[Libguestfs] [PATCH 0/4] libguestfs cannot open disk images which are symlinks to files that contain ':' (colon) character (RHBZ#812092).

Note: This is a regression in RHEL 6.3. Please review this patch urgently. The description of the bug is here: https://bugzilla.redhat.com/show_bug.cgi?id=812092 This patch set attempts to fix the problem conservatively, because it's a very high risk codepath and very late in the development of RHEL 6.3. The first patch reverts the behaviour of calling realpath(3) and checking for duplicate filenames. The second patch fixes 'check_path'. Only ':' is not permitted in qemu paths. (However symlinks to paths that contain ':' will work again because the first patch was reverted.) The third patch adds proper escaping of ',' in qemu command line parameters. The fourth patch adds a regression test for filenames containing unusual characters. Rich.