1 files changed, 104 insertions, 0 deletions
diff --git a/libnetfs/io-read.c b/libnetfs/io-read.c
new file mode 100644
index 00000000..a4b1b2e2
--- /dev/null
+++ b/libnetfs/io-read.c
@@ -0,0 +1,104 @@
+/*
+   Copyright (C) 1995, 1996, 1997, 1999 Free Software Foundation, Inc.
+   Written by Michael I. Bushnell, p/BSG.
+
+   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 "netfs.h"
+#include "io_S.h"
+#include <fcntl.h>
+#include <sys/mman.h>
+
+error_t
+netfs_S_io_read (struct protid *user,
+		 char **data,
+		 mach_msg_type_number_t *datalen,
+		 off_t offset,
+		 mach_msg_type_number_t amount)
+{
+  error_t err;
+  off_t start;
+  struct node *node;
+  int alloced = 0;
+
+  if (!user)
+    return EOPNOTSUPP;
+
+  node = user->po->np;
+  mutex_lock (&user->po->np->lock);
+
+  if ((user->po->openstat & O_READ) == 0)
+    {
+      mutex_unlock (&node->lock);
+      return EBADF;
+    }
+
+  if (amount > *datalen)
+    {
+      alloced = 1;
+      *data = mmap (0, amount, PROT_READ|PROT_WRITE, MAP_ANON, 0, 0);
+    }
+  *datalen = amount;
+
+  start = (offset == -1 ? user->po->filepointer : offset);
+
+  if (start < 0)
+    err = EINVAL;
+  else if (S_ISLNK (node->nn_stat.st_mode))
+    /* Read from a symlink.  */
+    {
+      off_t size = node->nn_stat.st_size;
+
+      if (start + amount > size)
+	amount = size - start;
+
+      if (start >= size)
+	{
+	  *datalen = 0;
+	  err = 0;
+	}
+      else if (amount < size || start > 0)
+	{
+	  char *whole_link = alloca (size);
+	  err = netfs_attempt_readlink (user->user, node, *data);
+	  if (! err)
+	    {
+	      memcpy (*data, whole_link + start, amount);
+	      *datalen = amount;
+	    }
+	}
+      else
+	err = netfs_attempt_readlink (user->user, node, *data);
+    }
+  else
+    /* Read from a normal file.  */
+    err = netfs_attempt_read (user->user, node, start, datalen, *data);
+
+  if (offset == -1 && !err)
+    user->po->filepointer += *datalen;
+
+  mutex_unlock (&node->lock);
+
+  if (err && alloced)
+    munmap (*data, amount);
+
+  if (!err && alloced && (round_page (*datalen) < round_page (amount)))
+    munmap (*data + round_page (*datalen),
+	    round_page (amount) - round_page (*datalen));
+
+  return err;
+}