2006-12-01 Thomas Koenig <Thomas.Koenig@online.de>

	PR libfortran/29568
	* gfortran.dg/convert_implied_open.f90:  Change to
	new default record length.
	* gfortran.dg/unf_short_record_1.f90:  Adapt to
	new error message.
	* gfortran.dg/unformatted_subrecords_1.f90:  New test.

2006-12-01  Thomas Koenig  <Thomas.Koenig@online.de>

	PR libfortran/29568
	* gfortran.h (gfc_option_t):  Add max_subrecord_length.
	(top level): Define MAX_SUBRECORD_LENGTH.
	* lang.opt:  Add option -fmax-subrecord-length=.
	* trans-decl.c:  Add new function set_max_subrecord_length.
	(gfc_generate_function_code): If we are within the main
	program and max_subrecord_length has been set, call
	set_max_subrecord_length.
	* options.c (gfc_init_options):  Add defaults for
	max_subrecord_lenght, convert and record_marker.
	(gfc_handle_option):  Add handling for
	-fmax_subrecord_length.
	* invoke.texi:  Document the new default for
	-frecord-marker=<n>.

2006-12-01  Thomas Koenig  <Thomas.Koenig@online.de>

	PR libfortran/29568
	* libgfortran/libgfortran.h (compile_options_t):  Add
	record_marker. (top level):  Define GFC_MAX_SUBRECORD_LENGTH.
	* runtime/compile_options.c (set_record_marker):  Change
	default to four-byte record marker.
	(set_max_subrecord_length):  New function.
	* runtime/error.c (translate_error):  Change error message
	for short record on unformatted read.
	* io/io.h (gfc_unit):  Add recl_subrecord, bytes_left_subrecord
	and continued.
	* io/file_pos.c (unformatted_backspace):  Change default of record
	marker size to four bytes.  Loop over subrecords.
	* io/open.c:  Default recl is max_offset.  If
	compile_options.max_subrecord_length has been set, set set
	u->recl_subrecord to its value, to the maximum value otherwise.
	* io/transfer.c (top level):  Add prototypes for us_read, us_write,
	next_record_r_unf and next_record_w_unf.
	(read_block_direct):  Separate codepaths for unformatted direct
	and unformatted sequential.  If a recl has been set by the
	user, use the number of bytes left for the record if it is smaller
	than the read request.  Loop over subrecords.  Set an error if the
	user has set a recl and the read was short.
	(write_buf):  Separate codepaths for unformatted direct and
	unformatted sequential. If a recl has been set by the
	user, use the number of bytes left for the record if it is smaller
	than the read request.  Loop over subrecords.  Set an error if the
	user has set a recl and the read was short.
	(us_read):  Add parameter continued (to indicate that bytes_left
	should not be intialized).  Change default of record marker size
	to four bytes. Use subrecord.  If the subrecord length is smaller than
	zero, this indicates a continuation.
	(us_write):  Add parameter continued (to indicate that the continued
	flag should be set).  Use subrecord.
	(pre_position):  Use 0 for continued on us_write and us_read calls.
	(skip_record):  New function.
	(next_record_r_unf):  New function.
	(next_record_r):  Use next_record_r_unf.
	(write_us_marker):  Default size for record markers is four bytes.
	(next_record_w_unf):  New function.
	(next_record_w):  Use next_record_w_unf.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@119412 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 482 insertions, 235 deletions

diff --git a/libgfortran/io/file_pos.c b/libgfortran/io/file_pos.c
index 979dec55513..df722e4cbc7 100644
--- a/libgfortran/io/file_pos.c
+++ b/libgfortran/io/file_pos.c
@@ -98,7 +98,7 @@ formatted_backspace (st_parameter_filepos *fpp, gfc_unit *u)
 
 /* unformatted_backspace(fpp) -- Move the file backwards for an unformatted
    sequential file.  We are guaranteed to be between records on entry and 
-   we have to shift to the previous record.  */
+   we have to shift to the previous record.  Loop over subrecords.  */
 
 static void
 unformatted_backspace (st_parameter_filepos *fpp, gfc_unit *u)
@@ -107,74 +107,74 @@ unformatted_backspace (st_parameter_filepos *fpp, gfc_unit *u)
   GFC_INTEGER_4 m4;
   GFC_INTEGER_8 m8;
   int length, length_read;
+  int continued;
   char *p;
 
   if (compile_options.record_marker == 0)
-    length = sizeof (gfc_offset);
+    length = sizeof (GFC_INTEGER_4);
   else
     length = compile_options.record_marker;
 
-  length_read = length;
+  do
+    {
+      length_read = length;
 
