Linux user memory access API change (initial patch by Thayne Harbaugh)

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@3583 c046a42c-6fe2-441c-8c8c-71466251a162

linux-user/uaccess.c

@@ -0,0 +1,51 @@
+/* User memory access */
+#include <stdio.h>
+#include <string.h>
+
+#include "qemu.h"
+
+/* copy_from_user() and copy_to_user() are usually used to copy data
+ * buffers between the target and host.  These internally perform
+ * locking/unlocking of the memory.
+ */
+abi_long copy_from_user(void *hptr, abi_ulong gaddr, size_t len)
+{
+    abi_long ret = 0;
+    void *ghptr;
+
+    if ((ghptr = lock_user(VERIFY_READ, gaddr, len, 1))) {
+        memcpy(hptr, ghptr, len);
+        unlock_user(ghptr, gaddr, 0);
+    } else
+        ret = -TARGET_EFAULT;
+
+    return ret;
+}
+
+
+abi_long copy_to_user(abi_ulong gaddr, void *hptr, size_t len)
+{
+    abi_long ret = 0;
+    void *ghptr;
+
+    if ((ghptr = lock_user(VERIFY_WRITE, gaddr, len, 0))) {
+        memcpy(ghptr, hptr, len);
+	unlock_user(ghptr, gaddr, len);
+    } else
+        ret = -TARGET_EFAULT;
+
+    return ret;
+}
+
+
+/* Return the length of a string in target memory.  */
+/* FIXME - this doesn't check access_ok() - it's rather complicated to
+ * do it correctly because we need to check the bytes in a page and then
+ * skip to the next page and check the bytes there until we find the
+ * terminator.  There should be a general function to do this that
+ * can look for any byte terminator in a buffer - not strlen().
+ */
+abi_long target_strlen(abi_ulong gaddr)
+{
+    return strlen(g2h(gaddr));
+}