[Xen-devel] [PATCH 08 of 27 v3] libxl: do not read f.e. xenstore dir in disk list function

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxx>
# Date 1318941375 -3600
# Node ID 70dc8cd5ba46742671166a603937205746248901
# Parent  0bbe2abadf82cb1bd86e1d37b860bb212255964d
libxl: do not read f.e. xenstore dir in disk list function

Instead store a duplicate of the "device-type" node in the backend dir
and use that instead.

This maintains the invariant that the list function is always "safe".

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

diff -r 0bbe2abadf82 -r 70dc8cd5ba46 tools/libxl/libxl.c
--- a/tools/libxl/libxl.c       Tue Oct 18 10:35:56 2011 +0100
+++ b/tools/libxl/libxl.c       Tue Oct 18 13:36:15 2011 +0100
@@ -1018,6 +1018,8 @@ int libxl_device_disk_add(libxl_ctx *ctx
     flexarray_append(back, 
libxl__device_disk_string_of_backend(disk->backend));
     flexarray_append(back, "mode");
     flexarray_append(back, disk->readwrite ? "w" : "r");
+    flexarray_append(back, "device-type");
+    flexarray_append(back, disk->is_cdrom ? "cdrom" : "disk");
 
     flexarray_append(front, "backend-id");
     flexarray_append(front, libxl__sprintf(&gc, "%d", disk->backend_domid));
@@ -1512,7 +1514,6 @@ static void libxl__device_disk_from_xs_b
     libxl_ctx *ctx = libxl__gc_owner(gc);
     unsigned int len;
     char *tmp;
-    const char *fe_path; /* XXX unsafe */
 
     memset(disk, 0, sizeof(*disk));
 
@@ -1544,10 +1545,8 @@ static void libxl__device_disk_from_xs_b
     else
         disk->readwrite = 0;
 
-    fe_path = libxl__xs_read(gc, XBT_NULL,
-                             libxl__sprintf(gc, "%s/frontend", be_path));
     tmp = libxl__xs_read(gc, XBT_NULL,
-                         libxl__sprintf(gc, "%s/device-type", fe_path));
+                         libxl__sprintf(gc, "%s/device-type", be_path));
     disk->is_cdrom = !strcmp(tmp, "cdrom");
 
     disk->format = LIBXL_DISK_FORMAT_UNKNOWN;

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