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Re: reading from a temp file

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Michael DOUBEZ <michael.doubez@free.fr> wrote:
> On Jun 28, 10:37 am, Ian Collins <ian-n...@hotmail.com> wrote:
>> On 06/28/11 08:34 PM, Ruben Safir wrote:
>>
>> > any clue why this isn't retrieving the contents of the temp file
>>
>> > Question Deck::create_question(WINDOW* menu_win, std::ostream&os ,std::istream&in ){
>>
>> >        char default_editor[20000] = "vi ";
>> >        char * editor;
>> >        char tmp[4096];
>> >        char path[] = "/tmp/fileXXXXXX";
>>
>> Why don't you use strings?
> 
> because mkstemp expect a char* that is modified. A solution is to
> using std::vector<char> instead.
> 

std::vector<char> or std::vector<char *> ?


>>
>> >        int fd;
>> >        fd = mkstemp(path);
>> >        editor = getenv("EDITOR");
>> >        if (editor == NULL){
>> >     editor  = default_editor;
>> >        }
>>
>> >        strcat(editor, path);
>> >        char quest_prompt[] = "Edit Your Question";
>> > .....
>> >        std::string input_q, input_a;
>> >        while( ( c=wgetch(quest_win) ) ){
>> >     if ( (c == 10) ){
>> >        def_prog_mode();
>> >        endwin();
>>
>> What are these?
>>
>> >        system(editor);
>> >        reset_prog_mode();
>>
>> and this?
> 
> A gnu extension for building a filebuf from a file descriptor. IMO
> closing the fildescriptor returned and using a simple ifstream with
> path, would be less trouble.

Those above are part of ncures.h, but those below as was you describe.

> 
> In particular, the openmode are not good: binary will not translate
> carriage return and app is irrelevant in input mode (and input mode is
> missing). Use plain std::ios::in instead.
> 

The editor is creating a text file so you might be correct, but I don't
think I want carriage returns altered or interpreted, just eventually
dumped into a data file at 4096 bit clips.  And I don't want to deal
with deliminators or terminators on input, or output, which is a problem
with getline and getchar.  I want them included in the input stream,
whole.


> I don't know how it works in conccurent access, stdio_sync_filebuf<>
> may be required here (with minimal buffer size in parameter for good
> measure).
> 

It didn't have trouble with two seperate streams from the same fd.  I
did have trouble using one stream for both in and out.

>> >         __gnu_cxx::stdio_filebuf<  char>   tmpfile_buf(fd, std::ios::binary|std::ios::app);
>>
>> What's one of those?
>>
>> >         std::istream is(&tmpfile_buf);
>> >         is.seekg(0, std::ios::beg);
> 
> seekg is not guaranteed to work
>

Upon input?  It didn't work away.  I thought maybe I as set to the end
of the stream but it didn't like binary mode at all, and the eof bits
behaved as I expected so I can only guess that it was behaving OK.
 
>> >         while(is){
>> >            is.read( tmp, 4096);
>> >            std::cerr<<  "What did we read"<<  tmp<<  std::endl;
>> >            input_q = tmp;
>> >         }
>> >         tmpfile_buf.close();
> 
> Note that you can dump the content of a file with:
>  std::err<<is.rdbuf();
>

I want a guaranteed chunk of 4096, no greater.
 
>> >         break;
>> >     }
>> >        }
>> >        remove(path);
>>
> 
> --
> Michael

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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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