Add args parsing callback for some future work, currently unused.

Add -b flags to insert a window before (like the existing -a for after)
to break-pane, move-window, new-window. GitHub issue 2261.

Improve join-pane, move-pane and break-pane:

- There is no need for join-pane and move-pane to be different.
- break-pane can just behave like move-window if the source has only one
pane, instead of failing.
- Add -a to break-pane like move-window.

Also add missing man page bits for previous window-tree.c changes.

GitHub issue 2176.

Also move cmdq_item and cmdq_list into cmd-queue.c (this is to make its
use more clearly defined and preparation for some future work).

Make struct cmd local to cmd.c and move it out of tmux.h.

Get rid of the extra layer of flags and cmd_prepare() and just store the
CMD_FIND_* flags in the cmd_entry and call it for the command. Commands
with special requirements call it themselves and update the target for
hooks to use.

Mass rename struct cmd_q to struct cmdq_item and related.

Add static in cmd-* and fix a few other nits.

Remove some dead code in cmd-move-window.c and make a load of local
functions static.

I no longer use my SourceForge address so replace it.

Instead of combined flags for -c, -s, -t, split into different sets
using an enum and simplify the parsing code.

Use member names in cmd_entry definitions so I stop getting confused
about the order.

Instead of every command resolving the target (-t or -s) itself, prepare
the state (client, session, winlink, pane) for it it before entering the
command. Each command provides some flags that tell the prepare step
what it is expecting.

This is a requirement for having hooks on commands (for example, if you
hook "select-window -t1:2", the hook command should to operate on window
1:2 not whatever it thinks is the current window), and should allow some
other target improvements.

The old cmd_find_* functions remain for the moment but that layer will
be dropped later.

Joint work with Thomas Adam.

Move struct options into options.c.

Move the shuffle code from new-window -a into a function and add a -a
flag for move-window too. From Thomas Adam.

Fix moving windows to nonexistent indexes when renumber-windows is
off. From Thomas Adam, reported by Daniel Levai and Theo Buehler.

Merge linkw and movew which are virtually identical.

Instead of setting up the default keys by building the key struct
directly with a helper function in the cmd_entry, include a table of
bind-key commands and pass them through the command parser and a
temporary cmd_q.

As well as being smaller, this will allow default bindings to be command
sequences which will probably be needed soon.

Remove the barely-used and unnecessary command check() function.

Add a command queue to standardize and simplify commands that call other
commands and allow a command to block execution of subsequent
commands. This allows run-shell and if-shell to be synchronous which has
been much requested.

Each client has a default command queue and commands are consumed one at
a time from it. A command may suspend execution from the queue by
returning CMD_RETURN_WAIT and then resume it by calling cmd_continue() -
for example run-shell does this from the callback that is fired after
the job is freed.

When the command queue becomes empty, command clients are automatically
exited (unless attaching). A callback is also fired - this is used for
nested commands in, for example, if-shell which can block execution of
the client's cmdq until a new cmdq becomes empty.

Also merge all the old error/info/print functions together and lose the
old curclient/cmdclient distinction - a cmdq is bound to one client (or
none if in the configuration file), this is a command client if
c->session is NULL otherwise an attached client.

Make command exec functions return an enum rather than -1/0/1 values and
add a new value to mean "leave client running but don't attach" to fix
problems with using some commands in a command sequence. Most of the
work by Thomas Adam, problem reported by "jspenguin" on SF bug 3535531.

xfree is not particularly helpful, remove it. From Thomas Adam.

Use -t for move-window with -r rather than dying. Reported by Ben
Boeckel and Thomas Adam.

Add a flag to move-window to renumber the windows in a session (closing
any gaps) and add an option to do this automatically each time a window
is killed. From Thomas Adam.

Clean up and simplify tmux command argument parsing.

Originally, tmux commands were parsed in the client process into a
struct with the command data which was then serialised and sent to the
server to be executed. The parsing was later moved into the server (an
argv was sent from the client), but the parse step and intermediate
struct was kept.

