posix runtime: getcwd: check malloc and set errno

* failing malloc was not handled before, now returns null/ENOMEM
* when path is non-null and size is zero return null/EINVAL

1 files changed, 8 insertions, 2 deletions

diff --git a/runtime/POSIX/fd.c b/runtime/POSIX/fd.c
index cfd2622f..35d0d315 100644
--- a/runtime/POSIX/fd.c
+++ b/runtime/POSIX/fd.c
@@ -1351,9 +1351,15 @@ char *getcwd(char *buf, size_t size) {
   }
 
   if (!buf) {
-    if (!size)
-      size = 1024;
+    size = 1024; // typically PATH_MAX
     buf = malloc(size);
+    if (!buf) {
+      errno = ENOMEM;
+      return NULL;
+    }
+  } else if (!size) {
+    errno = EINVAL;
+    return NULL;
   }
   
   buf = __concretize_ptr(buf);