[PATCH v2 2/7] tools: Create xc_domain_getinfo_single()

[Alejandro Vallejo <alejandro.vallejo@cloud.com>]

It's a stricter version of xc_domain_getinfo() where the returned domid
always matches the requested domid or the error code shows an error instead.
A few patches ahead usages of xc_domain_getinfo() are removed until only
xc_domain_getinfo_single() and xc_domain_getinfolist() remain.

Signed-off-by: Alejandro Vallejo <alejandro.vallejo@cloud.com>
---
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Wei Liu <wl@xen.org>
Cc: Anthony PERARD <anthony.perard@citrix.com>
Cc: Juergen Gross <jgross@suse.com>
---
 tools/include/xenctrl.h     | 16 ++++++++++++++++
 tools/libs/ctrl/xc_domain.c | 23 +++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/tools/include/xenctrl.h b/tools/include/xenctrl.h
index f5bc7f58b6..685df1c7ba 100644
--- a/tools/include/xenctrl.h
+++ b/tools/include/xenctrl.h
@@ -703,6 +703,22 @@ int xc_vcpu_getaffinity(xc_interface *xch,
 int xc_domain_get_guest_width(xc_interface *xch, uint32_t domid,
                               unsigned int *guest_width);
 
+/**
+ * This function will return information about a single domain. It looks
+ * up the domain by the provided domid and succeeds if the domain exists
+ * and is accesible by the current domain, or fails otherwise. A buffer
+ * may optionally passed on the `info` parameter in order to retrieve
+ * information about the domain. The buffer is ignored if NULL is
+ * passed instead.
+ *
+ * @parm xch a handle to an open hypervisor interface
+ * @parm domid domid to lookup
+ * @parm info Optional domain information buffer (may be NULL)
+ * @return 0 on success, otherwise the call failed and info is undefined
+ */
+int xc_domain_getinfo_single(xc_interface *xch,
+                             uint32_t domid,
+                             xc_domaininfo_t *info);
 
 /**
  * This function will return information about one or more domains. It is
diff --git a/tools/libs/ctrl/xc_domain.c b/tools/libs/ctrl/xc_domain.c
index e939d07157..6b11775d4c 100644
--- a/tools/libs/ctrl/xc_domain.c
+++ b/tools/libs/ctrl/xc_domain.c
@@ -345,6 +345,29 @@ int xc_dom_vuart_init(xc_interface *xch,
     return rc;
 }
 
+int xc_domain_getinfo_single(xc_interface *xch,
+                             uint32_t domid,
+                             xc_domaininfo_t *info)
+{
+    struct xen_domctl domctl = {
+        .cmd = XEN_DOMCTL_getdomaininfo,
+        .domain = domid,
+    };
+
+    if ( do_domctl(xch, &domctl) < 0 )
+        return -1;
+
+    if ( domctl.u.getdomaininfo.domain != domid ) {
+        errno = ESRCH;
+        return -1;
+    }
+
+    if ( info )
+        *info = domctl.u.getdomaininfo;
+
+    return 0;
+}
+
 int xc_domain_getinfo(xc_interface *xch,
                       uint32_t first_domid,
                       unsigned int max_doms,
-- 
2.34.1