X-Git-Url: http://git.annexia.org/?p=libguestfs.git;a=blobdiff_plain;f=src%2Fguestfs.c;h=4dc8dec7c98c46f7eb338b270aa1fd18c400b54d;hp=47272f268bac33c4b73ac1d818d7a2687780be35;hb=5f8c46db05966a6e31b696d629fd3f74e4fb6c71;hpb=42a8baf3c9abc6f742671f37e9e24b607e5f9857

diff --git a/src/guestfs.c b/src/guestfs.c
index 47272f2..4dc8dec 100644
--- a/src/guestfs.c
+++ b/src/guestfs.c
@@ -29,7 +29,9 @@
 #include <string.h>
 #include <fcntl.h>
 #include <time.h>
+#include <sys/stat.h>
 #include <sys/select.h>
+
 #include <rpc/types.h>
 #include <rpc/xdr.h>
 
@@ -56,13 +58,6 @@
 #include "guestfs.h"
 #include "guestfs_protocol.h"
 
-void guestfs_error (guestfs_h *g, const char *fs, ...);
-void guestfs_perrorf (guestfs_h *g, const char *fs, ...);
-void *guestfs_safe_malloc (guestfs_h *g, size_t nbytes);
-void *guestfs_safe_realloc (guestfs_h *g, void *ptr, int nbytes);
-char *guestfs_safe_strdup (guestfs_h *g, const char *str);
-void *guestfs_safe_memdup (guestfs_h *g, void *ptr, size_t size);
-
 #define error guestfs_error
 #define perrorf guestfs_perrorf
 #define safe_malloc guestfs_safe_malloc
@@ -163,6 +158,7 @@ struct guestfs_h
   int autosync;
 
   const char *path;
+  const char *qemu;
 
   char *last_error;
 
@@ -224,7 +220,9 @@ guestfs_create (void)
 
   str = getenv ("LIBGUESTFS_PATH");
   g->path = str != NULL ? str : GUESTFS_DEFAULT_PATH;
-  /* XXX We should probably make QEMU configurable as well. */
+
+  str = getenv ("LIBGUESTFS_QEMU");
+  g->qemu = str != NULL ? str : QEMU;
 
   g->main_loop = guestfs_get_default_main_loop ();
 
@@ -416,6 +414,40 @@ guestfs_safe_memdup (guestfs_h *g, void *ptr, size_t size)
   return p;
 }
 
+static int
+xwrite (int fd, const void *buf, size_t len)
+{
+  int r;
+
+  while (len > 0) {
+    r = write (fd, buf, len);
+    if (r == -1)
+      return -1;
+
+    buf += r;
+    len -= r;
+  }
+
+  return 0;
+}
+
+static int
+xread (int fd, void *buf, size_t len)
+{
+  int r;
+
+  while (len > 0) {
+    r = read (fd, buf, len);
+    if (r == -1)
+      return -1;
+
+    buf += r;
+    len -= r;
+  }
+
+  return 0;
+}
+
 void
 guestfs_set_out_of_memory_handler (guestfs_h *g, guestfs_abort_cb cb)
 {
@@ -484,6 +516,22 @@ guestfs_get_path (guestfs_h *g)
   return g->path;
 }
 
+int
+guestfs_set_qemu (guestfs_h *g, const char *qemu)
+{
+  if (qemu == NULL)
+    g->qemu = QEMU;
+  else
+    g->qemu = qemu;
+  return 0;
+}
+
+const char *
+guestfs_get_qemu (guestfs_h *g)
+{
+  return g->qemu;
+}
+
 /* Add a string to the current command line. */
 static void
 incr_cmdline_size (guestfs_h *g)
@@ -586,7 +634,7 @@ int
 guestfs_launch (guestfs_h *g)
 {
   static const char *dir_template = "/tmp/libguestfsXXXXXX";
-  int r, i, len, pmore;
+  int r, i, len, pmore, memsize;
   int wfd[2], rfd[2];
   int tries;
   const char *kernel_name = "vmlinuz." REPO "." host_cpu;
@@ -595,6 +643,7 @@ guestfs_launch (guestfs_h *g)
   char *kernel = NULL, *initrd = NULL;
   char unixsock[256];
   struct sockaddr_un addr;
+  struct stat statbuf;
 
