1 files changed, 109 insertions, 0 deletions
diff --git a/libdiskfs/io-read.c b/libdiskfs/io-read.c
new file mode 100644
index 00000000..4c2adf31
--- /dev/null
+++ b/libdiskfs/io-read.c
@@ -0,0 +1,109 @@
+/*
+   Copyright (C) 1994, 1995, 1996, 1997, 1999 Free Software Foundation
+
+   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 "priv.h"
+#include "io_S.h"
+#include <fcntl.h>
+
+/* Implement io_read as described in <hurd/io.defs>. */
+kern_return_t
+diskfs_S_io_read (struct protid *cred,
+		  char **data,
+		  mach_msg_type_number_t *datalen,
+		  off_t offset,
+		  mach_msg_type_number_t maxread)
+{
+  struct node *np;
+  int err;
+  int off = offset;
+  char *buf;
+  int ourbuf = 0;
+
+  if (!cred)
+    return EOPNOTSUPP;
+
+  np = cred->po->np;
+  if (!(cred->po->openstat & O_READ))
+    return EBADF;
+
+  mutex_lock (&np->lock);
+
+  iohelp_get_conch (&np->conch);
+
+  if (off == -1)
+    off = cred->po->filepointer;
+  if (off < 0)
+    {
+      mutex_unlock (&np->lock);
+      return EINVAL;
+    }
+
+  if (off > np->dn_stat.st_size)
+    maxread = 0;
+  else if (off + (off_t) maxread > np->dn_stat.st_size)
+    maxread = np->dn_stat.st_size - off;
+
+  if (maxread > *datalen)
+    {
+      ourbuf = 1;
+      buf = mmap (0, maxread, PROT_READ|PROT_WRITE, MAP_ANON, 0, 0);     
+      *data = buf;
+    }
+  else
+    buf = *data;
+
+  *datalen = maxread;
+
+  if (maxread == 0)
+    err = 0;
+  else if (S_ISLNK (np->dn_stat.st_mode))
+    {
+      /* Read from a symlink.  */
+      if (! diskfs_read_symlink_hook)
+	err = EINVAL;
+      else
+	{
+	  if (off == 0 && maxread == np->dn_stat.st_size)
+	    err = (*diskfs_read_symlink_hook)(np, buf);
+	  else
+	    {
+	      char *whole_link = alloca (np->dn_stat.st_size);
+	      err = (*diskfs_read_symlink_hook)(np, whole_link);
+	      if (! err)
+		memcpy (buf, whole_link + off, maxread);
+	    }
+	}
+    }
+  else
+    err = EINVAL;		/* Use read below.  */
+
+  if (err == EINVAL)
+    err = _diskfs_rdwr_internal (np, buf, off, datalen, 0,
+				 cred->po->openstat & O_NOATIME);
+
+  if (diskfs_synchronous)
+    diskfs_node_update (np, 1);	/* atime! */
+
+  if (offset == -1 && !err)
+    cred->po->filepointer += *datalen;
+
+  if (err && ourbuf)
+    munmap (buf, maxread);
+
+  mutex_unlock (&np->lock);
+  return err;
+}