feat: stdpath('run'), /tmp/nvim.user/ #18993

Problem:
- Since c57f6b28d71d #8519, sockets are created in ~/.local/… but XDG
  spec says: "XDG_RUNTIME_DIR: Must be on the local filesystem", which
  implies that XDG_STATE_DIR is potentially non-local.
- Not easy to inspect Nvim-created temp files (for debugging etc).

Solution:
- Store sockets in stdpath('run') ($XDG_RUNTIME_DIR).
- Establish "/tmp/nvim.user/" as the tempdir root shared by all Nvims.
- Make ok() actually useful.
- Introduce assert_nolog().

closes #3517
closes #17093

1 files changed, 9 insertions, 3 deletions

diff --git a/src/nvim/os/stdpaths.c b/src/nvim/os/stdpaths.c
index a382392bd3..5576e7ba07 100644
--- a/src/nvim/os/stdpaths.c
+++ b/src/nvim/os/stdpaths.c
@@ -4,6 +4,7 @@
 #include <stdbool.h>
 
 #include "nvim/ascii.h"
+#include "nvim/fileio.h"
 #include "nvim/memory.h"
 #include "nvim/os/os.h"
 #include "nvim/os/stdpaths_defs.h"
@@ -26,7 +27,7 @@ static const char *const xdg_defaults_env_vars[] = {
   [kXDGDataHome] = "LOCALAPPDATA",
   [kXDGCacheHome] = "TEMP",
   [kXDGStateHome] = "LOCALAPPDATA",
-  [kXDGRuntimeDir] = NULL,
+  [kXDGRuntimeDir] = NULL,  // Decided by vim_mktempdir().
   [kXDGConfigDirs] = NULL,
   [kXDGDataDirs] = NULL,
 };
@@ -41,7 +42,7 @@ static const char *const xdg_defaults[] = {
   [kXDGDataHome] = "~\\AppData\\Local",
   [kXDGCacheHome] = "~\\AppData\\Local\\Temp",
   [kXDGStateHome] = "~\\AppData\\Local",
-  [kXDGRuntimeDir] = NULL,
+  [kXDGRuntimeDir] = NULL,  // Decided by vim_mktempdir().
   [kXDGConfigDirs] = NULL,
   [kXDGDataDirs] = NULL,
 #else
@@ -49,7 +50,7 @@ static const char *const xdg_defaults[] = {
   [kXDGDataHome] = "~/.local/share",
   [kXDGCacheHome] = "~/.cache",
   [kXDGStateHome] = "~/.local/state",
-  [kXDGRuntimeDir] = NULL,
+  [kXDGRuntimeDir] = NULL,  // Decided by vim_mktempdir().
   [kXDGConfigDirs] = "/etc/xdg/",
   [kXDGDataDirs] = "/usr/local/share/:/usr/share/",
 #endif
@@ -83,6 +84,11 @@ char *stdpaths_get_xdg_var(const XDGVarType idx)
     ret = xstrdup(env_val);
   } else if (fallback) {
     ret = expand_env_save((char *)fallback);
+  } else if (idx == kXDGRuntimeDir) {
+    // Special-case: stdpath('run') is defined at startup.
+    ret = vim_gettempdir();
+    size_t len = strlen(ret);
+    ret = xstrndup(ret, len >= 2 ? len - 1 : 0);  // Trim trailing slash.
   }
 
   return ret;