From 1528e2153dfbd729916f1211a6f481a2171f855f Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Fri, 12 Aug 2022 15:26:57 +0200
Subject: user/libc: getcwd() bounds checking

---
 src/user/lib/stdlib.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

(limited to 'src/user')

diff --git a/src/user/lib/stdlib.c b/src/user/lib/stdlib.c
index a5d2d9b..43405d7 100644
--- a/src/user/lib/stdlib.c
+++ b/src/user/lib/stdlib.c
@@ -104,10 +104,14 @@ int chdir(const char *path) {
 	return 0;
 }
 
-char *getcwd(char *buf, size_t size) {
+char *getcwd(char *buf, size_t capacity) {
 	const char *realcwd = getrealcwd();
-	// TODO bounds checking
-	memcpy(buf, realcwd, strlen(realcwd) + 1);
+	size_t len = strlen(realcwd) + 1;
+	if (capacity < len) {
+		errno = capacity == 0 ? EINVAL : ERANGE;
+		return NULL;
+	}
+	memcpy(buf, realcwd, len);
 	return buf;
 }
 
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