   /* Configured? */
   if (!g->cmdline) {
@@ -654,6 +703,40 @@ guestfs_launch (guestfs_h *g)
     goto cleanup0;
   }
 
+  /* Choose a suitable memory size (in MB).  This is more art
+   * than science, but you can help by doing
+   *   ./configure --enable-debug-command
+   * and then running:
+   *   debug sh free
+   *   debug mem ''
+   * and seeing how much free memory is left for particular
+   * configurations.
+   *
+   * It's also helpful to report both the compressed and uncompressed
+   * size of the initramfs (ls -lh initramfs*.img; du -sh initramfs).
+   *
+   * XXX KVM virtio balloon driver?
+   */
+  if (stat (initrd, &statbuf) != -1) {
+    /* Approximate size of the initramfs after it is decompressed
+     * in kernel memory.  The compression factor is ~2.5-3.
+     */
+    memsize = 3 * statbuf.st_size / 1024 / 1024;
+
+    /* Approximate size used by the kernel. */
+    memsize += 10;
+
+    /* Want to give userspace some room, so: */
+    memsize += 128;
+
+#if AC_SIZEOF_LONG == 8
+    /* On 64 bit, assume some overhead. */
+    memsize += 32;
+#endif
+  } else
+    memsize = 512;
+  
+
   /* Make the temporary directory containing the socket. */
   if (!g->tmpdir) {
     g->tmpdir = safe_strdup (g, dir_template);
@@ -684,11 +767,12 @@ guestfs_launch (guestfs_h *g)
   if (r == 0) {			/* Child (qemu). */
     char vmchannel[256];
     char append[256];
+    char memsize_str[256];
 
     /* Set up the full command line.  Do this in the subprocess so we
      * don't need to worry about cleaning up.
      */
-    g->cmdline[0] = (char *) QEMU;
+    g->cmdline[0] = (char *) g->qemu;
 
     /* Construct the -net channel parameter for qemu. */
     snprintf (vmchannel, sizeof vmchannel,
@@ -697,11 +781,17 @@ guestfs_launch (guestfs_h *g)
 
     /* Linux kernel command line. */
     snprintf (append, sizeof append,
-	      "console=ttyS0 guestfs=%s:%d", VMCHANNEL_ADDR, VMCHANNEL_PORT);
+	      "console=ttyS0 guestfs=%s:%d%s",
+	      VMCHANNEL_ADDR, VMCHANNEL_PORT,
+	      g->verbose ? " guestfs_verbose=1" : "");
+
+    snprintf (memsize_str, sizeof memsize_str, "%d", memsize);
 
     add_cmdline (g, "-m");
-    add_cmdline (g, "384");	  /* XXX Choose best size. */
+    add_cmdline (g, memsize_str);
+#if 0
     add_cmdline (g, "-no-kqemu"); /* Avoids a warning. */
+#endif
     add_cmdline (g, "-kernel");
     add_cmdline (g, (char *) kernel);
     add_cmdline (g, "-initrd");
@@ -716,12 +806,12 @@ guestfs_launch (guestfs_h *g)
     add_cmdline (g, "-net");
     add_cmdline (g, "user,vlan=0");
     add_cmdline (g, "-net");
-    add_cmdline (g, "nic,vlan=0");
+    add_cmdline (g, "nic,model=rtl8139,vlan=0");
     incr_cmdline_size (g);
     g->cmdline[g->cmdline_size-1] = NULL;
 
     if (g->verbose) {
-      fprintf (stderr, "%s", QEMU);
+      fprintf (stderr, "%s", g->qemu);
       for (i = 0; g->cmdline[i]; ++i)
 	fprintf (stderr, " %s", g->cmdline[i]);
       fprintf (stderr, "\n");
@@ -744,8 +834,8 @@ guestfs_launch (guestfs_h *g)
     setpgid (0, 0);
 #endif
 
-    execv (QEMU, g->cmdline);	/* Run qemu. */
-    perror (QEMU);
+    execv (g->qemu, g->cmdline); /* Run qemu. */
+    perror (g->qemu);
     _exit (1);
   }
 