This change removes that struct and the separate parse step. Argument
parsing and printing is now common to all commands (in arguments.c) with
each command left with just an optional check function (to validate the
arguments at parse time), the exec function and a function to set up any
key bindings (renamed from the old init function).

This is overall more simple and consistent.

There should be no changes to any commands behaviour or syntax although
as this touches every command please watch for any unexpected changes.

Get rid of the ugly CMD_CHFLAG macro and use a const string (eg "dDU") in the
command entry structs and a couple of functions to check/set the flags.

Add "grouped sessions" which have independent name, options, current window and
so on but where the linked windows are synchronized (ie creating, killing
windows and so on are mirrored between the sessions). A grouped session may be
created by passing -t to new-session.

Had this around for a while, tested by a couple of people.

Nuke unused variables and fix stupid error message.

Move some common and untidy code for window link/unlink into generic functions
instead of duplicating it in move/link window..

Add a base-index session option to specify the first index checked when looking
for an index for a new window.

Make all messages sent between the client and server fixed size.

This is the first of two changes to make the protocol more resilient and less
sensitive to other changes in the code, particularly with commands. The client
now packs argv into a buffer and sends it to the server for parsing, rather
than doing it itself and sending the parsed command data.

As a side-effect this also removes a lot of now-unused command marshalling
code.

Mixing a server without this change and a client with or vice versa will cause
tmux to hang or crash, please ensure that tmux is entirely killed before
upgrading.

Having fixed flags for single-character getopt options is a bit hard to
maintain and is only going to get worse as more are used. So instead, add a new
uint64_t member to cmd_entry which is a bitmask of upper and lowercase options
accepted by the command.

This means new single character options can be used without the need to add it
explicitly to the list.

Tidy up and improve target (-t) argument parsing:

- move the code back into cmd.c and merge with the existing functions where
possible;
- accept "-tttyp0" as well as "-t/dev/ttyp0" for clients;
- when looking up session names, try an exact match first, and if that fails
look for it as an fnmatch pattern and then as the start of a name - if more
that one session matches an error is given; so if there is one session called
"mysession", -tmysession, -tmysess, -tmysess* are equivalent but if there
is also "mysession2", the last two are errors;
- similarly for windows, if the argument is not a valid index or exact window
name match, try it against the window names as an fnmatch pattern and a
prefix.

Import tmux, a terminal multiplexor allowing (among other things) a single
terminal to be switched between several different windows and programs
displayed on one terminal be detached from one terminal and moved to another.

ok deraadt pirofti

Add -b flags to insert a window before (like the existing -a for after)
to break-pane, move-window, new-window. GitHub issue 2261.

Improve join-pane, move-pane and break-pane:

- There is no need for join-pane and move-pane to be different.
- break-pane can just behave like move-window if the source has only one
pane, instead of failing.
- Add -a to break-pane like move-window.

Also add missing man page bits for previous window-tree.c changes.

GitHub issue 2176.

Also move cmdq_item and cmdq_list into cmd-queue.c (this is to make its
use more clearly defined and preparation for some future work).

Make struct cmd local to cmd.c and move it out of tmux.h.

Get rid of the extra layer of flags and cmd_prepare() and just store the
CMD_FIND_* flags in the cmd_entry and call it for the command. Commands
with special requirements call it themselves and update the target for
hooks to use.

Mass rename struct cmd_q to struct cmdq_item and related.

Add static in cmd-* and fix a few other nits.

Remove some dead code in cmd-move-window.c and make a load of local
functions static.

I no longer use my SourceForge address so replace it.

Instead of combined flags for -c, -s, -t, split into different sets
using an enum and simplify the parsing code.

Use member names in cmd_entry definitions so I stop getting confused
about the order.

