Add Glib::Environ and tests/glibmm_environ

Fixes #89

4 files changed, 154 insertions, 0 deletions

diff --git a/glib/glibmm/environ.cc b/glib/glibmm/environ.cc
new file mode 100755
index 00000000..4586ef58
--- /dev/null
+++ b/glib/glibmm/environ.cc
@@ -0,0 +1,58 @@
+/* Copyright (C) 2021 The glibmm Development Team
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <glibmm/environ.h>
+#include <glibmm/vectorutils.h>
+
+namespace Glib
+{
+
+Environ::Environ()
+: envp(g_get_environ(), &g_strfreev)
+{}
+
+Environ::Environ(const std::vector<std::string>& env_vec)
+: envp(g_new(char*, env_vec.size() + 1), &g_strfreev)
+{
+  for (unsigned int i = 0; i < env_vec.size(); ++i)
+    envp.get()[i] = g_strdup(env_vec[i].c_str());
+  envp.get()[env_vec.size()] = nullptr;
+}
+
+std::optional<std::string> Environ::get(StdStringView variable) const
+{
+  const char* value = g_environ_getenv(envp.get(), variable.c_str());
+  if (value)
+    return std::optional<std::string>(std::in_place, value);
+  return std::optional<std::string>();
+}
+
+void Environ::set(StdStringView variable, StdStringView value, bool overwrite)
+{
+  envp.reset(g_environ_setenv(envp.release(), variable.c_str(), value.c_str(), overwrite));
+}
+
+void Environ::unset(StdStringView variable)
+{
+  envp.reset(g_environ_unsetenv(envp.release(), variable.c_str()));
+}
+
+std::vector<std::string> Environ::to_vector() const
+{
+  return Glib::ArrayHandler<std::string>::array_to_vector(envp.get(), Glib::OWNERSHIP_NONE);
+}
+
+} // namespace Glib
diff --git a/glib/glibmm/environ.h b/glib/glibmm/environ.h
new file mode 100755
index 00000000..238ef532
--- /dev/null
+++ b/glib/glibmm/environ.h
@@ -0,0 +1,93 @@
+#ifndef _GLIBMM_ENVIRON_H
+#define _GLIBMM_ENVIRON_H
+/* Copyright (C) 2021 The glibmm Development Team
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <glibmm/ustring.h>
+#include <memory>
+#include <optional>
+#include <string>
+#include <vector>
+
+namespace Glib
+{
+
+/** A convenience class for manipulating a copy of the environment variables.
+ *
+ * Useful for generating the @a envp parameter in calls to
+ * Glib::spawn_async_with_pipes(), Glib::spawn_async() and Glib::spawn_sync().
+ *
+ * If you want to change the environment itself (i.e. not a copy of it),
+ * see Glib::getenv(), Glib::setenv() and Glib::unsetenv().
+ *
+ * @newin{2,70}
+ */
+class Environ
+{
+public:
+  /** Constructs a list of environment variables for the current process.
+   *
+   * Each item in the list is of the form 'NAME=VALUE'.
+   */
+  GLIBMM_API Environ();
+
+  /** Constructs a %Glib::Environ instance from a vector.
+   *
+   * @param env_vec A vector with the environment variables. Each element in
+   *                the vector must be of the form 'NAME=VALUE'.
+   */
+  GLIBMM_API explicit Environ(const std::vector<std::string>& env_vec);
+
+  /** Gets the value of the environment variable @a variable.
+   *
+   * @param variable The environment variable to get, must not contain '='.
+   * @return The value of the environment variable, or an empty std::optional
+   *         if the environment variable is not set in this %Environ.
+   */
+  GLIBMM_API std::optional<std::string> get(StdStringView variable) const;
+
+  /// Same as get().
+  GLIBMM_API std::optional<std::string> operator[](StdStringView variable) const
+  { return get(variable); }
+
+  /** Sets the environment variable @a variable in the provided list to @a value.
+   *
+   * @param variable The environment variable to set, must not contain '='.
+   * @param value The value to set the variable to.
+   * @param overwrite Whether to change the variable if it already exists.
+   */
+  GLIBMM_API void set(StdStringView variable, StdStringView value, bool overwrite = true);
+
+  /** Removes the environment variable @a variable from the provided list.
+   *
+   * @param variable The environment variable to remove, must not contain '='.
+   */
+  GLIBMM_API void unset(StdStringView variable);
+
+  /** Get a vector with the environment variables.
+   *
+   * @return A vector with the environment variables. Each element in the vector
+   *         is of the form 'NAME=VALUE'.
+   */
+  GLIBMM_API std::vector<std::string> to_vector() const;
+
+private:
+  std::unique_ptr<char*, decltype(&g_strfreev)> envp;
+};
+
+} // namespace Glib
+
+#endif /* _GLIBMM_ENVIRON_H */
diff --git a/glib/glibmm/filelist.am b/glib/glibmm/filelist.am
index e606d5fd..6bd16f1c 100644
--- a/glib/glibmm/filelist.am
+++ b/glib/glibmm/filelist.am
@@ -8,6 +8,7 @@ glibmm_files_extra_cc =			\
 	class.cc			\
 	debug.cc			\
 	dispatcher.cc			\
+	environ.cc		\
 	error.cc			\
 	exceptionhandler.cc		\
 	extraclassinit.cc		\
@@ -40,6 +41,7 @@ glibmm_files_extra_h =			\
 	containerhandle_shared.h	\
 	debug.h				\
 	dispatcher.h			\
+	environ.h		\
 	error.h				\
 	exceptionhandler.h		\
 	extraclassinit.h		\
diff --git a/glib/glibmm/meson.build b/glib/glibmm/meson.build
index b736a3cf..29f55bdd 100644
--- a/glib/glibmm/meson.build
+++ b/glib/glibmm/meson.build
@@ -76,6 +76,7 @@ glibmm_extra_h_cc_basenames = [
   'class',
   'debug',
   'dispatcher',
+  'environ',
   'error',
   'exceptionhandler',
   'extraclassinit',