1 files changed, 414 insertions, 0 deletions
diff --git a/storeio/dev.c b/storeio/dev.c
new file mode 100644
index 00000000..d9a4e083
--- /dev/null
+++ b/storeio/dev.c
@@ -0,0 +1,414 @@
+/* store `device' I/O
+
+   Copyright (C) 1995, 1996 Free Software Foundation, Inc.
+
+   Written by Miles Bader <miles@gnu.ai.mit.edu>
+
+   This program 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.
+
+   This program 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 <hurd.h>
+#include <assert.h>
+#include <string.h>
+#include <hurd/pager.h>
+#include <hurd/store.h>
+
+#include "dev.h"
+
+/* These functions deal with the buffer used for doing non-block-aligned I/O. */
+
+static inline int
+dev_buf_is_active (struct dev *dev)
+{
+  return dev->buf_offs >= 0;
+}
+
+/* Invalidate DEV's buffer, writing it to disk if necessary.  */
+static error_t
+dev_buf_discard (struct dev *dev)
+{
+  if (dev_buf_is_active (dev))
+    {
+      if (dev->buf_dirty)
+	{
+	  size_t amount;
+	  struct store *store = dev->store;
+	  error_t err =
+	    store_write (store, dev->buf_offs >> store->log2_block_size,
+			 dev->buf, store->block_size, &amount);
+	  if (amount < store->block_size)
+	    err = EIO;
+	  if (err)
+	    return err;
+	  dev->buf_dirty = 0;
+	}
+      dev->buf_offs = -1;
+    }
+  return 0;
+}
+
+/* Make DEV's buffer active, reading the block from DEV's store which
+   contains OFFS.  */
+static error_t
+dev_buf_fill (struct dev *dev, off_t offs)
+{
+  error_t err;
+  unsigned block_mask = dev->block_mask;
+  char *buf = dev->buf;
+  struct store *store = dev->store;
+  size_t buf_len = store->block_size;
+
+  if (dev_buf_is_active (dev))
+    if ((dev->buf_offs & ~block_mask) == (offs & ~block_mask))
+      return 0;			/* Correct block alredy in buffer.  */
+    else
+      {
+	err = dev_buf_discard (dev);
+	if (err)
+	  return err;
+      }
+
+  err = store_read (store, offs >> store->log2_block_size, store->block_size,
+		    &buf, &buf_len);
+  if (err)
+    return err;
+
+  if (buf != dev->buf)
+    {
+      vm_deallocate (mach_task_self (),
+		     (vm_address_t)dev->buf, store->block_size);
+      dev->buf = buf;
+    }
+
+  dev->buf_offs = offs & ~block_mask;
+
+  return 0;
+}
+
+/* Do an in-buffer partial-block I/O operation.  */
+static error_t
+dev_buf_rw (struct dev *dev, size_t buf_offs, size_t *io_offs, size_t *len,
+	    inline error_t (*const buf_rw) (size_t buf_offs,
+					    size_t io_offs, size_t len))
+{
+  size_t block_size = dev->store->block_size;
+
+  assert (dev_buf_is_active (dev));
+
+  if (buf_offs + *len >= block_size)
+    /* Only part of BUF lies within the buffer (or everything up
+       to the end of the block, in which case we want to flush
+       the buffer anyway).  */
+    {
+      size_t buf_len = block_size - buf_offs;
+      error_t err = (*buf_rw) (buf_offs, *io_offs, buf_len);
+      if (err)
+	return err;
+      *io_offs += buf_len;
+      *len -= buf_len;
+      return dev_buf_discard (dev);
+    }
+  else
+    /* All I/O is within the block.  */
+    {
+      error_t err = (*buf_rw) (buf_offs, *io_offs, *len);
+      if (err)
+	return err;
+      *io_offs += *len;
+      *len = 0;
+      return 0;
+    }
+}
+
+/* Returns a pointer to a new device structure in DEV for the kernel device
+   NAME, with the given FLAGS.  If BLOCK_SIZE is non-zero, it should be the
+   desired block size, and must be a multiple of the device block size.