-  p = salloc_r_at (u->s, &length_read,
-		   file_position (u->s) - length);
-  if (p == NULL || length_read != length)
-    goto io_error;
+      p = salloc_r_at (u->s, &length_read,
+		       file_position (u->s) - length);
+      if (p == NULL || length_read != length)
+	goto io_error;
 
-  /* Only CONVERT_NATIVE and CONVERT_SWAP are valid here.  */
-  if (u->flags.convert == CONVERT_NATIVE)
-    {
-      switch (compile_options.record_marker)
+      /* Only CONVERT_NATIVE and CONVERT_SWAP are valid here.  */
+      if (u->flags.convert == CONVERT_NATIVE)
 	{
-	case 0:
-	  memcpy (&m, p, sizeof(gfc_offset));
-	  break;
-
-	case sizeof(GFC_INTEGER_4):
-	  memcpy (&m4, p, sizeof (m4));
-	  m = m4;
-	  break;
-
-	case sizeof(GFC_INTEGER_8):
-	  memcpy (&m8, p, sizeof (m8));
-	  m = m8;
-	  break;
-
-	default:
-	  runtime_error ("Illegal value for record marker");
-	  break;
+	  switch (length)
+	    {
+	    case sizeof(GFC_INTEGER_4):
+	      memcpy (&m4, p, sizeof (m4));
+	      m = m4;
+	      break;
+
+	    case sizeof(GFC_INTEGER_8):
+	      memcpy (&m8, p, sizeof (m8));
+	      m = m8;
+	      break;
+
+	    default:
+	      runtime_error ("Illegal value for record marker");
+	      break;
+	    }
 	}
-    }
-  else
-    {
-      switch (compile_options.record_marker)
+      else
 	{
-	case 0:
-	  reverse_memcpy (&m, p, sizeof(gfc_offset));
-	  break;
-
-	case sizeof(GFC_INTEGER_4):
-	  reverse_memcpy (&m4, p, sizeof (m4));
-	  m = m4;
-	  break;
-
-	case sizeof(GFC_INTEGER_8):
-	  reverse_memcpy (&m8, p, sizeof (m8));
-	  m = m8;
-	  break;
-
-	default:
-	  runtime_error ("Illegal value for record marker");
-	  break;
+	  switch (length)
+	    {
+	    case sizeof(GFC_INTEGER_4):
+	      reverse_memcpy (&m4, p, sizeof (m4));
+	      m = m4;
+	      break;
+
+	    case sizeof(GFC_INTEGER_8):
+	      reverse_memcpy (&m8, p, sizeof (m8));
+	      m = m8;
+	      break;
+
+	    default:
+	      runtime_error ("Illegal value for record marker");
+	      break;
+	    }
+
 	}
 
-    }
+      continued = m < 0;
+      if (continued)
+	m = -m;
 
-  if ((new = file_position (u->s) - m - 2*length) < 0)
-    new = 0;
+      if ((new = file_position (u->s) - m - 2*length) < 0)
+	new = 0;
 
-  if (sseek (u->s, new) == FAILURE)
-    goto io_error;
+      if (sseek (u->s, new) == FAILURE)
+	goto io_error;
+    } while (continued);
 
   u->last_record--;
   return;
diff --git a/libgfortran/io/io.h b/libgfortran/io/io.h
index e8e8390d1c5..4d227dd3b8c 100644
--- a/libgfortran/io/io.h
+++ b/libgfortran/io/io.h
@@ -499,12 +499,19 @@ typedef struct gfc_unit
   unit_mode mode;
   unit_flags flags;
 
-  /* recl           -- Record length of the file.
-     last_record    -- Last record number read or written
-     maxrec         -- Maximum record number in a direct access file
-     bytes_left     -- Bytes left in current record.
-     strm_pos       -- Current position in file for STREAM I/O.  */
-  gfc_offset recl, last_record, maxrec, bytes_left, strm_pos;
+  /* recl                 -- Record length of the file.
+     last_record          -- Last record number read or written
+     maxrec               -- Maximum record number in a direct access file
+     bytes_left           -- Bytes left in current record.
+     strm_pos             -- Current position in file for STREAM I/O.
+     recl_subrecord       -- Maximum length for subrecord.
+     bytes_left_subrecord -- Bytes left in current subrecord.  */
+  gfc_offset recl, last_record, maxrec, bytes_left, strm_pos,
+    recl_subrecord, bytes_left_subrecord;
+
+  /* Set to 1 if we have read a subrecord.  */
+
+  int continued;
 
