[PATCH v2 3/3] xen-init-dom0: set Dom0 UUID if requested

[Wei Liu <wei.liu2@citrix.com>]

Read from XEN_CONFIG_DIR/dom0-uuid. If it contains a valid UUID, set
it for Dom0.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
v2:
1. add missing "goto out"
2. print file names more
3. also print errno in xc_interface_open error message
4. take care of short-read
---
 tools/examples/Makefile       |  1 +
 tools/examples/README         |  2 ++
 tools/examples/dom0-uuid      |  0
 tools/helpers/Makefile        |  3 +-
 tools/helpers/xen-init-dom0.c | 65 +++++++++++++++++++++++++++++++++++++++++--
 5 files changed, 67 insertions(+), 4 deletions(-)
 create mode 100644 tools/examples/dom0-uuid

diff --git a/tools/examples/Makefile b/tools/examples/Makefile
index f86ed3a271..f8492462db 100644
--- a/tools/examples/Makefile
+++ b/tools/examples/Makefile
@@ -9,6 +9,7 @@ XEN_CONFIGS += xlexample.hvm
 XEN_CONFIGS += xlexample.pvlinux
 XEN_CONFIGS += xl.conf
 XEN_CONFIGS += cpupool
+XEN_CONFIGS += dom0-uuid
 
 XEN_CONFIGS += $(XEN_CONFIGS-y)
 
diff --git a/tools/examples/README b/tools/examples/README
index 80a4652b06..8f940a55c1 100644
--- a/tools/examples/README
+++ b/tools/examples/README
@@ -14,6 +14,8 @@ block-common.sh     - sourced by block, block-*
 block-enbd          - binds/unbinds network block devices
 block-nbd           - binds/unbinds network block devices
 cpupool             - example configuration script for 'xl cpupool-create'
+dom0-uuid           - stores the UUID in canonical form for Dom0, will be
+                      read by xen-init-dom0
 external-device-migrate - called by xend for migrating external devices
 locking.sh          - locking functions to prevent concurrent access to
                       critical sections inside script files
diff --git a/tools/examples/dom0-uuid b/tools/examples/dom0-uuid
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/tools/helpers/Makefile b/tools/helpers/Makefile
index 4f3bbe6a7d..f759528322 100644
--- a/tools/helpers/Makefile
+++ b/tools/helpers/Makefile
@@ -14,6 +14,7 @@ XEN_INIT_DOM0_OBJS = xen-init-dom0.o init-dom-json.o
 $(XEN_INIT_DOM0_OBJS): CFLAGS += $(CFLAGS_libxentoollog)
 $(XEN_INIT_DOM0_OBJS): CFLAGS += $(CFLAGS_libxenstore)
 $(XEN_INIT_DOM0_OBJS): CFLAGS += $(CFLAGS_libxenlight)
+$(XEN_INIT_DOM0_OBJS): CFLAGS += $(CFLAGS_libxenctrl)
 
 INIT_XENSTORE_DOMAIN_OBJS = init-xenstore-domain.o init-dom-json.o
 $(INIT_XENSTORE_DOMAIN_OBJS): CFLAGS += $(CFLAGS_libxentoollog)
@@ -26,7 +27,7 @@ $(INIT_XENSTORE_DOMAIN_OBJS): CFLAGS += $(CFLAGS_libxenlight)
 all: $(PROGS)
 
 xen-init-dom0: $(XEN_INIT_DOM0_OBJS)
-	$(CC) $(LDFLAGS) -o $@ $(XEN_INIT_DOM0_OBJS) $(LDLIBS_libxentoollog) $(LDLIBS_libxenstore) $(LDLIBS_libxenlight) $(APPEND_LDFLAGS)
+	$(CC) $(LDFLAGS) -o $@ $(XEN_INIT_DOM0_OBJS) $(LDLIBS_libxenctrl) $(LDLIBS_libxentoollog) $(LDLIBS_libxenstore) $(LDLIBS_libxenlight) $(APPEND_LDFLAGS)
 
 $(INIT_XENSTORE_DOMAIN_OBJS): _paths.h
 
diff --git a/tools/helpers/xen-init-dom0.c b/tools/helpers/xen-init-dom0.c
index 09bc0027f9..e826da57b4 100644
--- a/tools/helpers/xen-init-dom0.c
+++ b/tools/helpers/xen-init-dom0.c
@@ -3,23 +3,72 @@
 #include <string.h>
 #include <stdio.h>
 
+#include <xenctrl.h>
 #include <xenstore.h>
+#include <libxl.h>
 
 #include "init-dom-json.h"
+#include "_paths.h"
 
 #define DOMNAME_PATH   "/local/domain/0/name"
 #define DOMID_PATH     "/local/domain/0/domid"
 
+#define DOM0_UUID_PATH XEN_CONFIG_DIR "/dom0-uuid"
+
+static void get_dom0_uuid(libxl_uuid *uuid)
+{
+    FILE *f = NULL;
+    size_t r;
+    char uuid_buf[LIBXL_UUID_FMTLEN+1];
+    bool ok = false;
+
+    f = fopen(DOM0_UUID_PATH, "r");
+    if (!f) {
+        fprintf(stderr, "failed to open %s, errno %d\n",
+                DOM0_UUID_PATH, errno);
+        goto out;
+    }
+
+    r = fread(uuid_buf, 1, LIBXL_UUID_FMTLEN, f);
+    if (r != LIBXL_UUID_FMTLEN) {
+        fprintf(stderr, "failed to read %s, read %zu, errno %d\n",
+                DOM0_UUID_PATH, r, ferror(f));
+        goto out;
+    }
+
+    uuid_buf[LIBXL_UUID_FMTLEN] = 0;
+
+    if (libxl_uuid_from_string(uuid, uuid_buf)) {
+        fprintf(stderr, "failed to parse UUID in %s\n", DOM0_UUID_PATH);
+        goto out;
+    }
+
+    ok = true;
+out:
+    if (f) fclose(f);
+    if (!ok) libxl_uuid_clear(uuid);
+}
+
 int main(int argc, char **argv)
 {
     int rc;
-    struct xs_handle *xsh;
+    struct xs_handle *xsh = NULL;
+    xc_interface *xch = NULL;
     char *domname_string = NULL, *domid_string = NULL;
+    libxl_uuid uuid;
 
     xsh = xs_open(0);
     if (!xsh) {
         fprintf(stderr, "cannot open xenstore connection\n");
-        exit(1);
+        rc = 1;
+        goto out;
+    }
+
+    xch = xc_interface_open(NULL, NULL, 0);
+    if (!xch) {
+        fprintf(stderr, "xc_interface_open() failed\n");
+        rc = 1;
+        goto out;
     }
 
     /* Sanity check: this program can only be run once. */
@@ -31,7 +80,16 @@ int main(int argc, char **argv)
         goto out;
     }
 
-    rc = gen_stub_json_config(0, NULL);
+    get_dom0_uuid(&uuid);
+
+    if (!libxl_uuid_is_nil(&uuid) &&
+        xc_domain_sethandle(xch, 0, libxl_uuid_bytearray(&uuid))) {
+        fprintf(stderr, "failed to set Dom0 UUID, errno %d\n", errno);
+        rc = 1;
+        goto out;
+    }
+
+    rc = gen_stub_json_config(0, &uuid);
     if (rc)
         goto out;
 
@@ -55,6 +113,7 @@ out:
     free(domid_string);
     free(domname_string);
     xs_close(xsh);
+    xc_interface_close(xch);
     return rc;
 }
 
-- 
2.11.0


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