@@ -963,6 +1053,28 @@ guestfs_get_state (guestfs_h *g)
   return g->state;
 }
 
+int
+guestfs_set_ready (guestfs_h *g)
+{
+  if (g->state != BUSY) {
+    error (g, "guestfs_set_ready: called when in state %d != BUSY", g->state);
+    return -1;
+  }
+  g->state = READY;
+  return 0;
+}
+
+int
+guestfs_set_busy (guestfs_h *g)
+{
+  if (g->state != READY) {
+    error (g, "guestfs_set_busy: called when in state %d != READY", g->state);
+    return -1;
+  }
+  g->state = BUSY;
+  return 0;
+}
+
 /* Structure-freeing functions.  These rely on the fact that the
  * structure format is identical to the XDR format.  See note in
  * generator.ml.
@@ -1101,6 +1213,7 @@ sock_read_event (struct guestfs_main_loop *ml, guestfs_h *g, void *data,
   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);
@@ -1113,7 +1226,7 @@ sock_read_event (struct guestfs_main_loop *ml, guestfs_h *g, void *data,
    * starts up it sends a "magic" value (longer than any possible
    * message).  Check for this.
    */
-  if (len == 0xf5f55ff5) {
+  if (len == GUESTFS_LAUNCH_FLAG) {
     if (g->state != LAUNCHING)
       error (g, "received magic signature from guestfsd, but in state %d",
 	     g->state);
@@ -1129,7 +1242,19 @@ sock_read_event (struct guestfs_main_loop *ml, guestfs_h *g, void *data,
     goto cleanup;
   }
 
-  /* If this happens, it's pretty bad and we've probably lost synchronization.*/
+  /* 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 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);
@@ -1138,14 +1263,6 @@ sock_read_event (struct guestfs_main_loop *ml, guestfs_h *g, void *data,
 
   if (g->msg_in_size-4 < len) return; /* Need more of this message. */
 
-  /* This should not happen, and if it does it probably means we've
-   * lost all hope of synchronization.
-   */
-  if (g->msg_in_size-4 > len) {
-    error (g, "len = %d, but msg_in_size-4 = %d", len, g->msg_in_size-4);
-    goto cleanup;
-  }
-
   /* Got the full message, begin processing it. */
   if (g->verbose) {
     int i, j;
@@ -1173,10 +1290,13 @@ sock_read_event (struct guestfs_main_loop *ml, guestfs_h *g, void *data,
     error (g, "state %d != BUSY", g->state);
 
   /* Push the message up to the higher layer. */
-  g->state = READY;
   if (g->reply_cb)
     g->reply_cb (g, g->reply_cb_data, &xdr);
 
+  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) {
@@ -1235,7 +1355,7 @@ sock_write_event (struct guestfs_main_loop *ml, guestfs_h *g, void *data,
     return;
 
   if (g->verbose)
-    fprintf (stderr, "sock_write_event: done writing, switching back to reading events\n");
+    fprintf (stderr, "sock_write_event: done writing, calling send_cb\n");
 
   free (g->msg_out);
   g->msg_out = NULL;
@@ -1305,22 +1425,83 @@ guestfs_get_default_main_loop (void)
   return (guestfs_main_loop *) &default_main_loop;
 }
 
-/* Dispatch a call (len + header + args) to the remote daemon.  This
- * function just queues the call in msg_out, to be sent when we next
- * enter the main loop.  Returns -1 for error, or the message serial
- * number.
+/* Change the daemon socket handler so that we are now writing.
+ * This sets the handle to sock_write_event.
  */
 int
-guestfs__send (guestfs_h *g, int proc_nr, xdrproc_t xdrp, char *args)
+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;
+    }
+  }
+
+  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;
+}
+
+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;
+    }
+  }
+
+  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;
+  }
+
+  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)
 {
   char buffer[GUESTFS_MESSAGE_MAX];
   struct guestfs_message_header hdr;
   XDR xdr;
   unsigned len;
   int serial = g->msg_next_serial++;
+  int sent;
+  guestfs_main_loop *ml = guestfs_get_main_loop (g);
 
