Initial checkin

1 files changed, 223 insertions, 0 deletions

diff --git a/libstore/remap.c b/libstore/remap.c
new file mode 100644
index 00000000..4bc02c31
--- /dev/null
+++ b/libstore/remap.c
@@ -0,0 +1,223 @@
+/* Block address translation
+
+   Copyright (C) 1996 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., 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+#include <malloc.h>
+#include <hurd/fs.h>
+
+#include "store.h"
+
+static error_t
+remap_read (struct store *store,
+	     off_t addr, size_t index, size_t amount,
+	     void **buf, size_t *len)
+{
+  return store_read (store->children[0], addr, amount, buf, len);
+}
+
+static error_t
+remap_write (struct store *store,
+	      off_t addr, size_t index, void *buf, size_t len,
+	      size_t *amount)
+{
+  return store_write (store->children[0], addr, buf, len, amount);
+}
+
+error_t
+remap_allocate_encoding (const struct store *store, struct store_enc *enc)
+{
+  enc->num_ints += 3;
+  enc->num_offsets += store->num_runs * 2;
+  return store_allocate_child_encodings (store, enc);
+}
+
+error_t
+remap_encode (const struct store *store, struct store_enc *enc)
+{
+  int i;
+  enc->ints[enc->cur_int++] = store->class->id;
+  enc->ints[enc->cur_int++] = store->flags;
+  enc->ints[enc->cur_int++] = store->num_runs;
+  for (i = 0; i < store->num_runs; i++)
+    {
+      enc->offsets[enc->cur_offset++] = store->runs[i].start;
+      enc->offsets[enc->cur_offset++] = store->runs[i].length;
+    }
+  return store_encode_children (store, enc);
+}
+
+error_t
+remap_decode (struct store_enc *enc, struct store_class *classes,
+	      struct store **store)
+{
+  if (enc->cur_int + 3 > enc->num_ints)
+    return EINVAL;
+  else
+    {
+      int type = enc->ints[enc->cur_int++];
+      int flags = enc->ints[enc->cur_int++];
+      int num_runs = enc->ints[enc->cur_int++];
+      error_t create_remap (const struct store_run *runs, size_t num_runs)
+	{
+	  struct store *source;
+	  error_t err = store_decode_children (enc, 1, classes, &source);
+	  if (! err)
+	    err =  store_remap_create (source, runs, num_runs, flags, store);
+	  return err;
+	}
+      return store_with_decoded_runs (enc, num_runs, create_remap);
+    }
+}
+
+static struct store_class
+remap_class =
+{
+  STORAGE_REMAP, "remap", remap_read, remap_write,
+  remap_allocate_encoding, remap_encode, remap_decode
+};
+_STORE_STD_CLASS (remap_class);
+
+/* Return a new store in STORE that reflects the blocks in RUNS & RUNS_LEN
+   from SOURCE; SOURCE is consumed, but RUNS is not.  Unlike the
+   store_remap function, this function always operates by creating a new
+   store of type `remap' which has SOURCE as a child, and so may be less
+   efficient than store_remap for some types of stores.  */
+error_t
+store_remap_create (struct store *source,
+		    const struct store_run *runs, size_t num_runs,
+		    int flags, struct store **store)
+{
+  error_t err;
+
+  *store = _make_store (&remap_class, MACH_PORT_NULL, flags,
+			source->block_size, runs, num_runs, 0);
+  if (! *store)
+    return ENOMEM;
+
+  err = store_set_children (*store, &source, 1);
+  if (err)
+    store_free (*store);
+
+  return err;
+}
+
+/* For each run in RUNS, of length NUM_RUNS, translate the  */
+error_t
+store_remap_runs (const struct store_run *runs, size_t num_runs,
+		  const struct store_run *base_runs, size_t num_base_runs,
+		  struct store_run **xruns, size_t *num_xruns)
+{
+  int i, j;
+  size_t xruns_alloced = num_runs + num_base_runs;
+
+  /* Add the single run [ADDR, LEN) to *XRUNS, returning true if successful. */
+  int add_run (off_t addr, off_t len)
+    {
+      if (*num_xruns == xruns_alloced)
+	/* Make some more space in *XRUNS.  */
+	{
+	  struct store_run *new;
+	  xruns_alloced *= 2;
+	  new = realloc (*xruns, xruns_alloced * sizeof (struct store_run));
+	  if (! new)
+	    return 0;
+	  *xruns = new;
+	}
+      (*xruns)[(*num_xruns)++] = (struct store_run){ addr, len };
+      return 1;
+    }
+
+  *xruns = malloc (xruns_alloced * sizeof (struct store_run));
+  if (! *xruns)
+    return ENOMEM;
+
+  /* Clean up and return error code CODE.  */
+#define ERR(code) do { free (*xruns); return (code); } while (0)
+
+  for (i = 0; i < num_runs; i++)
+    {
+      off_t addr = runs[i].start, left = runs[i].length;
+      
+      if (addr >= 0)
+	for (j = 0; j < num_base_runs && left > 0; j++)
+	  {
+	    off_t baddr = base_runs[j].start;
+	    off_t blen = base_runs[j].length;
+
+	    if (addr >= blen)
+	      addr -= blen;
+	    else if (baddr < 0)
+	      /* A hole, which is invalid.  */
+	      ERR (EINVAL);
+	    else
+	      /* Add another output run.  */
+	      {
+		off_t len = blen - addr; /* Size of next output run.  */
+		if (! add_run (baddr + addr, len > left ? left : len))
+		  ERR (ENOMEM);
+		addr = 0;
+		left -= len;
+	      }
+	  }
+      else
+	/* a hole */
+	if (! add_run (-1, left))
+	  ERR (ENOMEM);
+    }
+
+  if (xruns_alloced > *num_xruns)
+    *xruns = realloc (*xruns, *num_xruns * sizeof (struct store_run));
+
+  return 0;
+}
+
+/* Return a store in STORE that reflects the blocks in RUNS & RUNS_LEN from
+   SOURCE; SOURCE is consumed, but not RUNS.  Unlike the store_remap_create
+   function, this may simply modify SOURCE and return it.  */
+error_t
+store_remap (struct store *source,
+	     const struct store_run *runs, size_t num_runs,
+	     struct store **store)
+{
+  if (source->class->remap)
+    /* Use the class-specific remaping function.  */
+    return (* source->class->remap) (source, runs, num_runs, store);
+  else
+    /* Just replace SOURCE's runs-list by an appropiately translated RUNS. */
+    {
+      struct store_run *xruns = 0;
+      size_t num_xruns = 0;
+      error_t err =
+	store_remap_runs (runs, num_runs, source->runs, source->num_runs,
+			  &xruns, &num_xruns);
+      if (! err)
+	{
+	  /* Don't use store_set_runs because we've already allocated the
+	     storages.  */
+	  free (source->runs);
+	  source->runs = xruns;
+	  source->num_runs = num_xruns;
+	  _store_derive (source);
+	  *store = source;
+	}
+      return err;
+    }
+}