feat: $NVIM_APPNAME #22128

This commit implements the ability to control all of the XDG paths
Neovim should use. This is done by setting an environment variable named
NVIM_APPNAME. For example, setting $NVIM_APPNAME makes Neovim look for
its configuration directory in $XDG_CONFIG_HOME/$NVIM_APPNAME instead of
$XDG_CONFIG_HOME/nvim.

If NVIM_APPNAME is not set or is an empty string, "nvim" will be used as
default.

The usecase for this feature is to enable an easy way to switch from
configuration to configuration. One might argue that the various $XDG
environment variables can already be used for this usecase. However,
setting $XDG environment variables also affects tools spawned by Neovim.
For example, while setting $XDG_CONFIG_HOME will enable Neovim to use a
different configuration directory, it will also prevent Git from finding
its "default" configuration.

Closes https://github.com/neovim/neovim/issues/21691

runtime/doc/news.txt

@@ -55,6 +55,10 @@ NEW FEATURES                                                    *news-features*
 
 The following new APIs or features were added.
 
+• A new environment variable named NVIM_APPNAME enables configuring the
+  directories where Neovim should find its configuration and state files. See
+  `:help $NVIM_APPNAME` .
+
 • |nvim_open_win()| now accepts a relative `mouse` option to open a floating win
   relative to the mouse. Note that the mouse doesn't update frequently without
   setting `vim.o.mousemoveevent = true`

runtime/doc/starting.txt

@@ -1385,6 +1385,18 @@ STATE DIRECTORY (DEFAULT) ~
 Note: Throughout the user manual these defaults are used as placeholders, e.g.
 "~/.config" is understood to mean "$XDG_CONFIG_HOME or ~/.config".
 
+NVIM_APPNAME					*$NVIM_APPNAME*
+The XDG directories used by Nvim can be further configured by setting the
+`$NVIM_APPNAME` environment variable. This variable controls the directory
+Neovim will look for (and auto-create) in the various XDG parent directories.
+For example, setting `$NVIM_APPNAME` to "neovim" before running Neovim will
+result in Neovim looking for configuration files in `$XDG_CONFIG_HOME/neovim`
+instead of `$XDG_CONFIG_HOME/nvim`.
+
+Note: Similarly to the $XDG environment variables, when
+`$XDG_CONFIG_HOME/nvim` is mentionned, it should be understood as
+`$XDG_CONFIG_HOME/$NVIM_APPNAME`.
+
 LOG FILE					*$NVIM_LOG_FILE* *E5430*
 Besides 'debug' and 'verbose', Nvim keeps a general log file for internal
 debugging, plugins and RPC clients. >

src/nvim/eval.c

@@ -5368,13 +5368,14 @@ void get_xdg_var_list(const XDGVarType xdg, typval_T *rettv)
     return;
   }
   const void *iter = NULL;
+  const char *appname = get_appname();
   do {
     size_t dir_len;
     const char *dir;
     iter = vim_env_iter(ENV_SEPCHAR, dirs, iter, &dir, &dir_len);
     if (dir != NULL && dir_len > 0) {
       char *dir_with_nvim = xmemdupz(dir, dir_len);
-      dir_with_nvim = concat_fnames_realloc(dir_with_nvim, "nvim", true);
+      dir_with_nvim = concat_fnames_realloc(dir_with_nvim, appname, true);
       tv_list_append_string(list, dir_with_nvim, (ssize_t)strlen(dir_with_nvim));
       xfree(dir_with_nvim);
     }

src/nvim/fileio.c

@@ -5181,7 +5181,10 @@ static void vim_mktempdir(void)
 