-  if (g->state != READY) {
-    error (g, "dispatch: state %d != READY", g->state);
+  if (g->state != BUSY) {
+    error (g, "guestfs__send_sync: state %d != BUSY", g->state);
     return -1;
   }
 
@@ -1356,91 +1537,55 @@ guestfs__send (guestfs_h *g, int proc_nr, xdrproc_t xdrp, char *args)
 
   g->msg_out_size = len + 4;
   g->msg_out_pos = 0;
-  g->state = BUSY;
 
   xdrmem_create (&xdr, g->msg_out, 4, XDR_ENCODE);
-  if (!xdr_uint32_t (&xdr, &len)) {
-    error (g, "xdr_uint32_t failed in dispatch");
-    goto cleanup1;
-  }
+  xdr_uint32_t (&xdr, &len);
 
   memcpy (g->msg_out + 4, buffer, 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");
+    goto cleanup1;
+  }
+
   return serial;
 
  cleanup1:
   free (g->msg_out);
   g->msg_out = NULL;
   g->msg_out_size = 0;
-  g->state = READY;
   return -1;
 }
 
-/* Change the daemon socket handler so that we are now writing.
- * This sets the handle to sock_write_event.
+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);
+
+/* Synchronously send a file.
+ * Returns:
+ *   0 OK
+ *   -1 error
+ *   -2 daemon cancelled (we must read the error message)
  */
 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;
-    }
-  }
-
-  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;
-}
-
-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;
-    }
-  }
-
-  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;
-  }
-
-  return 0;
-}
-
-#if 0
-static int cancel = 0; /* XXX Implement file cancellation. */
-
-static int
-send_file (guestfs_h *g, const char *filename)
+guestfs__send_file_sync (guestfs_h *g, const char *filename)
 {
   char buf[GUESTFS_MAX_CHUNK_SIZE];
-  int fd, r;
+  int fd, r, err;
 
   fd = open (filename, O_RDONLY);
   if (fd == -1) {
     perrorf (g, "open: %s", filename);
-    send_file_cancellation (g);
+    send_file_cancellation_sync (g);
     /* Daemon sees cancellation and won't reply, so caller can
      * just return here.
      */
@@ -1449,18 +1594,22 @@ send_file (guestfs_h *g, const char *filename)
 
   /* Send file in chunked encoding. */
   while (!cancel && (r = read (fd, buf, sizeof buf)) > 0) {
-    if (send_file_data (g, buf, r) == -1)
-      return -1;
+    err = send_file_data_sync (g, buf, r);
+    if (err < 0) {
+      if (err == -2)		/* daemon sent cancellation */
+	send_file_cancellation_sync (g);
+      return err;
+    }
   }
 
-  if (cancel) {
-    send_file_cancellation (g);
+  if (cancel) {			/* cancel from either end */
+    send_file_cancellation_sync (g);
     return -1;
   }
 
   if (r == -1) {
     perrorf (g, "read: %s", filename);
-    send_file_cancellation (g);
+    send_file_cancellation_sync (g);
     return -1;
   }
 
@@ -1469,86 +1618,284 @@ send_file (guestfs_h *g, const char *filename)
    */
   if (close (fd) == -1) {
     perrorf (g, "close: %s", filename);
-    send_file_cancellation (g);
+    send_file_cancellation_sync (g);
     return -1;
   }
 
-  return send_file_complete (g);
+  return send_file_complete_sync (g);
 }
 
-/* Send a chunk, cancellation or end of file, wait for it to go. */
+/* Send a chunk of file data. */
 static int
-send_file_chunk (guestfs_h *g, int cancel, const char *buf, size_t len)
+send_file_data_sync (guestfs_h *g, const char *buf, size_t len)
 {
-  void *data;
+  return send_file_chunk_sync (g, 0, buf, len);
+}
+
+/* Send a cancellation message. */
+static int
+send_file_cancellation_sync (guestfs_h *g)
+{
+  return send_file_chunk_sync (g, 1, NULL, 0);
+}
+
+/* Send a file complete chunk. */
+static int
+send_file_complete_sync (guestfs_h *g)
+{
+  char buf[1];
+  return send_file_chunk_sync (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 len)
+{
+  char data[GUESTFS_MAX_CHUNK_SIZE + 48];
+  unsigned datalen;
+  int sent;
   guestfs_chunk chunk;
   XDR xdr;
+  guestfs_main_loop *ml = guestfs_get_main_loop (g);
 
