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[Libguestfs] [PATCH] Remove main loop



Please note this patch depends on these earlier patches:

    Add command trace functionality.
    https://www.redhat.com/archives/libguestfs/2009-September/msg00031.html

    Non-daemon actions indirect through generated code.
    https://www.redhat.com/archives/libguestfs/2009-September/msg00022.html

Rich.

-- 
Richard Jones, Emerging Technologies, Red Hat  http://et.redhat.com/~rjones
New in Fedora 11: Fedora Windows cross-compiler. Compile Windows
programs, test, and build Windows installers. Over 70 libraries supprt'd
http://fedoraproject.org/wiki/MinGW http://www.annexia.org/fedora_mingw
>From acf91d3d217bcd668a124da50f2ce289fe14805d Mon Sep 17 00:00:00 2001
From: Richard Jones <rjones trick home annexia org>
Date: Fri, 11 Sep 2009 20:00:30 +0100
Subject: [PATCH] Remove main loop.

This commit removes the external main loop, which never worked
and caused a number of bugs.  Requests are now done synchronously,
and if the user wants to have requests issued in the background
or to have a responsive GUI, then they'll just have to use threads.

The big change is to push all reads and writes through two
functions called send_to_daemon (for writes) and recv_from_daemon
(for reads) which operate synchronously.  These functions
read/write whole messages, and also handle checking for EOF
(ie. daemon died) and asynchronous log message events from
qemu (eg. from debug / dmesg printed by the guest).  A more
complete description of how these work can be found in the code.

This code passes a complete run of the tests.

Bugs believed to be fixed by this commit:

  https://bugzilla.redhat.com/show_bug.cgi?id=501888
  internal error: reply callback called twice

  https://bugzilla.redhat.com/show_bug.cgi?id=504418
  In virt-inspector: "download: guestfs_download reply failed, see earlier error messages"

I have tried to avoid reintroducing this:

  https://bugzilla.redhat.com/show_bug.cgi?id=508713
  libguestfs: error: write: Broken pipe (guestfish only)

One other benefit of this is that 'set_busy/end_busy' calls
no longer appear in traces.
---
 guestfs.pod      |  143 +------
 src/generator.ml |  216 +++------
 src/guestfs.c    | 1334 +++++++++++++++++++-----------------------------------
 src/guestfs.h    |   60 +--
 4 files changed, 549 insertions(+), 1204 deletions(-)

diff --git a/guestfs.pod b/guestfs.pod
index b8379d0..c5b756e 100644
--- a/guestfs.pod
+++ b/guestfs.pod
@@ -486,8 +486,7 @@ register to receive these messages.
 =head2 SETTING CALLBACKS TO HANDLE EVENTS
 
 The child process generates events in some situations.  Current events
-include: receiving a reply message after some action, receiving a log
-message, the child process exits, &c.
+include: receiving a log message, the child process exits.
 
 Use the C<guestfs_set_*_callback> functions to set a callback for
 different types of events.
@@ -497,39 +496,6 @@ Calling C<guestfs_set_*_callback> again overwrites the previous
 callback of that type.  Cancel all callbacks of this type by calling
 this function with C<cb> set to C<NULL>.
 
-=head2 NON-BLOCKING ACTIONS
-
-XXX This section was documented in previous versions but never
-implemented in a way which matched the documentation.  For now I have
-removed the documentation, pending a working implementation.  See also
-C<src/guestfs-actions.c> in the source.
-
-
-=head2 guestfs_set_send_callback
-
- typedef void (*guestfs_send_cb) (guestfs_h *g, void *opaque);
- void guestfs_set_send_callback (guestfs_h *handle,
-                                 guestfs_send_cb cb,
-                                 void *opaque);
-
-The callback function C<cb> will be called whenever a message
-which is queued for sending, has been sent.
-
-=head2 guestfs_set_reply_callback
-
- typedef void (*guestfs_reply_cb) (guestfs_h *g, void *opaque, XDR *xdr);
- void guestfs_set_reply_callback (guestfs_h *handle,
-                                  guestfs_reply_cb cb,
-                                  void *opaque);
-
-The callback function C<cb> will be called whenever a reply is
-received from the child process.  (This corresponds to a transition
-from the BUSY state to the READY state).
-
-Note that the C<xdr> that you get in the callback is in C<XDR_DECODE>
-mode, and you need to consume it before you return from the callback
-function (since it gets destroyed after).
-
 =head2 guestfs_set_log_message_callback
 
  typedef void (*guestfs_log_message_cb) (guestfs_h *g, void *opaque,
@@ -572,113 +538,6 @@ corresponds to a transition from LAUNCHING to the READY state).
 You can use this instead of C<guestfs_wait_ready> to implement a
 non-blocking wait for the child process to finish booting up.
 
-=head2 EVENT MAIN LOOP
-
-To use the low-level event API and/or to use handles from multiple
-threads, you have to provide an event "main loop".  You can write your
-own, but if you don't want to write one, two types are provided for
-you:
-
-=over 4
-
-=item libguestfs-select
-
-A simple main loop that is implemented using L<select(2)>.
-
-This is the default main loop for new guestfs handles, unless you
-call C<guestfs_set_main_loop> after a handle is created.
-
-=item libguestfs-glib
-
-An implementation which can be used with GLib and GTK+ programs.  You
-can use this to write graphical (GTK+) programs which use libguestfs
-without hanging during long or slow operations.
-
-=back
-
-=head2 MULTIPLE HANDLES AND MULTIPLE THREADS
-
-The support for multiple handles and multiple threads is modelled
-after glib (although doesn't require glib, if you use the select-based
-main loop).
-
-L<http://library.gnome.org/devel/glib/unstable/glib-The-Main-Event-Loop.html>
-
-You will need to create one main loop for each thread that wants to
-use libguestfs.  Each guestfs handle should be confined to one thread.
-If you try to pass guestfs handles between threads, you will get
-undefined results.
-
-If you only want to use guestfs handles from one thread in your
-program, but your program has other threads doing other things, then
-you don't need to do anything special.
-
-=head2 SINGLE THREAD CASE
-
-In the single thread case, there is a single select-based main loop
-created for you.  All guestfs handles will use this main loop to
-execute high level API actions.
-
-=head2 MULTIPLE THREADS CASE
-
-In the multiple threads case, you will need to create a main loop for
-each thread that wants to use libguestfs.
-
-To create main loops for other threads, use
-C<guestfs_create_main_loop> or C<guestfs_glib_create_main_loop>.
-
-Then you will need to attach each handle to the thread-specific main
-loop by calling:
-
- handle = guestfs_create ();
- guestfs_set_main_loop (handle, main_loop_of_current_thread);
-
-=head2 guestfs_set_main_loop
-
- void guestfs_set_main_loop (guestfs_h *handle,
-                             guestfs_main_loop *main_loop);
-
-Sets the main loop used by high level API actions for this handle.  By
-default, the select-based main loop is used (see
-C<guestfs_get_default_main_loop>).
-
-You only need to use this in multi-threaded programs, where multiple
-threads want to use libguestfs.  Create a main loop for each thread,
-then call this function.
-
-You cannot pass guestfs handles between threads.
-
-=head2 guestfs_get_main_loop
-
- guestfs_main_loop *guestfs_get_main_loop (guestfs_h *handle);
-
-Return the main loop used by C<handle>.
-
-=head2 guestfs_get_default_main_loop
-
- guestfs_main_loop *guestfs_get_default_main_loop (void);
-
-Return the default select-based main loop.
-
-=head2 guestfs_create_main_loop
-
- guestfs_main_loop *guestfs_create_main_loop (void);
-
-This creates a select-based main loop.  You should create one main
-loop for each additional thread that needs to use libguestfs.
-
-=head2 guestfs_free_main_loop
-
- void guestfs_free_main_loop (guestfs_main_loop *);
-
-Free the select-based main loop which was previously allocated with
-C<guestfs_create_main_loop>.
-
-=head2 WRITING A CUSTOM MAIN LOOP
-
-This isn't documented.  Please see the libguestfs-select and
-libguestfs-glib implementations.
-
 =head1 BLOCK DEVICE NAMING
 
 In the kernel there is now quite a profusion of schemata for naming
diff --git a/src/generator.ml b/src/generator.ml
index 5b18cfa..8b95ffb 100755
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -680,34 +680,6 @@ only useful for printing debug and internal error messages.
 
 For more information on states, see L<guestfs(3)>.");
 
-  ("set_busy", (RErr, []), -1, [NotInFish],
-   [],
-   "set state to busy",
-   "\
-This sets the state to C<BUSY>.  This is only used when implementing
-actions using the low-level API.
-
-For more information on states, see L<guestfs(3)>.");
-
-  ("set_ready", (RErr, []), -1, [NotInFish],
-   [],
-   "set state to ready",
-   "\
-This sets the state to C<READY>.  This is only used when implementing
-actions using the low-level API.
-
-For more information on states, see L<guestfs(3)>.");
-
-  ("end_busy", (RErr, []), -1, [NotInFish],
-   [],
-   "leave the busy state",
-   "\
-This sets the state to C<READY>, or if in C<CONFIG> then it leaves the
-state as is.  This is only used when implementing
-actions using the low-level API.
-
-For more information on states, see L<guestfs(3)>.");
-
   ("set_memsize", (RErr, [Int "memsize"]), -1, [FishAlias "memsize"],
    [InitNone, Always, TestOutputInt (
       [["set_memsize"; "500"];
@@ -806,8 +778,8 @@ For more information on the architecture of libguestfs,
 see L<guestfs(3)>.");
 
   ("set_trace", (RErr, [Bool "trace"]), -1, [FishAlias "trace"],
-   [InitNone, Always, TestOutputTrue (
-      [["set_trace"; "true"];
+   [InitNone, Always, TestOutputFalse (
+      [["set_trace"; "false"];
        ["get_trace"]])],
    "enable or disable command traces",
    "\
@@ -4639,16 +4611,16 @@ check_reply_header (guestfs_h *g,
 static int
 check_state (guestfs_h *g, const char *caller)
 {
-  if (!guestfs_is_ready (g)) {
-    if (guestfs_is_config (g))
+  if (!guestfs__is_ready (g)) {
+    if (guestfs__is_config (g))
       error (g, \"%%s: call launch before using this function\\n(in guestfish, don't forget to use the 'run' command)\",
         caller);
-    else if (guestfs_is_launching (g))
+    else if (guestfs__is_launching (g))
       error (g, \"%%s: call wait_ready() before using this function\",
         caller);
     else
       error (g, \"%%s called from the wrong state, %%d != READY\",
-        caller, guestfs_get_state (g));
+        caller, guestfs__get_state (g));
     return -1;
   }
   return 0;
@@ -4723,76 +4695,6 @@ check_state (guestfs_h *g, const char *caller)
     fun (shortname, style, _, _, _, _, _) ->
       let name = "guestfs_" ^ shortname in
 