     // "/tmp/" exists, now try to create "/tmp/nvim.<user>/".
     add_pathsep(tmp);
-    xstrlcat(tmp, "nvim.", sizeof(tmp));
+
+    const char *appname = get_appname();
+    xstrlcat(tmp, appname, sizeof(tmp));
+    xstrlcat(tmp, ".", sizeof(tmp));
     xstrlcat(tmp, user, sizeof(tmp));
     (void)os_mkdir(tmp, 0700);  // Always create, to avoid a race.
     bool owned = os_file_owned(tmp);

src/nvim/msgpack_rpc/server.c

@@ -91,13 +91,14 @@ char *server_address_new(const char *name)
 {
   static uint32_t count = 0;
   char fmt[ADDRESS_MAX_SIZE];
+  const char *appname = get_appname();
 #ifdef MSWIN
   int r = snprintf(fmt, sizeof(fmt), "\\\\.\\pipe\\%s.%" PRIu64 ".%" PRIu32,
-                   name ? name : "nvim", os_get_pid(), count++);
+                   name ? name : appname, os_get_pid(), count++);
 #else
   char *dir = stdpaths_get_xdg_var(kXDGRuntimeDir);
   int r = snprintf(fmt, sizeof(fmt), "%s/%s.%" PRIu64 ".%" PRIu32,
-                   dir, name ? name : "nvim", os_get_pid(), count++);
+                   dir, name ? name : appname, os_get_pid(), count++);
   xfree(dir);
 #endif
   if ((size_t)r >= sizeof(fmt)) {

src/nvim/os/stdpaths.c

@@ -57,6 +57,18 @@ static const char *const xdg_defaults[] = {
 #endif
 };
 
+/// Get the value of $NVIM_APPNAME or "nvim" if not set.
+///
+/// @return $NVIM_APPNAME value
+const char *get_appname(void)
+{
+  const char *env_val = os_getenv("NVIM_APPNAME");
+  if (env_val == NULL || *env_val == '\0') {
+    env_val = "nvim";
+  }
+  return env_val;
+}
+
 /// Return XDG variable value
 ///
 /// @param[in]  idx  XDG variable to use.
@@ -100,25 +112,28 @@ char *stdpaths_get_xdg_var(const XDGVarType idx)
 
 /// Return Nvim-specific XDG directory subpath.
 ///
-/// Windows: Uses "…/nvim-data" for kXDGDataHome to avoid storing
+/// Windows: Uses "…/$NVIM_APPNAME-data" for kXDGDataHome to avoid storing
 /// configuration and data files in the same path. #4403
 ///
 /// @param[in]  idx  XDG directory to use.
 ///
-/// @return [allocated] "{xdg_directory}/nvim"
+/// @return [allocated] "{xdg_directory}/$NVIM_APPNAME"
 char *get_xdg_home(const XDGVarType idx)
   FUNC_ATTR_WARN_UNUSED_RESULT
 {
   char *dir = stdpaths_get_xdg_var(idx);
+  const char *appname = get_appname();
+  size_t appname_len = strlen(appname);
+  assert(appname_len < (IOSIZE - sizeof("-data")));
+
   if (dir) {
+    xstrlcpy(IObuff, appname, appname_len + 1);
 #if defined(MSWIN)
-    dir = concat_fnames_realloc(dir,
-                                ((idx == kXDGDataHome
-                                  || idx == kXDGStateHome) ? "nvim-data" : "nvim"),
-                                true);
-#else
-    dir = concat_fnames_realloc(dir, "nvim", true);
+    if (idx == kXDGDataHome || idx == kXDGStateHome) {
+      STRCAT(IObuff, "-data");
+    }
 #endif
+    dir = concat_fnames_realloc(dir, IObuff, true);
 