   if (g->state != BUSY) {
-    error (g, "send_file_chunk: state %d != READY", g->state);
+    error (g, "send_file_chunk_sync: state %d != READY", g->state);
     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;
+  }
+
   /* Serialize the chunk. */
   chunk.cancel = cancel;
   chunk.data.data_len = len;
   chunk.data.data_val = (char *) buf;
 
-  data = safe_malloc (g, GUESTFS_MAX_CHUNK_SIZE + 48);
-  xdrmem_create (&xdr, data, GUESTFS_MAX_CHUNK_SIZE + 48, XDR_ENCODE);
-  if (xdr_guestfs_chunk (&xdr, &chunk)) {
-    error (g, "xdr_guestfs_chunk failed");
-    free (data);
+  if (g->verbose)
+    fprintf (stderr,
+	     "library sending chunk cancel = %d, len = %zu, buf = %p\n",
+	     cancel, len, buf);
+
+  xdrmem_create (&xdr, data, sizeof data, XDR_ENCODE);
+  if (!xdr_guestfs_chunk (&xdr, &chunk)) {
+    error (g, "xdr_guestfs_chunk failed (buf = %p, len = %zu)", buf, len);
+    xdr_destroy (&xdr);
     return -1;
   }
 
-  chunkdatalen = xdr_getpos (&xdr);
-  xdr_destroy (&xdr);
-
-  len = xdr_getpos (&xdr);
+  datalen = xdr_getpos (&xdr);
   xdr_destroy (&xdr);
 
-  data = safe_realloc (g, data, len);
-  g->msg_out = data;
-  g->msg_out_size = len;
+  /* Allocate outgoing message buffer. */
+  g->msg_out = safe_malloc (g, datalen + 4);
+  g->msg_out_size = datalen + 4;
   g->msg_out_pos = 0;
 
+  xdrmem_create (&xdr, g->msg_out, 4, XDR_ENCODE);
+  xdr_uint32_t (&xdr, &datalen);
+
+  memcpy (g->msg_out + 4, data, datalen);
+
   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 file chunk failed, see earlier error messages");
+    goto cleanup1;
+  }
+
   return 0;
 
  cleanup1:
   free (g->msg_out);
   g->msg_out = NULL;
   g->msg_out_size = 0;
-  g->state = READY;
   return -1;
 }
 
-/* Send a chunk of file data. */
+/* 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
-send_file_data (guestfs_h *g, const char *buf, size_t len)
+check_for_daemon_cancellation (guestfs_h *g)
+{
+  fd_set rset;
+  struct timeval tv;
+  int r;
+  char buf[4];
+  uint32_t flag;
+  XDR xdr;
+
+  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;
+
+  /* Read the message from the daemon. */
+  r = xread (g->sock, buf, sizeof buf);
+  if (r == -1) {
+    perrorf (g, "read");
+    return 0;
+  }
+
+  xdrmem_create (&xdr, buf, sizeof buf, XDR_DECODE);
+  xdr_uint32_t (&xdr, &flag);
+  xdr_destroy (&xdr);
+
+  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;
+  }
+
+  return 1;
+}
+
+/* Synchronously receive a file. */
+
+static int receive_file_data_sync (guestfs_h *g, void **buf);
+
+int
+guestfs__receive_file_sync (guestfs_h *g, const char *filename)
 {
-  return send_file_chunk (g, 0, buf, len);
+  void *buf;
+  int fd, r;
+
+  fd = open (filename, O_WRONLY|O_CREAT|O_TRUNC|O_NOCTTY, 0666);
+  if (fd == -1) {
+    perrorf (g, "open: %s", filename);
+    goto cancel;
+  }
+
+  /* Receive the file in chunked encoding. */
+  while ((r = receive_file_data_sync (g, &buf)) > 0) {
+    if (xwrite (fd, buf, r) == -1) {
+      perrorf (g, "%s: write", filename);
+      free (buf);
+      goto cancel;
+    }
+    free (buf);
+  }
+
+  if (r == -1) {
+    error (g, "%s: error in chunked encoding", filename);
+    return -1;
+  }
+
+  if (close (fd) == -1) {
+    perrorf (g, "close: %s", filename);
+    return -1;
+  }
+
+  return 0;
+
+ cancel: ;
+  /* Send cancellation message to daemon, then wait until it
+   * cancels (just throwing away data).
+   */
+  XDR xdr;
+  char fbuf[4];
+  uint32_t flag = GUESTFS_CANCEL_FLAG;
+
+  xdrmem_create (&xdr, fbuf, sizeof fbuf, XDR_ENCODE);
+  xdr_uint32_t (&xdr, &flag);
+  xdr_destroy (&xdr);
+
+  if (xwrite (g->sock, fbuf, sizeof fbuf) == -1) {
+    perrorf (g, "write to daemon socket");
+    return -1;
+  }
+
+  while ((r = receive_file_data_sync (g, &buf)) > 0)
+    free (buf);			/* just discard it */
+
+  return -1;
 }
 