   __gthread_mutex_t lock;
   /* Number of threads waiting to acquire this unit's lock.
diff --git a/libgfortran/io/open.c b/libgfortran/io/open.c
index 9b4f0cd7122..06fba75e1df 100644
--- a/libgfortran/io/open.c
+++ b/libgfortran/io/open.c
@@ -413,23 +413,29 @@ new_unit (st_parameter_open *opp, gfc_unit *u, unit_flags * flags)
   else
     {
       u->flags.has_recl = 0;
-      switch (compile_options.record_marker)
+      u->recl = max_offset;
+      if (compile_options.max_subrecord_length)
 	{
-	case 0:
-	  u->recl = max_offset;
-	  break;
-
-	case sizeof (GFC_INTEGER_4):
-	  u->recl = GFC_INTEGER_4_HUGE;
-	  break;
-
-	case sizeof (GFC_INTEGER_8):
-	  u->recl = max_offset;
-	  break;
-
-	default:
-	  runtime_error ("Illegal value for record marker");
-	  break;
+	  u->recl_subrecord = compile_options.max_subrecord_length;
+	}
+      else
+	{
+	  switch (compile_options.record_marker)
+	    {
+	    case 0:
+	      /* Fall through */
+	    case sizeof (GFC_INTEGER_4):
+	      u->recl_subrecord = GFC_MAX_SUBRECORD_LENGTH;
+	      break;
+
+	    case sizeof (GFC_INTEGER_8):
+	      u->recl_subrecord = max_offset - 16;
+	      break;
+
+	    default:
+	      runtime_error ("Illegal value for record marker");
+	      break;
+	    }
 	}
     }
 
diff --git a/libgfortran/io/transfer.c b/libgfortran/io/transfer.c
index 329d49828d4..4270d61e693 100644
--- a/libgfortran/io/transfer.c
+++ b/libgfortran/io/transfer.c
@@ -82,6 +82,11 @@ extern void transfer_array (st_parameter_dt *, gfc_array_char *, int,
 			    gfc_charlen_type);
 export_proto(transfer_array);
 
+static void us_read (st_parameter_dt *, int);
+static void us_write (st_parameter_dt *, int);
+static void next_record_r_unf (st_parameter_dt *, int);
+static void next_record_w_unf (st_parameter_dt *, int);
+
 static const st_option advance_opt[] = {
   {"yes", ADVANCE_YES},
   {"no", ADVANCE_NO},
@@ -336,12 +341,16 @@ read_block (st_parameter_dt *dtp, int *length)
 }
 
 
-/* Reads a block directly into application data space.  */
+/* Reads a block directly into application data space.  This is for
+   unformatted files.  */
 
 static void
 read_block_direct (st_parameter_dt *dtp, void *buf, size_t *nbytes)
 {
-  size_t nread;
+  size_t to_read_record;
+  size_t have_read_record;
+  size_t to_read_subrecord;
+  size_t have_read_subrecord;
   int short_record;
 
   if (is_stream_io (dtp))
@@ -353,62 +362,169 @@ read_block_direct (st_parameter_dt *dtp, void *buf, size_t *nbytes)
 	  return;
 	}
 
-      nread = *nbytes;
-      if (sread (dtp->u.p.current_unit->s, buf, &nread) != 0)
+      to_read_record = *nbytes;
+      have_read_record = to_read_record;
+      if (sread (dtp->u.p.current_unit->s, buf, &have_read_record) != 0)
 	{
 	  generate_error (&dtp->common, ERROR_OS, NULL);
 	  return;
 	}
 
-      dtp->u.p.current_unit->strm_pos += (gfc_offset) nread; 
-
-      if (nread != *nbytes)  /* Short read, e.g. if we hit EOF.  */
-	generate_error (&dtp->common, ERROR_END, NULL);	  
+      dtp->u.p.current_unit->strm_pos += (gfc_offset) have_read_record; 
 
+      if (to_read_record != have_read_record)
+	{
+	  /* Short read,  e.g. if we hit EOF.  */
+	  generate_error (&dtp->common, ERROR_END, NULL);
+	  return;
+	}
       return;
     }
 
-  /* Unformatted file with records */
-  if (dtp->u.p.current_unit->bytes_left < (gfc_offset) *nbytes)
+  if (dtp->u.p.current_unit->flags.access == ACCESS_DIRECT)
     {
-      short_record = 1;
-      nread = (size_t) dtp->u.p.current_unit->bytes_left;
-      *nbytes = nread;
+      if (dtp->u.p.current_unit->bytes_left < (gfc_offset) *nbytes)
+	{
+	  short_record = 1;
+	  to_read_record = (size_t) dtp->u.p.current_unit->bytes_left;
+	  *nbytes = to_read_record;
 