 #ifdef BACKSLASH_IN_FILENAME
     slash_adjust(dir);
@@ -131,7 +146,7 @@ char *get_xdg_home(const XDGVarType idx)
 ///
 /// @param[in]  fname  New component of the path.
 ///
-/// @return [allocated] `$XDG_CACHE_HOME/nvim/{fname}`
+/// @return [allocated] `$XDG_CACHE_HOME/$NVIM_APPNAME/{fname}`
 char *stdpaths_user_cache_subpath(const char *fname)
   FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL FUNC_ATTR_NONNULL_RET
 {
@@ -142,7 +157,7 @@ char *stdpaths_user_cache_subpath(const char *fname)
 ///
 /// @param[in]  fname  New component of the path.
 ///
-/// @return [allocated] `$XDG_CONFIG_HOME/nvim/{fname}`
+/// @return [allocated] `$XDG_CONFIG_HOME/$NVIM_APPNAME/{fname}`
 char *stdpaths_user_conf_subpath(const char *fname)
   FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL FUNC_ATTR_NONNULL_RET
 {
@@ -153,7 +168,7 @@ char *stdpaths_user_conf_subpath(const char *fname)
 ///
 /// @param[in]  fname  New component of the path.
 ///
-/// @return [allocated] `$XDG_DATA_HOME/nvim/{fname}`
+/// @return [allocated] `$XDG_DATA_HOME/$NVIM_APPNAME/{fname}`
 char *stdpaths_user_data_subpath(const char *fname)
   FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL FUNC_ATTR_NONNULL_RET
 {
@@ -166,7 +181,7 @@ char *stdpaths_user_data_subpath(const char *fname)
 /// @param[in]  trailing_pathseps  Amount of trailing path separators to add.
 /// @param[in]  escape_commas  If true, all commas will be escaped.
 ///
-/// @return [allocated] `$XDG_STATE_HOME/nvim/{fname}`.
+/// @return [allocated] `$XDG_STATE_HOME/$NVIM_APPNAME/{fname}`.
 char *stdpaths_user_state_subpath(const char *fname, const size_t trailing_pathseps,
                                   const bool escape_commas)
   FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL FUNC_ATTR_NONNULL_RET

src/nvim/runtime.c

@@ -1435,7 +1435,6 @@ static inline size_t compute_double_env_sep_len(const char *const val, const siz
   return ret;
 }
 
-#define NVIM_SIZE (sizeof("nvim") - 1)
 /// Add directories to a ENV_SEPCHAR-separated array from a colon-separated one
 ///
 /// Commas are escaped in process. To each item PATHSEP "nvim" is appended in
@@ -1464,6 +1463,8 @@ static inline char *add_env_sep_dirs(char *dest, const char *const val, const ch
     return dest;
   }
   const void *iter = NULL;
+  const char *appname = get_appname();
+  const size_t appname_len = strlen(appname);
   do {
     size_t dir_len;
     const char *dir;
@@ -1474,8 +1475,8 @@ static inline char *add_env_sep_dirs(char *dest, const char *const val, const ch
       if (!after_pathsep(dest - 1, dest)) {
         *dest++ = PATHSEP;
       }
-      memmove(dest, "nvim", NVIM_SIZE);
-      dest += NVIM_SIZE;
+      memmove(dest, appname, appname_len);
+      dest += appname_len;
       if (suf1 != NULL) {
         *dest++ = PATHSEP;
         memmove(dest, suf1, len1);
@@ -1529,14 +1530,18 @@ static inline char *add_dir(char *dest, const char *const dir, const size_t dir_
     if (!after_pathsep(dest - 1, dest)) {
       *dest++ = PATHSEP;
     }
+    const char *appname = get_appname();
+    size_t appname_len = strlen(appname);
+    assert(appname_len < (IOSIZE - sizeof("-data")));
+    xstrlcpy(IObuff, appname, appname_len + 1);
 #if defined(MSWIN)
-    size_t size = (type == kXDGDataHome ? sizeof("nvim-data") - 1 : NVIM_SIZE);
-    memmove(dest, (type == kXDGDataHome ? "nvim-data" : "nvim"), size);
-    dest += size;
-#else
-    memmove(dest, "nvim", NVIM_SIZE);
-    dest += NVIM_SIZE;
+    if (type == kXDGDataHome || type == kXDGStateHome) {
+      STRCAT(IObuff, "-data");
+      appname_len += 5;
+    }
 #endif
+    xstrlcpy(dest, IObuff, appname_len + 1);
+    dest += appname_len;
     if (suf1 != NULL) {
       *dest++ = PATHSEP;
       memmove(dest, suf1, len1);
@@ -1596,16 +1601,17 @@ char *runtimepath_default(bool clean_arg)
   size_t config_len = 0;
   size_t vimruntime_len = 0;
   size_t libdir_len = 0;
+  const char *appname = get_appname();
+  size_t appname_len = strlen(appname);
   if (data_home != NULL) {
     data_len = strlen(data_home);
-    if (data_len != 0) {
+    size_t nvim_data_size = appname_len;
 #if defined(MSWIN)
-      size_t nvim_size = (sizeof("nvim-data") - 1);
-#else
-      size_t nvim_size = NVIM_SIZE;
+    nvim_data_size += sizeof("-data");
 #endif
+    if (data_len != 0) {
       rtp_size += ((data_len + memcnt(data_home, ',', data_len)
-                    + nvim_size + 1 + SITE_SIZE + 1
+                    + nvim_data_size + 1 + SITE_SIZE + 1
                     + !after_pathsep(data_home, data_home + data_len)) * 2
                    + AFTER_SIZE + 1);
     }
@@ -1614,7 +1620,7 @@ char *runtimepath_default(bool clean_arg)
     config_len = strlen(config_home);
     if (config_len != 0) {
       rtp_size += ((config_len + memcnt(config_home, ',', config_len)
-                    + NVIM_SIZE + 1
+                    + appname_len + 1
                     + !after_pathsep(config_home, config_home + config_len)) * 2
                    + AFTER_SIZE + 1);
     }
@@ -1632,9 +1638,9 @@ char *runtimepath_default(bool clean_arg)
     }
   }
   rtp_size += compute_double_env_sep_len(data_dirs,
-                                         NVIM_SIZE + 1 + SITE_SIZE + 1,
+                                         appname_len + 1 + SITE_SIZE + 1,
                                          AFTER_SIZE + 1);
-  rtp_size += compute_double_env_sep_len(config_dirs, NVIM_SIZE + 1,
+  rtp_size += compute_double_env_sep_len(config_dirs, appname_len + 1,
                                          AFTER_SIZE + 1);
   char *rtp = NULL;
   if (rtp_size == 0) {
@@ -1675,7 +1681,6 @@ freeall:
 