Instead of every command resolving the target (-t or -s) itself, prepare
the state (client, session, winlink, pane) for it it before entering the
command. Each command provides some flags that tell the prepare step
what it is expecting.

This is a requirement for having hooks on commands (for example, if you
hook "select-window -t1:2", the hook command should to operate on window
1:2 not whatever it thinks is the current window), and should allow some
other target improvements.

The old cmd_find_* functions remain for the moment but that layer will
be dropped later.

Joint work with Thomas Adam.

Move struct options into options.c.

Move the shuffle code from new-window -a into a function and add a -a
flag for move-window too. From Thomas Adam.

Fix moving windows to nonexistent indexes when renumber-windows is
off. From Thomas Adam, reported by Daniel Levai and Theo Buehler.

Merge linkw and movew which are virtually identical.

Instead of setting up the default keys by building the key struct
directly with a helper function in the cmd_entry, include a table of
bind-key commands and pass them through the command parser and a
temporary cmd_q.

As well as being smaller, this will allow default bindings to be command
sequences which will probably be needed soon.

Remove the barely-used and unnecessary command check() function.

Add a command queue to standardize and simplify commands that call other
commands and allow a command to block execution of subsequent
commands. This allows run-shell and if-shell to be synchronous which has
been much requested.

Each client has a default command queue and commands are consumed one at
a time from it. A command may suspend execution from the queue by
returning CMD_RETURN_WAIT and then resume it by calling cmd_continue() -
for example run-shell does this from the callback that is fired after
the job is freed.

When the command queue becomes empty, command clients are automatically
exited (unless attaching). A callback is also fired - this is used for
nested commands in, for example, if-shell which can block execution of
the client's cmdq until a new cmdq becomes empty.

Also merge all the old error/info/print functions together and lose the
old curclient/cmdclient distinction - a cmdq is bound to one client (or
none if in the configuration file), this is a command client if
c->session is NULL otherwise an attached client.

Make command exec functions return an enum rather than -1/0/1 values and
add a new value to mean "leave client running but don't attach" to fix
problems with using some commands in a command sequence. Most of the
work by Thomas Adam, problem reported by "jspenguin" on SF bug 3535531.

xfree is not particularly helpful, remove it. From Thomas Adam.

Use -t for move-window with -r rather than dying. Reported by Ben
Boeckel and Thomas Adam.

Add a flag to move-window to renumber the windows in a session (closing
any gaps) and add an option to do this automatically each time a window
is killed. From Thomas Adam.

Clean up and simplify tmux command argument parsing.

Originally, tmux commands were parsed in the client process into a
struct with the command data which was then serialised and sent to the
server to be executed. The parsing was later moved into the server (an
argv was sent from the client), but the parse step and intermediate
struct was kept.

This change removes that struct and the separate parse step. Argument
parsing and printing is now common to all commands (in arguments.c) with
each command left with just an optional check function (to validate the
arguments at parse time), the exec function and a function to set up any
key bindings (renamed from the old init function).

This is overall more simple and consistent.

There should be no changes to any commands behaviour or syntax although
as this touches every command please watch for any unexpected changes.

Get rid of the ugly CMD_CHFLAG macro and use a const string (eg "dDU") in the
command entry structs and a couple of functions to check/set the flags.

Add "grouped sessions" which have independent name, options, current window and
so on but where the linked windows are synchronized (ie creating, killing
windows and so on are mirrored between the sessions). A grouped session may be
created by passing -t to new-session.

Had this around for a while, tested by a couple of people.

Nuke unused variables and fix stupid error message.

Move some common and untidy code for window link/unlink into generic functions
instead of duplicating it in move/link window..

Add a base-index session option to specify the first index checked when looking
for an index for a new window.

Make all messages sent between the client and server fixed size.

This is the first of two changes to make the protocol more resilient and less
sensitive to other changes in the code, particularly with commands. The client
now packs argv into a buffer and sends it to the server for parsing, rather
than doing it itself and sending the parsed command data.

