[libvirt] [PATCH V2] virsh: rework command parsing

[Chris Lalancette]

On 09/16/10 - 05:36:11PM, Lai Jiangshan wrote:
> 
> Old virsh command parsing mashes all the args back into a string and
> miss the quotes, this patch fixes it. It is also needed for introducing
> qemu-monitor-command which is very useful.
> 
> This patch split the command-parsing into 2 phrases:
> 1) parse command string and make it into <args, argv> style arguments.
> 2) parse <args, argv> style arguments and make it into vshCmd structure.

This is some nice work, and indeed does seem to fix the behavior for
qemu-monitor-command.  I have a few comments inline.

<snip>

> --- libvirt-0.8.4.old/tools/virsh.c	2010-09-10 20:47:06.000000000 +0800
> +++ libvirt-0.8.4/tools/virsh.c	2010-09-16 17:13:55.000000000 +0800
...
> @@ -10257,130 +10333,42 @@ vshCommandParse(vshControl *ctl, char *c
>  
>      str = cmdstr;
>      while (str && *str) {
> -        vshCmdOpt *last = NULL;
> -        const vshCmdDef *cmd = NULL;
> -        int tk = VSH_TK_NONE;
> -        int data_ct = 0;
> -
> -        first = NULL;
> -
> -        while (tk != VSH_TK_END) {
> -            char *end = NULL;
> -            const vshCmdOptDef *opt = NULL;
> -
> -            tkdata = NULL;
> -
> -            /* get token */
> -            tk = vshCommandGetToken(ctl, str, &end, &tkdata);
> -
> -            str = end;
> -
> -            if (tk == VSH_TK_END) {
> -                VIR_FREE(tkdata);
> -                break;
> -            }
> -            if (tk == VSH_TK_ERROR)
> +        vshCmd *c;
> +        int args = 0;
> +        char *argv[20];

Why argv[20] here?  It seems like an arbitrary number, and the check below
seems like an arbitrary check.  Can we just make this unlimited and allocate
memory as needed?

> +        char *arg;
> +        int last_arg = 0;
> +
> +        while ((arg = vshCmdStrGetArg(ctl, str, &str, &last_arg)) != NULL) {
> +            if (args == sizeof(argv) / sizeof(argv[0])) {
> +                vshError(ctl, _("too many args"));
>                  goto syntaxError;
> -

<snip>

> @@ -10939,7 +10927,8 @@ static void
>  vshUsage(void)
>  {
>      const vshCmdDef *cmd;
> -    fprintf(stdout, _("\n%s [options] [commands]\n\n"
> +    fprintf(stdout, _("\n%s [options]... [<command_name> args...]"
> +                      "\n%s [options]... <command_string>\n\n"
>                        "  options:\n"
>                        "    -c | --connect <uri>    hypervisor connection URI\n"
>                        "    -r | --readonly         connect readonly\n"
> @@ -10949,7 +10938,7 @@ vshUsage(void)
>                        "    -t | --timing           print timing information\n"
>                        "    -l | --log <file>       output logging to file\n"
>                        "    -v | --version          program version\n\n"
> -                      "  commands (non interactive mode):\n"), progname);
> +                      "  commands (non interactive mode):\n"), progname, progname);
>  
>      for (cmd = commands; cmd->name; cmd++)
>          fprintf(stdout,
> @@ -11069,25 +11058,25 @@ vshParseArgv(vshControl *ctl, int argc, 

Very minor note, but I think you should be able to remove the forward prototype
of vshParseArgv at the top of virsh.c.

>  
>      if (argc > end) {
>          /* parse command */
> -        char *cmdstr;
> -        int sz = 0, ret;
> +        int ret = TRUE;
>  
>          ctl->imode = FALSE;
>  
> -        for (i = end; i < argc; i++)
> -            sz += strlen(argv[i]) + 1;  /* +1 is for blank space between items */
> -
> -        cmdstr = vshCalloc(ctl, sz + 1, 1);
> -
> -        for (i = end; i < argc; i++) {
> -            strncat(cmdstr, argv[i], sz);
> -            sz -= strlen(argv[i]);
> -            strncat(cmdstr, " ", sz--);
> +        if (argc - end == 1) {
> +            char *cmdstr = vshStrdup(ctl, argv[end]);
> +            vshDebug(ctl, 2, "commands: \"%s\"\n", cmdstr);
> +            ret = vshCommandParse(ctl, cmdstr);
> +            VIR_FREE(cmdstr);
> +        } else {
> +            if (ctl->cmd) {
> +                vshCommandFree(ctl->cmd);
> +                ctl->cmd = NULL;
> +            }

I don't think you need to free up ctl->cmd here.  From what I can tell
vshParseArgv can only be called during virsh startup, so there should never
be a previous command.

Other than that, it looks pretty good.  I did some basic testing of it with
my qemu-monitor-command patch, and things seemed to work pretty well with it.
The code is still a bit more complicated than I would like, but given what it
has to do that is probably unavoidable.  Once you've made the changes I
suggested above (or tell me why they aren't needed), I would be happy to ACK
this.

Thanks!
-- 
Chris Lalancette