[fs][fidl] Replaced filesystem ioctls with FIDL.

This patch allows "ioctl" to be removed from the
C++ VFS Vnode interface.

IOCTL_VFS_MOUNT_FS -> Mount()
IOCTL_VFS_UNMOUNT_FS -> Unmount()
IOCTL_VFS_UNMOUNT_NODE -> UnmounteNode()
IOCTL_VFS_QUERY_FS -> QueryFilesystem()
IOCTL_VFS_MOUNT_MKDIR_FS -> MountAndCreate()
IOCTL_VFS_GET_DEVICE_PATH -> GetDevicePath()
IOCTL_VFS_WATCH_DIR -> WatchDir()

Test: fs-management / fs / blobfs / fvm tests, df manually

Change-Id: Iefe8ec251ca6b8f4e4578ceb61bae6dff7a59e3d

[virtcon] Make run-vc agnostic to fdio implementation

Bug: US-534 #done
Bug: ZX-2680 #done
Test: Check that run-vc works
Change-Id: Icb733697aa5b1f10acca57503e40d6d969dd12c4

[compiler.h] Migrate many C++ clients of countof to fbl::count_of

The latter is safer in C++, and the former is a namespace violation in
compiler.h that eventually needs to be resolved.

Test: CQ; should be no functional change
Change-Id: I9809b9fe062fd5f07226323035bf094b3f9de798

[debuglog] Migrate to zx_debuglog_create

Test: cq

Change-Id: Ia7aa2efefd0c1ac0ce3460159a9405d6f0b1777e

[virtcon] Switch to fdio_spawn_etc

Most codepaths that create processes should use fdio_spawn rather than
launchpad directly.

Test: Manually verified that virtual consoles continue to work (both
normally and in zedbood)

Change-Id: Ic3e1cdf77b38e7fa3f33596443da4efa8b9db5bc

[cleanup] Use zx_handle_close_many in several places

zx_handle_close_many is more readable than a loop.

Test: No behavior change.
Change-Id: I52e07f1006c955dcea39be508ce4053b6489b54a

[virtcon] Revert "Switch to fdio_spawn_etc"

This reverts commit a3c1715d3163ebd51f4e3f734bae27e955c3e67c.

The original change broke the ability to get to a virtual console
while in zedboot, which makes a number of classes of failure much
more difficult to recover from.

TEST=manual, now I have virtual consoles in zedboot

Change-Id: I77428e999c4bb2e9e6f97ce89d313c3bd2b5e29f

[syscalls] zx_channel_write should always consume handles

Previously, whether zx_channel_write consumed handles depended on
whether it succeeded or failed.

ZX-2204 #comment

Test: utest/core/channel
Change-Id: Ie44a8e101fa5e7d0cefc1e1e65cfd084640aa54f

[logging] Migrate zircon off zx_log_read and zx_log_write

zx_log_create is trickier. It's essentially a version of
zx_debuglog_create that allows not passing a root resource.

ZX-2184

Change-Id: Ida3d6bacce2c4601a4c6a00fd0cf13c902eb1d41

[virtcon] Switch to fdio_spawn_etc

Most codepaths that create processes should use fdio_spawn rather than
launchpad directly.

Test: Manually verified that virtual consoles continue to work.

Change-Id: Ia2f2f62ef28565973da7c2e7d364800a7ecf815f

[musl] Rename zx_get_startup_handle to zx_take_startup_handle

The new name more clearly describes the ownership semantics.

ZX-2235 #comment

Change-Id: I887c1f2ad657e3aff9716b9f1865184cb8cf05f7

[fdio] Move headers into lib/fdio/...

Change-Id: Ie8d74e716da913bf6e2672c4acf8cd67b4962b7f

[devmgr][virtcon] Don't start virtcon if require_system

These shells will be started by appmgr instead.

