From 84b890e949f89da5237ba62232998698406db450 Mon Sep 17 00:00:00 2001
From: Miles Bader <miles@gnu.org>
Date: Fri, 21 Feb 1997 21:55:43 +0000
Subject: (netfs_S_io_read): Support reading from symlinks.
---
libnetfs/io-read.c | 47 +++++++++++++++++++++++++++++++++++++++++------
1 file changed, 41 insertions(+), 6 deletions(-)
diff --git a/libnetfs/io-read.c b/libnetfs/io-read.c
index 09887153..7603a9d8 100644
--- a/libnetfs/io-read.c
+++ b/libnetfs/io-read.c
@@ -1,5 +1,5 @@
/*
- Copyright (C) 1995, 1996 Free Software Foundation, Inc.
+ Copyright (C) 1995, 1996, 1997 Free Software Foundation, Inc.
Written by Michael I. Bushnell, p/BSG.
This file is part of the GNU Hurd.
@@ -30,16 +30,19 @@ netfs_S_io_read (struct protid *user,
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 (&user->po->np->lock);
+ mutex_unlock (&node->lock);
return EBADF;
}
@@ -50,12 +53,44 @@ netfs_S_io_read (struct protid *user,
}
*datalen = amount;
- err = netfs_attempt_read (user->user, user->po->np,
- offset == -1 ? user->po->filepointer : offset,
- datalen, *data);
+ 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 (&user->po->np->lock);
+
+ mutex_unlock (&node->lock);
if (err && alloced)
vm_deallocate (mach_task_self (), (vm_address_t) *data, amount);
--
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