+   If an error occurs, the error code is returned, otherwise 0.  */
+error_t
+dev_open (struct store_parsed *name, int flags, struct dev **dev)
+{
+  error_t err;
+  struct dev *new = malloc (sizeof (struct dev));
+
+  if (! new)
+    return ENOMEM;
+
+  err = store_parsed_open (name, flags, 0, &new->store);
+  if (err)
+    {
+      free (new);
+      return err;
+    }
+
+#if 0 /* valloc doesn't work */
+  new->buf = valloc (new->store->block_size);
+  if (new->buf == 0)
+#else
+  if (vm_allocate (mach_task_self (),
+		   (vm_address_t *)&new->buf, new->store->block_size, 1))
+#endif
+    {
+      store_free (new->store);
+      free (new);
+      return ENOMEM;
+    }
+
+  new->buf_offs = -1;
+  rwlock_init (&new->io_lock);
+  new->owner = 0;
+  new->block_mask = (1 << new->store->log2_block_size) - 1;
+  new->pager = 0;
+  mutex_init (&new->pager_lock);
+  *dev = new;
+
+  return 0;
+}
+
+/* Free DEV and any resources it consumes.  */
+void 
+dev_close (struct dev *dev)
+{
+  if (dev->pager != NULL)
+    pager_shutdown (dev->pager);
+
+  dev_buf_discard (dev);
+
+#if 0
+  free (dev->buf);
+#else
+  vm_deallocate (mach_task_self (),
+		 (vm_address_t)dev->buf, dev->store->block_size);
+#endif
+
+  store_free (dev->store);
+
+  free (dev);
+}
+
+/* Try and write out any pending writes to DEV.  If WAIT is true, will wait
+   for any paging activity to cease.  */
+error_t
+dev_sync(struct dev *dev, int wait)
+{
+  error_t err;
+
+  /* Sync any paged backing store.  */
+  if (dev->pager != NULL)
+    pager_sync (dev->pager, wait);
+
+  rwlock_writer_lock (&dev->io_lock);
+  err = dev_buf_discard (dev);
+  rwlock_writer_unlock (&dev->io_lock);
+
+  return err;
+}
+
+/* Takes care of buffering I/O to/from DEV for a transfer at position OFFS,
+   length LEN; the amount of I/O sucessfully done is returned in AMOUNT.
+   BUF_RW is called to do I/O that's entirely inside DEV's internal buffer,
+   and RAW_RW to do I/O directly to DEV's store.  */
+static inline error_t
+buffered_rw (struct dev *dev, off_t offs, size_t len, size_t *amount,
+	     inline error_t (* const buf_rw) (size_t buf_offs,
+					      size_t io_offs, size_t len),
+	     inline error_t (* const raw_rw) (off_t offs,
+					      size_t io_offs, size_t len,
+					      size_t *amount))
+{
+  error_t err = 0;
+  unsigned block_mask = dev->block_mask;
+  unsigned block_size = dev->store->block_size;
+  size_t io_offs = 0;		/* Offset within this I/O operation.  */
+  unsigned block_offs = offs & block_mask; /* Offset within a block.  */
+
+  rwlock_writer_lock (&dev->io_lock);
+
+  if (block_offs != 0)
+    /* The start of the I/O isn't block aligned.  */
+    {
+      err = dev_buf_fill (dev, offs);
+      if (! err)
+	err = dev_buf_rw (dev, block_offs, &io_offs, &len, buf_rw);
+    }
+
+  if (!err && len > 0)
+    /* Now the I/O should be block aligned.  */
+    {
+      if (len >= block_size)
+	{
+	  size_t amount;
+	  err = dev_buf_discard (dev);
+	  if (! err)
+	    err =
+	      (*raw_rw) (offs + io_offs, io_offs, len & ~block_mask, &amount);
+	  if (! err)
+	    {
+	      io_offs += amount;
+	      len -= amount;
+	    }
+	}
+      if (len > 0 && len < block_size)
+	/* All full blocks were written successfully, so write
+	   the tail end into the buffer.  */
+	{
+	  err = dev_buf_fill (dev, offs + io_offs);
+	  if (! err)
+	    err = dev_buf_rw (dev, 0, &io_offs, &len, buf_rw);
+	}
+    }
+
+  if (! err)
+    *amount = io_offs;
+
+  rwlock_writer_unlock (&dev->io_lock);
+
+  return err;
+}
+
+/* Takes care of buffering I/O to/from DEV for a transfer at position OFFS,
+   length LEN, and direction DIR.  BUF_RW is called to do I/O to/from data
+   buffered in DEV, and RAW_RW to do I/O directly to DEV's store.  */
+static inline error_t
+dev_rw (struct dev *dev, off_t offs, size_t len, size_t *amount,
+	inline error_t (* const buf_rw) (size_t buf_offs,
+					 size_t io_offs, size_t len),