Change-Id: Ib93ca91753898f5dee0c8afcc2f4db39819f188f

[virtcon] Migrate to new display APIs

Change-Id: Ia204796d3e52a7ca934fc171f4a231c89110dc1f

[virtcon] Add support for hotplugging

This change adds support for hotplugging to the virtcon. If multiple
displays are connected, the virtcon will use the display which was
attached first. The virtcon's contents and scrollback are kept when
switching between displays, although long lines will be truncated if
the virtcon moves to a smaller display.

When no display is connected, the console continues to function
normally, except without rendering anything. All checks for whether or
not any gfx operations should be done are in vc-device.

Change-Id: I467b9b1792f4d43803b521ec564dfe1873b85a97

[virtcon] Read kernel log messages with repeating mode

And for consistency establish a convention of having port_wait_repeating()
handlers return ZX_ERR_NEXT.

Change-Id: I6ae0c879a5fbc373369f77e5c9f7ca0d73f25667

[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[devmgr][virtcon] display netsvc output on vc1 in netboot mode

- virtcon can now execute a specific command in vc1 if one is
provided via the --run option
- virtcon uses a white-on-blue color scheme for this
- devmgr provides --run dlog ... when starting netsvc in netboot
mode

Change-Id: I7008db178aa25a8f3dc549a7af46d790d11c6472

[virtcon] 'Keep log visible' should default to 'false'

This reverts the behavior of 9637f2a857b5f7b7af1dd1f94e875d1918c3fc57,
which set "keep_log" to true even when "virtcon.keep-log-visible"
was actually NULL.

Change-Id: Ib303da4cef128faba1b9aaafa8230a746004a609

[system] [core] getenv_bool for cmdline bools

The core kernel behavior for parsing boolean flags is supported by a
cmdline_get_bool. devmgr maps command line arguments to environment
variables. getenv_bool implements the same value semantics as
cmdline_get_bool. The same semantics are also applied in virtcon as a
special case, as it is the only place in core, outside of devmgr, that
inherits boolean options.

Change-Id: Icff00d9a2597ab8fa482f30002120717ce61748b

[virtcon] Limit consumption of pty input in each attempt

If a pty was sending us data faster than we could process it, it would
starve out all other events in the virtcon process (since it's
single-threaded).

MG-921 #done

Change-Id: I25c57850f166cd54a5a884eef77c8c47c2864545

[vfs][watcher] Use the new ioctl_vfs_watch_dir name in magenta

Change-Id: I3877addebcf951bdca89445760d1506bba86124e

[launchpad] Add LP_CLONE_MXIO_NAMESPACE

This constant has the same value and semantics as LP_CLONE_MXIO_ROOT but refers
to namespaces, which will shortly replace MXIO_ROOT.

Change-Id: Ida671c001b45046cf36b39754f24f04aad3160a5

[virtcon] Use the new MX_OK and MX_ERR_* mx_status_t names

Change-Id: I89dd39bd11d4d4b89321424cfc910b605688e307

[virtcon] fix directory watch event parser

Change-Id: I58751cdc8a8966cd6659066fe3dd26b57ea268b3

[virtcon] cleanup

- remove some unused header includes
- remove unused vcdebug.h (xprintf was not used and now virtcon
filters its own debug prints out of the debug log console so
printf is safe to use if needed)
- clean up rules.mk to better reflect shared sources, libraries
- move shared code from main.cpp to vc-input.cpp
- no longer include main.cpp in virtual-console-test
- remove global lock, no longer needed in new single threaded design

Change-Id: I5aacc0f95f817f25ce96bbfa2f74d4877e9c4a16

[virtcon] tidy up watcher message handling, fix bug

Change-Id: I6419cafbe2c1eb24758f3771112106dcb8a6a65c

[virtcon] eliminate input threads, use ports instead

Change-Id: I35616723c597840400d4155a108829dab5f00793

[gfxconsole][virtcon] move and rename gfxconsole to virtcon

It's no longer a device, it's time for it to leave the
land of devices.

Change-Id: I977c56dbacb0794e6f67daac1dd6e3f4f2632f3d