-      (* Generate the context struct which stores the high-level
-       * state between callback functions.
-       *)
-      pr "struct %s_ctx {\n" shortname;
-      pr "  /* This flag is set by the callbacks, so we know we've done\n";
-      pr "   * the callbacks as expected, and in the right sequence.\n";
-      pr "   * 0 = not called, 1 = reply_cb called.\n";
-      pr "   */\n";
-      pr "  int cb_sequence;\n";
-      pr "  struct guestfs_message_header hdr;\n";
-      pr "  struct guestfs_message_error err;\n";
-      (match fst style with
-       | RErr -> ()
-       | RConstString _ | RConstOptString _ ->
-           failwithf "RConstString|RConstOptString cannot be used by daemon functions"
-       | RInt _ | RInt64 _
-       | RBool _ | RString _ | RStringList _
-       | RStruct _ | RStructList _
-       | RHashtable _ | RBufferOut _ ->
-           pr "  struct %s_ret ret;\n" name
-      );
-      pr "};\n";
-      pr "\n";
-
-      (* Generate the reply callback function. *)
-      pr "static void %s_reply_cb (guestfs_h *g, void *data, XDR *xdr)\n" shortname;
-      pr "{\n";
-      pr "  guestfs_main_loop *ml = guestfs_get_main_loop (g);\n";
-      pr "  struct %s_ctx *ctx = (struct %s_ctx *) data;\n" shortname shortname;
-      pr "\n";
-      pr "  /* This should definitely not happen. */\n";
-      pr "  if (ctx->cb_sequence != 0) {\n";
-      pr "    ctx->cb_sequence = 9999;\n";
-      pr "    error (g, \"%%s: internal error: reply callback called twice\", \"%s\");\n" name;
-      pr "    return;\n";
-      pr "  }\n";
-      pr "\n";
-      pr "  ml->main_loop_quit (ml, g);\n";
-      pr "\n";
-      pr "  if (!xdr_guestfs_message_header (xdr, &ctx->hdr)) {\n";
-      pr "    error (g, \"%%s: failed to parse reply header\", \"%s\");\n" name;
-      pr "    return;\n";
-      pr "  }\n";
-      pr "  if (ctx->hdr.status == GUESTFS_STATUS_ERROR) {\n";
-      pr "    if (!xdr_guestfs_message_error (xdr, &ctx->err)) {\n";
-      pr "      error (g, \"%%s: failed to parse reply error\", \"%s\");\n"
-        name;
-      pr "      return;\n";
-      pr "    }\n";
-      pr "    goto done;\n";
-      pr "  }\n";
-
-      (match fst style with
-       | RErr -> ()
-       | RConstString _ | RConstOptString _ ->
-           failwithf "RConstString|RConstOptString cannot be used by daemon functions"
-       | RInt _ | RInt64 _
-       | RBool _ | RString _ | RStringList _
-       | RStruct _ | RStructList _
-       | RHashtable _ | RBufferOut _ ->
-           pr "  if (!xdr_%s_ret (xdr, &ctx->ret)) {\n" name;
-           pr "    error (g, \"%%s: failed to parse reply\", \"%s\");\n" name;
-           pr "    return;\n";
-           pr "  }\n";
-      );
-
-      pr " done:\n";
-      pr "  ctx->cb_sequence = 1;\n";
-      pr "}\n\n";
-
       (* Generate the action stub. *)
       generate_prototype ~extern:false ~semicolon:false ~newline:true
         ~handle:"g" name style;
@@ -4814,21 +4716,32 @@ check_state (guestfs_h *g, const char *caller)
        | _ -> pr "  struct %s_args args;\n" name
       );
 
-      pr "  struct %s_ctx ctx;\n" shortname;
-      pr "  guestfs_main_loop *ml = guestfs_get_main_loop (g);\n";
+      pr "  guestfs_message_header hdr;\n";
+      pr "  guestfs_message_error err;\n";
+      let has_ret =
+	match fst style with
+	| RErr -> false
+	| RConstString _ | RConstOptString _ ->
+            failwithf "RConstString|RConstOptString cannot be used by daemon functions"
+	| RInt _ | RInt64 _
+	| RBool _ | RString _ | RStringList _
+	| RStruct _ | RStructList _
+	| RHashtable _ | RBufferOut _ ->
+            pr "  struct %s_ret ret;\n" name;
+	    true in
+
       pr "  int serial;\n";
+      pr "  int r;\n";
       pr "\n";
       trace_call shortname style;
       pr "  if (check_state (g, \"%s\") == -1) return %s;\n" name error_code;
-      pr "  guestfs_set_busy (g);\n";
-      pr "\n";
-      pr "  memset (&ctx, 0, sizeof ctx);\n";
+      pr "  guestfs___set_busy (g);\n";
       pr "\n";
 
       (* Send the main header and arguments. *)
       (match snd style with
        | [] ->
-           pr "  serial = guestfs__send_sync (g, GUESTFS_PROC_%s, NULL, NULL);\n"
+           pr "  serial = guestfs___send (g, GUESTFS_PROC_%s, NULL, NULL);\n"
              (String.uppercase shortname)
        | args ->
            List.iter (
@@ -4846,13 +4759,13 @@ check_state (guestfs_h *g, const char *caller)
                  pr "  args.%s = %s;\n" n n
              | FileIn _ | FileOut _ -> ()
            ) args;
-           pr "  serial = guestfs__send_sync (g, GUESTFS_PROC_%s,\n"
+           pr "  serial = guestfs___send (g, GUESTFS_PROC_%s,\n"
              (String.uppercase shortname);
            pr "        (xdrproc_t) xdr_%s_args, (char *) &args);\n"
              name;
       );
       pr "  if (serial == -1) {\n";
-      pr "    guestfs_end_busy (g);\n";
+      pr "    guestfs___end_busy (g);\n";
       pr "    return %s;\n" error_code;
       pr "  }\n";
       pr "\n";
@@ -4862,47 +4775,48 @@ check_state (guestfs_h *g, const char *caller)
       List.iter (
         function
         | FileIn n ->
-            pr "  {\n";
-            pr "    int r;\n";
-            pr "\n";
-            pr "    r = guestfs__send_file_sync (g, %s);\n" n;
-            pr "    if (r == -1) {\n";
-            pr "      guestfs_end_busy (g);\n";
-            pr "      return %s;\n" error_code;
-            pr "    }\n";
-            pr "    if (r == -2) /* daemon cancelled */\n";
-            pr "      goto read_reply;\n";
-            need_read_reply_label := true;
+            pr "  r = guestfs___send_file (g, %s);\n" n;
+            pr "  if (r == -1) {\n";
+            pr "    guestfs___end_busy (g);\n";
+            pr "    return %s;\n" error_code;
             pr "  }\n";
+            pr "  if (r == -2) /* daemon cancelled */\n";
+            pr "    goto read_reply;\n";
+            need_read_reply_label := true;
             pr "\n";
         | _ -> ()
       ) (snd style);
 
       (* Wait for the reply from the remote end. *)
       if !need_read_reply_label then pr " read_reply:\n";
-      pr "  guestfs__switch_to_receiving (g);\n";
-      pr "  ctx.cb_sequence = 0;\n";
-      pr "  guestfs_set_reply_callback (g, %s_reply_cb, &ctx);\n" shortname;
-      pr "  (void) ml->main_loop_run (ml, g);\n";
-      pr "  guestfs_set_reply_callback (g, NULL, NULL);\n";
-      pr "  if (ctx.cb_sequence != 1) {\n";
-      pr "    error (g, \"%%s reply failed, see earlier error messages\", \"%s\");\n" name;
-      pr "    guestfs_end_busy (g);\n";
+      pr "  memset (&hdr, 0, sizeof hdr);\n";
+      pr "  memset (&err, 0, sizeof err);\n";
+      if has_ret then pr "  memset (&ret, 0, sizeof ret);\n";
+      pr "\n";
+      pr "  r = guestfs___recv (g, \"%s\", &hdr, &err,\n        " shortname;
+      if not has_ret then
+	pr "NULL, NULL"
+      else
+        pr "(xdrproc_t) xdr_guestfs_%s_ret, (char *) &ret" shortname;
+      pr ");\n";
+
+      pr "  if (r == -1) {\n";
+      pr "    guestfs___end_busy (g);\n";
       pr "    return %s;\n" error_code;
       pr "  }\n";
       pr "\n";
 
-      pr "  if (check_reply_header (g, &ctx.hdr, GUESTFS_PROC_%s, serial) == -1) {\n"
+      pr "  if (check_reply_header (g, &hdr, GUESTFS_PROC_%s, serial) == -1) {\n"
         (String.uppercase shortname);
-      pr "    guestfs_end_busy (g);\n";
+      pr "    guestfs___end_busy (g);\n";
       pr "    return %s;\n" error_code;
       pr "  }\n";
       pr "\n";
 
-      pr "  if (ctx.hdr.status == GUESTFS_STATUS_ERROR) {\n";
-      pr "    error (g, \"%%s\", ctx.err.error_message);\n";
-      pr "    free (ctx.err.error_message);\n";
-      pr "    guestfs_end_busy (g);\n";
+      pr "  if (hdr.status == GUESTFS_STATUS_ERROR) {\n";
+      pr "    error (g, \"%%s: %%s\", \"%s\", err.error_message);\n" shortname;
+      pr "    free (err.error_message);\n";
+      pr "    guestfs___end_busy (g);\n";
       pr "    return %s;\n" error_code;
       pr "  }\n";
       pr "\n";
@@ -4911,41 +4825,41 @@ check_state (guestfs_h *g, const char *caller)
       List.iter (
         function
         | FileOut n ->
-            pr "  if (guestfs__receive_file_sync (g, %s) == -1) {\n" n;
-            pr "    guestfs_end_busy (g);\n";
+            pr "  if (guestfs___recv_file (g, %s) == -1) {\n" n;
+            pr "    guestfs___end_busy (g);\n";
             pr "    return %s;\n" error_code;
             pr "  }\n";
             pr "\n";
         | _ -> ()
       ) (snd style);
 
-      pr "  guestfs_end_busy (g);\n";
+      pr "  guestfs___end_busy (g);\n";
 
       (match fst style with
        | RErr -> pr "  return 0;\n"
        | RInt n | RInt64 n | RBool n ->
-           pr "  return ctx.ret.%s;\n" n
+           pr "  return ret.%s;\n" n
        | RConstString _ | RConstOptString _ ->
            failwithf "RConstString|RConstOptString cannot be used by daemon functions"
        | RString n ->
-           pr "  return ctx.ret.%s; /* caller will free */\n" n
+           pr "  return ret.%s; /* caller will free */\n" n
        | RStringList n | RHashtable n ->
            pr "  /* caller will free this, but we need to add a NULL entry */\n";
-           pr "  ctx.ret.%s.%s_val =\n" n n;
-           pr "    safe_realloc (g, ctx.ret.%s.%s_val,\n" n n;
-           pr "                  sizeof (char *) * (ctx.ret.%s.%s_len + 1));\n"
+           pr "  ret.%s.%s_val =\n" n n;
+           pr "    safe_realloc (g, ret.%s.%s_val,\n" n n;
+           pr "                  sizeof (char *) * (ret.%s.%s_len + 1));\n"
              n n;
-           pr "  ctx.ret.%s.%s_val[ctx.ret.%s.%s_len] = NULL;\n" n n n n;
-           pr "  return ctx.ret.%s.%s_val;\n" n n
+           pr "  ret.%s.%s_val[ret.%s.%s_len] = NULL;\n" n n n n;
+           pr "  return ret.%s.%s_val;\n" n n
        | RStruct (n, _) ->
            pr "  /* caller will free this */\n";
-           pr "  return safe_memdup (g, &ctx.ret.%s, sizeof (ctx.ret.%s));\n" n n
+           pr "  return safe_memdup (g, &ret.%s, sizeof (ret.%s));\n" n n
        | RStructList (n, _) ->
            pr "  /* caller will free this */\n";
-           pr "  return safe_memdup (g, &ctx.ret.%s, sizeof (ctx.ret.%s));\n" n n
+           pr "  return safe_memdup (g, &ret.%s, sizeof (ret.%s));\n" n n
        | RBufferOut n ->
-           pr "  *size_r = ctx.ret.%s.%s_len;\n" n n;
-           pr "  return ctx.ret.%s.%s_val; /* caller will free */\n" n n
+           pr "  *size_r = ret.%s.%s_len;\n" n n;
+           pr "  return ret.%s.%s_val; /* caller will free */\n" n n
       );
 
       pr "}\n\n"
diff --git a/src/guestfs.c b/src/guestfs.c
index 98d99b8..43f2a56 100644
--- a/src/guestfs.c
+++ b/src/guestfs.c
@@ -78,65 +78,10 @@
 //#define safe_memdup guestfs_safe_memdup
 
 static void default_error_cb (guestfs_h *g, void *data, const char *msg);
-static void stdout_event (struct guestfs_main_loop *ml, guestfs_h *g, void *data, int watch, int fd, int events);
-static void sock_read_event (struct guestfs_main_loop *ml, guestfs_h *g, void *data, int watch, int fd, int events);
-static void sock_write_event (struct guestfs_main_loop *ml, guestfs_h *g, void *data, int watch, int fd, int events);
-
+static int send_to_daemon (guestfs_h *g, const void *v_buf, size_t n);
+static int recv_from_daemon (guestfs_h *g, uint32_t *size_rtn, void **buf_rtn);
 static void close_handles (void);
 