   return rtp;
 }
-#undef NVIM_SIZE
 
 static void cmd_source(char *fname, exarg_T *eap)
 {

test/functional/options/defaults_spec.lua

@@ -566,8 +566,12 @@ end)
 describe('stdpath()', function()
   -- Windows appends 'nvim-data' instead of just 'nvim' to prevent collisions
   -- due to XDG_CONFIG_HOME, XDG_DATA_HOME and XDG_STATE_HOME being the same.
-  local datadir = is_os('win') and 'nvim-data' or 'nvim'
-  local statedir = is_os('win') and 'nvim-data' or 'nvim'
+  local function maybe_data(name)
+    return is_os('win') and name .. '-data' or name
+  end
+
+  local datadir = maybe_data('nvim')
+  local statedir = maybe_data('nvim')
   local env_sep = is_os('win') and ';' or ':'
 
   it('acceptance', function()
@@ -583,6 +587,24 @@ describe('stdpath()', function()
     assert_alive()  -- Check for crash. #8393
   end)
 
+  it('reacts to #NVIM_APPNAME', function()
+    local appname = "NVIM_APPNAME_TEST____________________________________" ..
+      "______________________________________________________________________"
+    clear({env={ NVIM_APPNAME=appname }})
+    eq(appname, funcs.fnamemodify(funcs.stdpath('config'), ':t'))
+    eq(appname, funcs.fnamemodify(funcs.stdpath('cache'), ':t'))
+    eq(maybe_data(appname), funcs.fnamemodify(funcs.stdpath('log'), ':t'))
+    eq(maybe_data(appname), funcs.fnamemodify(funcs.stdpath('data'), ':t'))
+    eq(maybe_data(appname), funcs.fnamemodify(funcs.stdpath('state'), ':t'))
+    -- config_dirs and data_dirs are empty on windows, so don't check them on
+    -- that platform
+    if not is_os('win') then
+      eq(appname, funcs.fnamemodify(funcs.stdpath('config_dirs')[1], ':t'))
+      eq(appname, funcs.fnamemodify(funcs.stdpath('data_dirs')[1], ':t'))
+    end
+    assert_alive()  -- Check for crash. #8393
+  end)
+
   context('returns a String', function()
 
     describe('with "config"' , function ()