-/* Send a cancellation message. */
-static int
-send_file_cancellation (guestfs_h *g)
+struct receive_file_ctx {
+  int code;
+  void **buf;
+};
+
+static void
+receive_file_cb (guestfs_h *g, void *data, XDR *xdr)
 {
-  char buf[1];
-  return send_file_chunk (g, 1, buf, 0);
+  guestfs_main_loop *ml = guestfs_get_main_loop (g);
+  struct receive_file_ctx *ctx = (struct receive_file_ctx *) data;
+  guestfs_chunk chunk;
+
+  ml->main_loop_quit (ml, g);
+
+  memset (&chunk, 0, sizeof chunk);
+
+  if (!xdr_guestfs_chunk (xdr, &chunk)) {
+    error (g, "failed to parse file chunk");
+    ctx->code = -1;
+    return;
+  }
+  if (chunk.cancel) {
+    error (g, "file receive cancelled by daemon");
+    ctx->code = -2;
+    return;
+  }
+  if (chunk.data.data_len == 0) { /* end of transfer */
+    ctx->code = 0;
+    return;
+  }
+
+  ctx->code = chunk.data.data_len;
+  *ctx->buf = chunk.data.data_val; /* caller frees */
 }
 
-/* Send a file complete chunk. */
+/* Receive a chunk of file data. */
 static int
-send_file_complete (guestfs_h *g)
+receive_file_data_sync (guestfs_h *g, void **buf)
 {
-  char buf[0];
-  return send_file_chunk (g, 0, buf, 0);
+  struct receive_file_ctx ctx;
+  guestfs_main_loop *ml = guestfs_get_main_loop (g);
+
+  ctx.code = -3;
+  ctx.buf = buf;
+
+  guestfs_set_reply_callback (g, receive_file_cb, &ctx);
+  (void) ml->main_loop_run (ml, g);
+  guestfs_set_reply_callback (g, NULL, NULL);
+
+  if (g->verbose)
+    fprintf (stderr, "receive_file_data_sync: code %d\n", ctx.code);
+
+  switch (ctx.code) {
+  case 0:			/* end of file */
+    return 0;
+  case -1: case -2:
+    return -1;
+  case -3:
+    error (g, "failed to call receive_file_cb");
+    return -1;
+  default:			/* received n bytes of data */
+    return ctx.code;
+  }
 }
-#endif
 
 /* This is the default main loop implementation, using select(2). */
 
@@ -1720,10 +2067,9 @@ select_main_loop_quit (guestfs_main_loop *mlv, guestfs_h *g)
 {
   struct select_main_loop *ml = (struct select_main_loop *) mlv;
 
-  if (!ml->is_running) {
-    error (g, "cannot quit, we are not running in a main loop");
-    return -1;
-  }
+  /* Note that legitimately ml->is_running can be zero when
+   * this function is called.
+   */
 
   ml->is_running = 0;
   return 0;