As a side-effect this also removes a lot of now-unused command marshalling
code.

Mixing a server without this change and a client with or vice versa will cause
tmux to hang or crash, please ensure that tmux is entirely killed before
upgrading.

Having fixed flags for single-character getopt options is a bit hard to
maintain and is only going to get worse as more are used. So instead, add a new
uint64_t member to cmd_entry which is a bitmask of upper and lowercase options
accepted by the command.

This means new single character options can be used without the need to add it
explicitly to the list.

Tidy up and improve target (-t) argument parsing:

- move the code back into cmd.c and merge with the existing functions where
possible;
- accept "-tttyp0" as well as "-t/dev/ttyp0" for clients;
- when looking up session names, try an exact match first, and if that fails
look for it as an fnmatch pattern and then as the start of a name - if more
that one session matches an error is given; so if there is one session called
"mysession", -tmysession, -tmysess, -tmysess* are equivalent but if there
is also "mysession2", the last two are errors;
- similarly for windows, if the argument is not a valid index or exact window
name match, try it against the window names as an fnmatch pattern and a
prefix.

Import tmux, a terminal multiplexor allowing (among other things) a single
terminal to be switched between several different windows and programs
displayed on one terminal be detached from one terminal and moved to another.

ok deraadt pirofti

Improve join-pane, move-pane and break-pane:

- There is no need for join-pane and move-pane to be different.
- break-pane can just behave like move-window if the source has only one
pane, instead of failing.
- Add -a to break-pane like move-window.

Also add missing man page bits for previous window-tree.c changes.

GitHub issue 2176.

Also move cmdq_item and cmdq_list into cmd-queue.c (this is to make its
use more clearly defined and preparation for some future work).

Make struct cmd local to cmd.c and move it out of tmux.h.

Get rid of the extra layer of flags and cmd_prepare() and just store the
CMD_FIND_* flags in the cmd_entry and call it for the command. Commands
with special requirements call it themselves and update the target for
hooks to use.

Mass rename struct cmd_q to struct cmdq_item and related.

Add static in cmd-* and fix a few other nits.

Remove some dead code in cmd-move-window.c and make a load of local
functions static.

I no longer use my SourceForge address so replace it.

Instead of combined flags for -c, -s, -t, split into different sets
using an enum and simplify the parsing code.

Use member names in cmd_entry definitions so I stop getting confused
about the order.

Instead of every command resolving the target (-t or -s) itself, prepare
the state (client, session, winlink, pane) for it it before entering the
command. Each command provides some flags that tell the prepare step
what it is expecting.

This is a requirement for having hooks on commands (for example, if you
hook "select-window -t1:2", the hook command should to operate on window
1:2 not whatever it thinks is the current window), and should allow some
other target improvements.

The old cmd_find_* functions remain for the moment but that layer will
be dropped later.

Joint work with Thomas Adam.

Move struct options into options.c.

Move the shuffle code from new-window -a into a function and add a -a
flag for move-window too. From Thomas Adam.

Fix moving windows to nonexistent indexes when renumber-windows is
off. From Thomas Adam, reported by Daniel Levai and Theo Buehler.

Merge linkw and movew which are virtually identical.

Instead of setting up the default keys by building the key struct
directly with a helper function in the cmd_entry, include a table of
bind-key commands and pass them through the command parser and a
temporary cmd_q.

As well as being smaller, this will allow default bindings to be command
sequences which will probably be needed soon.

Remove the barely-used and unnecessary command check() function.

Add a command queue to standardize and simplify commands that call other
commands and allow a command to block execution of subsequent
commands. This allows run-shell and if-shell to be synchronous which has
been much requested.

Each client has a default command queue and commands are consumed one at
a time from it. A command may suspend execution from the queue by
returning CMD_RETURN_WAIT and then resume it by calling cmd_continue() -
for example run-shell does this from the callback that is fired after
the job is freed.