-      if (dtp->u.p.current_unit->bytes_left == 0)
+	  if (dtp->u.p.current_unit->bytes_left == 0)
+	    {
+	      dtp->u.p.current_unit->endfile = AT_ENDFILE;
+	      generate_error (&dtp->common, ERROR_END, NULL);
+	      return;
+	    }
+	}
+
+      else
+	{
+	  short_record = 0;
+	  to_read_record = *nbytes;
+	}
+
+      dtp->u.p.current_unit->bytes_left -= to_read_record;
+
+      if (sread (dtp->u.p.current_unit->s, buf, &to_read_record) != 0)
+	{
+	  generate_error (&dtp->common, ERROR_OS, NULL);
+	  return;
+	}
+
+      if (to_read_record != *nbytes)  /* Short read, e.g. if we hit EOF.  */
 	{
-	  dtp->u.p.current_unit->endfile = AT_ENDFILE;
+	  *nbytes = to_read_record;
 	  generate_error (&dtp->common, ERROR_END, NULL);
 	  return;
 	}
+
+      if (short_record)
+	{
+	  generate_error (&dtp->common, ERROR_SHORT_RECORD, NULL);
+	  return;
+	}
+      return;
     }
 
+  /* Unformatted sequential.  We loop over the subrecords, reading
+     until the request has been fulfilled or the record has run out
+     of continuation subrecords.  */
+
+  /* Check whether we exceed the total record length.  */
+
+  if (dtp->u.p.current_unit->flags.has_recl)
+    {
+      to_read_record =
+	*nbytes > (size_t) dtp->u.p.current_unit->bytes_left ?
+	*nbytes : (size_t) dtp->u.p.current_unit->bytes_left;
+      short_record = 1;
+    }
   else
     {
+      to_read_record = *nbytes;
       short_record = 0;
-      nread = *nbytes;
     }
+  have_read_record = 0;
 
-  dtp->u.p.current_unit->bytes_left -= nread;
-
-  if (sread (dtp->u.p.current_unit->s, buf, &nread) != 0)
+  while(1)
     {
-      generate_error (&dtp->common, ERROR_OS, NULL);
-      return;
-    }
+      if (dtp->u.p.current_unit->bytes_left_subrecord
+	  < (gfc_offset) to_read_record)
+	{
+	  to_read_subrecord = (size_t) dtp->u.p.current_unit->bytes_left_subrecord;
+	  to_read_record -= to_read_subrecord;
 
-  if (nread != *nbytes)  /* Short read, e.g. if we hit EOF.  */
-    {
-      *nbytes = nread;
-      generate_error (&dtp->common, ERROR_END, NULL);
-      return;
+	  if (dtp->u.p.current_unit->bytes_left_subrecord == 0)
+	    {
+	      if (dtp->u.p.current_unit->continued)
+		{
+		  /* Skip to the next subrecord */
+		  next_record_r_unf (dtp, 0);
+		  us_read (dtp, 1);
+		  continue;
+		}
+	      else
+		{
+		  dtp->u.p.current_unit->endfile = AT_ENDFILE;
+		  generate_error (&dtp->common, ERROR_END, NULL);
+		  return;
+		}
+	    }
+	}
+
+      else
+	{
+	  to_read_subrecord = to_read_record;
+	  to_read_record = 0;
+	}
+
+      dtp->u.p.current_unit->bytes_left_subrecord -= to_read_subrecord;
+
+      have_read_subrecord = to_read_subrecord;
+      if (sread (dtp->u.p.current_unit->s, buf + have_read_record,
+		 &have_read_subrecord) != 0)
+	{
+	  generate_error (&dtp->common, ERROR_OS, NULL);
+	  return;
+	}
+
+      have_read_record += have_read_subrecord;
+
+      if (to_read_subrecord != have_read_subrecord)  /* Short read,
+							e.g. if we hit EOF.  */
+	{
+	  *nbytes = have_read_record;
+	  generate_error (&dtp->common, ERROR_END, NULL);
+	  return;
+	}
+
+      if (to_read_record > 0)
+	{
+	  if (dtp->u.p.current_unit->continued)
+	    {
+	      next_record_r_unf (dtp, 0);
+	      us_read (dtp, 1);
+	    }
+	  else
+	    {
+	      generate_error (&dtp->common, ERROR_SHORT_RECORD, NULL);
+	      return;
+	    }
+	}
+      else
+	{
+	  /* Normal exit, the read request has been fulfilled.  */
+	  break;
+	}
     }
 
+  dtp->u.p.current_unit->bytes_left -= have_read_record;
   if (short_record)
     {
       generate_error (&dtp->common, ERROR_SHORT_RECORD, NULL);
       return;
     }
+  return;
 }
 
