[Mesa-dev] [PATCH 2/6] util: add disk_cache_get_function_identifier()

[Timothy Arceri]

This can be used as a drop in replacement for
disk_cache_get_function_timestamp().

Here we use build-id to generate a driver-id rather than build
timestamp if available. This should resolve issues such as
distros using reproducable builds and flatpack not having
real build timestamps.
---
 src/util/disk_cache.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/util/disk_cache.h b/src/util/disk_cache.h
index 50bd9f41ac4..962a26ffc8c 100644
--- a/src/util/disk_cache.h
+++ b/src/util/disk_cache.h
@@ -26,6 +26,7 @@
 
 #ifdef HAVE_DLFCN_H
 #include <dlfcn.h>
+#include "util/build_id.h"
 #endif
 #include <assert.h>
 #include <stdint.h>
@@ -103,6 +104,21 @@ disk_cache_get_function_timestamp(void *ptr, uint32_t* timestamp)
    *timestamp = st.st_mtime;
    return true;
 }
+
+static inline bool
+disk_cache_get_function_identifier(void *ptr, uint32_t *id)
+{
+#ifdef HAVE_DL_ITERATE_PHDR
+   const struct build_id_note *note = NULL;
+   if ((note = build_id_find_nhdr_for_addr(ptr))) {
+      const uint8_t *id_sha1 = build_id_data(note);
+      assert(id_sha1);
+      *id = *id_sha1;
+      return true;
+   } else
+#endif
+   return disk_cache_get_function_timestamp(ptr, id);
+}
 #endif
 
 /* Provide inlined stub functions if the shader cache is disabled. */
-- 
2.17.1