Implement zip_fdopen and ZIP_AFL_RDONLY.
This allows to open a zip archive from an already open file descriptor;
archives opened this way are marked read-only.

--HG--
branch : HEAD

lib/zip_set_archive_comment.c

diff --git a/lib/zip_set_archive_comment.c b/lib/zip_set_archive_comment.c
index 343fa54..3bb85d1 100644
--- a/lib/zip_set_archive_comment.c
+++ b/lib/zip_set_archive_comment.c
@@ -1,6 +1,6 @@
 /*
   zip_set_archive_comment.c -- set archive comment
-  Copyright (C) 2006-2007 Dieter Baron and Thomas Klausner
+  Copyright (C) 2006-2009 Dieter Baron and Thomas Klausner
 
   This file is part of libzip, a library to manipulate ZIP archives.
   The authors can be contacted at <libzip@nih.at>
@@ -50,6 +50,11 @@
 	return -1;
     }
 
+    if (ZIP_IS_RDONLY(za)) {
+	_zip_error_set(&za->error, ZIP_ER_RDONLY, 0);
+	return -1;
+    }
+
     if (len > 0) {
 	if ((tmpcom=(char *)_zip_memdup(comment, len, &za->error)) == NULL)
 	    return -1;