 
@@ -471,11 +587,20 @@ write_block (st_parameter_dt *dtp, int length)
 }
 
 
-/* High level interface to swrite(), taking care of errors.  */
+/* High level interface to swrite(), taking care of errors.  This is only
+   called for unformatted files.  There are three cases to consider:
+   Stream I/O, unformatted direct, unformatted sequential.  */
 
 static try
 write_buf (st_parameter_dt *dtp, void *buf, size_t nbytes)
 {
+
+  size_t have_written, to_write_subrecord;
+  int short_record;
+
+
+  /* Stream I/O.  */
+
   if (is_stream_io (dtp))
     {
       if (sseek (dtp->u.p.current_unit->s,
@@ -484,42 +609,88 @@ write_buf (st_parameter_dt *dtp, void *buf, size_t nbytes)
 	  generate_error (&dtp->common, ERROR_OS, NULL);
 	  return FAILURE;
 	}
+
+      if (swrite (dtp->u.p.current_unit->s, buf, &nbytes) != 0)
+	{
+	  generate_error (&dtp->common, ERROR_OS, NULL);
+	  return FAILURE;
+	}
+
+      dtp->u.p.current_unit->strm_pos += (gfc_offset) nbytes; 
+
+      return SUCCESS;
     }
-  else
+
+  /* Unformatted direct access.  */
+
+  if (dtp->u.p.current_unit->flags.access == ACCESS_DIRECT)
     {
       if (dtp->u.p.current_unit->bytes_left < (gfc_offset) nbytes)
 	{
-	  /* For preconnected units with default record length, set
-	     bytes left to unit record length and proceed, otherwise
-	     error.  */
-	  if ((dtp->u.p.current_unit->unit_number == options.stdout_unit
-	       || dtp->u.p.current_unit->unit_number == options.stderr_unit)
-	      && dtp->u.p.current_unit->recl == DEFAULT_RECL)
-	    dtp->u.p.current_unit->bytes_left = dtp->u.p.current_unit->recl;
-	  else
-	    {
-	      if (dtp->u.p.current_unit->flags.access == ACCESS_DIRECT)
-		generate_error (&dtp->common, ERROR_DIRECT_EOR, NULL);
-	      else
-		generate_error (&dtp->common, ERROR_EOR, NULL);
-	      return FAILURE;
-	    }
+	  generate_error (&dtp->common, ERROR_DIRECT_EOR, NULL);
+	  return FAILURE;
+	}
+
+      if (swrite (dtp->u.p.current_unit->s, buf, &nbytes) != 0)
+	{
+	  generate_error (&dtp->common, ERROR_OS, NULL);
+	  return FAILURE;
 	}
 
-      dtp->u.p.current_unit->bytes_left -= (gfc_offset) nbytes;
+      dtp->u.p.current_unit->strm_pos += (gfc_offset) nbytes; 
+
+      return SUCCESS;
+
     }
 
-  if (swrite (dtp->u.p.current_unit->s, buf, &nbytes) != 0)
+  /* Unformatted sequential.  */
+
+  have_written = 0;
+
+  if (dtp->u.p.current_unit->flags.has_recl
+      && (gfc_offset) nbytes > dtp->u.p.current_unit->bytes_left)
     {
-      generate_error (&dtp->common, ERROR_OS, NULL);
-      return FAILURE;
+      nbytes = dtp->u.p.current_unit->bytes_left;
+      short_record = 1;
+    }
+  else
+    {
+      short_record = 0;
     }
 
-  if ((dtp->common.flags & IOPARM_DT_HAS_SIZE) != 0)
-	dtp->u.p.size_used += (gfc_offset) nbytes;
+  while (1)
+    {
+
+      to_write_subrecord =
+	(size_t) dtp->u.p.current_unit->bytes_left_subrecord < nbytes ?
+	(size_t) dtp->u.p.current_unit->bytes_left_subrecord : nbytes;
+
+      dtp->u.p.current_unit->bytes_left_subrecord -=
+	(gfc_offset) to_write_subrecord;
 
-  dtp->u.p.current_unit->strm_pos += (gfc_offset) nbytes; 
+      if (swrite (dtp->u.p.current_unit->s, buf + have_written,
+		  &to_write_subrecord) != 0)
+	{
+	  generate_error (&dtp->common, ERROR_OS, NULL);
+	  return FAILURE;
+	}
+
+      dtp->u.p.current_unit->strm_pos += (gfc_offset) to_write_subrecord; 
+      nbytes -= to_write_subrecord;
+      have_written += to_write_subrecord;
 
+      if (nbytes == 0)
+	break;
+
+      next_record_w_unf (dtp, 1);
+      us_write (dtp, 1);
+    }
+  dtp->u.p.current_unit->bytes_left -= have_written;
+  if (short_record)
+    {
+      generate_error (&dtp->common, ERROR_SHORT_RECORD, NULL);
+      return FAILURE;
+    }
   return SUCCESS;
 }
 
