2 files changed, 36 insertions, 20 deletions

diff --git a/src/kernel/mem/virt.c b/src/kernel/mem/virt.c
index f0dca06..bff4b5e 100644
--- a/src/kernel/mem/virt.c
+++ b/src/kernel/mem/virt.c
@@ -1,5 +1,6 @@
 #include <kernel/arch/generic.h>
 #include <kernel/mem/virt.h>
+#include <kernel/panic.h>
 #include <kernel/util.h>
 #include <shared/mem.h>
 
@@ -52,12 +53,13 @@ bool virt_iter_next(struct virt_iter *iter) {
 	return true;
 }
 
-bool virt_cpy(
+size_t virt_cpy(
 		struct pagedir *dest_pages,       void __user *dest,
-		struct pagedir  *src_pages, const void __user *src, size_t length)
+		struct pagedir  *src_pages, const void __user *src,
+		size_t length, struct virt_cpy_error *err)
 {
 	struct virt_iter dest_iter, src_iter;
-	size_t cur_len;
+	size_t total = 0, partial;
 
 	virt_iter_new(&dest_iter,           dest, length, dest_pages, true, true);
 	virt_iter_new( &src_iter, (userptr_t)src, length,  src_pages, true, false);
@@ -65,19 +67,26 @@ bool virt_cpy(
 	src_iter.frag_len  = 0;
 
 	for (;;) {
-		if (dest_iter.frag_len <= 0)
-			if (!virt_iter_next(&dest_iter)) break;
-		if ( src_iter.frag_len <= 0)
-			if (!virt_iter_next( &src_iter)) break;
+		if (dest_iter.frag_len <= 0 && !virt_iter_next(&dest_iter)) break;
+		if ( src_iter.frag_len <= 0 && !virt_iter_next( &src_iter)) break;
 
-		cur_len = min(src_iter.frag_len, dest_iter.frag_len);
-		memcpy(dest_iter.frag, src_iter.frag, cur_len);
+		partial = min(src_iter.frag_len, dest_iter.frag_len);
+		total += partial;
+		memcpy(dest_iter.frag, src_iter.frag, partial);
 
-		dest_iter.frag_len -= cur_len;
-		dest_iter.frag     += cur_len;
-		src_iter.frag_len  -= cur_len;
-		src_iter.frag      += cur_len;
+		dest_iter.frag_len -= partial;
+		dest_iter.frag     += partial;
+		src_iter.frag_len  -= partial;
+		src_iter.frag      += partial;
 	}
 
-	return !(dest_iter.error || src_iter.error);
+	if (err) {
+		err->read_fail  = src_iter.error;
+		err->write_fail = dest_iter.error;
+	}
+	if (src_iter.error || dest_iter.error)
+		assert(total != length);
+	else
+		assert(total == length);
+	return total;
 }
diff --git a/src/kernel/mem/virt.h b/src/kernel/mem/virt.h
index 7d95b3b..cf22a75 100644
--- a/src/kernel/mem/virt.h
+++ b/src/kernel/mem/virt.h
@@ -18,6 +18,10 @@ struct virt_iter {
 	bool _writeable;
 };
 
+struct virt_cpy_error {
+	bool read_fail, write_fail;
+};
+
 /* if pages == NULL, create an iterator over physical memory. */
 void virt_iter_new(
 		struct virt_iter *iter, void __user *virt, size_t length,
@@ -25,17 +29,20 @@ void virt_iter_new(
 
 bool virt_iter_next(struct virt_iter *);
 
-bool virt_cpy(
+size_t virt_cpy(
 		struct pagedir *dest_pages,       void __user *dest,
-		struct pagedir  *src_pages, const void __user *src, size_t length);
+		struct pagedir  *src_pages, const void __user *src,
+		size_t length, struct virt_cpy_error *err);
 
 
-static inline bool virt_cpy_to(struct pagedir *dest_pages, // physical -> virtual
+/* copies to virtual memory, returns true on success */
+static inline bool virt_cpy_to(struct pagedir *dest_pages,
 		void __user *dest, const void *src, size_t length) {
-	return virt_cpy(dest_pages, dest, NULL, (userptr_t)src, length);
+	return length == virt_cpy(dest_pages, dest, NULL, (userptr_t)src, length, NULL);
 }
 
-static inline bool virt_cpy_from(struct pagedir *src_pages, // virtual -> physical
+/* copies from virtual memory, returns true on success */
+static inline bool virt_cpy_from(struct pagedir *src_pages,
 		void *dest, const void __user *src, size_t length) {
-	return virt_cpy(NULL, (userptr_t)dest, src_pages, src, length);
+	return length == virt_cpy(NULL, (userptr_t)dest, src_pages, src, length, NULL);
 }