Added a j6_proto_vfs_tag/_get_tag pair of messages to the VFS protocol
to allow filesystems to label themselves, and gave 6s the concept of
current fs and current working directory.
This commit adds the 6s shell, and a bunch of supporting work for it.
Major changes include:
- New shell.yaml manifest to give 6s control of the TTY instead of
srv.logger
- Changes to mailbox syscalls to add max handles array size separate
from input size. Also reversed the meaning of the similar data size
argument in those syscalls. (Using the second arg as the max array
size and the first as the current valid size allows for the auto
verify code to verify handles properly, and simplifies user-side
code.)
- New util::unique_ptr smart pointer class similar to std::unique_ptr
- New ipc::message format that uses util::unique_ptr to manage ownership
and lifetimes and avoid extra copying.
- The service locator protocol now supports multiple handles per entry
- Channels got a major overhaul. They are now split into two VMAs, each
containing a mutex, a condition, and a util::bip_buffer. The order of
the VMAs determines which end of the pipe you're on. (ie, the creator
swaps them before handing them to the other thread.) Their API also
changed to be similar to that of util::bip_buffer, to avoid extra
copies.
- util::bip_buffer now keeps its state and its buffer together, so that
there are no pointers. This allows multiple processes to share them in
shared memory, like in channels.
- The UART driver changed from keeping buffers for the serial ports to
just keeping a channel, and the serial port objects read/write
directly from/to the channel.
Known issues:
- The shell doesn't actually do anything yet. It echos its input back to
the serial line and injects a prompt on new lines.
- The shell is one character behind in printing back to the serial line.
User code can now set the log area and severity of log messages. This also updates the j6_log
syscall to take these parameters, but removes all calls to it except through j6::syslog().
ld.so will now go through all DT_NEEDED entries in the dynamic table and load and relocate
those shared libraries as well. Lazy linking of functions via the PLT is not yet supported,
all PLT entries are looked up ahead of time by ld.so.
This change allows the `vma_map` and `vma_create_map` syscalls to map to
addresses other than the one specified, and therefore makes the address
parameter to those syscalls `inout` in order to return the mapped
address.
Also add the `exact` flag for specifying that mapping needs to be done
at the exact address given. If the mapping collides with another, the
new `j6_err_collision` error is returned.
This commit includes a number of changes to enable loading of PIE
executables:
- The loader in srv.init checks for a `PT_INTERP` segment in the program
its loading, and if it exists, loads the specified interpreter and
passes control to it instead of the program itself.
- Added ld.so the dynamic linker executable and set it as the
interpreter for all user-target programs.
- Program initial stack changed again to now contain a number of
possible tagged structures, including a new one for ld.so's arguments,
and for passing handles tagged with protocol ids.
- Added a stub for a new VFS protocol. Unused so far, but srv.init will
need to serve VFS requests from ld.so once I transition libraries to
shared libs for user-target programs. (Right now all executables are
PIE but statically linked, so they only need internal relocations.)
- Added 16 and 8 bit variants of `util::bitset`. This ended up not being
used, but could be useful.