-static int select_add_handle (guestfs_main_loop *ml, guestfs_h *g, int fd, int events, guestfs_handle_event_cb cb, void *data);
-static int select_remove_handle (guestfs_main_loop *ml, guestfs_h *g, int watch);
-static int select_add_timeout (guestfs_main_loop *ml, guestfs_h *g, int interval, guestfs_handle_timeout_cb cb, void *data);
-static int select_remove_timeout (guestfs_main_loop *ml, guestfs_h *g, int timer);
-static int select_main_loop_run (guestfs_main_loop *ml, guestfs_h *g);
-static int select_main_loop_quit (guestfs_main_loop *ml, guestfs_h *g);
-
-/* Default select-based main loop. */
-struct select_handle_cb_data {
-  guestfs_handle_event_cb cb;
-  guestfs_h *g;
-  void *data;
-};
-
-struct select_main_loop {
-  /* NB. These fields must be the same as in struct guestfs_main_loop: */
-  guestfs_add_handle_cb add_handle;
-  guestfs_remove_handle_cb remove_handle;
-  guestfs_add_timeout_cb add_timeout;
-  guestfs_remove_timeout_cb remove_timeout;
-  guestfs_main_loop_run_cb main_loop_run;
-  guestfs_main_loop_quit_cb main_loop_quit;
-
-  /* Additional private data: */
-  int is_running;
-
-  fd_set rset;
-  fd_set wset;
-  fd_set xset;
-
-  int max_fd;
-  int nr_fds;
-  struct select_handle_cb_data *handle_cb_data;
-};
-
-/* Default main loop. */
-static struct select_main_loop default_main_loop = {
-  .add_handle = select_add_handle,
-  .remove_handle = select_remove_handle,
-  .add_timeout = select_add_timeout,
-  .remove_timeout = select_remove_timeout,
-  .main_loop_run = select_main_loop_run,
-  .main_loop_quit = select_main_loop_quit,
-
-  /* XXX hopefully .rset, .wset, .xset are initialized to the empty
-   * set by the normal action of everything being initialized to zero.
-   */
-  .is_running = 0,
-  .max_fd = -1,
-  .nr_fds = 0,
-  .handle_cb_data = NULL,
-};
-
 #define UNIX_PATH_MAX 108
 
 /* Also in guestfsd.c */
@@ -159,9 +104,6 @@ struct guestfs_h
   pid_t recoverypid;		/* Recovery process PID. */
   time_t start_t;		/* The time when we started qemu. */
 
-  int stdout_watch;		/* Watches qemu stdout for log messages. */
-  int sock_watch;		/* Watches daemon comm socket. */
-
   char *tmpdir;			/* Temporary directory containing socket. */
 
   char *qemu_help, *qemu_version; /* Output of qemu -help, qemu -version. */
@@ -187,10 +129,6 @@ struct guestfs_h
   guestfs_abort_cb           abort_cb;
   guestfs_error_handler_cb   error_cb;
   void *                     error_cb_data;
-  guestfs_send_cb            send_cb;
-  void *                     send_cb_data;
-  guestfs_reply_cb           reply_cb;
-  void *                     reply_cb_data;
   guestfs_log_message_cb     log_message_cb;
   void *                     log_message_cb_data;
   guestfs_subprocess_quit_cb subprocess_quit_cb;
@@ -198,15 +136,6 @@ struct guestfs_h
   guestfs_launch_done_cb     launch_done_cb;
   void *                     launch_done_cb_data;
 
-  /* Main loop used by this handle. */
-  guestfs_main_loop *main_loop;
-
-  /* Messages sent and received from the daemon. */
-  char *msg_in;
-  unsigned int msg_in_size, msg_in_allocated;
-  char *msg_out;
-  unsigned int msg_out_size, msg_out_pos;
-
   int msg_next_serial;
 };
 
@@ -229,8 +158,6 @@ guestfs_create (void)
   g->fd[0] = -1;
   g->fd[1] = -1;
   g->sock = -1;
-  g->stdout_watch = -1;
-  g->sock_watch = -1;
 
   g->abort_cb = abort;
   g->error_cb = default_error_cb;
@@ -272,8 +199,6 @@ guestfs_create (void)
   } else
     g->memsize = 500;
 
-  g->main_loop = guestfs_get_default_main_loop ();
-
   /* Start with large serial numbers so they are easy to spot
    * inside the protocol.
    */
@@ -334,14 +259,7 @@ guestfs_close (guestfs_h *g)
   if (g->state != CONFIG)
     guestfs_kill_subprocess (g);
 
-  /* Close any sockets and deregister any handlers. */
-  if (g->stdout_watch >= 0)
-    g->main_loop->remove_handle (g->main_loop, g, g->stdout_watch);
-  if (g->sock_watch >= 0)
-    g->main_loop->remove_handle (g->main_loop, g, g->sock_watch);
-  g->stdout_watch = -1;
-  g->sock_watch = -1;
-
+  /* Close sockets. */
   if (g->fd[0] >= 0)
     close (g->fd[0]);
   if (g->fd[1] >= 0)
@@ -391,8 +309,6 @@ guestfs_close (guestfs_h *g)
   }
   /* release mutex (XXX) */
 
-  free (g->msg_in);
-  free (g->msg_out);
   free (g->last_error);
   free (g->path);
   free (g->qemu);
@@ -565,6 +481,7 @@ xwrite (int fd, const void *v_buf, size_t len)
   return 0;
 }
 
+#if 0
 static int
 xread (int fd, void *v_buf, size_t len)
 {
@@ -585,6 +502,7 @@ xread (int fd, void *v_buf, size_t len)
 
   return 0;
 }
+#endif
 
 void
 guestfs_set_out_of_memory_handler (guestfs_h *g, guestfs_abort_cb cb)
@@ -848,7 +766,7 @@ guestfs__add_drive (guestfs_h *g, const char *filename)
     }
   }
 
-  return guestfs_config (g, "-drive", buf);
+  return guestfs__config (g, "-drive", buf);
 }
 
 int
@@ -869,7 +787,7 @@ guestfs__add_drive_ro (guestfs_h *g, const char *filename)
 
   snprintf (buf, len, "file=%s,snapshot=on,if=%s", filename, DRIVE_IF);
 
-  return guestfs_config (g, "-drive", buf);
+  return guestfs__config (g, "-drive", buf);
 }
 
 int
@@ -885,7 +803,7 @@ guestfs__add_cdrom (guestfs_h *g, const char *filename)
     return -1;
   }
 
-  return guestfs_config (g, "-cdrom", filename);
+  return guestfs__config (g, "-cdrom", filename);
 }
 
 /* Returns true iff file is contained in dir. */
@@ -1309,37 +1227,9 @@ guestfs__launch (guestfs_h *g)
   goto cleanup2;
 
  connected:
-  /* Watch the file descriptors. */
-  free (g->msg_in);
-  g->msg_in = NULL;
-  g->msg_in_size = g->msg_in_allocated = 0;
-
-  free (g->msg_out);
-  g->msg_out = NULL;
-  g->msg_out_size = 0;
-  g->msg_out_pos = 0;
-
-  g->stdout_watch =
-    g->main_loop->add_handle (g->main_loop, g, g->fd[1],
-                              GUESTFS_HANDLE_READABLE,
-                              stdout_event, NULL);
-  if (g->stdout_watch == -1) {
-    error (g, _("could not watch qemu stdout"));
-    goto cleanup3;
-  }
-
-  if (guestfs__switch_to_receiving (g) == -1)
-    goto cleanup3;
-
   g->state = LAUNCHING;
   return 0;
 
- cleanup3:
-  if (g->stdout_watch >= 0)
-    g->main_loop->remove_handle (g->main_loop, g, g->stdout_watch);
-  if (g->sock_watch >= 0)
-    g->main_loop->remove_handle (g->main_loop, g, g->sock_watch);
-
  cleanup2:
   close (g->sock);
 
@@ -1356,8 +1246,6 @@ guestfs__launch (guestfs_h *g)
   g->pid = 0;
   g->recoverypid = 0;
   g->start_t = 0;
-  g->stdout_watch = -1;
-  g->sock_watch = -1;
 
  cleanup0:
   free (kernel);
@@ -1513,20 +1401,12 @@ qemu_supports (guestfs_h *g, const char *option)
   return g->qemu_help && strstr (g->qemu_help, option) != NULL;
 }
 
-static void
-finish_wait_ready (guestfs_h *g, void *vp)
-{
-  if (g->verbose)
-    fprintf (stderr, "finish_wait_ready called, %p, vp = %p\n", g, vp);
-
-  *((int *)vp) = 1;
-  g->main_loop->main_loop_quit (g->main_loop, g);
-}
-
 int
 guestfs__wait_ready (guestfs_h *g)
 {
-  int finished = 0, r;
+  int r;
+  uint32_t size;
+  void *buf = NULL;
 
   if (g->state == READY) return 0;
 
@@ -1540,15 +1420,12 @@ guestfs__wait_ready (guestfs_h *g)
     return -1;
   }
 
-  g->launch_done_cb = finish_wait_ready;
-  g->launch_done_cb_data = &finished;
-  r = g->main_loop->main_loop_run (g->main_loop, g);
-  g->launch_done_cb = NULL;
-  g->launch_done_cb_data = NULL;
+  r = recv_from_daemon (g, &size, &buf);
+  free (buf);
 
   if (r == -1) return -1;
 
-  if (finished != 1) {
+  if (size != GUESTFS_LAUNCH_FLAG) {
     error (g, _("guestfs_wait_ready failed, see earlier error messages"));
     return -1;
   }
@@ -1614,20 +1491,82 @@ guestfs__get_state (guestfs_h *g)
   return g->state;
 }
 
-int
-guestfs__set_ready (guestfs_h *g)
+void
+guestfs_set_log_message_callback (guestfs_h *g,
+                                  guestfs_log_message_cb cb, void *opaque)
 {
-  if (g->state != BUSY) {
-    error (g, _("guestfs_set_ready: called when in state %d != BUSY"),
-           g->state);
-    return -1;
-  }
-  g->state = READY;
-  return 0;
+  g->log_message_cb = cb;
+  g->log_message_cb_data = opaque;
+}
+
+void
+guestfs_set_subprocess_quit_callback (guestfs_h *g,
+                                      guestfs_subprocess_quit_cb cb, void *opaque)
+{
+  g->subprocess_quit_cb = cb;
+  g->subprocess_quit_cb_data = opaque;
 }
 