@@ -1357,7 +1528,7 @@ transfer_array (st_parameter_dt *dtp, gfc_array_char *desc, int kind,
 /* Preposition a sequential unformatted file while reading.  */
 
 static void
-us_read (st_parameter_dt *dtp)
+us_read (st_parameter_dt *dtp, int continued)
 {
   char *p;
   int n;
@@ -1370,7 +1541,7 @@ us_read (st_parameter_dt *dtp)
     return;
 
   if (compile_options.record_marker == 0)
-    n = sizeof (gfc_offset);
+    n = sizeof (GFC_INTEGER_4);
   else
     n = compile_options.record_marker;
 
@@ -1393,12 +1564,8 @@ us_read (st_parameter_dt *dtp)
   /* Only CONVERT_NATIVE and CONVERT_SWAP are valid here.  */
   if (dtp->u.p.current_unit->flags.convert == CONVERT_NATIVE)
     {
-      switch (compile_options.record_marker)
+      switch (nr)
 	{
-	case 0:
-	  memcpy (&i, p, sizeof(gfc_offset));
-	  break;
-
 	case sizeof(GFC_INTEGER_4):
 	  memcpy (&i4, p, sizeof (i4));
 	  i = i4;
@@ -1415,12 +1582,8 @@ us_read (st_parameter_dt *dtp)
 	}
     }
   else
-      switch (compile_options.record_marker)
+      switch (nr)
 	{
-	case 0:
-	  reverse_memcpy (&i, p, sizeof(gfc_offset));
-	  break;
-
 	case sizeof(GFC_INTEGER_4):
 	  reverse_memcpy (&i4, p, sizeof (i4));
 	  i = i4;
@@ -1436,7 +1599,19 @@ us_read (st_parameter_dt *dtp)
 	  break;
 	}
 
-  dtp->u.p.current_unit->bytes_left = i;
+  if (i >= 0)
+    {
+      dtp->u.p.current_unit->bytes_left_subrecord = i;
+      dtp->u.p.current_unit->continued = 0;
+    }
+  else
+    {
+      dtp->u.p.current_unit->bytes_left_subrecord = -i;
+      dtp->u.p.current_unit->continued = 1;
+    }
+
+  if (! continued)
+    dtp->u.p.current_unit->bytes_left = dtp->u.p.current_unit->recl;
 }
 
 
@@ -1444,7 +1619,7 @@ us_read (st_parameter_dt *dtp)
    amount to writing a bogus length that will be filled in later.  */
 
 static void
-us_write (st_parameter_dt *dtp)
+us_write (st_parameter_dt *dtp, int continued)
 {
   size_t nbytes;
   gfc_offset dummy;
@@ -1452,7 +1627,7 @@ us_write (st_parameter_dt *dtp)
   dummy = 0;
 
   if (compile_options.record_marker == 0)
-    nbytes = sizeof (gfc_offset);
+    nbytes = sizeof (GFC_INTEGER_4);
   else
     nbytes = compile_options.record_marker ;
 
@@ -1460,12 +1635,12 @@ us_write (st_parameter_dt *dtp)
     generate_error (&dtp->common, ERROR_OS, NULL);
 
   /* For sequential unformatted, if RECL= was not specified in the OPEN
-     we write until we have more bytes than can fit in the record markers.
-     If disk space runs out first, it will error on the write.  */
-  if (dtp->u.p.current_unit->flags.has_recl == 0)
-    dtp->u.p.current_unit->recl = max_offset;
+     we write until we have more bytes than can fit in the subrecord
+     markers, then we write a new subrecord.  */
 
-  dtp->u.p.current_unit->bytes_left = dtp->u.p.current_unit->recl;
+  dtp->u.p.current_unit->bytes_left_subrecord =
+    dtp->u.p.current_unit->recl_subrecord;
+  dtp->u.p.current_unit->continued = continued;
 }
 
 
@@ -1491,9 +1666,9 @@ pre_position (st_parameter_dt *dtp)
     
     case UNFORMATTED_SEQUENTIAL:
       if (dtp->u.p.mode == READING)
-	us_read (dtp);
+	us_read (dtp, 0);
       else
-	us_write (dtp);
+	us_write (dtp, 0);
 
       break;
 
@@ -1886,17 +2061,92 @@ next_array_record (st_parameter_dt *dtp, array_loop_spec *ls)
   return index;
 }
 
-/* Space to the next record for read mode.  If the file is not
-   seekable, we read MAX_READ chunks until we get to the right
+
+
+/* Skip to the end of the current record, taking care of an optional
+   record marker of size bytes.  If the file is not seekable, we
+   read chunks of size MAX_READ until we get to the right
    position.  */
 