When the command queue becomes empty, command clients are automatically
exited (unless attaching). A callback is also fired - this is used for
nested commands in, for example, if-shell which can block execution of
the client's cmdq until a new cmdq becomes empty.

Also merge all the old error/info/print functions together and lose the
old curclient/cmdclient distinction - a cmdq is bound to one client (or
none if in the configuration file), this is a command client if
c->session is NULL otherwise an attached client.

Make command exec functions return an enum rather than -1/0/1 values and
add a new value to mean "leave client running but don't attach" to fix
problems with using some commands in a command sequence. Most of the
work by Thomas Adam, problem reported by "jspenguin" on SF bug 3535531.

xfree is not particularly helpful, remove it. From Thomas Adam.

Use -t for move-window with -r rather than dying. Reported by Ben
Boeckel and Thomas Adam.

Add a flag to move-window to renumber the windows in a session (closing
any gaps) and add an option to do this automatically each time a window
is killed. From Thomas Adam.

Clean up and simplify tmux command argument parsing.

Originally, tmux commands were parsed in the client process into a
struct with the command data which was then serialised and sent to the
server to be executed. The parsing was later moved into the server (an
argv was sent from the client), but the parse step and intermediate
struct was kept.

This change removes that struct and the separate parse step. Argument
parsing and printing is now common to all commands (in arguments.c) with
each command left with just an optional check function (to validate the
arguments at parse time), the exec function and a function to set up any
key bindings (renamed from the old init function).

This is overall more simple and consistent.

There should be no changes to any commands behaviour or syntax although
as this touches every command please watch for any unexpected changes.

Get rid of the ugly CMD_CHFLAG macro and use a const string (eg "dDU") in the
command entry structs and a couple of functions to check/set the flags.

Add "grouped sessions" which have independent name, options, current window and
so on but where the linked windows are synchronized (ie creating, killing
windows and so on are mirrored between the sessions). A grouped session may be
created by passing -t to new-session.

Had this around for a while, tested by a couple of people.

Nuke unused variables and fix stupid error message.

Move some common and untidy code for window link/unlink into generic functions
instead of duplicating it in move/link window..

Add a base-index session option to specify the first index checked when looking
for an index for a new window.

Make all messages sent between the client and server fixed size.

This is the first of two changes to make the protocol more resilient and less
sensitive to other changes in the code, particularly with commands. The client
now packs argv into a buffer and sends it to the server for parsing, rather
than doing it itself and sending the parsed command data.

As a side-effect this also removes a lot of now-unused command marshalling
code.

Mixing a server without this change and a client with or vice versa will cause
tmux to hang or crash, please ensure that tmux is entirely killed before
upgrading.

Having fixed flags for single-character getopt options is a bit hard to
maintain and is only going to get worse as more are used. So instead, add a new
uint64_t member to cmd_entry which is a bitmask of upper and lowercase options
accepted by the command.

This means new single character options can be used without the need to add it
explicitly to the list.

Tidy up and improve target (-t) argument parsing:

- move the code back into cmd.c and merge with the existing functions where
possible;
- accept "-tttyp0" as well as "-t/dev/ttyp0" for clients;
- when looking up session names, try an exact match first, and if that fails
look for it as an fnmatch pattern and then as the start of a name - if more
that one session matches an error is given; so if there is one session called
"mysession", -tmysession, -tmysess, -tmysess* are equivalent but if there
is also "mysession2", the last two are errors;
- similarly for windows, if the argument is not a valid index or exact window
name match, try it against the window names as an fnmatch pattern and a
prefix.

Import tmux, a terminal multiplexor allowing (among other things) a single
terminal to be switched between several different windows and programs
displayed on one terminal be detached from one terminal and moved to another.

ok deraadt pirofti

Also move cmdq_item and cmdq_list into cmd-queue.c (this is to make its
use more clearly defined and preparation for some future work).

Make struct cmd local to cmd.c and move it out of tmux.h.