+void
+guestfs_set_launch_done_callback (guestfs_h *g,
+                                  guestfs_launch_done_cb cb, void *opaque)
+{
+  g->launch_done_cb = cb;
+  g->launch_done_cb_data = opaque;
+}
+
+/*----------------------------------------------------------------------*/
+
+/* This is the code used to send and receive RPC messages and (for
+ * certain types of message) to perform file transfers.  This code is
+ * driven from the generated actions (src/guestfs-actions.c).  There
+ * are five different cases to consider:
+ *
+ * (1) A non-daemon function.  There is no RPC involved at all, it's
+ * all handled inside the library.
+ *
+ * (2) A simple RPC (eg. "mount").  We write the request, then read
+ * the reply.  The sequence of calls is:
+ *
+ *   guestfs___set_busy
+ *   guestfs___send
+ *   guestfs___recv
+ *   guestfs___end_busy
+ *
+ * (3) An RPC with FileOut parameters (eg. "upload").  We write the
+ * request, then write the file(s), then read the reply.  The sequence
+ * of calls is:
+ *
+ *   guestfs___set_busy
+ *   guestfs___send
+ *   guestfs___send_file  (possibly multiple times)
+ *   guestfs___recv
+ *   guestfs___end_busy
+ *
+ * (4) An RPC with FileIn parameters (eg. "download").  We write the
+ * request, then read the reply, then read the file(s).  The sequence
+ * of calls is:
+ *
+ *   guestfs___set_busy
+ *   guestfs___send
+ *   guestfs___recv
+ *   guestfs___recv_file  (possibly multiple times)
+ *   guestfs___end_busy
+ *
+ * (5) Both FileOut and FileIn parameters.  There are no calls like
+ * this in the current API, but they would be implemented as a
+ * combination of cases (3) and (4).
+ *
+ * During all writes and reads, we also select(2) on qemu stdout
+ * looking for messages (guestfsd stderr and guest kernel dmesg), and
+ * anything received is passed up through the log_message_cb.  This is
+ * also the reason why all the sockets are non-blocking.  We also have
+ * to check for EOF (qemu died).  All of this is handled by the
+ * functions send_to_daemon and recv_from_daemon.
+ */
+
 int
-guestfs__set_busy (guestfs_h *g)
+guestfs___set_busy (guestfs_h *g)
 {
   if (g->state != READY) {
     error (g, _("guestfs_set_busy: called when in state %d != READY"),
@@ -1639,7 +1578,7 @@ guestfs__set_busy (guestfs_h *g)
 }
 
 int
-guestfs__end_busy (guestfs_h *g)
+guestfs___end_busy (guestfs_h *g)
 {
   switch (g->state)
     {
@@ -1659,23 +1598,17 @@ guestfs__end_busy (guestfs_h *g)
   return 0;
 }
 
-/* We don't know if stdout_event or sock_read_event will be the
- * first to receive EOF if the qemu process dies.  This function
- * has the common cleanup code for both.
- */
+/* This is called if we detect EOF, ie. qemu died. */
 static void
 child_cleanup (guestfs_h *g)
 {
   if (g->verbose)
-    fprintf (stderr, "stdout_event: %p: child process died\n", g);
+    fprintf (stderr, "child_cleanup: %p: child process died\n", g);
+
   /*kill (g->pid, SIGTERM);*/
   if (g->recoverypid > 0) kill (g->recoverypid, 9);
   waitpid (g->pid, NULL, 0);
   if (g->recoverypid > 0) waitpid (g->recoverypid, NULL, 0);
-  if (g->stdout_watch >= 0)
-    g->main_loop->remove_handle (g->main_loop, g, g->stdout_watch);
-  if (g->sock_watch >= 0)
-    g->main_loop->remove_handle (g->main_loop, g, g->sock_watch);
   close (g->fd[0]);
   close (g->fd[1]);
   close (g->sock);
@@ -1685,47 +1618,44 @@ child_cleanup (guestfs_h *g)
   g->pid = 0;
   g->recoverypid = 0;
   g->start_t = 0;
-  g->stdout_watch = -1;
-  g->sock_watch = -1;
   g->state = CONFIG;
   if (g->subprocess_quit_cb)
     g->subprocess_quit_cb (g, g->subprocess_quit_cb_data);
 }
 
-/* This function is called whenever qemu prints something on stdout.
- * Qemu's stdout is also connected to the guest's serial console, so
- * we see kernel messages here too.
- */
-static void
-stdout_event (struct guestfs_main_loop *ml, guestfs_h *g, void *data,
-              int watch, int fd, int events)
+static int
+read_log_message_or_eof (guestfs_h *g, int fd)
 {
-  char buf[4096];
+  char buf[BUFSIZ];
   int n;
 
 #if 0
   if (g->verbose)
     fprintf (stderr,
-             "stdout_event: %p g->state = %d, fd = %d, events = 0x%x\n",
-             g, g->state, fd, events);
+             "read_log_message_or_eof: %p g->state = %d, fd = %d\n",
+             g, g->state, fd);
 #endif
 
-  if (g->fd[1] != fd) {
-    error (g, _("stdout_event: internal error: %d != %d"), g->fd[1], fd);
-    return;
-  }
-
+  /* QEMU's console emulates a 16550A serial port.  The real 16550A
+   * device has a small FIFO buffer (16 bytes) which means here we see
+   * lots of small reads of 1-16 bytes in length, usually single
+   * bytes.  For this reason, we loop here until the port would block
+   * again, so we can avoid going back into the event loop too often.
+   */
+ again:
   n = read (fd, buf, sizeof buf);
   if (n == 0) {
     /* Hopefully this indicates the qemu child process has died. */
     child_cleanup (g);
-    return;
+    return -1;
   }
 
   if (n == -1) {
-    if (errno != EINTR && errno != EAGAIN)
-      perrorf (g, "read");
-    return;
+    if (errno == EINTR || errno == EAGAIN)
+      return 0;
+
+    perrorf (g, "read");
+    return -1;
   }
 
   /* In verbose mode, copy all log messages to stderr. */
@@ -1735,354 +1665,300 @@ stdout_event (struct guestfs_main_loop *ml, guestfs_h *g, void *data,
   /* It's an actual log message, send it upwards if anyone is listening. */
   if (g->log_message_cb)
     g->log_message_cb (g, g->log_message_cb_data, buf, n);
+
+  /* See comment above. */
+  usleep (100);
+  goto again;
 }
 
-/* The function is called whenever we can read something on the
- * guestfsd (daemon inside the guest) communication socket.
- */
-static void
-sock_read_event (struct guestfs_main_loop *ml, guestfs_h *g, void *data,
-                 int watch, int fd, int events)
+static int
+check_for_daemon_cancellation_or_eof (guestfs_h *g, int fd)
 {
-  XDR xdr;
-  u_int32_t len;
+  char buf[4];
   int n;
+  uint32_t flag;
+  XDR xdr;
 
   if (g->verbose)
     fprintf (stderr,
-             "sock_read_event: %p g->state = %d, fd = %d, events = 0x%x\n",
-             g, g->state, fd, events);
+             "check_for_daemon_cancellation_or_eof: %p g->state = %d, fd = %d\n",
+             g, g->state, fd);
 
-  if (g->sock != fd) {
-    error (g, _("sock_read_event: internal error: %d != %d"), g->sock, fd);
-    return;
-  }
-
-  if (g->msg_in_size <= g->msg_in_allocated) {
-    g->msg_in_allocated += 4096;
-    g->msg_in = safe_realloc (g, g->msg_in, g->msg_in_allocated);
-  }
-  n = read (g->sock, g->msg_in + g->msg_in_size,
-            g->msg_in_allocated - g->msg_in_size);
+  n = read (fd, buf, 4);
   if (n == 0) {
-    /* Disconnected. */
+    /* Hopefully this indicates the qemu child process has died. */
     child_cleanup (g);
-    return;
+    return -1;
   }
 
   if (n == -1) {
-    if (errno != EINTR && errno != EAGAIN)
-      perrorf (g, "read");
-    return;
-  }
-
-  g->msg_in_size += n;
-
-  /* Have we got enough of a message to be able to process it yet? */
- again:
-  if (g->msg_in_size < 4) return;
-
-  xdrmem_create (&xdr, g->msg_in, g->msg_in_size, XDR_DECODE);
-  if (!xdr_uint32_t (&xdr, &len)) {
-    error (g, _("can't decode length word"));
-    goto cleanup;
-  }
-
-  /* Length is normally the length of the message, but when guestfsd
-   * starts up it sends a "magic" value (longer than any possible
-   * message).  Check for this.
-   */
-  if (len == GUESTFS_LAUNCH_FLAG) {
-    if (g->state != LAUNCHING)
-      error (g, _("received magic signature from guestfsd, but in state %d"),
-             g->state);
-    else if (g->msg_in_size != 4)
-      error (g, _("received magic signature from guestfsd, but msg size is %d"),
-             g->msg_in_size);
-    else {
-      g->state = READY;
-      if (g->launch_done_cb)
-        g->launch_done_cb (g, g->launch_done_cb_data);
-    }
-
-    goto cleanup;
-  }
-
-  /* This can happen if a cancellation happens right at the end
-   * of us sending a FileIn parameter to the daemon.  Discard.  The
-   * daemon should send us an error message next.
-   */
-  if (len == GUESTFS_CANCEL_FLAG) {
-    g->msg_in_size -= 4;
-    memmove (g->msg_in, g->msg_in+4, g->msg_in_size);
-    goto again;
-  }
+    if (errno == EINTR || errno == EAGAIN)
+      return 0;
 
-  /* If this happens, it's pretty bad and we've probably lost
-   * synchronization.
-   */
-  if (len > GUESTFS_MESSAGE_MAX) {
-    error (g, _("message length (%u) > maximum possible size (%d)"),
-           len, GUESTFS_MESSAGE_MAX);
-    goto cleanup;
+    perrorf (g, "read");
+    return -1;
   }
 
-  if (g->msg_in_size-4 < len) return; /* Need more of this message. */
-
-  /* Got the full message, begin processing it. */
-#if 0
-  if (g->verbose) {
-    int i, j;
+  xdrmem_create (&xdr, buf, 4, XDR_DECODE);
+  xdr_uint32_t (&xdr, &flag);
+  xdr_destroy (&xdr);
 
-    for (i = 0; i < g->msg_in_size; i += 16) {
-      printf ("%04x: ", i);
-      for (j = i; j < MIN (i+16, g->msg_in_size); ++j)
-        printf ("%02x ", (unsigned char) g->msg_in[j]);
-      for (; j < i+16; ++j)
-        printf ("   ");
-      printf ("|");
-      for (j = i; j < MIN (i+16, g->msg_in_size); ++j)
-        if (isprint (g->msg_in[j]))
-          printf ("%c", g->msg_in[j]);
-        else
-          printf (".");
-      for (; j < i+16; ++j)
-        printf (" ");
-      printf ("|\n");
-    }
+  if (flag != GUESTFS_CANCEL_FLAG) {
+    error (g, _("check_for_daemon_cancellation_or_eof: read 0x%x from daemon, expected 0x%x\n"),
+           flag, GUESTFS_CANCEL_FLAG);
+    return -1;
   }
-#endif
 
