[Xen-devel] [RFC PATCH 2/6] libxl: stop using libxl__xs_mkdir() for ~/control/shutdown

[Paul Durrant <paul.durrant@xxxxxxxxxx>]

As documented in docs/misc/xenstore, the XS_MKDIR operation merely makes
sure a path exists whereas ~/control/shutdown needs to start empty. Also
using XS_MKDIR for a node which is never supposed to have children is
somewhat counterintuitive.

This patch introduces a new libxl__xs_printf_perms() function analogous
to libxl__xs_printf() but taking explicit permissions arguments, and then
uses this to create an empty ~/control/shutdown node.

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 tools/libxl/libxl_create.c   | 16 ++++++++++------
 tools/libxl/libxl_internal.h | 10 ++++++++++
 tools/libxl/libxl_xshelp.c   | 44 ++++++++++++++++++++++++++++++++++++++------
 3 files changed, 58 insertions(+), 12 deletions(-)

diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 921d155..279deda 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -484,7 +484,7 @@ int libxl__domain_make(libxl__gc *gc, libxl_domain_config 
*d_config,
     libxl_ctx *ctx = libxl__gc_owner(gc);
     int flags, ret, rc, nb_vm;
     char *uuid_string;
-    char *dom_path, *vm_path, *libxl_path;
+    char *dom_path, *vm_path, *libxl_path, *control_path;
     struct xs_permissions roperm[2];
     struct xs_permissions rwperm[1];
     struct xs_permissions noperm[1];
@@ -605,17 +605,21 @@ retry_transaction:
     libxl__xs_mkdir(gc, t,
                     libxl__sprintf(gc, "%s/device", dom_path),
                     roperm, ARRAY_SIZE(roperm));
-    libxl__xs_mkdir(gc, t,
-                    libxl__sprintf(gc, "%s/control", dom_path),
+
+    control_path = libxl__sprintf(gc, "%s/control", dom_path);
+
+    libxl__xs_mkdir(gc, t, control_path,
                     roperm, ARRAY_SIZE(roperm));
     if (info->type == LIBXL_DOMAIN_TYPE_HVM)
         libxl__xs_mkdir(gc, t,
                         libxl__sprintf(gc, "%s/hvmloader", dom_path),
                         roperm, ARRAY_SIZE(roperm));
 
-    libxl__xs_mkdir(gc, t,
-                    libxl__sprintf(gc, "%s/control/shutdown", dom_path),
-                    rwperm, ARRAY_SIZE(rwperm));
+    libxl__xs_printf_perms(gc, t,
+                           libxl__sprintf(gc, "%s/shutdown", control_path),
+                           rwperm, ARRAY_SIZE(rwperm),
+                           "");
+
     libxl__xs_mkdir(gc, t,
                     libxl__sprintf(gc, "%s/device/suspend/event-channel", 
dom_path),
                     rwperm, ARRAY_SIZE(rwperm));
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 4710804..04d8a29 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -666,6 +666,16 @@ _hidden int libxl__xs_writev_perms(libxl__gc *gc, 
xs_transaction_t t,
 _hidden int libxl__xs_writev_atonce(libxl__gc *gc,
                              const char *dir, char **kvs);
 
+_hidden int libxl__xs_vprintf_perms(libxl__gc *gc, xs_transaction_t t,
+                                    const char *path,
+                                    struct xs_permissions *perms,
+                                    unsigned int num_perms,
+                                    const char *fmt, va_list ap);
+_hidden int libxl__xs_printf_perms(libxl__gc *gc, xs_transaction_t t,
+                                   const char *path,
+                                   struct xs_permissions *perms,
+                                   unsigned int num_perms,
+                                   const char *fmt, ...) PRINTF_ATTRIBUTE(6, 
7);
 _hidden int libxl__xs_printf(libxl__gc *gc, xs_transaction_t t,
                              const char *path, const char *fmt, ...) 
PRINTF_ATTRIBUTE(4, 5);
    /* Each fn returns 0 on success.
diff --git a/tools/libxl/libxl_xshelp.c b/tools/libxl/libxl_xshelp.c
index 3cac4f2..0b56f8b 100644
--- a/tools/libxl/libxl_xshelp.c
+++ b/tools/libxl/libxl_xshelp.c
@@ -96,25 +96,57 @@ out:
 
 }
 
-int libxl__xs_printf(libxl__gc *gc, xs_transaction_t t,
-                     const char *path, const char *fmt, ...)
+int libxl__xs_vprintf_perms(libxl__gc *gc, xs_transaction_t t,
+                            const char *path,
+                            struct xs_permissions *perms,
+                            unsigned int num_perms,
+                            const char *fmt,
+                            va_list ap)
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
     char *s;
-    va_list ap;
     int ret;
-    va_start(ap, fmt);
-    ret = vasprintf(&s, fmt, ap);
-    va_end(ap);
 
+    ret = vasprintf(&s, fmt, ap);
     if (ret == -1) {
         return -1;
     }
     xs_write(ctx->xsh, t, path, s, ret);
+    if (perms)
+        xs_set_permissions(ctx->xsh, t, path, perms, num_perms);
     free(s);
     return 0;
 }
 
+int libxl__xs_printf_perms(libxl__gc *gc, xs_transaction_t t,
+                           const char *path,
+                           struct xs_permissions *perms,
+                           unsigned int num_perms,
+                           const char *fmt, ...)
+{
+    va_list ap;
+    int ret;
+
+    va_start(ap, fmt);
+    ret = libxl__xs_vprintf_perms(gc, t, path, perms, num_perms, fmt, ap);
+    va_end(ap);
+
+    return ret;
+}
+
+int libxl__xs_printf(libxl__gc *gc, xs_transaction_t t,
+                     const char *path, const char *fmt, ...)
+{
+    va_list ap;
+    int ret;
+
+    va_start(ap, fmt);
+    ret = libxl__xs_vprintf_perms(gc, t, path, NULL, 0, fmt, ap);
+    va_end(ap);
+
+    return ret;
+}
+
 char * libxl__xs_read(libxl__gc *gc, xs_transaction_t t, const char *path)
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
-- 
2.1.4


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