Added os_version_minor sys variable

Ticket: ENT-8118
Changelog: Title
Signed-off-by: Victor Moene <victor.moene@northern.tech>

Author: victormlg

libenv/sysinfo.c

@@ -3771,6 +3771,58 @@ static void SysOsVersionMajor(EvalContext *ctx)
     free(flavor);
 }
 
+/*****************************************************************************/
+
+static const char *OSReleaseGet(EvalContext *ctx, const char *field)
+{
+    DataType type_out;
+    const JsonElement *os_rel = EvalContextVariableGetSpecial(
+        ctx, SPECIAL_SCOPE_SYS, "os_release", &type_out);
+
+    if (type_out != CF_DATA_TYPE_CONTAINER)
+    {
+        return NULL;
+    }
+    const JsonElement *child = JsonObjectGet(os_rel, field);
+    if (child == NULL)
+    {
+        return NULL;
+    }
+    const char *result = JsonPrimitiveGetAsString(child);
+    return result;
+}
+
+static void SysOSVersionMinor(EvalContext *ctx)
+{
+    const char *version_id = OSReleaseGet(ctx, "VERSION_ID");
+
+    char *minor;
+    if (version_id != NULL)
+    {
+        Item *version_tuple = SplitString(version_id, '.');
+
+        if (version_tuple != NULL && version_tuple->next != NULL)
+        {
+            minor = version_tuple->next->name;
+        }
+    }
+
+    if (NULL_OR_EMPTY(minor))
+    {
+        EvalContextVariablePutSpecial(ctx, SPECIAL_SCOPE_SYS,
+                                      "os_version_minor", "Unknown",
+                                      CF_DATA_TYPE_STRING, "source=agent");
+    }
+    else
+    {
+        EvalContextVariablePutSpecial(ctx, SPECIAL_SCOPE_SYS,
+                                      "os_version_minor", minor,
+                                      CF_DATA_TYPE_STRING,
+                                      "source=agent,derived-from=os_release");
+    }
+}
+
+
 /*****************************************************************************/
 
 void DetectEnvironment(EvalContext *ctx)
@@ -3785,4 +3837,5 @@ void DetectEnvironment(EvalContext *ctx)
     GetDefVars(ctx);
     SysOSNameHuman(ctx);
     SysOsVersionMajor(ctx);
+    SysOSVersionMinor(ctx);
 }