-  /* Not in the expected state. */
-  if (g->state != BUSY)
-    error (g, _("state %d != BUSY"), g->state);
-
-  /* Push the message up to the higher layer. */
-  if (g->reply_cb)
-    g->reply_cb (g, g->reply_cb_data, &xdr);
-  else
-    /* This message (probably) should never be printed. */
-    fprintf (stderr, "libguesfs: sock_read_event: !!! dropped message !!!\n");
-
-  g->msg_in_size -= len + 4;
-  memmove (g->msg_in, g->msg_in+len+4, g->msg_in_size);
-  if (g->msg_in_size > 0) goto again;
-
- cleanup:
-  /* Free the message buffer if it's grown excessively large. */
-  if (g->msg_in_allocated > 65536) {
-    free (g->msg_in);
-    g->msg_in = NULL;
-    g->msg_in_size = g->msg_in_allocated = 0;
-  } else
-    g->msg_in_size = 0;
-
-  xdr_destroy (&xdr);
+  return -2;
 }
 
-/* The function is called whenever we can write something on the
- * guestfsd (daemon inside the guest) communication socket.
+/* This writes the whole N bytes of BUF to the daemon socket.
+ *
+ * If the whole write is successful, it returns 0.
+ * If there was an error, it returns -1.
+ * If the daemon sent a cancellation message, it returns -2.
+ *
+ * It also checks qemu stdout for log messages and passes those up
+ * through log_message_cb.
+ *
+ * It also checks for EOF (qemu died) and passes that up through the
+ * child_cleanup function above.
  */
-static void
-sock_write_event (struct guestfs_main_loop *ml, guestfs_h *g, void *data,
-                  int watch, int fd, int events)
+static int
+send_to_daemon (guestfs_h *g, const void *v_buf, size_t n)
 {
-  int n, err;
+  const char *buf = v_buf;
+  fd_set rset, rset2;
+  fd_set wset, wset2;
 
   if (g->verbose)
     fprintf (stderr,
-             "sock_write_event: %p g->state = %d, fd = %d, events = 0x%x\n",
-             g, g->state, fd, events);
+             "send_to_daemon: %p g->state = %d, n = %zu\n", g, g->state, n);
 
-  if (g->sock != fd) {
-    error (g, _("sock_write_event: internal error: %d != %d"), g->sock, fd);
-    return;
-  }
+  FD_ZERO (&rset);
+  FD_ZERO (&wset);
 
-  if (g->state != BUSY) {
-    error (g, _("sock_write_event: state %d != BUSY"), g->state);
-    return;
-  }
+  FD_SET (g->fd[1], &rset);     /* Read qemu stdout for log messages & EOF. */
+  FD_SET (g->sock, &rset);      /* Read socket for cancellation & EOF. */
+  FD_SET (g->sock, &wset);      /* Write to socket to send the data. */
 
-  if (g->verbose)
-    fprintf (stderr, "sock_write_event: writing %d bytes ...\n",
-             g->msg_out_size - g->msg_out_pos);
+  int max_fd = g->sock > g->fd[1] ? g->sock : g->fd[1];
 
-  n = write (g->sock, g->msg_out + g->msg_out_pos,
-             g->msg_out_size - g->msg_out_pos);
-  if (n == -1) {
-    err = errno;
-    if (err != EAGAIN)
-      perrorf (g, "write");
-    if (err == EPIPE)	/* Disconnected from guest (RHBZ#508713). */
-      child_cleanup (g);
-    return;
-  }
+  while (n > 0) {
+    rset2 = rset;
+    wset2 = wset;
+    int r = select (max_fd+1, &rset2, &wset2, NULL, NULL);
+    if (r == -1) {
+      if (errno == EINTR || errno == EAGAIN)
+        continue;
+      perrorf (g, "select");
+      return -1;
+    }
 
-  if (g->verbose)
-    fprintf (stderr, "sock_write_event: wrote %d bytes\n", n);
+    if (FD_ISSET (g->fd[1], &rset2)) {
+      if (read_log_message_or_eof (g, g->fd[1]) == -1)
+        return -1;
+    }
+    if (FD_ISSET (g->sock, &rset2)) {
+      r = check_for_daemon_cancellation_or_eof (g, g->sock);
+      if (r < 0)
+        return r;
+    }
+    if (FD_ISSET (g->sock, &wset2)) {
+      r = write (g->sock, buf, n);
+      if (r == -1) {
+        if (errno == EINTR || errno == EAGAIN)
+          continue;
+        perrorf (g, "write");
+        if (errno == EPIPE) /* Disconnected from guest (RHBZ#508713). */
+          child_cleanup (g);
+        return -1;
+      }
+      buf += r;
+      n -= r;
+    }
+  }
 
-  g->msg_out_pos += n;
+  return 0;
+}
 
-  /* More to write? */
-  if (g->msg_out_pos < g->msg_out_size)
-    return;
+/* This reads a single message, file chunk, launch flag or
+ * cancellation flag from the daemon.  If something was read, it
+ * returns 0, otherwise -1.
+ *
+ * Both size_rtn and buf_rtn must be passed by the caller as non-NULL.
+ *
+ * *size_rtn returns the size of the returned message or it may be
+ * GUESTFS_LAUNCH_FLAG or GUESTFS_CANCEL_FLAG.
+ *
+ * *buf_rtn is returned containing the message (if any) or will be set
+ * to NULL.  *buf_rtn must be freed by the caller.
+ *
+ * It also checks qemu stdout for log messages and passes those up
+ * through log_message_cb.
+ *
+ * It also checks for EOF (qemu died) and passes that up through the
+ * child_cleanup function above.
+ */
+static int
+recv_from_daemon (guestfs_h *g, uint32_t *size_rtn, void **buf_rtn)
+{
+  fd_set rset, rset2;
 
   if (g->verbose)
-    fprintf (stderr, "sock_write_event: done writing, calling send_cb\n");
+    fprintf (stderr,
+             "recv_from_daemon: %p g->state = %d, size_rtn = %p, buf_rtn = %p\n",
+             g, g->state, size_rtn, buf_rtn);
 
-  free (g->msg_out);
-  g->msg_out = NULL;
-  g->msg_out_pos = g->msg_out_size = 0;
+  FD_ZERO (&rset);
 
-  /* Done writing, call the higher layer. */
-  if (g->send_cb)
-    g->send_cb (g, g->send_cb_data);
-}
+  FD_SET (g->fd[1], &rset);     /* Read qemu stdout for log messages & EOF. */
+  FD_SET (g->sock, &rset);      /* Read socket for data & EOF. */
 
-void
-guestfs_set_send_callback (guestfs_h *g,
-                           guestfs_send_cb cb, void *opaque)
-{
-  g->send_cb = cb;
-  g->send_cb_data = opaque;
-}
+  int max_fd = g->sock > g->fd[1] ? g->sock : g->fd[1];
 
-void
-guestfs_set_reply_callback (guestfs_h *g,
-                            guestfs_reply_cb cb, void *opaque)
-{
-  g->reply_cb = cb;
-  g->reply_cb_data = opaque;
-}
+  *size_rtn = 0;
+  *buf_rtn = NULL;
 
-void
-guestfs_set_log_message_callback (guestfs_h *g,
-                                  guestfs_log_message_cb cb, void *opaque)
-{
-  g->log_message_cb = cb;
-  g->log_message_cb_data = opaque;
-}
+  char lenbuf[4];
+  /* nr is the size of the message, but we prime it as -4 because we
+   * have to read the message length word first.
+   */
+  ssize_t nr = -4;
 
-void
-guestfs_set_subprocess_quit_callback (guestfs_h *g,
-                                      guestfs_subprocess_quit_cb cb, void *opaque)
-{
-  g->subprocess_quit_cb = cb;
-  g->subprocess_quit_cb_data = opaque;
-}
+  for (;;) {
+    rset2 = rset;
+    int r = select (max_fd+1, &rset2, NULL, NULL, NULL);
+    if (r == -1) {
+      if (errno == EINTR || errno == EAGAIN)
+        continue;
+      perrorf (g, "select");
+      return -1;
+    }
 
-void
-guestfs_set_launch_done_callback (guestfs_h *g,
-                                  guestfs_launch_done_cb cb, void *opaque)
-{
-  g->launch_done_cb = cb;
-  g->launch_done_cb_data = opaque;
-}
+    if (FD_ISSET (g->fd[1], &rset2)) {
+      if (read_log_message_or_eof (g, g->fd[1]) == -1)
+        return -1;
+    }
+    if (FD_ISSET (g->sock, &rset2)) {
+      if (nr < 0) {    /* Have we read the message length word yet? */
+        r = read (g->sock, lenbuf+nr+4, -nr);
+        if (r == -1) {
+          if (errno == EINTR || errno == EAGAIN)
+            continue;
+          int err = errno;
+          perrorf (g, "read");
+          /* Under some circumstances we see "Connection reset by peer"
+           * here when the child dies suddenly.  Catch this and call
+           * the cleanup function, same as for EOF.
+           */
+          if (err == ECONNRESET)
+            child_cleanup (g);
+          return -1;
+        }
+        if (r == 0) {
+          error (g, _("unexpected end of file when reading from daemon"));
+          child_cleanup (g);
+          return -1;
+        }
+        nr += r;
+
+        if (nr < 0)         /* Still not got the whole length word. */
+          continue;
+
+        XDR xdr;
+        xdrmem_create (&xdr, lenbuf, 4, XDR_DECODE);
+        xdr_uint32_t (&xdr, size_rtn);
+        xdr_destroy (&xdr);
+
+        if (*size_rtn == GUESTFS_LAUNCH_FLAG) {
+          if (g->state != LAUNCHING)
+            error (g, _("received magic signature from guestfsd, but in state %d"),
+                   g->state);
+          else {
+            g->state = READY;
+            if (g->launch_done_cb)
+              g->launch_done_cb (g, g->launch_done_cb_data);
+          }
+          return 0;
+        }
+        else if (*size_rtn == GUESTFS_CANCEL_FLAG)
+          return 0;
+        /* If this happens, it's pretty bad and we've probably lost
+         * synchronization.
+         */
+        else if (*size_rtn > GUESTFS_MESSAGE_MAX) {
+          error (g, _("message length (%u) > maximum possible size (%d)"),
+                 (unsigned) *size_rtn, GUESTFS_MESSAGE_MAX);
+          return -1;
+        }
+        /*FALLTHROUGH*/
+      }
 
-/* Access to the handle's main loop and the default main loop. */
-void
-guestfs_set_main_loop (guestfs_h *g, guestfs_main_loop *main_loop)
-{
-  g->main_loop = main_loop;
-}
+      size_t sizetoread = *size_rtn - nr;
+      if (sizetoread > BUFSIZ) sizetoread = BUFSIZ;
 
-guestfs_main_loop *
-guestfs_get_main_loop (guestfs_h *g)
-{
-  return g->main_loop;
-}
+      *buf_rtn = safe_realloc (g, *buf_rtn, nr + sizetoread);
 
-guestfs_main_loop *
-guestfs_get_default_main_loop (void)
-{
-  return (guestfs_main_loop *) &default_main_loop;
-}
+      r = read (g->sock, (char *) (*buf_rtn) + nr, sizetoread);
+      if (r == -1) {
+        if (errno == EINTR || errno == EAGAIN)
+          continue;
+        perrorf (g, "read");
+        return -1;
+      }
+      if (r == 0) {
+        error (g, _("unexpected end of file when reading from daemon"));
+        child_cleanup (g);
+        return -1;
+      }
+      nr += r;
 
-/* Change the daemon socket handler so that we are now writing.
- * This sets the handle to sock_write_event.
- */
-int
-guestfs__switch_to_sending (guestfs_h *g)
-{
-  if (g->sock_watch >= 0) {
-    if (g->main_loop->remove_handle (g->main_loop, g, g->sock_watch) == -1) {
-      error (g, _("remove_handle failed"));
-      g->sock_watch = -1;
-      return -1;
+      if (nr >= *size_rtn)
+        break;
     }
   }
 
