Issue #194: Change --args to match 'gdb --args'. 'cmd' now only takes program name.

[fritzr]

Here is a patch which does what I think is reasonable: causes --args to take all remaining arguments as program arguments as with 'gdb --args'. The 'cmd' argument only takes the program name now. There are three options for 'cmd':

1. Leave 'cmd' as nargs='*'; then any flags passed as '-' are ambiguous with gdbgui arguments unless the entire command string is qutoed, in which case it might as well be nargs=1. (i.e. gdbgui [gdbgui-args] cmd [these-are-more-gdbgui-args])
2. Set 'cmd' as nargs=1; this essentially works the same as above, but shows this explicitly in the usage string. Then to pass a full command string you would either do gdgbui 'quoted-command --with-arguments' [gdbgui-args...].
3. Set 'cmd' as nargs=argparse.REMAINDER; in this case the first non-option argument would begin debug program arguments. This acts more like non-GNU option parsing, i.e. gdbgui [gdbgui-options] cmd-name [cmd-arguments...]. However, with '--args' already set to argparse.REMAINDER, the two are equivalent. And then it is possible confusing if you want to do something like gdbgui cmd-name --no-browser, because --no-browser would be interpreted as a command arg.

For this reason I chose the second option. It is still convenient to debug simply with gdbgui [gdbgui-args...] program but you have gdb-like control with gdbgui --args program [program-args...].

[cs01]

First, thanks for putting so much work and detail into this.

I am on board with #2. I tested it and it worked with --args but it failed when I tried the "cmd" option:

>> gdbgui/backend.py examples/c/hello_c.a
Opening gdbgui in browser at http://127.0.0.1:5000
exit gdbgui by pressing CTRL+C
Traceback (most recent call last):
  File "/Users/cs/.virtualenvs/gdbgui2/lib/python3.6/site-packages/engineio/server.py", line 411, in _trigger_event
    return self.handlers[event](*args)
  File "/Users/cs/.virtualenvs/gdbgui2/lib/python3.6/site-packages/socketio/server.py", line 518, in _handle_eio_message
    self._handle_connect(sid, pkt.namespace)
  File "/Users/cs/.virtualenvs/gdbgui2/lib/python3.6/site-packages/socketio/server.py", line 421, in _handle_connect
    self.environ[sid]) is False:
  File "/Users/cs/.virtualenvs/gdbgui2/lib/python3.6/site-packages/socketio/server.py", line 490, in _trigger_event
    return self.handlers[namespace][event](*args)
  File "/Users/cs/.virtualenvs/gdbgui2/lib/python3.6/site-packages/flask_socketio/__init__.py", line 251, in _handler
    *args)
  File "/Users/cs/.virtualenvs/gdbgui2/lib/python3.6/site-packages/flask_socketio/__init__.py", line 632, in _handle_event
    ret = handler()
  File "gdbgui/backend.py", line 324, in client_connected
    payload = _state.connect_client(request.sid, desired_gdbpid)
  File "/Users/cs/git/gdbgui/gdbgui/statemanager.py", line 58, in connect_client
    ) + REQUIRED_GDB_FLAGS
TypeError: must be str, not list

It is easily fixable by changing

cmd = args.cmd

to

cmd = [args.cmd]

in backend.py.

When viewing the help text I think the arguments should be ordered from most commonly used/useful to least commonly. I think cmd and --args are the most useful. What do you think? Probably also makes sense to put cmd before --args so the help text doesn't show anything after --args.

Can the arg help text be changed to this?

Specify the executable file and any arguments. All arguments are taken literally, so if used, this must be the last argument passed to gdbgui. Example: gdbgui [...] --args ./mybinary myarg -flag1 -flag2

Might be worth considering using dest and mutual exclusion since we can't have cmd and --args at the same time and they overload to the same variable in the end.

[fritzr]

I've submitted an update (caa69a4). I had considered using mutex groups, but I found the usage turns out like this:

usage: backend.py [-h] [-x GDB_CMD_FILE] [-g GDB] [--rr] [-p PORT]
                  [--host HOST] [-r] [--auth-file AUTH_FILE] [--user USER]
                  [--password PASSWORD] [--key KEY] [--cert CERT]
                  [--license LICENSE] [--project PROJECT] [-v]
                  [--hide_gdbgui_upgrades] [-n] [--debug]
                  [--args ...]
                  [cmd]

A server that provides a graphical user interface to the gnu debugger (gdb).
https://github.com/cs01/gdbgui

positional arguments:
  cmd                   Name of the binary to run in gdb. To pass flags to the
                        binary, use --args instead. Example: gdbgui ./mybinary
                        [gdbgui-args...]

optional arguments:
  -h, --help            show this help message and exit
  --args ...            All remaining args are taken as the binary and
                        arguments to run in gdb (as with gdb --args). Example:
                        gdbgui [...] --args ./mybinary myarg -flag1 -flag2
gdb commands:
[...]

In which case --args or cmd are not shown under gdb commands section; nor are they shown with a mutex pipe as I would expect (i.e. [--args ...|cmd]). The latter is likely because cmd is a positional argument whereas --args is an optional argument. I believe it is for the same reason that --args shows up before cmd in the list, even though --args is set to argparse.REMAINDER and I add --args after cmd. That could be considered a deficiency in argparse because argparse.REMAINDER options should always occur last, even after positional arguments, unless GNU parsing is disabled... oh well. It's worth noting that I tried using dest='cmd' on --args, but argparse cannot use the same dest for two different flags.

However, it does accomplish placing both cmd and --args at the top of the usage like we want (I agree that makes sense) and it saves us having to check the mutex condition ourselves.

I also realized I could fix 'cmd' from str->list using type=.

[fritzr]

Oh yeah, and d5d55b9 fixes the --args text to match your request:

usage: backend.py [-h] [-x GDB_CMD_FILE] [-g GDB] [--rr] [-p PORT]
                  [--host HOST] [-r] [--auth-file AUTH_FILE] [--user USER]
                  [--password PASSWORD] [--key KEY] [--cert CERT]
                  [--license LICENSE] [--project PROJECT] [-v]
                  [--hide_gdbgui_upgrades] [-n] [--debug] [--args ...]
                  [cmd]

A server that provides a graphical user interface to the gnu debugger (gdb).
https://github.com/cs01/gdbgui

positional arguments:
  cmd                   Name of the binary to run in gdb. To pass flags to the
                        binary, use --args instead. Example: gdbgui ./mybinary
                        [gdbgui-args...]

optional arguments:
  -h, --help            show this help message and exit
  --args ...            Specify the executable file and any arguments. All
                        arguments are taken literally, so if used, this must
                        be the last argument passed to gdbgui. Example: gdbgui
                        [...] --args ./mybinary myarg -flag1 -flag2

[cs01]

I also realized I could fix 'cmd' from str->list using type=.

Nice!

[vcunat]

This is bad. When I start

gdbgui --args cmd arg1 arg2

(as of current latest 0.13.1.1) it gets transformed into

gdb cmd arg1 arg2 --interpreter=mi2

which just can't work. AFAIK it needs to be

gdb --interpreter=mi2 cmd --args arg1 arg2

[jhgoebbert]

I can confirm, that the "--args" issue is not yet fixed in 0.13.2.0:
Please check #272 (comment)

[cs01]

Sorry for the inconvenience. If you have the time/ability please submit a PR. Otherwise I will get to it when I can.