1 files changed, 108 insertions, 0 deletions
diff --git a/src/nvim/os/stdpaths.c b/src/nvim/os/stdpaths.c
new file mode 100644
index 0000000000..ce374828f9
--- /dev/null
+++ b/src/nvim/os/stdpaths.c
@@ -0,0 +1,108 @@
+#include <stdbool.h>
+
+#include "nvim/os/stdpaths_defs.h"
+#include "nvim/os/os.h"
+#include "nvim/path.h"
+#include "nvim/memory.h"
+#include "nvim/ascii.h"
+
+/// Names of the environment variables, mapped to XDGVarType values
+static const char *xdg_env_vars[] = {
+  [kXDGConfigHome] = "XDG_CONFIG_HOME",
+  [kXDGDataHome] = "XDG_DATA_HOME",
+  [kXDGCacheHome] = "XDG_CACHE_HOME",
+  [kXDGRuntimeDir] = "XDG_RUNTIME_DIR",
+  [kXDGConfigDirs] = "XDG_CONFIG_DIRS",
+  [kXDGDataDirs] = "XDG_DATA_DIRS",
+};
+
+/// Defaults for XDGVarType values
+///
+/// Used in case environment variables contain nothing. Need to be expanded.
+static const char *const xdg_defaults[] = {
+#ifdef WIN32
+  // Windows
+  [kXDGConfigHome] = "$LOCALAPPDATA\\nvim\\config",
+  [kXDGDataHome]   = "$LOCALAPPDATA\\nvim\\data",
+  [kXDGCacheHome]  = "$LOCALAPPDATA\\nvim\\cache",
+  [kXDGRuntimeDir] = "",
+  [kXDGConfigDirs] = NULL,
+  [kXDGDataDirs] = NULL,
+#else
+  // Linux, BSD, CYGWIN, Apple
+  [kXDGConfigHome] = "~/.config",
+  [kXDGDataHome] = "~/.local/share",
+  [kXDGCacheHome] = "~/.cache",
+  [kXDGRuntimeDir] = "",
+  [kXDGConfigDirs] = "/etc/xdg/",
+  [kXDGDataDirs] = "/usr/local/share/:/usr/share/",
+#endif
+};
+
+/// Return XDG variable value
+///
+/// @param[in]  idx  XDG variable to use.
+///
+/// @return [allocated] variable value.
+char *stdpaths_get_xdg_var(const XDGVarType idx)
+  FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  const char *const env = xdg_env_vars[idx];
+  const char *const fallback = xdg_defaults[idx];
+
+  const char *const env_val = os_getenv(env);
+  char *ret = NULL;
+  if (env_val != NULL) {
+    ret = xstrdup(env_val);
+  } else if (fallback) {
+    ret = (char *) expand_env_save((char_u *)fallback);
+  }
+
+  return ret;
+}
+
+/// Return nvim-specific XDG directory subpath
+///
+/// @param[in]  idx  XDG directory to use.
+///
+/// @return [allocated] `{xdg_directory}/nvim`
+static char *get_xdg_home(const XDGVarType idx)
+  FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  char *dir = stdpaths_get_xdg_var(idx);
+  if (dir) {
+    dir = concat_fnames_realloc(dir, "nvim", true);
+  }
+  return dir;
+}
+
+/// Return subpath of $XDG_CONFIG_HOME
+///
+/// @param[in]  fname  New component of the path.
+///
+/// @return [allocated] `$XDG_CONFIG_HOME/nvim/{fname}`
+char *stdpaths_user_conf_subpath(const char *fname)
+  FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL
+{
+  return concat_fnames_realloc(get_xdg_home(kXDGConfigHome), fname, true);
+}
+
+/// Return subpath of $XDG_DATA_HOME
+///
+/// @param[in]  fname  New component of the path.
+/// @param[in]  trailing_pathseps  Amount of trailing path separators to add.
+///
+/// @return [allocated] `$XDG_DATA_HOME/nvim/{fname}`
+char *stdpaths_user_data_subpath(const char *fname,
+                                 const size_t trailing_pathseps)
+  FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL
+{
+  char *ret = concat_fnames_realloc(get_xdg_home(kXDGDataHome), fname, true);
+  if (trailing_pathseps) {
+    const size_t len = strlen(ret);
+    ret = xrealloc(ret, len + trailing_pathseps + 1);
+    memset(ret + len, PATHSEP, trailing_pathseps);
+    ret[len + trailing_pathseps] = NUL;
+  }
+  return ret;
+}