librados, rados.py: add conf_parse_argv_remainder()

New parsing function to extract any known arguments from a vector
and return any unknowns; useful for ceph CLI to allow librados
first dibs on arguments so it doesn't have to reproduce the
argument recognition

Signed-off-by: Dan Mick <dan.mick@inktank.com>

src/include/rados/librados.h

@@ -298,6 +298,22 @@ int rados_conf_read_file(rados_t cluster, const char *path);
  */
 int rados_conf_parse_argv(rados_t cluster, int argc, const char **argv);
 
+
+/**
+ * Configure the cluster handle with command line arguments, returning
+ * any remainders.  Same rados_conf_parse_argv, except for extra
+ * remargv argument to hold returns unrecognized arguments.
+ *
+ * @pre rados_connect() has not been called on the cluster handle
+ *
+ * @param cluster cluster handle to configure
+ * @param argc number of arguments in argv
+ * @param argv arguments to parse
+ * @param remargv char* array for returned unrecognized arguments
+ * @returns 0 on success, negative error code on failure
+ */
+int rados_conf_parse_argv_remainder(rados_t cluster, int argc,
+				    const char **argv, const char **remargv);
 /**
  * Configure the cluster handle based on an environment variable
  *

src/include/rados/librados.hpp

@@ -655,6 +655,8 @@ namespace librados
     void shutdown();
     int conf_read_file(const char * const path) const;
     int conf_parse_argv(int argc, const char ** argv) const;
+    int conf_parse_argv_remainder(int argc, const char ** argv,
+				  const char ** remargv) const;
     int conf_parse_env(const char *env) const;
     int conf_set(const char *option, const char *value);
     int conf_get(const char *option, std::string &val);

src/librados/librados.cc

@@ -1244,6 +1244,12 @@ int librados::Rados::conf_parse_argv(int argc, const char ** argv) const
   return rados_conf_parse_argv((rados_t)client, argc, argv);
 }
 
+int librados::Rados::conf_parse_argv_remainder(int argc, const char ** argv,
+					       const char ** remargv) const
+{
+  return rados_conf_parse_argv_remainder((rados_t)client, argc, argv, remargv);
+}
+
 int librados::Rados::conf_parse_env(const char *name) const
 {
   return rados_conf_parse_env((rados_t)client, name);
@@ -1546,6 +1552,35 @@ extern "C" int rados_conf_parse_argv(rados_t cluster, int argc, const char **arg
   return 0;
 }
 
+// like above, but return the remainder of argv to contain remaining
+// unparsed args.  Must be allocated to at least argc by caller.
+// remargv will contain n <= argc pointers to original argv[], the end
+// of which may be NULL
+
+extern "C" int rados_conf_parse_argv_remainder(rados_t cluster, int argc,
+					       const char **argv,
+					       const char **remargv)
+{
+  librados::RadosClient *client = (librados::RadosClient *)cluster;
+  md_config_t *conf = client->cct->_conf;
+  vector<const char*> args;
+  for (int i=0; i<argc; i++)
+    args.push_back(argv[i]);
+  int ret = conf->parse_argv(args);
+  if (ret)
+    return ret;
+  conf->apply_changes(NULL);
+  assert(args.size() <= (unsigned int)argc);
+  unsigned int i;
+  for (i = 0; i < argc; ++i) {
+    if (i < args.size())
+      remargv[i] = args[i];
+    else
+      remargv[i] = (const char *)NULL;
+  }
+  return 0;
+}
+
 extern "C" int rados_conf_parse_env(rados_t cluster, const char *env)
 {
   librados::RadosClient *client = (librados::RadosClient *)cluster;

src/pybind/rados.py

@@ -252,6 +252,29 @@ Rados object in state %s." % (self.state))
         if (ret != 0):
             raise make_ex(ret, "error calling conf_read_file")
 
+    def conf_parse_argv(self, args):
+        """
+        Parse known arguments from args, and remove; returned
+        args contain only those unknown to ceph
+        """
+        self.require_state("configuring", "connected")
+        if not args:
+            return
+        # create instances of arrays of c_char_p's, both len(args) long
+        # cretargs will always be a subset of cargs (perhaps identical)
+        cargs = (c_char_p * len(args))(*args)
+        cretargs = (c_char_p * len(args))()
+        ret = run_in_thread(self.librados.rados_conf_parse_argv_remainder,
+                            (self.cluster, len(args), cargs, cretargs))
+        if ret:
+           raise make_ex("error calling conf_parse_argv_remainder")
+
+        # cretargs was allocated with fixed length; collapse return
+        # list to eliminate any missing args
+
+        retargs = [a for a in cretargs if a is not None]
+        return retargs
+
     def conf_get(self, option):
         """
         Get the value of a configuration option