Get rid of the extra layer of flags and cmd_prepare() and just store the
CMD_FIND_* flags in the cmd_entry and call it for the command. Commands
with special requirements call it themselves and update the target for
hooks to use.

Mass rename struct cmd_q to struct cmdq_item and related.

Add static in cmd-* and fix a few other nits.

Remove some dead code in cmd-move-window.c and make a load of local
functions static.

I no longer use my SourceForge address so replace it.

Instead of combined flags for -c, -s, -t, split into different sets
using an enum and simplify the parsing code.

Use member names in cmd_entry definitions so I stop getting confused
about the order.

Instead of every command resolving the target (-t or -s) itself, prepare
the state (client, session, winlink, pane) for it it before entering the
command. Each command provides some flags that tell the prepare step
what it is expecting.

This is a requirement for having hooks on commands (for example, if you
hook "select-window -t1:2", the hook command should to operate on window
1:2 not whatever it thinks is the current window), and should allow some
other target improvements.

The old cmd_find_* functions remain for the moment but that layer will
be dropped later.

Joint work with Thomas Adam.

Move struct options into options.c.

Move the shuffle code from new-window -a into a function and add a -a
flag for move-window too. From Thomas Adam.

Fix moving windows to nonexistent indexes when renumber-windows is
off. From Thomas Adam, reported by Daniel Levai and Theo Buehler.

Merge linkw and movew which are virtually identical.

Instead of setting up the default keys by building the key struct
directly with a helper function in the cmd_entry, include a table of
bind-key commands and pass them through the command parser and a
temporary cmd_q.

As well as being smaller, this will allow default bindings to be command
sequences which will probably be needed soon.

Remove the barely-used and unnecessary command check() function.

Add a command queue to standardize and simplify commands that call other
commands and allow a command to block execution of subsequent
commands. This allows run-shell and if-shell to be synchronous which has
been much requested.

Each client has a default command queue and commands are consumed one at
a time from it. A command may suspend execution from the queue by
returning CMD_RETURN_WAIT and then resume it by calling cmd_continue() -
for example run-shell does this from the callback that is fired after
the job is freed.

When the command queue becomes empty, command clients are automatically
exited (unless attaching). A callback is also fired - this is used for
nested commands in, for example, if-shell which can block execution of
the client's cmdq until a new cmdq becomes empty.

Also merge all the old error/info/print functions together and lose the
old curclient/cmdclient distinction - a cmdq is bound to one client (or
none if in the configuration file), this is a command client if
c->session is NULL otherwise an attached client.

Make command exec functions return an enum rather than -1/0/1 values and
add a new value to mean "leave client running but don't attach" to fix
problems with using some commands in a command sequence. Most of the
work by Thomas Adam, problem reported by "jspenguin" on SF bug 3535531.

xfree is not particularly helpful, remove it. From Thomas Adam.

Use -t for move-window with -r rather than dying. Reported by Ben
Boeckel and Thomas Adam.

Add a flag to move-window to renumber the windows in a session (closing
any gaps) and add an option to do this automatically each time a window
is killed. From Thomas Adam.

Clean up and simplify tmux command argument parsing.

Originally, tmux commands were parsed in the client process into a
struct with the command data which was then serialised and sent to the
server to be executed. The parsing was later moved into the server (an
argv was sent from the client), but the parse step and intermediate
struct was kept.

This change removes that struct and the separate parse step. Argument
parsing and printing is now common to all commands (in arguments.c) with
each command left with just an optional check function (to validate the
arguments at parse time), the exec function and a function to set up any
key bindings (renamed from the old init function).

This is overall more simple and consistent.

There should be no changes to any commands behaviour or syntax although
as this touches every command please watch for any unexpected changes.

Get rid of the ugly CMD_CHFLAG macro and use a const string (eg "dDU") in the
command entry structs and a couple of functions to check/set the flags.

