[PATCH v3 02/14] libxl: sanitize error handling in libxl_get_max_{cpus, nodes}

[Dario Faggioli <dario.faggioli@citrix.com>]

as well as both error handling and logging in libxl_cpu_bitmap_alloc
and libxl_node_bitmap_alloc.

Now libxl_get_max_{cpus,nodes} either return a positive number, or
a libxl error code. Thanks to that, it is possible to fix loggig for
the two bitmap allocation functions, which now happens _inside_ the
functions themselves, and report what happens more accurately.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
---
Changes from v2:
 * this wasn't there in v2, but fixing this for v3 was requested
   during v2 review.
---
 tools/libxl/libxl.c       |    8 ++------
 tools/libxl/libxl_utils.c |   48 +++++++++++++++++++++++++++++++++++++++++++--
 tools/libxl/libxl_utils.h |   32 ++++++------------------------
 3 files changed, 54 insertions(+), 34 deletions(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 0de1112..d3ab65e 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -616,10 +616,8 @@ static int cpupool_info(libxl__gc *gc,
     info->n_dom = xcinfo->n_dom;
     rc = libxl_cpu_bitmap_alloc(CTX, &info->cpumap, 0);
     if (rc)
-    {
-        LOG(ERROR, "unable to allocate cpumap %d\n", rc);
         goto out;
-    }
+
     memcpy(info->cpumap.map, xcinfo->cpumap, info->cpumap.size);
 
     rc = 0;
@@ -4204,10 +4202,8 @@ libxl_vcpuinfo *libxl_list_vcpu(libxl_ctx *ctx, uint32_t domid,
     }
 
     for (*nb_vcpu = 0; *nb_vcpu <= domaininfo.max_vcpu_id; ++*nb_vcpu, ++ptr) {
-        if (libxl_cpu_bitmap_alloc(ctx, &ptr->cpumap, 0)) {
-            LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "allocating cpumap");
+        if (libxl_cpu_bitmap_alloc(ctx, &ptr->cpumap, 0))
             return NULL;
-        }
         if (xc_vcpu_getinfo(ctx->xch, domid, *nb_vcpu, &vcpuinfo) == -1) {
             LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "getting vcpu info");
             return NULL;
diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c
index 682f874..2a51c9c 100644
--- a/tools/libxl/libxl_utils.c
+++ b/tools/libxl/libxl_utils.c
@@ -645,6 +645,46 @@ char *libxl_bitmap_to_hex_string(libxl_ctx *ctx, const libxl_bitmap *bitmap)
     return q;
 }
 
+inline int libxl_cpu_bitmap_alloc(libxl_ctx *ctx,
+                                  libxl_bitmap *cpumap,
+                                  int max_cpus)
+{
+    if (max_cpus < 0)
+        return ERROR_INVAL;
+
+    if (max_cpus == 0)
+        max_cpus = libxl_get_max_cpus(ctx);
+
+    if (max_cpus <= 0) {
+        LIBXL__LOG(ctx, LIBXL__LOG_ERROR,
+                   "failed to retrieve the maximum number of cpus");
+        return ERROR_FAIL;
+    }
+
+    /* This can't fail: no need to check and log */
+    return libxl_bitmap_alloc(ctx, cpumap, max_cpus);
+}
+
+int libxl_node_bitmap_alloc(libxl_ctx *ctx,
+                            libxl_bitmap *nodemap,
+                            int max_nodes)
+{
+    if (max_nodes < 0)
+        return ERROR_INVAL;
+
+    if (max_nodes == 0)
+        max_nodes = libxl_get_max_nodes(ctx);
+
+    if (max_nodes <= 0) {
+        LIBXL__LOG(ctx, LIBXL__LOG_ERROR,
+                   "failed to retrieve the maximum number of nodes");
+        return ERROR_FAIL;
+    }
+
+    /* This can't fail: no need to check and log */
+    return libxl_bitmap_alloc(ctx, nodemap, max_nodes);
+}
+
 int libxl_nodemap_to_cpumap(libxl_ctx *ctx,
                             const libxl_bitmap *nodemap,
                             libxl_bitmap *cpumap)
@@ -713,12 +753,16 @@ int libxl_cpumap_to_nodemap(libxl_ctx *ctx,
 
 int libxl_get_max_cpus(libxl_ctx *ctx)
 {
-    return xc_get_max_cpus(ctx->xch);
+    int max_cpus = xc_get_max_cpus(ctx->xch);
+
+    return max_cpus <= 0 ? ERROR_FAIL : max_cpus;
 }
 
 int libxl_get_max_nodes(libxl_ctx *ctx)
 {
-    return xc_get_max_nodes(ctx->xch);
+    int max_nodes = xc_get_max_nodes(ctx->xch);
+
+    return max_nodes <= 0 ? ERROR_FAIL : max_nodes;
 }
 
 int libxl__enum_from_string(const libxl_enum_string_table *t,
diff --git a/tools/libxl/libxl_utils.h b/tools/libxl/libxl_utils.h
index 7b84e6a..b11cf28 100644
--- a/tools/libxl/libxl_utils.h
+++ b/tools/libxl/libxl_utils.h
@@ -98,32 +98,12 @@ static inline int libxl_bitmap_cpu_valid(libxl_bitmap *bitmap, int bit)
 #define libxl_for_each_set_bit(v, m) for (v = 0; v < (m).size * 8; v++) \
                                              if (libxl_bitmap_test(&(m), v))
 
-static inline int libxl_cpu_bitmap_alloc(libxl_ctx *ctx, libxl_bitmap *cpumap,
-                                         int max_cpus)
-{
-    if (max_cpus < 0)
-        return ERROR_INVAL;
-    if (max_cpus == 0)
-        max_cpus = libxl_get_max_cpus(ctx);
-    if (max_cpus == 0)
-        return ERROR_FAIL;
-
-    return libxl_bitmap_alloc(ctx, cpumap, max_cpus);
-}
-
-static inline int libxl_node_bitmap_alloc(libxl_ctx *ctx,
-                                          libxl_bitmap *nodemap,
-                                          int max_nodes)
-{
-    if (max_nodes < 0)
-        return ERROR_INVAL;
-    if (max_nodes == 0)
-        max_nodes = libxl_get_max_nodes(ctx);
-    if (max_nodes == 0)
-        return ERROR_FAIL;
-
-    return libxl_bitmap_alloc(ctx, nodemap, max_nodes);
-}
+int libxl_cpu_bitmap_alloc(libxl_ctx *ctx,
+                           libxl_bitmap *cpumap,
+                           int max_cpus);
+int libxl_node_bitmap_alloc(libxl_ctx *ctx,
+                            libxl_bitmap *nodemap,
+                            int max_nodes);
 
 /* Populate cpumap with the cpus spanned by the nodes in nodemap */
 int libxl_nodemap_to_cpumap(libxl_ctx *ctx,