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From 35a740847bea0a2aede72de7b2b8b49eef36e4eb Mon Sep 17 00:00:00 2001
From: Ian Jackson <ian.jackson@eu.citrix.com>
Date: Wed, 27 Apr 2016 16:34:19 +0100
Subject: [PATCH 02/10] libxl: Provide libxl__backendpath_parse_domid
Multiple places in libxl need to figure out the backend domid of a
device. This can be discovered easily by looking at the backend path,
which always starts /local/domain/$backend_domid/.
There are no call sites yet.
This is part of XSA-175.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
---
tools/libxl/libxl_device.c | 15 +++++++++++++++
tools/libxl/libxl_internal.h | 2 ++
2 files changed, 17 insertions(+)
diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index e9d2424..b500264 100644
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -270,6 +270,21 @@ static int disk_try_backend(disk_try_backend_args *a,
return 0;
}
+int libxl__backendpath_parse_domid(libxl__gc *gc, const char *be_path,
+ libxl_domid *domid_out) {
+ int r;
+ unsigned int domid_sc;
+ char delim_sc;
+
+ r = sscanf(be_path, "/local/domain/%u%c", &domid_sc, &delim_sc);
+ if (!(r==2 && delim_sc=='/')) {
+ LOG(ERROR, "internal error: backend path %s unparseable!", be_path);
+ return ERROR_FAIL;
+ }
+ *domid_out = domid_sc;
+ return 0;
+}
+
int libxl__device_disk_set_backend(libxl__gc *gc, libxl_device_disk *disk) {
libxl_disk_backend ok;
disk_try_backend_args a;
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 801e95d..3fc9997 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -574,6 +574,8 @@ _hidden bool libxl__xs_mkdir(libxl__gc *gc, xs_transaction_t t,
_hidden char *libxl__xs_libxl_path(libxl__gc *gc, uint32_t domid);
+_hidden int libxl__backendpath_parse_domid(libxl__gc *gc, const char *be_path,
+ libxl_domid *domid_out);
/*----- "checked" xenstore access functions -----*/
/* Each of these functions will check that it succeeded; if it
--
2.1.4
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