Add "grouped sessions" which have independent name, options, current window and
so on but where the linked windows are synchronized (ie creating, killing
windows and so on are mirrored between the sessions). A grouped session may be
created by passing -t to new-session.

Had this around for a while, tested by a couple of people.

Nuke unused variables and fix stupid error message.

Move some common and untidy code for window link/unlink into generic functions
instead of duplicating it in move/link window..

Add a base-index session option to specify the first index checked when looking
for an index for a new window.

Make all messages sent between the client and server fixed size.

This is the first of two changes to make the protocol more resilient and less
sensitive to other changes in the code, particularly with commands. The client
now packs argv into a buffer and sends it to the server for parsing, rather
than doing it itself and sending the parsed command data.

As a side-effect this also removes a lot of now-unused command marshalling
code.

Mixing a server without this change and a client with or vice versa will cause
tmux to hang or crash, please ensure that tmux is entirely killed before
upgrading.

Having fixed flags for single-character getopt options is a bit hard to
maintain and is only going to get worse as more are used. So instead, add a new
uint64_t member to cmd_entry which is a bitmask of upper and lowercase options
accepted by the command.

This means new single character options can be used without the need to add it
explicitly to the list.

Tidy up and improve target (-t) argument parsing:

- move the code back into cmd.c and merge with the existing functions where
possible;
- accept "-tttyp0" as well as "-t/dev/ttyp0" for clients;
- when looking up session names, try an exact match first, and if that fails
look for it as an fnmatch pattern and then as the start of a name - if more
that one session matches an error is given; so if there is one session called
"mysession", -tmysession, -tmysess, -tmysess* are equivalent but if there
is also "mysession2", the last two are errors;
- similarly for windows, if the argument is not a valid index or exact window
name match, try it against the window names as an fnmatch pattern and a
prefix.

Import tmux, a terminal multiplexor allowing (among other things) a single
terminal to be switched between several different windows and programs
displayed on one terminal be detached from one terminal and moved to another.

ok deraadt pirofti

Get rid of the extra layer of flags and cmd_prepare() and just store the
CMD_FIND_* flags in the cmd_entry and call it for the command. Commands
with special requirements call it themselves and update the target for
hooks to use.

Mass rename struct cmd_q to struct cmdq_item and related.

Add static in cmd-* and fix a few other nits.

Remove some dead code in cmd-move-window.c and make a load of local
functions static.

I no longer use my SourceForge address so replace it.

Instead of combined flags for -c, -s, -t, split into different sets
using an enum and simplify the parsing code.

Use member names in cmd_entry definitions so I stop getting confused
about the order.

Instead of every command resolving the target (-t or -s) itself, prepare
the state (client, session, winlink, pane) for it it before entering the
command. Each command provides some flags that tell the prepare step
what it is expecting.

This is a requirement for having hooks on commands (for example, if you
hook "select-window -t1:2", the hook command should to operate on window
1:2 not whatever it thinks is the current window), and should allow some
other target improvements.

The old cmd_find_* functions remain for the moment but that layer will
be dropped later.

Joint work with Thomas Adam.

Move struct options into options.c.

Move the shuffle code from new-window -a into a function and add a -a
flag for move-window too. From Thomas Adam.

Fix moving windows to nonexistent indexes when renumber-windows is
off. From Thomas Adam, reported by Daniel Levai and Theo Buehler.

Merge linkw and movew which are virtually identical.

Instead of setting up the default keys by building the key struct
directly with a helper function in the cmd_entry, include a table of
bind-key commands and pass them through the command parser and a
temporary cmd_q.

As well as being smaller, this will allow default bindings to be command
sequences which will probably be needed soon.

Remove the barely-used and unnecessary command check() function.

Add a command queue to standardize and simplify commands that call other
commands and allow a command to block execution of subsequent
commands. This allows run-shell and if-shell to be synchronous which has
been much requested.

