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

1 files changed, 3 insertions, 2 deletions

diff --git a/src/nvim/msgpack_rpc/server.c b/src/nvim/msgpack_rpc/server.c
index 1d75c208be..c6a0a4d8cc 100644
--- a/src/nvim/msgpack_rpc/server.c
+++ b/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)) {