Re: More Configure problems

[Zoltan Hidvegi <hzoli@xxxxxxxxxx>]

I wrote:
> Peter wrote:
> > > Next problem with Configure... actually with the makedepend script
> > > that comes with it:  this assignment is failing:
> > > 
> > >     defrule=`<$mf sed -n		\
> > > ...
> > > 
> > > That first interestingly positioned <$mf (sometimes I wonder if people
> > > do this deliberately) is supposed to be a redirection, but zsh is
> > > treating it like $(<...).  ksh behaves like sh here, i.e. only $(<...)
> > > has that behaviour.  Perhaps we should follow suit.
> > 
> > Well, there's only about one possible fix, as follows.  The manual
> > page mentions $(<...) and specifically fails to mention `<...`, so I
> > think we're in line with that after the patch.  No other Configure
> > problems that I've noticed.  (This is actually non-trivial, if you
> > want to install perl on Linux without having to have bash around.)
> 
> I'd prefer a different fix.  I think it is better to parse each command
> substitution lexically and if it consists of a single redirection to stdin
> than behave as $(< file) behaves now.  This is really preferrable since $(<
> file command) should execute the given command.  That's the ksh behaviour
> and that's what required by POSIX.  I'll try to write a patch for that.

I made the patch below.  It really makes the code cleaner but unfortunately
the change is not trivial because it removes pushheap()/popheap() from
parse_string().  So far parse_string() used pushheap() before starting the
parser and it did not pop the heap if the parsing was successful.  Of
course this increases the possibility of a forgotten popheap() and indeed
I've found that there was no popheap() after calling getshunc() which
called getfpfunc() which called parse_string().  So this only happened when
getshfunc used on an autoloaded function, e.g. when chpwd was autoloaded.
Of course this did not cause any noticable problem except that it was a
memory leak.

The change below would be more difficult without removing this heap stuff
because the parsed list must be preserved somehow after popheap (it would
not be much more difficult, just 2 more lines I think).

I did not test this patch, since I'd like to catch the last but home from
the university so it may be buggy.  Please test it.

Zoltan


*** Src/exec.c	1996/07/31 14:05:25	2.78
--- Src/exec.c	1996/08/01 20:59:39
***************
*** 48,61 ****
      lexsave();
      inpush(s, 0);
      strinbeg();
-     pushheap();
      stophist = 2;
      l = parse_list();
      strinend();
      inpop();
      lexrestore();
-     if (!l)
- 	popheap();
      return l;
  }
  
--- 48,58 ----
***************
*** 475,484 ****
  {
      List list;
  
!     if ((list = parse_string(s))) {
  	execlist(list, dont_change_job, exiting);
! 	popheap();
!     }
  }
  
  /* Main routine for executing a list.                                *
--- 472,481 ----
  {
      List list;
  
!     pushheap();
!     if ((list = parse_string(s)))
  	execlist(list, dont_change_job, exiting);
!     popheap();
  }
  
  /* Main routine for executing a list.                                *
***************
*** 1991,2033 ****
      List list;
      int pipes[2];
      pid_t pid;
  
!     if (*cmd == '<') {
! 	int stream, l;
! 	char *fi, *s;
! 
! 	for (cmd++; *cmd == ' '; cmd++);
! 	for (fi = s = cmd + strlen(cmd); s > cmd && s[-1] == ' '; s--);
! 	if (s > cmd && s < fi && (s[-1] == '\\' || s[-1] == Meta))
! 	    s++;
! 	l = s - cmd;
! 	fi = ncalloc(l + 1);
! 	strncpy(fi, cmd, l);
! 	fi[l] = '\0';
! 	if (parsestr(fi))
! 	    return NULL;
! 	if (*fi == '~')
! 	    *fi = Tilde;
! 	else if (*fi == '=')
! 	    *fi = Equals;
! 	singsub(&fi);
  	if (errflag)
  	    return NULL;
! 	stream = open(unmeta(fi), O_RDONLY);
! 	if (stream == -1) {
! 	    zerr("%e: %s", fi, errno);
! 	    return NULL;
! 	}
  	return readoutput(stream, qt);
      }
!     if (!(list = parse_string(cmd)))
! 	return NULL;
      mpipe(pipes);
      child_block();
      cmdoutval = 0;
      if ((cmdoutpid = pid = zfork()) == -1) {
  	/* fork error */
- 	popheap();
  	zclose(pipes[0]);
  	zclose(pipes[1]);
  	errflag = 1;
--- 1988,2021 ----
      List list;
      int pipes[2];
      pid_t pid;
+     Cmd c;
+     Redir r;
  
!     if (!(list = parse_string(cmd)))
! 	return NULL;
!     if (list != &dummy_list && !list->right && !list->left->flags &&
! 	list->left->type == END && list->left->left->type == END &&
! 	(c = list->left->left->left)->type == SIMPLE && empty(c->args) &&
! 	empty(c->vars) && nonempty(c->redir) &&
! 	!nextnode(firstnode(c->redir)) &&
! 	(r = (Redir) getdata(firstnode(c->redir)))->fd1 == 0 &&
! 	r->type == READ) {
! 	/* $(< word) */
! 	int stream;
! 	char *s = r->name;
! 
! 	singsub(&s);
  	if (errflag)
  	    return NULL;
! 	stream = open(unmeta(s), O_RDONLY);
  	return readoutput(stream, qt);
      }
! 
      mpipe(pipes);
      child_block();
      cmdoutval = 0;
      if ((cmdoutpid = pid = zfork()) == -1) {
  	/* fork error */
  	zclose(pipes[0]);
  	zclose(pipes[1]);
  	errflag = 1;
***************
*** 2037,2043 ****
      } else if (pid) {
  	LinkList retval;
  
- 	popheap();
  	zclose(pipes[1]);
  	retval = readoutput(pipes[0], qt);
  	fdtable[pipes[0]] = 0;
--- 2025,2030 ----
***************
*** 2159,2172 ****
  
      if (fd < 0 || (cmdoutpid = pid = zfork()) == -1) {
  	/* fork or open error */
- 	popheap();
  	child_unblock();
  	return nam;
      } else if (pid) {
  	int os;
  
  	close(fd);
- 	popheap();
  	os = jobtab[thisjob].stat;
  	waitforpid(pid);
  	cmdoutval = 0;
--- 2146,2157 ----
***************
*** 2248,2254 ****
  	zclose(pipes[out]);
  	fdtable[pipes[!out]] = 2;
  #endif
- 	popheap();
  	return pnam;
      }
  #ifndef HAVE_DEV_FD
--- 2233,2238 ----
***************
*** 2285,2291 ****
  	return -1;
      mpipe(pipes);
      if (zfork()) {
- 	popheap();
  	zclose(pipes[out]);
  	return pipes[!out];
      }
--- 2269,2274 ----
***************
*** 2412,2418 ****
  	    shf->flags &= ~PM_UNDEFINED;
  	    funcdef = shf->funcdef = (List) dupstruct(funcdef);
  	} LASTALLOC;
- 	popheap();
  
  	/* Execute the function definition, we just retrived */
  	doshfunc(shf->funcdef, cmd->args, shf->flags, 0);
--- 2395,2400 ----
*** Src/builtin.c	1996/07/31 15:45:25	2.71
--- Src/builtin.c	1996/08/01 20:24:46
***************
*** 5501,5508 ****
  	if (settrap(sig, t))
  	    freestruct(t);
      }
-     if (l)
- 	popheap();
      return *argv != NULL;
  }
  
--- 5501,5506 ----