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Re: reading from a temp file

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Ruben Safir <ruben@mrbrklyn.com> wrote:
> On Tue, 28 Jun 2011 09:55:53 +0000, Jens Thoms Toerring wrote:

> > Also note that if the 'EDITOR' environment variable should be set you're
> > now trying to write into memory belonging to what- ever returned the
> > environment string. Definitely not a good idea - while getenv()
> > unfortunately returns a 'char *' and not a 'char const *' (which would
> > make this mistake impossible) it's not meant as allowing you to modify
> > that string (or, worse, write past its trailing '\0').

> what are you say?  That I can overwrite the environmental variable?

>>>      editor = getenv("EDITOR");
>>>      if (editor == NULL){
>>>         editor  = default_editor;
>>>      }
>>>      strcat(editor, path);

With that code you append to the string you got from
getenv() unless it did return NULL, i.e. in the case
that the 'EDITOR' environment variable is set. And
that's not such a good thing to try - you're not even
supposed to change that string. To be (more or less)
on the safe side you would need

      editor = getenv( "EDITOR" );
      if ( editor != NULL )
      {
          strcpy( default_editor, editor );
          strcat( default_editor, " " ); // needed between command and path
      }
      editor = default_editor;
      strcat( editor, path );

More or less safe because, of course, the 'default_editor'
buffer needs to be large enough and there aren't any tests
for that here (and you have no idea what the 'EDITOR' envi-
ronment variable had been set to). So it probably would be
more prudent to use std::string since then the size gets
adapted automatically to whatever is needed, e.g. something
like

    std::string editor( "vi " );
    if ( ( char *env = getenv( "EDITOR" ) ) != 0 )
		editor = std::string( env ) + " ";
    editor += path;
    ...
    system( editor.c_str( ) );          

                           Regards, Jens
-- 
  \   Jens Thoms Toerring  ___      jt@toerring.de
   \__________________________      http://toerring.de

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Thread

reading from a temp file Ruben Safir <ruben@mrbrklyn.com> - 2011-06-28 08:34 +0000
  Re: reading from a temp file Ian Collins <ian-news@hotmail.com> - 2011-06-28 20:37 +1200
    Re: reading from a temp file jt@toerring.de (Jens Thoms Toerring) - 2011-06-28 09:55 +0000
      Re: reading from a temp file Ruben Safir <ruben@mrbrklyn.com> - 2011-06-28 12:32 +0000
        Re: reading from a temp file jt@toerring.de (Jens Thoms Toerring) - 2011-06-28 13:54 +0000
          Re: reading from a temp file Ruben Safir <mrbrklyn@panix.com> - 2011-07-01 05:14 +0000
        Re: reading from a temp file Michael DOUBEZ <michael.doubez@free.fr> - 2011-07-01 00:54 -0700
    Re: reading from a temp file Michael DOUBEZ <michael.doubez@free.fr> - 2011-07-01 01:20 -0700
      Re: reading from a temp file Ruben Safir <mrbrklyn@panix.com> - 2011-07-02 00:47 +0000

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