[Libguestfs] [PATCH libguestfs] daemon: diagnose socket write failure

[Jim Meyering]

Richard W.M. Jones wrote:
...
>> Ok with all that?
>
> Both should check the return value.  Whether they can do anything
> useful about it is questionable though.

Ok.  Per discussion on IRC, here's an update:

>From f3542cad8d9a092099967a3983e922003a57c211 Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyering at redhat.com>
Date: Thu, 20 Aug 2009 12:29:46 +0200
Subject: [PATCH libguestfs] daemon: diagnose socket write failure

* daemon/proto.c (send_chunk): Don't ignore socket-write error.
* daemon/proto.c (send_file_end): Return "int", not void,
so we can propagate send_chunk failure to caller.
* daemon/daemon.h (send_file_end): Update prototype.
* daemon/tar.c (do_tar_out, do_tgz_out): Update uses of send_file_end.
* daemon/upload.c (do_download): Likewise.
---
 daemon/daemon.h |    2 +-
 daemon/proto.c  |   14 +++++++++-----
 daemon/tar.c    |    8 ++++++--
 daemon/upload.c |    4 +++-
 4 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/daemon/daemon.h b/daemon/daemon.h
index 0ce56e1..83c9672 100644
--- a/daemon/daemon.h
+++ b/daemon/daemon.h
@@ -116,7 +116,7 @@ extern void cancel_receive (void);
  * Note max write size if GUESTFS_MAX_CHUNK_SIZE.
  */
 extern int send_file_write (const void *buf, int len);
-extern void send_file_end (int cancel);
+extern int send_file_end (int cancel);

 /* only call this if there is a FileOut parameter */
 extern void reply (xdrproc_t xdrp, char *ret);
diff --git a/daemon/proto.c b/daemon/proto.c
index 9b33902..d935ded 100644
--- a/daemon/proto.c
+++ b/daemon/proto.c
@@ -462,7 +462,7 @@ check_for_library_cancellation (void)
   return 1;
 }

-void
+int
 send_file_end (int cancel)
 {
   guestfs_chunk chunk;
@@ -470,7 +470,7 @@ send_file_end (int cancel)
   chunk.cancel = cancel;
   chunk.data.data_len = 0;
   chunk.data.data_val = NULL;
-  send_chunk (&chunk);
+  return send_chunk (&chunk);
 }

 static int
@@ -495,8 +495,12 @@ send_chunk (const guestfs_chunk *chunk)
   xdr_uint32_t (&xdr, &len);
   xdr_destroy (&xdr);

-  (void) xwrite (sock, lenbuf, 4);
-  (void) xwrite (sock, buf, len);
+  int err = (xwrite (sock, lenbuf, 4) == 0
+             && xwrite (sock, buf, len) == 0 ? 0 : -1);
+  if (err) {
+    fprintf (stderr, "send_chunk: write failed\n");
+    exit (1);
+  }

-  return 0;
+  return err;
 }
diff --git a/daemon/tar.c b/daemon/tar.c
index 03dc512..c3bdcf7 100644
--- a/daemon/tar.c
+++ b/daemon/tar.c
@@ -149,7 +149,9 @@ do_tar_out (const char *dir)
     return -1;
   }

-  send_file_end (0);		/* Normal end of file. */
+  if (send_file_end (0))	/* Normal end of file. */
+    return -1;
+
   return 0;
 }

@@ -268,6 +270,8 @@ do_tgz_out (const char *dir)
     return -1;
   }

-  send_file_end (0);		/* Normal end of file. */
+  if (send_file_end (0))	/* Normal end of file. */
+    return -1;
+
   return 0;
 }
diff --git a/daemon/upload.c b/daemon/upload.c
index 143fa82..da86bd6 100644
--- a/daemon/upload.c
+++ b/daemon/upload.c
@@ -129,6 +129,8 @@ do_download (const char *filename)
     return -1;
   }

-  send_file_end (0);		/* Normal end of file. */
+  if (send_file_end (0))	/* Normal end of file. */
+    return -1;
+
   return 0;
 }
--
1.6.4.378.g88f2f