Initial checkin.

1 files changed, 151 insertions, 0 deletions

diff --git a/libstore/mvol.c b/libstore/mvol.c
new file mode 100644
index 00000000..b0753dac
--- /dev/null
+++ b/libstore/mvol.c
@@ -0,0 +1,151 @@
+/* Multiple-volume store backend
+
+   Copyright (C) 1996, 1997 Free Software Foundation, Inc.
+   Written by Miles Bader <miles@gnu.ai.mit.edu>
+   This file is part of the GNU Hurd.
+
+   The GNU Hurd is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2, or (at
+   your option) any later version.
+
+   The GNU Hurd is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA. */
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+#include "store.h"
+
+struct mvol_state
+{
+  /* The current `volume'.  */
+  ssize_t cur_vol;
+
+  /* A function to change volumes, making NEW_VOL readable on the store
+     instead of OLD_VOL.  OLD_VOL is initially -1, */
+  error_t (*swap_vols) (struct store *store, size_t new_vol, ssize_t old_vol);
+};
+
+static error_t
+ensure_vol (struct store *store, size_t vol)
+{
+  error_t err = 0;
+  struct mvol_state *mv = store->hook;
+  if (vol != mv->cur_vol)
+    {
+      err = (*mv->swap_vols) (store, vol, mv->cur_vol);
+      if (! err)
+	mv->cur_vol = vol;
+    }
+  return err;
+}
+
+static error_t
+mvol_read (struct store *store,
+	   off_t addr, size_t index, size_t amount,
+	   void **buf, size_t *len)
+{
+  error_t err = ensure_vol (store, index);
+  if (! err)
+    err = store_read (store->children[0], addr, amount, buf, len);
+  return err;
+}
+
+static error_t
+mvol_write (struct store *store,
+	    off_t addr, size_t index, void *buf, size_t len,
+	    size_t *amount)
+{
+  error_t err = ensure_vol (store, index);
+  if (! err)
+    err = store_write (store->children[0], addr, buf, len, amount);
+  return err;
+}
+
+error_t
+mvol_remap (struct store *source,
+	    const struct store_run *runs, size_t num_runs,
+	    struct store **store)
+{
+  return store_remap_create (source, runs, num_runs, 0, store);
+}
+
+struct store_class
+store_mvol_class =
+{
+  -1, "mvol", mvol_read, mvol_write,
+  0, 0, 0,
+  store_set_child_flags, store_clear_child_flags, 0, 0, mvol_remap
+};
+
+/* Return a new store in STORE that multiplexes multiple physical volumes
+   from PHYS as one larger virtual volume.  SWAP_VOLS is a function that will
+   be called whenever the volume currently active isn't correct.  PHYS is
+   consumed.  */
+error_t
+store_mvol_create (struct store *phys,
+		   error_t (*swap_vols) (struct store *store, size_t new_vol,
+					 ssize_t old_vol),
+		   int flags,
+		   struct store **store)
+{
+  error_t err;
+  struct store_run run;
+
+  run.start = 0;
+  run.length = phys->end;
+
+  err = _store_create (&store_mvol_class, MACH_PORT_NULL,
+		       flags | phys->flags, phys->block_size,
+		       &run, 1, 0, store);
+  if (! err)
+    {
+      struct mvol_state *mv = malloc (sizeof (struct mvol_state));
+      if (mv)
+	{
+	  mv->swap_vols = swap_vols;
+	  mv->cur_vol = -1;
+	  (*store)->hook = mv;
+	}
+      else
+	err = ENOMEM;
+      
+      if (! err)
+	err = store_set_children (*store, &phys, 1);
+
+      if (! err)
+	{
+	  if (phys->name)
+	    {
+	      size_t nlen =
+		strlen (phys->class->name) + 1 + strlen (phys->name) + 1;
+	      char *name = malloc (nlen);
+
+	      if (name)
+		{
+		  snprintf (name, nlen, "%s:%s", phys->class->name, phys->name);
+		  (*store)->name = name;
+		}
+	      else
+		err = ENOMEM;
+	    }
+	}
+
+      if (err)
+	{
+	  if (mv)
+	    free (mv);
+	  store_free (*store);
+	}
+    }
+
+  return err;
+}