+	inline error_t (* const raw_rw) (off_t offs,
+					 size_t io_offs, size_t len,
+					 size_t *amount))
+{
+  error_t err;
+  unsigned block_mask = dev->block_mask;
+
+  if (offs < 0)
+    return EINVAL;
+  else if (offs > dev->store->size)
+    return EIO;
+  else if (offs + len > dev->store->size)
+    len = dev->store->size - offs;
+
+  rwlock_reader_lock (&dev->io_lock);
+  if (dev_buf_is_active (dev)
+      || (offs & block_mask) != 0 || (len & block_mask) != 0)
+    /* Some non-aligned I/O has been done, or is needed, so we need to deal
+       with DEV's buffer, which means getting an exclusive lock.  */
+    {
+      /* Aquire a writer lock instead of a reader lock.  Note that other
+	 writers may have aquired the lock by the time we get it.  */
+      rwlock_reader_unlock (&dev->io_lock);
+      err = buffered_rw (dev, offs, len, amount, buf_rw, raw_rw);
+    }
+  else
+    /* Only block-aligned I/O is being done, so things are easy.  */
+    {
+      err = (*raw_rw) (offs, 0, len, amount);
+      rwlock_reader_unlock (&dev->io_lock);
+    }
+
+  return err;
+}
+
+/* Write LEN bytes from BUF to DEV, returning the amount actually written in
+   AMOUNT.  If successful, 0 is returned, otherwise an error code is
+   returned.  */
+error_t
+dev_write (struct dev *dev, off_t offs, char *buf, size_t len,
+	   size_t *amount)
+{
+  error_t buf_write (size_t buf_offs, size_t io_offs, size_t len)
+    {
+      bcopy (buf + io_offs, dev->buf + buf_offs, len);
+      dev->buf_dirty = 1;
+      return 0;
+    }
+  error_t raw_write (off_t offs, size_t io_offs, size_t len, size_t *amount)
+    {
+      struct store *store = dev->store;
+      return
+	store_write (store, offs >> store->log2_block_size,
+		     buf + io_offs, len, amount);
+    }
+
+  return dev_rw (dev, offs, len, amount, buf_write, raw_write);
+}
+
+/* Read up to WHOLE_AMOUNT bytes from DEV, returned in BUF and LEN in the
+   with the usual mach memory result semantics.  If successful, 0 is
+   returned, otherwise an error code is returned.  */
+error_t
+dev_read (struct dev *dev, off_t offs, size_t whole_amount,
+	  char **buf, size_t *len)
+{
+  error_t err;
+  int allocated_buf = 0;
+  error_t ensure_buf ()
+    {
+      error_t err;
+      if (*len < whole_amount)
+	{
+	  err = vm_allocate (mach_task_self (),
+			     (vm_address_t *)buf, whole_amount, 1);
+	  if (! err)
+	    allocated_buf = 1;
+	}
+      else
+	err = 0;
+      return err;
+    }
+  error_t buf_read (size_t buf_offs, size_t io_offs, size_t len)
+    {
+      error_t err = ensure_buf ();
+      if (! err)
+	bcopy (dev->buf + buf_offs, *buf + io_offs, len);
+      return err;
+    }
+  error_t raw_read (off_t offs, size_t io_offs, size_t len, size_t *amount)
+    {
+      struct store *store = dev->store;
+      off_t addr = offs >> store->log2_block_size;
+      if (len == whole_amount)
+	/* Just return whatever the device does.  */
+	return store_read (store, addr, len, buf, amount);
+      else
+	/* This read is returning less than the whole request, so we allocate
+	   a buffer big enough to hold everything, in case we have to
+	   coalesce multiple reads into a single return buffer.  */
+	{
+	  error_t err = ensure_buf ();
+	  if (! err)
+	    {
+	      char *_req_buf = *buf + io_offs, *req_buf = _req_buf;
+	      size_t req_len = len;
+	      err = store_read (store, addr, len, &req_buf, &req_len);
+	      if (! err)
+		{
+		  if (req_buf != _req_buf)
+		    /* Copy from wherever the read put it. */
+		    {
+		      bcopy (req_buf, _req_buf, req_len);
+		      vm_deallocate (mach_task_self (),
+				     (vm_address_t)req_buf, req_len);
+		    }
+		  *amount = req_len;
+		}
+	    }
+	  return err;
+	}
+    }
+
+  err = dev_rw (dev, offs, whole_amount, len, buf_read, raw_read);
+  if (err && allocated_buf)
+    vm_deallocate (mach_task_self (), (vm_address_t)*buf, whole_amount);
+
+  return err;
+}