-  g->sock_watch =
-    g->main_loop->add_handle (g->main_loop, g, g->sock,
-                              GUESTFS_HANDLE_WRITABLE,
-                              sock_write_event, NULL);
-  if (g->sock_watch == -1) {
-    error (g, _("add_handle failed"));
-    return -1;
-  }
-
-  return 0;
-}
+  /* Got the full message, caller can start processing it. */
+#if 0
+  if (g->verbose) {
+    size_t i, j;
 
-int
-guestfs__switch_to_receiving (guestfs_h *g)
-{
-  if (g->sock_watch >= 0) {
-    if (g->main_loop->remove_handle (g->main_loop, g, g->sock_watch) == -1) {
-      error (g, _("remove_handle failed"));
-      g->sock_watch = -1;
-      return -1;
+    for (i = 0; i < nr; i += 16) {
+      printf ("%04x: ", i);
+      for (j = i; j < MIN (i+16, nr); ++j)
+        printf ("%02x ", (unsigned char) (*buf_rtn)[j]);
+      for (; j < i+16; ++j)
+        printf ("   ");
+      printf ("|");
+      for (j = i; j < MIN (i+16, g->nr); ++j)
+        if (isprint ((*buf_rtn)[j]))
+          printf ("%c", (*buf_rtn)[j]);
+        else
+          printf (".");
+      for (; j < i+16; ++j)
+        printf (" ");
+      printf ("|\n");
     }
   }
-
-  g->sock_watch =
-    g->main_loop->add_handle (g->main_loop, g, g->sock,
-                              GUESTFS_HANDLE_READABLE,
-                              sock_read_event, NULL);
-  if (g->sock_watch == -1) {
-    error (g, _("add_handle failed"));
-    return -1;
-  }
+#endif
 
   return 0;
 }
 
-/* Dispatch a call (len + header + args) to the remote daemon,
- * synchronously (ie. using the guest's main loop to wait until
- * it has been sent).  Returns -1 for error, or the serial
- * number of the message.
- */
-static void
-send_cb (guestfs_h *g, void *data)
-{
-  guestfs_main_loop *ml = guestfs_get_main_loop (g);
-
-  *((int *)data) = 1;
-  ml->main_loop_quit (ml, g);
-}
-
 int
-guestfs__send_sync (guestfs_h *g, int proc_nr,
-                    xdrproc_t xdrp, char *args)
+guestfs___send (guestfs_h *g, int proc_nr, xdrproc_t xdrp, char *args)
 {
   struct guestfs_message_header hdr;
   XDR xdr;
   u_int32_t len;
   int serial = g->msg_next_serial++;
-  int sent;
-  guestfs_main_loop *ml = guestfs_get_main_loop (g);
+  int r;
+  char *msg_out;
+  size_t msg_out_size;
 
   if (g->state != BUSY) {
-    error (g, _("guestfs__send_sync: state %d != BUSY"), g->state);
-    return -1;
-  }
-
-  /* This is probably an internal error.  Or perhaps we should just
-   * free the buffer anyway?
-   */
-  if (g->msg_out != NULL) {
-    error (g, _("guestfs__send_sync: msg_out should be NULL"));
+    error (g, _("guestfs___send: state %d != BUSY"), g->state);
     return -1;
   }
 
@@ -2092,8 +1968,8 @@ guestfs__send_sync (guestfs_h *g, int proc_nr,
    * we have quite limited stack space available, notably when
    * running in the JVM.
    */
-  g->msg_out = safe_malloc (g, GUESTFS_MESSAGE_MAX + 4);
-  xdrmem_create (&xdr, g->msg_out + 4, GUESTFS_MESSAGE_MAX, XDR_ENCODE);
+  msg_out = safe_malloc (g, GUESTFS_MESSAGE_MAX + 4);
+  xdrmem_create (&xdr, msg_out + 4, GUESTFS_MESSAGE_MAX, XDR_ENCODE);
 
   /* Serialize the header. */
   hdr.prog = GUESTFS_PROGRAM;
@@ -2124,48 +2000,40 @@ guestfs__send_sync (guestfs_h *g, int proc_nr,
   len = xdr_getpos (&xdr);
   xdr_destroy (&xdr);
 
-  g->msg_out = safe_realloc (g, g->msg_out, len + 4);
-  g->msg_out_size = len + 4;
-  g->msg_out_pos = 0;
+  msg_out = safe_realloc (g, msg_out, len + 4);
+  msg_out_size = len + 4;
 
-  xdrmem_create (&xdr, g->msg_out, 4, XDR_ENCODE);
+  xdrmem_create (&xdr, msg_out, 4, XDR_ENCODE);
   xdr_uint32_t (&xdr, &len);
 
-  if (guestfs__switch_to_sending (g) == -1)
-    goto cleanup1;
-
-  sent = 0;
-  guestfs_set_send_callback (g, send_cb, &sent);
-  if (ml->main_loop_run (ml, g) == -1)
-    goto cleanup1;
-  if (sent != 1) {
-    error (g, _("send failed, see earlier error messages"));
+ again:
+  r = send_to_daemon (g, msg_out, msg_out_size);
+  if (r == -2)                  /* Ignore stray daemon cancellations. */
+    goto again;
+  if (r == -1)
     goto cleanup1;
-  }
 
   return serial;
 
  cleanup1:
-  free (g->msg_out);
-  g->msg_out = NULL;
-  g->msg_out_size = 0;
+  free (msg_out);
   return -1;
 }
 
 static int cancel = 0; /* XXX Implement file cancellation. */
-static int send_file_chunk_sync (guestfs_h *g, int cancel, const char *buf, size_t len);
-static int send_file_data_sync (guestfs_h *g, const char *buf, size_t len);
-static int send_file_cancellation_sync (guestfs_h *g);
-static int send_file_complete_sync (guestfs_h *g);
+static int send_file_chunk (guestfs_h *g, int cancel, const char *buf, size_t len);
+static int send_file_data (guestfs_h *g, const char *buf, size_t len);
+static int send_file_cancellation (guestfs_h *g);
+static int send_file_complete (guestfs_h *g);
 
-/* Synchronously send a file.
+/* Send a file.
  * Returns:
  *   0 OK
  *   -1 error
  *   -2 daemon cancelled (we must read the error message)
  */
 int
-guestfs__send_file_sync (guestfs_h *g, const char *filename)
+guestfs___send_file (guestfs_h *g, const char *filename)
 {
   char buf[GUESTFS_MAX_CHUNK_SIZE];
   int fd, r, err;
@@ -2173,7 +2041,7 @@ guestfs__send_file_sync (guestfs_h *g, const char *filename)
   fd = open (filename, O_RDONLY);
   if (fd == -1) {
     perrorf (g, "open: %s", filename);
-    send_file_cancellation_sync (g);
+    send_file_cancellation (g);
     /* Daemon sees cancellation and won't reply, so caller can
      * just return here.
      */
@@ -2186,22 +2054,22 @@ guestfs__send_file_sync (guestfs_h *g, const char *filename)
     if (r == -1 && (errno == EINTR || errno == EAGAIN))
       continue;
     if (r <= 0) break;
-    err = send_file_data_sync (g, buf, r);
+    err = send_file_data (g, buf, r);
     if (err < 0) {
       if (err == -2)		/* daemon sent cancellation */
-        send_file_cancellation_sync (g);
+        send_file_cancellation (g);
       return err;
     }
   }
 
   if (cancel) {			/* cancel from either end */
-    send_file_cancellation_sync (g);
+    send_file_cancellation (g);
     return -1;
   }
 
   if (r == -1) {
     perrorf (g, "read: %s", filename);
-    send_file_cancellation_sync (g);
+    send_file_cancellation (g);
     return -1;
   }
 
@@ -2210,74 +2078,55 @@ guestfs__send_file_sync (guestfs_h *g, const char *filename)
    */
   if (close (fd) == -1) {
     perrorf (g, "close: %s", filename);
-    send_file_cancellation_sync (g);
+    send_file_cancellation (g);
     return -1;
   }
 
-  return send_file_complete_sync (g);
+  return send_file_complete (g);
 }
 
 /* Send a chunk of file data. */
 static int
-send_file_data_sync (guestfs_h *g, const char *buf, size_t len)
+send_file_data (guestfs_h *g, const char *buf, size_t len)
 {
-  return send_file_chunk_sync (g, 0, buf, len);
+  return send_file_chunk (g, 0, buf, len);
 }
 
 /* Send a cancellation message. */
 static int
-send_file_cancellation_sync (guestfs_h *g)
+send_file_cancellation (guestfs_h *g)
 {
-  return send_file_chunk_sync (g, 1, NULL, 0);
+  return send_file_chunk (g, 1, NULL, 0);
 }
 
 /* Send a file complete chunk. */
 static int
-send_file_complete_sync (guestfs_h *g)
+send_file_complete (guestfs_h *g)
 {
   char buf[1];
-  return send_file_chunk_sync (g, 0, buf, 0);
+  return send_file_chunk (g, 0, buf, 0);
 }
 
-/* Send a chunk, cancellation or end of file, synchronously (ie. wait
- * for it to go).
- */
-static int check_for_daemon_cancellation (guestfs_h *g);
-
 static int
-send_file_chunk_sync (guestfs_h *g, int cancel, const char *buf, size_t buflen)
+send_file_chunk (guestfs_h *g, int cancel, const char *buf, size_t buflen)
 {
   u_int32_t len;
-  int sent;
+  int r;
   guestfs_chunk chunk;
   XDR xdr;
-  guestfs_main_loop *ml = guestfs_get_main_loop (g);
+  char *msg_out;
+  size_t msg_out_size;
 
   if (g->state != BUSY) {
-    error (g, _("send_file_chunk_sync: state %d != READY"), g->state);
+    error (g, _("send_file_chunk: state %d != READY"), g->state);
     return -1;
   }
 
-  /* This is probably an internal error.  Or perhaps we should just
-   * free the buffer anyway?
-   */
-  if (g->msg_out != NULL) {
-    error (g, _("guestfs__send_sync: msg_out should be NULL"));
-    return -1;
-  }
-
-  /* Did the daemon send a cancellation message? */
-  if (check_for_daemon_cancellation (g)) {
-    if (g->verbose)
-      fprintf (stderr, "got daemon cancellation\n");
-    return -2;
-  }
-
   /* Allocate the chunk buffer.  Don't use the stack to avoid
    * excessive stack usage and unnecessary copies.
    */
-  g->msg_out = safe_malloc (g, GUESTFS_MAX_CHUNK_SIZE + 4 + 48);
-  xdrmem_create (&xdr, g->msg_out + 4, GUESTFS_MAX_CHUNK_SIZE + 48, XDR_ENCODE);
+  msg_out = safe_malloc (g, GUESTFS_MAX_CHUNK_SIZE + 4 + 48);
+  xdrmem_create (&xdr, msg_out + 4, GUESTFS_MAX_CHUNK_SIZE + 48, XDR_ENCODE);
 
   /* Serialize the chunk. */
   chunk.cancel = cancel;
@@ -2295,87 +2144,96 @@ send_file_chunk_sync (guestfs_h *g, int cancel, const char *buf, size_t buflen)
   xdr_destroy (&xdr);
 
   /* Reduce the size of the outgoing message buffer to the real length. */
-  g->msg_out = safe_realloc (g, g->msg_out, len + 4);
-  g->msg_out_size = len + 4;
-  g->msg_out_pos = 0;
+  msg_out = safe_realloc (g, msg_out, len + 4);
+  msg_out_size = len + 4;
 
