System commands with error escaping

System commands with error escaping

[白熊 @相撲道]

Hello everyone: 

I'd like to ask for help with the following: 

I'm programming a Guile automation interface for GNU software compilation and need to issue system calls with error escaping. I have package recipes, which then issue mostly specific configure and make system calls and need to catch errors, that mostly happen during configure and make runs. 

Currently, I use the following to issue the configure and make recipes: 

(use-modules (ice-9 popen)
             (ice-9 rdelim))
(let* ((port (open-input-pipe command-string))
       (str (read-line port)))
  (close-pipe port)
  str)

where command-string is the configure syntax or whatever...

The problem with this is, when configure fails for example due to an error, I don't catch the error and next command gets executed... But I need to catch the error and stop Guile from proceeding, so I see what happened. 

How can I best do this? 

Thanks a lot for any advice. 
--
白熊 @相撲道

Re: System commands with error escaping

[Thien-Thi Nguyen]

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() "白熊 @相撲道" <guile-user_gnu.org@sumou.com>
() Thu, 27 Nov 2014 00:18:22 +0300

   The problem with this is, when configure fails for example due
   to an error, I don't catch the error and next command gets
   executed... But I need to catch the error and stop Guile from
   proceeding, so I see what happened.

   How can I best do this? 

Personally, i use ‘(ttn-do zzz subprocess) call-process’, from
package ttn-do (http://www.gnuvola.org/software/ttn-do/).  Here is
its description (excerpt from .info file):

 -- Scheme Procedure: call-process program [keyword value…]
          Keywords: inp, outp, errp, norm, args

     Call PROGRAM synchronously in separate process.  Unless given
     ‘#:outp 0’, wait for PROGRAM to terminate and return a numeric exit
     status.

     ‘#:inp (current-input-port)’
          Input port.  ‘#f’ means ‘/dev/null’.

     ‘#:outp (current-output-port)’
          Output port.  ‘#f’ means discard output; 0 (zero) means
          discard, don’t wait for PROGRAM to terminate, and return ‘#f’.

     ‘#:errp (current-error-port)’
          Error output port.  ‘#f’ means discard output.

     ‘#:norm #f’
          Non-‘#f’ means PROGRAM and ARGS should be passed through
          ‘args->normalized-list’.

     ‘#:args ()’
          List of additional args to pass to PROGRAM.

See also ‘make-buffered-caller’ in that module for a more involved
(albeit still synchronous) interface.

-- 
Thien-Thi Nguyen
   GPG key: 4C807502
   (if you're human and you know it)
      read my lisp: (responsep (questions 'technical)
                               (not (via 'mailing-list)))
                     => nil

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Re: System commands with error escaping

[白熊@相撲道]

On 2014年11月27日 9:45:26 GMT+03:00, Thien-Thi Nguyen <ttn@gnu.org> wrote:
>
>Personally, i use ‘(ttn-do zzz subprocess) call-process’, from
>package ttn-do (http://www.gnuvola.org/software/ttn-do/).   
Hi: 

Thanks for the recommendation. I've inspected ttn-do, however it seems too old to me, for instance relies on the obsolete (ice-9 optargs-kw). Didn't check further, anyhow couldn't build it...

I've settled on the simple approach now: 

(let ((return (system command-string)))
  (if (not (eqv? 0 return))
       (throw 'error)))

Which stop fine if run like this. However the problem is, if I define a routine like this: 

(define (test-command command-string)
(let ((return (system command-string)))
  (if (not (eqv? 0 return))
       (throw 'error))))


then call it from somewhere, it doesn't halt code execution, throws the error, then continues with other commands, that follow the test-command call...

Tried with (exit) instead of (throw 'error), but same thing, can't initiate a break of all subroutines and immediate code execution halt, with no further commands. 

I'm sure I'm missing something simple... Can anyone point me in the right direction?
--
白熊＠相撲道