The Kitty graphics file and temporary file mediums open a
client-supplied path and the Kitty specification only specifies the
blocklist for Unix-style machines.
Windows has various unsafe paths as well that we should very obviously
block. This diverges from the Kitty specification for now (I plan
on reporting this upstream and asking for feedback) but I think its the
right move for security.
Windows dangerous namespaces:
- A UNC path (`\\server\share\x`, also `//server/share/x`) makes the
process resolve the host and authenticate to it over SMB.
- The device namespaces (`\\.\`, `\\?\`, `\??\`) reach raw volumes and
named pipes, where the open connects to something or blocks.
- Reserved DOS device names (CON, NUL, COM1, ...) resolve to devices
from inside any directory.
These are now blocked.
This commit also heap allocates the path buffer because max path on
windows is around 100KB. :)
0b54463649