Each client has a default command queue and commands are consumed one at
a time from it. A command may suspend execution from the queue by
returning CMD_RETURN_WAIT and then resume it by calling cmd_continue() -
for example run-shell does this from the callback that is fired after
the job is freed.

When the command queue becomes empty, command clients are automatically
exited (unless attaching). A callback is also fired - this is used for
nested commands in, for example, if-shell which can block execution of
the client's cmdq until a new cmdq becomes empty.

Also merge all the old error/info/print functions together and lose the
old curclient/cmdclient distinction - a cmdq is bound to one client (or
none if in the configuration file), this is a command client if
c->session is NULL otherwise an attached client.

Make command exec functions return an enum rather than -1/0/1 values and
add a new value to mean "leave client running but don't attach" to fix
problems with using some commands in a command sequence. Most of the
work by Thomas Adam, problem reported by "jspenguin" on SF bug 3535531.

xfree is not particularly helpful, remove it. From Thomas Adam.

Use -t for move-window with -r rather than dying. Reported by Ben
Boeckel and Thomas Adam.

Add a flag to move-window to renumber the windows in a session (closing
any gaps) and add an option to do this automatically each time a window
is killed. From Thomas Adam.

Clean up and simplify tmux command argument parsing.

Originally, tmux commands were parsed in the client process into a
struct with the command data which was then serialised and sent to the
server to be executed. The parsing was later moved into the server (an
argv was sent from the client), but the parse step and intermediate
struct was kept.

This change removes that struct and the separate parse step. Argument
parsing and printing is now common to all commands (in arguments.c) with
each command left with just an optional check function (to validate the
arguments at parse time), the exec function and a function to set up any
key bindings (renamed from the old init function).

This is overall more simple and consistent.

There should be no changes to any commands behaviour or syntax although
as this touches every command please watch for any unexpected changes.

Get rid of the ugly CMD_CHFLAG macro and use a const string (eg "dDU") in the
command entry structs and a couple of functions to check/set the flags.

Add "grouped sessions" which have independent name, options, current window and
so on but where the linked windows are synchronized (ie creating, killing
windows and so on are mirrored between the sessions). A grouped session may be
created by passing -t to new-session.

Had this around for a while, tested by a couple of people.

Nuke unused variables and fix stupid error message.

Move some common and untidy code for window link/unlink into generic functions
instead of duplicating it in move/link window..

Add a base-index session option to specify the first index checked when looking
for an index for a new window.

Make all messages sent between the client and server fixed size.

This is the first of two changes to make the protocol more resilient and less
sensitive to other changes in the code, particularly with commands. The client
now packs argv into a buffer and sends it to the server for parsing, rather
than doing it itself and sending the parsed command data.

As a side-effect this also removes a lot of now-unused command marshalling
code.

Mixing a server without this change and a client with or vice versa will cause
tmux to hang or crash, please ensure that tmux is entirely killed before
upgrading.

Having fixed flags for single-character getopt options is a bit hard to
maintain and is only going to get worse as more are used. So instead, add a new
uint64_t member to cmd_entry which is a bitmask of upper and lowercase options
accepted by the command.

This means new single character options can be used without the need to add it
explicitly to the list.

Tidy up and improve target (-t) argument parsing:

- move the code back into cmd.c and merge with the existing functions where
possible;
- accept "-tttyp0" as well as "-t/dev/ttyp0" for clients;
- when looking up session names, try an exact match first, and if that fails
look for it as an fnmatch pattern and then as the start of a name - if more
that one session matches an error is given; so if there is one session called
"mysession", -tmysession, -tmysess, -tmysess* are equivalent but if there
is also "mysession2", the last two are errors;
- similarly for windows, if the argument is not a valid index or exact window
name match, try it against the window names as an fnmatch pattern and a
prefix.

Import tmux, a terminal multiplexor allowing (among other things) a single
terminal to be switched between several different windows and programs
displayed on one terminal be detached from one terminal and moved to another.

ok deraadt pirofti