-  xdrmem_create (&xdr, g->msg_out, 4, XDR_ENCODE);
+  xdrmem_create (&xdr, msg_out, 4, XDR_ENCODE);
   xdr_uint32_t (&xdr, &len);
 
-  if (guestfs__switch_to_sending (g) == -1)
-    goto cleanup1;
+  r = send_to_daemon (g, msg_out, msg_out_size);
 
-  sent = 0;
-  guestfs_set_send_callback (g, send_cb, &sent);
-  if (ml->main_loop_run (ml, g) == -1)
-    goto cleanup1;
-  if (sent != 1) {
-    error (g, _("send file chunk failed, see earlier error messages"));
-    goto cleanup1;
+  /* Did the daemon send a cancellation message? */
+  if (r == -2) {
+    if (g->verbose)
+      fprintf (stderr, "got daemon cancellation\n");
+    return -2;
   }
 
+  if (r == -1)
+    goto cleanup1;
+
   return 0;
 
  cleanup1:
-  free (g->msg_out);
-  g->msg_out = NULL;
-  g->msg_out_size = 0;
+  free (msg_out);
   return -1;
 }
 
-/* At this point we are sending FileIn file(s) to the guest, and not
- * expecting to read anything, so if we do read anything, it must be
- * a cancellation message.  This checks for this case without blocking.
- */
-static int
-check_for_daemon_cancellation (guestfs_h *g)
+/* Receive a reply. */
+int
+guestfs___recv (guestfs_h *g, const char *fn,
+                guestfs_message_header *hdr,
+                guestfs_message_error *err,
+                xdrproc_t xdrp, char *ret)
 {
-  fd_set rset;
-  struct timeval tv;
-  int r;
-  char buf[4];
-  uint32_t flag;
   XDR xdr;
+  void *buf;
+  uint32_t size;
+  int r;
 
-  FD_ZERO (&rset);
-  FD_SET (g->sock, &rset);
-  tv.tv_sec = 0;
-  tv.tv_usec = 0;
-  r = select (g->sock+1, &rset, NULL, NULL, &tv);
-  if (r == -1) {
-    perrorf (g, "select");
-    return 0;
-  }
-  if (r == 0)
-    return 0;
+ again:
+  r = recv_from_daemon (g, &size, &buf);
+  if (r == -1)
+    return -1;
 
-  /* Read the message from the daemon. */
-  r = xread (g->sock, buf, sizeof buf);
-  if (r == -1) {
-    perrorf (g, "read");
-    return 0;
+  /* This can happen if a cancellation happens right at the end
+   * of us sending a FileIn parameter to the daemon.  Discard.  The
+   * daemon should send us an error message next.
+   */
+  if (size == GUESTFS_CANCEL_FLAG)
+    goto again;
+
+  if (size == GUESTFS_LAUNCH_FLAG) {
+    error (g, "%s: received unexpected launch flag from daemon when expecting reply", fn);
+    return -1;
   }
 
-  xdrmem_create (&xdr, buf, sizeof buf, XDR_DECODE);
-  xdr_uint32_t (&xdr, &flag);
-  xdr_destroy (&xdr);
+  xdrmem_create (&xdr, buf, size, XDR_DECODE);
 
-  if (flag != GUESTFS_CANCEL_FLAG) {
-    error (g, _("check_for_daemon_cancellation: read 0x%x from daemon, expected 0x%x\n"),
-           flag, GUESTFS_CANCEL_FLAG);
-    return 0;
+  if (!xdr_guestfs_message_header (&xdr, hdr)) {
+    error (g, "%s: failed to parse reply header", fn);
+    xdr_destroy (&xdr);
+    free (buf);
+    return -1;
+  }
+  if (hdr->status == GUESTFS_STATUS_ERROR) {
+    if (!xdr_guestfs_message_error (&xdr, err)) {
+      error (g, "%s: failed to parse reply error", fn);
+      xdr_destroy (&xdr);
+      free (buf);
+      return -1;
+    }
+  } else {
+    if (xdrp && ret && !xdrp (&xdr, ret)) {
+      error (g, "%s: failed to parse reply", fn);
+      xdr_destroy (&xdr);
+      free (buf);
+      return -1;
+    }
   }
+  xdr_destroy (&xdr);
+  free (buf);
 
-  return 1;
+  return 0;
 }
 
-/* Synchronously receive a file. */
+/* Receive a file. */
 
-/* Returns -1 = error, 0 = EOF, 1 = more data */
-static int receive_file_data_sync (guestfs_h *g, void **buf, size_t *len);
+/* Returns -1 = error, 0 = EOF, > 0 = more data */
+static ssize_t receive_file_data (guestfs_h *g, void **buf);
 
 int
-guestfs__receive_file_sync (guestfs_h *g, const char *filename)
+guestfs___recv_file (guestfs_h *g, const char *filename)
 {
   void *buf;
   int fd, r;
@@ -2388,14 +2246,13 @@ guestfs__receive_file_sync (guestfs_h *g, const char *filename)
   }
 
   /* Receive the file in chunked encoding. */
-  while ((r = receive_file_data_sync (g, &buf, &len)) >= 0) {
-    if (xwrite (fd, buf, len) == -1) {
+  while ((r = receive_file_data (g, &buf)) > 0) {
+    if (xwrite (fd, buf, r) == -1) {
       perrorf (g, "%s: write", filename);
       free (buf);
       goto cancel;
     }
     free (buf);
-    if (r == 0) break; /* End of file. */
   }
 
   if (r == -1) {
@@ -2431,304 +2288,59 @@ guestfs__receive_file_sync (guestfs_h *g, const char *filename)
     return -1;
   }
 
-  while (receive_file_data_sync (g, NULL, NULL) > 0)
-    ;				/* just discard it */
+  while (receive_file_data (g, NULL) > 0)
+    ;                           /* just discard it */
 
   return -1;
 }
 
-/* Note that the reply callback can be called multiple times before
- * the main loop quits and we get back to the synchronous code.  So
- * we have to be prepared to save multiple chunks on a list here.
- */
-struct receive_file_ctx {
-  int count;			/* 0 if receive_file_cb not called, or
-                                 * else count number of chunks.
-                                 */
-  guestfs_chunk *chunks;	/* Array of chunks. */
-};
-
-static void
-free_chunks (struct receive_file_ctx *ctx)
-{
-  int i;
-
-  for (i = 0; i < ctx->count; ++i)
-    free (ctx->chunks[i].data.data_val);
-
-  free (ctx->chunks);
-}
-
-static void
-receive_file_cb (guestfs_h *g, void *data, XDR *xdr)
-{
-  guestfs_main_loop *ml = guestfs_get_main_loop (g);
-  struct receive_file_ctx *ctx = (struct receive_file_ctx *) data;
-  guestfs_chunk chunk;
-
-  if (ctx->count == -1)		/* Parse error occurred previously. */
-    return;
-
-  ml->main_loop_quit (ml, g);
-
-  memset (&chunk, 0, sizeof chunk);
-
-  if (!xdr_guestfs_chunk (xdr, &chunk)) {
-    error (g, _("failed to parse file chunk"));
-    free_chunks (ctx);
-    ctx->chunks = NULL;
-    ctx->count = -1;
-    return;
-  }
-
-  /* Copy the chunk to the list. */
-  ctx->chunks = safe_realloc (g, ctx->chunks,
-                              sizeof (guestfs_chunk) * (ctx->count+1));
-  ctx->chunks[ctx->count] = chunk;
-  ctx->count++;
-}
-
 /* Receive a chunk of file data. */
-/* Returns -1 = error, 0 = EOF, 1 = more data */
-static int
-receive_file_data_sync (guestfs_h *g, void **buf, size_t *len_r)
-{
-  struct receive_file_ctx ctx;
-  guestfs_main_loop *ml = guestfs_get_main_loop (g);
-  int i;
-  size_t len;
-
-  ctx.count = 0;
-  ctx.chunks = NULL;
-
-  guestfs_set_reply_callback (g, receive_file_cb, &ctx);
-  (void) ml->main_loop_run (ml, g);
-  guestfs_set_reply_callback (g, NULL, NULL);
-
-  if (ctx.count == 0) {
-    error (g, _("receive_file_data_sync: reply callback not called\n"));
-    return -1;
-  }
-
-  if (ctx.count == -1) {
-    error (g, _("receive_file_data_sync: parse error in reply callback\n"));
-    /* callback already freed the chunks */
-    return -1;
-  }
-
-  if (g->verbose)
-    fprintf (stderr, "receive_file_data_sync: got %d chunks\n", ctx.count);
-
-  /* Process each chunk in the list. */
-  if (buf) *buf = NULL;		/* Accumulate data in this buffer. */
-  len = 0;
-
-  for (i = 0; i < ctx.count; ++i) {
-    if (ctx.chunks[i].cancel) {
-      error (g, _("file receive cancelled by daemon"));
-      free_chunks (&ctx);
-      if (buf) free (*buf);
-      if (len_r) *len_r = 0;
-      return -1;
-    }
-
-    if (ctx.chunks[i].data.data_len == 0) { /* end of transfer */
-      free_chunks (&ctx);
-      if (len_r) *len_r = len;
-      return 0;
-    }
-
-    if (buf) {
-      *buf = safe_realloc (g, *buf, len + ctx.chunks[i].data.data_len);
-      memcpy (((char *)*buf)+len, ctx.chunks[i].data.data_val,
-              ctx.chunks[i].data.data_len);
-    }
-    len += ctx.chunks[i].data.data_len;
-  }
-
-  if (len_r) *len_r = len;
-  free_chunks (&ctx);
-  return 1;
-}
-
-/* This is the default main loop implementation, using select(2). */
-
-static int
-select_add_handle (guestfs_main_loop *mlv, guestfs_h *g, int fd, int events,
-                   guestfs_handle_event_cb cb, void *data)
+/* Returns -1 = error, 0 = EOF, > 0 = more data */
+static ssize_t
+receive_file_data (guestfs_h *g, void **buf_r)
 {
-  struct select_main_loop *ml = (struct select_main_loop *) mlv;
-
-  if (fd < 0 || fd >= FD_SETSIZE) {
-    error (g, _("fd %d is out of range"), fd);
-    return -1;
-  }
-
-  if ((events & ~(GUESTFS_HANDLE_READABLE |
-                  GUESTFS_HANDLE_WRITABLE |
-                  GUESTFS_HANDLE_HANGUP |
-                  GUESTFS_HANDLE_ERROR)) != 0) {
-    error (g, _("set of events (0x%x) contains unknown events"), events);
-    return -1;
-  }
-
-  if (events == 0) {
-    error (g, _("set of events is empty"));
-    return -1;
-  }
+  int r;
+  void *buf;
+  uint32_t len;
+  XDR xdr;
+  guestfs_chunk chunk;
 
-  if (FD_ISSET (fd, &ml->rset) ||
-      FD_ISSET (fd, &ml->wset) ||
-      FD_ISSET (fd, &ml->xset)) {
-    error (g, _("fd %d is already registered"), fd);
+  r = recv_from_daemon (g, &len, &buf);
+  if (r == -1) {
+    error (g, _("receive_file_data: parse error in reply callback"));
     return -1;
   }
 
-  if (cb == NULL) {
-    error (g, _("callback is NULL"));
+  if (len == GUESTFS_LAUNCH_FLAG || len == GUESTFS_CANCEL_FLAG) {
+    error (g, _("receive_file_data: unexpected flag received when reading file chunks"));
     return -1;
   }
 
