[Xen-devel] [PATCH v3 1/5] libxl: introduce libxl__device_model_xs_path

[Wei Liu <wei.liu2@xxxxxxxxxx>]

Factor out libxl__vsprintf. Use it to implement
libxl__device_model_xs_patch helper to return xenstore path for device
model to avoid handcoded paths.

Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
Changes in v3:
1. Factor out libxl__vsprintf.
---
 tools/libxl/libxl_internal.c | 40 ++++++++++++++++++++++++++++++++++------
 tools/libxl/libxl_internal.h |  4 ++++
 2 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/tools/libxl/libxl_internal.c b/tools/libxl/libxl_internal.c
index ddc68ab..c2c67bd 100644
--- a/tools/libxl/libxl_internal.c
+++ b/tools/libxl/libxl_internal.c
@@ -127,21 +127,33 @@ void *libxl__realloc(libxl__gc *gc, void *ptr, size_t 
new_size)
     return new_ptr;
 }
 
-char *libxl__sprintf(libxl__gc *gc, const char *fmt, ...)
+char *libxl__vsprintf(libxl__gc *gc, const char *fmt, va_list ap)
 {
     char *s;
-    va_list ap;
+    va_list aq;
     int ret;
 
-    va_start(ap, fmt);
-    ret = vsnprintf(NULL, 0, fmt, ap);
-    va_end(ap);
+    va_copy(aq, ap);
+    ret = vsnprintf(NULL, 0, fmt, aq);
+    va_end(aq);
 
     assert(ret >= 0);
 
     s = libxl__zalloc(gc, ret + 1);
+    va_copy(aq, ap);
+    ret = vsnprintf(s, ret + 1, fmt, aq);
+    va_end(aq);
+
+    return s;
+}
+
+char *libxl__sprintf(libxl__gc *gc, const char *fmt, ...)
+{
+    char *s;
+    va_list ap;
+
     va_start(ap, fmt);
-    ret = vsnprintf(s, ret + 1, fmt, ap);
+    s = libxl__vsprintf(gc, fmt, ap);
     va_end(ap);
 
     return s;
@@ -555,6 +567,22 @@ void libxl__update_domain_configuration(libxl__gc *gc,
     dst->b_info.video_memkb = src->b_info.video_memkb;
 }
 
+char *libxl__device_model_xs_path(libxl__gc *gc, uint32_t dm_domid,
+                                  uint32_t domid, const char *format,  ...)
+{
+    char *s, *fmt;
+    va_list ap;
+
+    fmt = GCSPRINTF("/local/domain/%u/device-model/%u%s", dm_domid,
+                    domid, format);
+
+    va_start(ap, format);
+    s = libxl__vsprintf(gc, fmt, ap);
+    va_end(ap);
+
+    return s;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 934465a..2f952d4 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -521,6 +521,7 @@ _hidden void *libxl__realloc(libxl__gc *gc_opt, void *ptr, 
size_t new_size) NN1;
 /* print @fmt into an allocated string large enoughto contain the result.
  * (similar to gc'd asprintf(3)). */
 _hidden char *libxl__sprintf(libxl__gc *gc_opt, const char *fmt, ...) 
PRINTF_ATTRIBUTE(2, 3) NN1;
+_hidden char *libxl__vsprintf(libxl__gc *gc, const char *format, va_list ap);
 /* duplicate the string @c (similar to a gc'd strdup(3)). */
 _hidden char *libxl__strdup(libxl__gc *gc_opt, const char *c) NN1;
 /* duplicate at most @n bytes of string @c (similar to a gc'd strndup(3)). */
@@ -1794,6 +1795,9 @@ _hidden libxl__json_object *libxl__json_parse(libxl__gc 
*gc_opt, const char *s);
 _hidden int libxl__device_model_version_running(libxl__gc *gc, uint32_t domid);
   /* Return the system-wide default device model */
 _hidden libxl_device_model_version libxl__default_device_model(libxl__gc *gc);
+_hidden char *libxl__device_model_xs_path(libxl__gc *gc, uint32_t dm_domid,
+                                          uint32_t domid,
+                                          const char *format,  ...);
 
 /* Check how executes hotplug script currently */
 int libxl__hotplug_settings(libxl__gc *gc, xs_transaction_t t);
-- 
1.9.1


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