 #define MAX_READ 4096
 
 static void
+skip_record (st_parameter_dt *dtp, size_t bytes)
+{
+  gfc_offset new;
+  int rlength, length;
+  char *p;
+
+  dtp->u.p.current_unit->bytes_left_subrecord += bytes;
+  if (dtp->u.p.current_unit->bytes_left_subrecord == 0)
+    return;
+
+  if (is_seekable (dtp->u.p.current_unit->s))
+    {
+      new = file_position (dtp->u.p.current_unit->s)
+	+ dtp->u.p.current_unit->bytes_left_subrecord;
+
+      /* Direct access files do not generate END conditions,
+	 only I/O errors.  */
+      if (sseek (dtp->u.p.current_unit->s, new) == FAILURE)
+	generate_error (&dtp->common, ERROR_OS, NULL);
+    }
+  else
+    {			/* Seek by reading data.  */
+      while (dtp->u.p.current_unit->bytes_left_subrecord > 0)
+	{
+	  rlength = length =
+	    (MAX_READ > dtp->u.p.current_unit->bytes_left_subrecord) ?
+	    MAX_READ : dtp->u.p.current_unit->bytes_left_subrecord;
+
+	  p = salloc_r (dtp->u.p.current_unit->s, &rlength);
+	  if (p == NULL)
+	    {
+	      generate_error (&dtp->common, ERROR_OS, NULL);
+	      return;
+	    }
+
+	  dtp->u.p.current_unit->bytes_left_subrecord -= length;
+	}
+    }
+
+}
+
+#undef MAX_READ
+
+/* Advance to the next record reading unformatted files, taking
+   care of subrecords.  If complete_record is nonzero, we loop
+   until all subrecords are cleared.  */
+
+static void
+next_record_r_unf (st_parameter_dt *dtp, int complete_record)
+{
+  size_t bytes;
+
+  bytes =  compile_options.record_marker == 0 ?
+    sizeof (GFC_INTEGER_4) : compile_options.record_marker;
+
+  while(1)
+    {
+
+      /* Skip over tail */
+
+      skip_record (dtp, bytes);
+
+      if ( ! (complete_record && dtp->u.p.current_unit->continued))
+	return;
+
+      us_read (dtp, 1);
+    }
+}
+
+/* Space to the next record for read mode.  */
+
+static void
 next_record_r (st_parameter_dt *dtp)
 {
-  gfc_offset new, record;
-  int bytes_left, rlength, length;
+  gfc_offset record;
+  int length, bytes_left;
   char *p;
 
   switch (current_mode (dtp))
@@ -1906,47 +2156,12 @@ next_record_r (st_parameter_dt *dtp)
       return;
     
     case UNFORMATTED_SEQUENTIAL:
-
-      /* Skip over tail */
-      dtp->u.p.current_unit->bytes_left +=
-	compile_options.record_marker == 0 ?
-	sizeof (gfc_offset) : compile_options.record_marker;
-      
-      /* Fall through...  */
+      next_record_r_unf (dtp, 1);
+      break;
 
     case FORMATTED_DIRECT:
     case UNFORMATTED_DIRECT:
-      if (dtp->u.p.current_unit->bytes_left == 0)
-	break;
-
-      if (is_seekable (dtp->u.p.current_unit->s))
-	{
-	  new = file_position (dtp->u.p.current_unit->s)
-		+ dtp->u.p.current_unit->bytes_left;
-
-	  /* Direct access files do not generate END conditions,
-	     only I/O errors.  */
-	  if (sseek (dtp->u.p.current_unit->s, new) == FAILURE)
-	    generate_error (&dtp->common, ERROR_OS, NULL);
-
-	}
-      else
-	{			/* Seek by reading data.  */
-	  while (dtp->u.p.current_unit->bytes_left > 0)
-	    {
-	      rlength = length = (MAX_READ > dtp->u.p.current_unit->bytes_left) ?
-		MAX_READ : dtp->u.p.current_unit->bytes_left;
-
-	      p = salloc_r (dtp->u.p.current_unit->s, &rlength);
-	      if (p == NULL)
-		{
-		  generate_error (&dtp->common, ERROR_OS, NULL);
-		  break;
-		}
-
-	      dtp->u.p.current_unit->bytes_left -= length;
-	    }
-	}
+      skip_record (dtp, 0);
       break;
 
     case FORMATTED_STREAM:
@@ -2025,19 +2240,15 @@ write_us_marker (st_parameter_dt *dtp, const gfc_offset buf)
   char p[sizeof (GFC_INTEGER_8)];
 
   if (compile_options.record_marker == 0)
-    len = sizeof (gfc_offset);
+    len = sizeof (GFC_INTEGER_4);
   else
     len = compile_options.record_marker;
 
