rework config management

* Add standard way to do str2val and val2str conversion
* Add support for a config file
* Add support for reading and writing settings via ioctl

src/from_string.cpp

@@ -0,0 +1,115 @@
+/*
+  ISC License
+
+  Copyright (c) 2019, Antonio SJ Musumeci <trapexit@spawn.link>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#include "ef.hpp"
+
+#include <string>
+
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+namespace str
+{
+  int
+  from(const std::string &value_,
+       bool              *bool_)
+  {
+    if((value_ == "true") ||
+       (value_ == "1")    ||
+       (value_ == "on")   ||
+       (value_ == "yes"))
+      *bool_ = true;
+    ef((value_ == "false") ||
+       (value_ == "0")     ||
+       (value_ == "off")   ||
+       (value_ == "no"))
+      *bool_ = false;
+    else
+      return -EINVAL;
+
+    return 0;
+  }
+
+  int
+  from(const std::string &value_,
+       int               *int_)
+  {
+    *int_ = ::strtol(value_.c_str(),NULL,10);
+
+    return 0;
+  }
+
+  int
+  from(const std::string &value_,
+       uint64_t          *uint64_)
+  {
+    char *endptr;
+    uint64_t tmp;
+
+    tmp = ::strtoll(value_.c_str(),&endptr,10);
+    switch(*endptr)
+      {
+      case 'k':
+      case 'K':
+        tmp *= 1024;
+        break;
+
+      case 'm':
+      case 'M':
+        tmp *= (1024 * 1024);
+        break;
+
+      case 'g':
+      case 'G':
+        tmp *= (1024 * 1024 * 1024);
+        break;
+
+      case 't':
+      case 'T':
+        tmp *= (1024ULL * 1024 * 1024 * 1024);
+        break;
+
+      case '\0':
+        break;
+
+      default:
+        return -EINVAL;
+      }
+
+    *uint64_ = tmp;
+
+    return 0;
+  }
+
+  int
+  from(const std::string &value_,
+       std::string       *str_)
+  {
+    *str_ = value_;
+
+    return 0;
+  }
+
+  int
+  from(const std::string &value_,
+       const std::string *key_)
+  {
+    return -EINVAL;
+  }
+}