58 -0400
Subject: heap (brk / sbrk)

---
 user/heap.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 user/heap.c

(limited to 'user/heap.c')

diff --git a/user/heap.c b/user/heap.c
new file mode 100644
index 0000000..ffa107b
--- /dev/null
+++ b/user/heap.c
@@ -0,0 +1,46 @@
+
+#include <unistd.h>
+#include <string.h>
+#include <stdio.h>
+
+#define PAGE_SIZE 4096
+
+int main(void)
+{
+	void *start, *brk;
+
+	start = sbrk(0);
+	printf("heap start: %p\n", start);
+
+	// test extending
+	if (sbrk(PAGE_SIZE) == NULL) {
+		fprintf(stderr, "failed to extend break\n");
+		return 1;
+	}
+
+	brk = sbrk(0);
+	printf("new break: %p\n", brk);
+
+	// test reextending
+	if (sbrk(PAGE_SIZE) == NULL) {
+		fprintf(stderr, "failed to extend break\n");
+		return 1;
+	}
+
+	brk = sbrk(0);
+	printf("new new break: %p\n", brk);
+
+	// test shrinking
+	if (sbrk(-PAGE_SIZE) == NULL) {
+		fprintf(stderr, "failed to shrink break\n");
+		return 1;
+	}
+
+	brk = sbrk(0);
+	printf("new new new break: %p\n", brk);
+
+	// test write
+	memset(start, 1, PAGE_SIZE);
+
+	return 0;
+}
-- 
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