From 2a1e32b4105fe95413a615a44d40938920ea1a19 Mon Sep 17 00:00:00 2001
From: David McFarland <corngood@gmail.com>
Date: Mon, 6 Aug 2018 15:52:11 -0300
Subject: [PATCH] disk_cache: include dri driver path in cache key

This fixes invalid cache hits on NixOS where all shared library
timestamps in /nix/store are zero.
---
 src/util/Makefile.am  | 3 +++
 src/util/disk_cache.c | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/src/util/Makefile.am b/src/util/Makefile.am
index bafb57439a..a22e2e41eb 100644
--- a/src/util/Makefile.am
+++ b/src/util/Makefile.am
@@ -35,6 +35,9 @@ noinst_LTLIBRARIES = \
 	libmesautil.la \
 	libxmlconfig.la
 
+AM_CFLAGS = \
+	-DDISK_CACHE_KEY=\"$(drivers)\"
+
 AM_CPPFLAGS = \
 	$(PTHREAD_CFLAGS) \
 	-I$(top_srcdir)/include
diff --git a/src/util/disk_cache.c b/src/util/disk_cache.c
index 368ec41792..071220b2ba 100644
--- a/src/util/disk_cache.c
+++ b/src/util/disk_cache.c
@@ -388,8 +388,10 @@ disk_cache_create(const char *gpu_name, const char *driver_id,
 
    /* Create driver id keys */
    size_t id_size = strlen(driver_id) + 1;
+   size_t key_size = strlen(DISK_CACHE_KEY) + 1;
    size_t gpu_name_size = strlen(gpu_name) + 1;
    cache->driver_keys_blob_size += id_size;
+   cache->driver_keys_blob_size += key_size;
    cache->driver_keys_blob_size += gpu_name_size;
 
    /* We sometimes store entire structs that contains a pointers in the cache,
@@ -410,6 +412,7 @@ disk_cache_create(const char *gpu_name, const char *driver_id,
    uint8_t *drv_key_blob = cache->driver_keys_blob;
    DRV_KEY_CPY(drv_key_blob, &cache_version, cv_size)
    DRV_KEY_CPY(drv_key_blob, driver_id, id_size)
+   DRV_KEY_CPY(drv_key_blob, DISK_CACHE_KEY, key_size)
    DRV_KEY_CPY(drv_key_blob, gpu_name, gpu_name_size)
    DRV_KEY_CPY(drv_key_blob, &ptr_size, ptr_size_size)
    DRV_KEY_CPY(drv_key_blob, &driver_flags, driver_flags_size)
-- 
2.19.1