   /* Only CONVERT_NATIVE and CONVERT_SWAP are valid here.  */
   if (dtp->u.p.current_unit->flags.convert == CONVERT_NATIVE)
     {
-      switch (compile_options.record_marker)
+      switch (len)
 	{
-	case 0:
-	  return swrite (dtp->u.p.current_unit->s, &buf, &len);
-	  break;
-
 	case sizeof (GFC_INTEGER_4):
 	  buf4 = buf;
 	  return swrite (dtp->u.p.current_unit->s, &buf4, &len);
@@ -2055,13 +2266,8 @@ write_us_marker (st_parameter_dt *dtp, const gfc_offset buf)
     }
   else
     {
-      switch (compile_options.record_marker)
+      switch (len)
 	{
-	case 0:
-	  reverse_memcpy (p, &buf, sizeof (gfc_offset));
-	  return swrite (dtp->u.p.current_unit->s, p, &len);
-	  break;
-
 	case sizeof (GFC_INTEGER_4):
 	  buf4 = buf;
 	  reverse_memcpy (p, &buf4, sizeof (GFC_INTEGER_4));
@@ -2070,7 +2276,7 @@ write_us_marker (st_parameter_dt *dtp, const gfc_offset buf)
 
 	case sizeof (GFC_INTEGER_8):
 	  buf8 = buf;
-	  reverse_memcpy (p, &buf8, sizeof (GFC_INTEGER_4));
+	  reverse_memcpy (p, &buf8, sizeof (GFC_INTEGER_8));
 	  return swrite (dtp->u.p.current_unit->s, p, &len);
 	  break;
 
@@ -2082,16 +2288,72 @@ write_us_marker (st_parameter_dt *dtp, const gfc_offset buf)
 
 }
 
+/* Position to the next (sub)record in write mode for
+   unformatted sequential files.  */
+
+static void
+next_record_w_unf (st_parameter_dt *dtp, int next_subrecord)
+{
+  gfc_offset c, m, m_write;
+  size_t record_marker;
+
+  /* Bytes written.  */
+  m = dtp->u.p.current_unit->recl_subrecord
+    - dtp->u.p.current_unit->bytes_left_subrecord;
+  c = file_position (dtp->u.p.current_unit->s);
+
+  /* Write the length tail.  If we finish a record containing
+     subrecords, we write out the negative length.  */
+
+  if (dtp->u.p.current_unit->continued)
+    m_write = -m;
+  else
+    m_write = m;
+
+  if (write_us_marker (dtp, m_write) != 0)
+    goto io_error;
+
+  if (compile_options.record_marker == 0)
+    record_marker = sizeof (GFC_INTEGER_4);
+  else
+    record_marker = compile_options.record_marker;
+
+  /* Seek to the head and overwrite the bogus length with the real
+     length.  */
+
+  if (sseek (dtp->u.p.current_unit->s, c - m - record_marker)
+      == FAILURE)
+    goto io_error;
+
+  if (next_subrecord)
+    m_write = -m;
+  else
+    m_write = m;
+
+  if (write_us_marker (dtp, m_write) != 0)
+    goto io_error;
+
+  /* Seek past the end of the current record.  */
+
+  if (sseek (dtp->u.p.current_unit->s, c + record_marker) == FAILURE)
+    goto io_error;
+
+  return;
+
+ io_error:
+  generate_error (&dtp->common, ERROR_OS, NULL);
+  return;
+
+}
 
 /* Position to the next record in write mode.  */
 
 static void
 next_record_w (st_parameter_dt *dtp, int done)
 {
-  gfc_offset c, m, record, max_pos;
+  gfc_offset m, record, max_pos;
   int length;
   char *p;
-  size_t record_marker;
 
   /* Zero counters for X- and T-editing.  */
   max_pos = dtp->u.p.max_pos;
@@ -2119,35 +2381,7 @@ next_record_w (st_parameter_dt *dtp, int done)
       break;
 
     case UNFORMATTED_SEQUENTIAL:
-      /* Bytes written.  */
-      m = dtp->u.p.current_unit->recl - dtp->u.p.current_unit->bytes_left;
-      c = file_position (dtp->u.p.current_unit->s);
-
-      /* Write the length tail.  */
-
-      if (write_us_marker (dtp, m) != 0)
-	goto io_error;
-
-      if (compile_options.record_marker == 4)
-	record_marker = sizeof(GFC_INTEGER_4);
-      else
-	record_marker = sizeof (gfc_offset);
-
-      /* Seek to the head and overwrite the bogus length with the real
-	 length.  */
-
-      if (sseek (dtp->u.p.current_unit->s, c - m - record_marker)
-	  == FAILURE)
-	goto io_error;
-
-      if (write_us_marker (dtp, m) != 0)
-	goto io_error;
-
-      /* Seek past the end of the current record.  */
-
-      if (sseek (dtp->u.p.current_unit->s, c + record_marker) == FAILURE)
-	goto io_error;
-
+      next_record_w_unf (dtp, 0);
       break;
 
     case FORMATTED_STREAM: