Patch for libgfortran PR 18891

[Steve Ellcey]

> > !   memcpy (p, &zero, sizeof (gfc_offset));   /* Bogus value for now.  */
>
> Better to use memset.
>
> r~

I don't know why that never occured to me.  I will change it.

> > I also changed some of my memcpy calls to use an
> > existing variable as the length of the memcpy instead of sizeof()
> > because the variable in question was set based on sizeof() earlier in
> > the routine.
> 
> I don't buy this argument.
> 
> > +   gfc_offset i;
> ...
> > !   memcpy (&i, p, n);
> > !   current_unit->bytes_left = i;
> 
> n had better be sizeof(i), or you are reading from uninitialized memory.
> 
> r~

I made sure the variables in question are always set to the right value
and they are because the libgfortran alloc routine (salloc_r & salloc_w)
require a pointer to a size so these variables are set to the sizeof
value for that use.  But I agree that it really isn't better to use the
variables instead of sizeof and I am not sure why I thought it was so I
switched it back.

I retested with no regressions and here is the updated patch:

OK for checkin?

Steve Ellcey
sje@cup.hp.com


2004-12-13  Steve Ellcey  <sje@cup.hp.com>

	* libgfortran/io/transfer.c (us_read): Use memcpy/memset
	instead of assignment to fill unaligned buffer.
	(us_write): Ditto.
	(next_record_w): Ditto.



*** gcc.orig/libgfortran/io/transfer.c	Fri Dec 10 08:57:51 2004
--- gcc/libgfortran/io/transfer.c	Mon Dec 13 09:08:27 2004
*************** transfer_complex (void *p, int kind)
*** 819,829 ****
  static void
  us_read (void)
  {
!   gfc_offset *p;
    int n;
  
    n = sizeof (gfc_offset);
!   p = (gfc_offset *) salloc_r (current_unit->s, &n);
  
    if (p == NULL || n != sizeof (gfc_offset))
      {
--- 819,830 ----
  static void
  us_read (void)
  {
!   char *p;
    int n;
+   gfc_offset i;
  
    n = sizeof (gfc_offset);
!   p = salloc_r (current_unit->s, &n);
  
    if (p == NULL || n != sizeof (gfc_offset))
      {
*************** us_read (void)
*** 831,837 ****
        return;
      }
  
!   current_unit->bytes_left = *p;
  }
  
  
--- 832,839 ----
        return;
      }
  
!   memcpy (&i, p, sizeof (gfc_offset));
!   current_unit->bytes_left = i;
  }
  
  
*************** us_read (void)
*** 841,851 ****
  static void
  us_write (void)
  {
!   gfc_offset *p;
    int length;
  
    length = sizeof (gfc_offset);
!   p = (gfc_offset *) salloc_w (current_unit->s, &length);
  
    if (p == NULL)
      {
--- 843,853 ----
  static void
  us_write (void)
  {
!   char *p;
    int length;
  
    length = sizeof (gfc_offset);
!   p = salloc_w (current_unit->s, &length);
  
    if (p == NULL)
      {
*************** us_write (void)
*** 853,859 ****
        return;
      }
  
!   *p = 0;			/* Bogus value for now.  */
    if (sfree (current_unit->s) == FAILURE)
      generate_error (ERROR_OS, NULL);
  
--- 855,861 ----
        return;
      }
  
!   memset (p, '\0', sizeof (gfc_offset));	/* Bogus value for now.  */
    if (sfree (current_unit->s) == FAILURE)
      generate_error (ERROR_OS, NULL);
  
*************** next_record_w (int done)
*** 1281,1287 ****
        if (p == NULL)
  	goto io_error;
  
!       *((gfc_offset *) p) = m;
        if (sfree (current_unit->s) == FAILURE)
  	goto io_error;
  
--- 1283,1289 ----
        if (p == NULL)
  	goto io_error;
  
!       memcpy (p, &m, sizeof (gfc_offset));
        if (sfree (current_unit->s) == FAILURE)
  	goto io_error;
  
*************** next_record_w (int done)
*** 1292,1298 ****
        if (p == NULL)
  	generate_error (ERROR_OS, NULL);
  
!       *((gfc_offset *) p) = m;
        if (sfree (current_unit->s) == FAILURE)
  	goto io_error;
  
--- 1294,1300 ----
        if (p == NULL)
  	generate_error (ERROR_OS, NULL);
  
!       memcpy (p, &m, sizeof (gfc_offset));
        if (sfree (current_unit->s) == FAILURE)
  	goto io_error;