Re: Getting the file name from a FILE *

jacob navia wrote:
> CBFalconer wrote:
>
>> If you just want the name under which the file was opened, save
>> that at fopen time.  No load on the library, no muss, no fuss.  See
>> the strcpy function.
> 
> Yes sure. And how do the other functions that need this information
> will be able to get it????
> 
> int readfromLog(FILE *fp) {
>         char buf[512];
>         size_t bufsiz=sizeof(buf);
>         int s = fread(buf,1,bufsiz,fp);
>         if (s <= 0) {
>                 // How do I get the name of the file here Mr Falconer?
>         }
> }
> 
> You see the problem?

For example, create a thing:

  typdef struct fdata {
     FILE *f;
     char *fn;
  } fdata;

and replace your FILE * variables with that.  Initialize the
structures of that type to NULL and NULL.  Now you can store all
the data you require, no impingement on the standard, etc.  If you
want to pass the structure onward you can write:

   int getcx(fdata *ff) {
      int ch;
      if (EOF == (ch = getc(ff->f)) {
         printf("EOF received from %s\n", ff-?fn);
         /* here you can access whatever you wish */
      }
      return ch;
   }

or whatever is really needed.  You can make your own version of
fopen that initializes the fn field (use a deep copy of the actual
string).  Now it is never attempting to do the impossible.  No
tables needed.

The real point is that there are absolute impossibilities involved
in providing the ability in general through the system library. 
There are no difficulties in providing things at the user level
where the user can see exactly what is happening.

-- 
 [mail]: Chuck F (cbfalconer at maineline dot net) 
 [page]: <http://cbfalconer.home.att.net>
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