-  if ((events & GUESTFS_HANDLE_READABLE))
-    FD_SET (fd, &ml->rset);
-  if ((events & GUESTFS_HANDLE_WRITABLE))
-    FD_SET (fd, &ml->wset);
-  if ((events & GUESTFS_HANDLE_HANGUP) || (events & GUESTFS_HANDLE_ERROR))
-    FD_SET (fd, &ml->xset);
-
-  if (fd > ml->max_fd) {
-    ml->max_fd = fd;
-    ml->handle_cb_data =
-      safe_realloc (g, ml->handle_cb_data,
-                    sizeof (struct select_handle_cb_data) * (ml->max_fd+1));
-  }
-  ml->handle_cb_data[fd].cb = cb;
-  ml->handle_cb_data[fd].g = g;
-  ml->handle_cb_data[fd].data = data;
-
-  ml->nr_fds++;
-
-  /* Any integer >= 0 can be the handle, and this is as good as any ... */
-  return fd;
-}
-
-static int
-select_remove_handle (guestfs_main_loop *mlv, guestfs_h *g, int fd)
-{
-  struct select_main_loop *ml = (struct select_main_loop *) mlv;
-
-  if (fd < 0 || fd >= FD_SETSIZE) {
-    error (g, _("fd %d is out of range"), fd);
-    return -1;
-  }
+  memset (&chunk, 0, sizeof chunk);
 
-  if (!FD_ISSET (fd, &ml->rset) &&
-      !FD_ISSET (fd, &ml->wset) &&
-      !FD_ISSET (fd, &ml->xset)) {
-    error (g, _("fd %d was not registered"), fd);
+  xdrmem_create (&xdr, buf, len, XDR_DECODE);
+  if (!xdr_guestfs_chunk (&xdr, &chunk)) {
+    error (g, _("failed to parse file chunk"));
+    free (buf);
     return -1;
   }
+  xdr_destroy (&xdr);
+  /* After decoding, the original buffer is no longer used. */
+  free (buf);
 
-  FD_CLR (fd, &ml->rset);
-  FD_CLR (fd, &ml->wset);
-  FD_CLR (fd, &ml->xset);
-
-  if (fd == ml->max_fd) {
-    ml->max_fd--;
-    ml->handle_cb_data =
-      safe_realloc (g, ml->handle_cb_data,
-                    sizeof (struct select_handle_cb_data) * (ml->max_fd+1));
-  }
-
-  ml->nr_fds--;
-
-  return 0;
-}
-
-static int
-__attribute__((noreturn))
-select_add_timeout (guestfs_main_loop *mlv, guestfs_h *g, int interval,
-                    guestfs_handle_timeout_cb cb, void *data)
-{
-  //struct select_main_loop *ml = (struct select_main_loop *) mlv;
-
-  abort ();			/* XXX not implemented yet */
-}
-
-static int
-__attribute__((noreturn))
-select_remove_timeout (guestfs_main_loop *mlv, guestfs_h *g, int timer)
-{
-  //struct select_main_loop *ml = (struct select_main_loop *) mlv;
-
-  abort ();			/* XXX not implemented yet */
-}
-
-/* The 'g' parameter is just used for error reporting.  Events
- * for multiple handles can be dispatched by running the main
- * loop.
- */
-static int
-select_main_loop_run (guestfs_main_loop *mlv, guestfs_h *g)
-{
-  struct select_main_loop *ml = (struct select_main_loop *) mlv;
-  int fd, r, events;
-  fd_set rset2, wset2, xset2;
-
-  if (ml->is_running) {
-    error (g, _("select_main_loop_run: this cannot be called recursively"));
+  if (chunk.cancel) {
+    error (g, _("file receive cancelled by daemon"));
+    free (chunk.data.data_val);
     return -1;
   }
 
-  ml->is_running = 1;
-
-  while (ml->is_running) {
-    if (ml->nr_fds == 0)
-      break;
-
-    rset2 = ml->rset;
-    wset2 = ml->wset;
-    xset2 = ml->xset;
-    r = select (ml->max_fd+1, &rset2, &wset2, &xset2, NULL);
-    if (r == -1) {
-      if (errno == EINTR || errno == EAGAIN)
-        continue;
-      perrorf (g, "select");
-      ml->is_running = 0;
-      return -1;
-    }
-
-    for (fd = 0; r > 0 && fd <= ml->max_fd; ++fd) {
-      events = 0;
-      if (FD_ISSET (fd, &rset2))
-        events |= GUESTFS_HANDLE_READABLE;
-      if (FD_ISSET (fd, &wset2))
-        events |= GUESTFS_HANDLE_WRITABLE;
-      if (FD_ISSET (fd, &xset2))
-        events |= GUESTFS_HANDLE_ERROR | GUESTFS_HANDLE_HANGUP;
-      if (events) {
-        r--;
-        ml->handle_cb_data[fd].cb ((guestfs_main_loop *) ml,
-                                   ml->handle_cb_data[fd].g,
-                                   ml->handle_cb_data[fd].data,
-                                   fd, fd, events);
-      }
-    }
+  if (chunk.data.data_len == 0) { /* end of transfer */
+    free (chunk.data.data_val);
+    return 0;
   }
 
-  ml->is_running = 0;
-  return 0;
-}
-
-static int
-select_main_loop_quit (guestfs_main_loop *mlv, guestfs_h *g)
-{
-  struct select_main_loop *ml = (struct select_main_loop *) mlv;
+  if (buf_r) *buf_r = chunk.data.data_val;
+  else free (chunk.data.data_val); /* else caller frees */
 
-  /* Note that legitimately ml->is_running can be zero when
-   * this function is called.
-   */
-
-  ml->is_running = 0;
-  return 0;
+  return chunk.data.data_len;
 }
diff --git a/src/guestfs.h b/src/guestfs.h
index 6412a53..35f995d 100644
--- a/src/guestfs.h
+++ b/src/guestfs.h
@@ -31,7 +31,6 @@ extern "C" {
 #endif
 
 typedef struct guestfs_h guestfs_h;
-typedef struct guestfs_main_loop guestfs_main_loop;
 
 /* Connection management. */
 extern guestfs_h *guestfs_create (void);
@@ -52,19 +51,18 @@ extern guestfs_abort_cb guestfs_get_out_of_memory_handler (guestfs_h *g);
 #include <guestfs-structs.h>
 #include <guestfs-actions.h>
 
-/* Low-level event API. */
-typedef void (*guestfs_send_cb) (guestfs_h *g, void *data);
-typedef void (*guestfs_reply_cb) (guestfs_h *g, void *data, XDR *xdr);
+/* Events. */
 typedef void (*guestfs_log_message_cb) (guestfs_h *g, void *data, char *buf, int len);
 typedef void (*guestfs_subprocess_quit_cb) (guestfs_h *g, void *data);
 typedef void (*guestfs_launch_done_cb) (guestfs_h *g, void *data);
 
-extern void guestfs_set_send_callback (guestfs_h *g, guestfs_send_cb cb, void *opaque);
-extern void guestfs_set_reply_callback (guestfs_h *g, guestfs_reply_cb cb, void *opaque);
 extern void guestfs_set_log_message_callback (guestfs_h *g, guestfs_log_message_cb cb, void *opaque);
 extern void guestfs_set_subprocess_quit_callback (guestfs_h *g, guestfs_subprocess_quit_cb cb, void *opaque);
 extern void guestfs_set_launch_done_callback (guestfs_h *g, guestfs_launch_done_cb cb, void *opaque);
 
+/* Private, for use only by the actions. */
+struct guestfs_message_header;
+struct guestfs_message_error;
 extern void guestfs_error (guestfs_h *g, const char *fs, ...)
   __attribute__((format (printf,2,3)));
 extern void guestfs_perrorf (guestfs_h *g, const char *fs, ...)
@@ -74,50 +72,12 @@ extern void *guestfs_safe_calloc (guestfs_h *g, size_t n, size_t s);
 extern void *guestfs_safe_realloc (guestfs_h *g, void *ptr, int nbytes);
 extern char *guestfs_safe_strdup (guestfs_h *g, const char *str);
 extern void *guestfs_safe_memdup (guestfs_h *g, void *ptr, size_t size);
-
-extern int guestfs__switch_to_sending (guestfs_h *g);
-extern int guestfs__switch_to_receiving (guestfs_h *g);
-
-/* These *_sync calls wait until the action is performed, using the
- * main loop.  We should implement asynchronous versions too.
- */
-extern int guestfs__send_sync (guestfs_h *g, int proc_nr, xdrproc_t xdrp, char *args);
-extern int guestfs__send_file_sync (guestfs_h *g, const char *filename);
-extern int guestfs__receive_file_sync (guestfs_h *g, const char *filename);
-
-/* Main loop. */
-#define GUESTFS_HANDLE_READABLE 0x1
-#define GUESTFS_HANDLE_WRITABLE 0x2
-#define GUESTFS_HANDLE_HANGUP   0x4
-#define GUESTFS_HANDLE_ERROR    0x8
-
-typedef void (*guestfs_handle_event_cb) (guestfs_main_loop *ml, guestfs_h *g, void *data, int watch, int fd, int events);
-typedef int (*guestfs_add_handle_cb) (guestfs_main_loop *ml, guestfs_h *g, int fd, int events, guestfs_handle_event_cb cb, void *data);
-typedef int (*guestfs_remove_handle_cb) (guestfs_main_loop *ml, guestfs_h *g, int watch);
-typedef void (*guestfs_handle_timeout_cb) (guestfs_main_loop *ml, guestfs_h *g, void *data, int timer);
-typedef int (*guestfs_add_timeout_cb) (guestfs_main_loop *ml, guestfs_h *g, int interval, guestfs_handle_timeout_cb cb, void *data);
-typedef int (*guestfs_remove_timeout_cb) (guestfs_main_loop *ml, guestfs_h *g, int timer);
-typedef int (*guestfs_main_loop_run_cb) (guestfs_main_loop *ml, guestfs_h *g);
-typedef int (*guestfs_main_loop_quit_cb) (guestfs_main_loop *ml, guestfs_h *g);
-
-/* This is the head of the main loop structure.  Concrete implementations
- * use additional private data after this struct.
- */
-struct guestfs_main_loop {
-  guestfs_add_handle_cb add_handle;
-  guestfs_remove_handle_cb remove_handle;
-  guestfs_add_timeout_cb add_timeout;
-  guestfs_remove_timeout_cb remove_timeout;
-  guestfs_main_loop_run_cb main_loop_run;
-  guestfs_main_loop_quit_cb main_loop_quit;
-};
-
-extern void guestfs_set_main_loop (guestfs_h *handle, guestfs_main_loop *main_loop);
-extern guestfs_main_loop *guestfs_get_main_loop (guestfs_h *handle);
-extern guestfs_main_loop *guestfs_get_default_main_loop (void);
-
-extern guestfs_main_loop *guestfs_create_main_loop (void);
-extern void guestfs_free_main_loop (guestfs_main_loop *);
+extern int guestfs___set_busy (guestfs_h *g);
+extern int guestfs___end_busy (guestfs_h *g);
+extern int guestfs___send (guestfs_h *g, int proc_nr, xdrproc_t xdrp, char *args);
+extern int guestfs___recv (guestfs_h *g, const char *fn, struct guestfs_message_header *hdr, struct guestfs_message_error *err, xdrproc_t xdrp, char *ret);
+extern int guestfs___send_file (guestfs_h *g, const char *filename);
+extern int guestfs___recv_file (guestfs_h *g, const char *filename);
 
 #ifdef __cplusplus
 }
-- 
1.6.2.5


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