Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!decwrl!shelby!polya!rokicki
From: rokicki@polya.Stanford.EDU (Tomas G. Rokicki)
Newsgroups: comp.sys.amiga.tech
Subject: Re: getcwd() and chdir() functions
Message-ID: <8116@polya.Stanford.EDU>
Date: 2 Apr 89 11:03:13 GMT
References: <6481@dayton.UUCP>
Sender: Tomas G. Rokicki <rokicki@polya.Stanford.EDU>
Reply-To: rokicki@polya.Stanford.EDU (Tomas G. Rokicki)
Distribution: usa
Organization: Stanford University
Lines: 104

/*
 *   All you ever wanted to know about changing your current
 *   working directory.  Make *sure* you call initcd() during
 *   startup.  cleancd() can be called anytime as many times
 *   as you feel.  cwd(s) returns a success code---1=success,
 *   and can be called at any point.  getcwd() returns the
 *   name of the current working directory if you pass it "" as
 *   the first argument, or it returns the full name of the file
 *   referenced by the given name.
 *
 *   This code assumes that no one else will change the current
 *   working directory out from under you.
 */
#include "exec/memory.h"
#include "libraries/dos.h"
#include "functions.h"
static struct Lock *original_lock = -1 ;
/*
 *   Call me before any others!
 */
initcd() {
   register struct Lock *new_lock ;

   new_lock = Lock("",SHARED_LOCK);
   if (!new_lock)
      error("! can't lock cwd") ;
   original_lock = CurrentDir(new_lock);
}
/*
 *   Call me before you exit!
 */
cleancd() {
   register struct Lock *new_lock ;

   if (original_lock != -1) {
      new_lock = CurrentDir(original_lock);
      if (new_lock)
         UnLock(new_lock);
      original_lock = -1 ;
   }
}
/*
 *   Call me to set the current working directory!
 *   Returns `0' on failure.
 */
int cwd(s)
char *s ;
{
   register struct Lock *new_lock ;

   new_lock = Lock(s,SHARED_LOCK);
   if (!new_lock)
      return(0) ;
   new_lock = CurrentDir(new_lock);
   if (new_lock)
      UnLock(new_lock);
   return(1) ;
}
/*
 *   Call me to get the full path name of a file!  Pass "" as the name for
 *   a `pwd'.  Give me the buffer to use and the size of that buffer.
 */
char *getcwd(name, buffer, size)
char *name ;
char *buffer ;
int size ;
{
   register struct Lock *lock, *nlock ;
   register int len ;
   register struct FileInfoBlock *fib ;
   register char *p ;

   fib = (struct FileInfoBlock *)AllocMem((long)sizeof(struct FileInfoBlock),
                                            MEMF_PUBLIC | MEMF_CLEAR) ;

   size -= 2 ;
   p = buffer + size + 1 ;
   *p = 0 ;
   if (fib) {
      lock = Lock(name, SHARED_LOCK) ;
      while (1) {
         Examine(lock, fib) ;
         len = strlen(fib->fib_FileName) ;
         p -= len + 1 ;
         if (p < buffer)
            return(NULL) ;
         strcpy(p, fib->fib_FileName) ;
         p[len] = '/' ;
         nlock = ParentDir(lock) ;
         UnLock(lock) ;
         if (nlock != NULL)
            lock = nlock ;
         else
            break ;
      }
      p[len] = ':' ;
      if (buffer[size] == '/')
         buffer[size] = 0 ;
      FreeMem(fib, (long)sizeof(struct FileInfoBlock)) ;
      return(p) ;
   } else
      return(NULL) ;
}

-tom