From 876509ae8b95f76adebdfa1f2380d75a49f9871d Mon Sep 17 00:00:00 2001
From: Joel Rosdahl <joel@rosdahl.net>
Date: Sun, 13 Nov 2022 14:43:35 +0100
Subject: fix: Use $XDG_RUNTIME_DIR/ccache-tmp as the default temporary
 directory

See discussion in #1221.
---
 cmake/GenerateConfigurationFile.cmake | 1 -
 cmake/config.h.in                     | 3 ---
 doc/MANUAL.adoc                       | 3 ++-
 src/Config.cpp                        | 7 ++++---
 4 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/cmake/GenerateConfigurationFile.cmake b/cmake/GenerateConfigurationFile.cmake
index 20be4eac..858567b9 100644
--- a/cmake/GenerateConfigurationFile.cmake
+++ b/cmake/GenerateConfigurationFile.cmake
@@ -26,7 +26,6 @@ endforeach()
 include(CheckFunctionExists)
 set(functions
     asctime_r
-    geteuid
     getopt_long
     getpwuid
     posix_fallocate
diff --git a/cmake/config.h.in b/cmake/config.h.in
index 28ea3c2a..1537119b 100644
--- a/cmake/config.h.in
+++ b/cmake/config.h.in
@@ -76,9 +76,6 @@
 // Define if your compiler supports AVX2.
 #cmakedefine HAVE_AVX2
 
-// Define if you have the "geteuid" function.
-#cmakedefine HAVE_GETEUID
-
 // Define if you have the "getopt_long" function.
 #cmakedefine HAVE_GETOPT_LONG
 
diff --git a/doc/MANUAL.adoc b/doc/MANUAL.adoc
index b9a202ca..48328fa8 100644
--- a/doc/MANUAL.adoc
+++ b/doc/MANUAL.adoc
@@ -1036,7 +1036,8 @@ NOTE: Lines in the stats log starting with a hash sign (`#`) are comments.
 *temporary_dir* (*CCACHE_TEMPDIR*)::
 
     This option specifies where ccache will put temporary files. The default is
-    `/run/user/<UID>/ccache-tmp` if `/run/user/<UID>` exists, otherwise
+    `$XDG_RUNTIME_DIR/ccache-tmp` (typically `/run/user/<UID>/ccache-tmp`) if
+    `XDG_RUNTIME_DIR` is set and the directory exists, otherwise
     `<cache_dir>/tmp`.
 +
 NOTE: In previous versions of ccache, *CCACHE_TEMPDIR* had to be on the same
diff --git a/src/Config.cpp b/src/Config.cpp
index 5755c1b6..75a1358d 100644
--- a/src/Config.cpp
+++ b/src/Config.cpp
@@ -1114,9 +1114,10 @@ std::string
 Config::default_temporary_dir() const
 {
   static const std::string run_user_tmp_dir = [] {
-#ifdef HAVE_GETEUID
-    if (Stat::stat("/run").is_directory()) {
-      auto dir = FMT("/run/user/{}/ccache-tmp", geteuid());
+#ifndef _WIN32
+    const char* const xdg_runtime_dir = getenv("XDG_RUNTIME_DIR");
+    if (xdg_runtime_dir && Stat::stat(xdg_runtime_dir).is_directory()) {
+      auto dir = FMT("{}/ccache-tmp", xdg_runtime_dir);
       if (Util::create_dir(dir) && access(dir.c_str(), W_OK) == 0) {
         return dir;
       }
-- 
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