Re: [PATCH v2 1/2] cmdline: add function to verify valid commands

[Olivier Matz <olivier.matz@6wind.com>]

On Fri, Jun 10, 2022 at 03:08:49PM +0100, Bruce Richardson wrote:
> On Tue, Jun 07, 2022 at 10:08:30AM +0200, Olivier Matz wrote:
> > Hi Bruce,
> > 
> > Just few minor comments below.
> > 
> > On Fri, May 20, 2022 at 04:12:39PM +0100, Bruce Richardson wrote:
> > > The cmdline library cmdline_parse() function parses a command and
> > > executes the action automatically too. The cmdline_valid_buffer function
> > > also uses this function to validate commands, meaning that there is no
> > > function to validate a command as ok without executing it.
> > > 
> > > To fix this omission, we extract the body of cmdline_parse into a new
> > > static inline function with an extra parameter to indicate whether the
> > > action should be performed or not. Then we create two wrappers around
> > > that - a replacement for the existing cmdline_parse function where the
> > > extra parameter is "true" to execute the command, and a new function
> > > "cmdline_parse_check" which passes the parameter as "false" to perform
> > > cmdline validation only.
> > > 
> > > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> > > ---
> > >  lib/cmdline/cmdline_parse.c | 20 +++++++++++++++++---
> > >  lib/cmdline/cmdline_parse.h | 17 +++++++++++++++--
> > >  lib/cmdline/version.map     |  3 +++
> > >  3 files changed, 35 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/lib/cmdline/cmdline_parse.c b/lib/cmdline/cmdline_parse.c
> > > index 349ec87bd7..b7fdc67ae5 100644
> > > --- a/lib/cmdline/cmdline_parse.c
> > > +++ b/lib/cmdline/cmdline_parse.c
> > > @@ -7,6 +7,7 @@
> > >  #include <stdio.h>
> > >  #include <errno.h>
> > >  #include <string.h>
> > > +#include <stdbool.h>
> > >  
> > >  #include <rte_string_fns.h>
> > >  
> > > @@ -182,8 +183,8 @@ match_inst(cmdline_parse_inst_t *inst, const char *buf,
> > >  }
> > >  
> > >  
> > > -int
> > > -cmdline_parse(struct cmdline *cl, const char * buf)
> > > +static inline int
> > > +__cmdline_parse(struct cmdline *cl, const char *buf, bool call_fn)
> > >  {
> > >  	unsigned int inst_num=0;
> > >  	cmdline_parse_inst_t *inst;
> > > @@ -284,7 +285,8 @@ cmdline_parse(struct cmdline *cl, const char * buf)
> > >  
> > >  	/* call func */
> > >  	if (f) {
> > > -		f(result.buf, cl, data);
> > > +		if (call_fn)
> > > +			f(result.buf, cl, data);
> > 
> > Maybe nicer to test in one line:
> > 
> > if (f && call_fn)
> > 
> 
> If we do so, then we need to also change the "else" leg to "else if

Oh yes I missed the else part!


> (!call_fn)" because we don't want to have the debug_printf being output in
> the case that we have call_fn == false. A better alternative is to slightly
> restructure the whole block, to have the error leg first, which removes the
> need for two condition checks before calling the function:
> 
>         /* no match */
>         if (f == NULL) {
>                 debug_printf("No match err=%d\n", err);
>                 return err;
>         }
> 
>         /* call func if requested*/
>         if (call_fn)
>                 f(result.buf, cl, data);
> 
>         return linelen;
> 
> I think this latter option is better, so will implement in v3.

Yes, it looks good to me, thanks!


> 
> > 
> > >  	}
> > >  
> > >  	/* no match */
> > > @@ -296,6 +298,18 @@ cmdline_parse(struct cmdline *cl, const char * buf)
> > >  	return linelen;
> > >  }
> > >  
> > > +int
> > > +cmdline_parse(struct cmdline *cl, const char *buf)
> > > +{
> > > +	return __cmdline_parse(cl, buf, true);
> > > +}
> > > +
> > > +int
> > > +cmdline_parse_check(struct cmdline *cl, const char *buf)
> > > +{
> > > +	return __cmdline_parse(cl, buf, false);
> > > +}
> > > +
> > >  int
> > >  cmdline_complete(struct cmdline *cl, const char *buf, int *state,
> > >  		 char *dst, unsigned int size)
> > > diff --git a/lib/cmdline/cmdline_parse.h b/lib/cmdline/cmdline_parse.h
> > > index e4d802fff7..6dd210d843 100644
> > > --- a/lib/cmdline/cmdline_parse.h
> > > +++ b/lib/cmdline/cmdline_parse.h
> > > @@ -7,6 +7,8 @@
> > >  #ifndef _CMDLINE_PARSE_H_
> > >  #define _CMDLINE_PARSE_H_
> > >  
> > > +#include <rte_compat.h>
> > > +
> > >  #ifdef __cplusplus
> > >  extern "C" {
> > >  #endif
> > > @@ -149,11 +151,22 @@ typedef cmdline_parse_inst_t *cmdline_parse_ctx_t;
> > >   * argument buf must ends with "\n\0". The function returns
> > >   * CMDLINE_PARSE_AMBIGUOUS, CMDLINE_PARSE_NOMATCH or
> > >   * CMDLINE_PARSE_BAD_ARGS on error. Else it calls the associated
> > > - * function (defined in the context) and returns 0
> > > - * (CMDLINE_PARSE_SUCCESS).
> > > + * function (defined in the context) and returns the parsed line length (>= 0)
> > 
> > Can we add a dot at the end?
> 
> Ack.
> 
> > 
> > >   */
> > >  int cmdline_parse(struct cmdline *cl, const char *buf);
> > >  
> > > +/**
> > > + * Try to parse a buffer according to the specified context, but do not
> > > + * perform any function calls if parse is successful.
> > > + *
> > > + * The argument buf must ends with "\n\0".
> > > + * The function returns CMDLINE_PARSE_AMBIGUOUS, CMDLINE_PARSE_NOMATCH or
> > > + * CMDLINE_PARSE_BAD_ARGS on error and returns the parsed line length (>=0).
> > > + * on successful parse
> > 
> > Same here.
> 
> Ack.
> 
> > 
> > > + */
> > > +__rte_experimental
> > > +int cmdline_parse_check(struct cmdline *cl, const char *buf);
> > > +
> > >  /**
> > >   * complete() must be called with *state==0 (try to complete) or
> > >   * with *state==-1 (just display choices), then called without
> > > diff --git a/lib/cmdline/version.map b/lib/cmdline/version.map
> > > index b9bbb87510..fc7fdd6ea4 100644
> > > --- a/lib/cmdline/version.map
> > > +++ b/lib/cmdline/version.map
> > > @@ -81,5 +81,8 @@ EXPERIMENTAL {
> > >  	rdline_get_history_buffer_size;
> > >  	rdline_get_opaque;
> > >  
> > > +	# added in 22.07
> > > +	cmdline_parse_check;
> > > +
> > >  	local: *;
> > >  };
> > > -- 
> > > 2.34.1
> > > 
> > 
> > With these changes:
> > Acked-by: Olivier Matz <olivier.matz@6wind.com>
> >