upstream: import some hacked systemd headers

This brings journal-file data structures and byte swapping
helpers I may as well just reuse.

I've had to do some minor messing about to make things workable in
isolation out of the systemd tree without pulling in too much.

I've also added a new HashedObjectHeader type to encompass the
slightly larger common header components of FieldObject and
DataObject to facilitate a generic hash table iterator that can
operate on just loading HashedObjectHeader when nothing more
than the object size is needed for accounting.  Basically the
HashedObjectHeader is ObjectHeader+hash+next_hash_offset.

1 files changed, 20 insertions, 0 deletions

diff --git a/src/upstream/lookup3.h b/src/upstream/lookup3.h
new file mode 100644
index 0000000..ce8a468
--- /dev/null
+++ b/src/upstream/lookup3.h
@@ -0,0 +1,20 @@
+#pragma once
+
+#include <inttypes.h>
+#include <sys/types.h>
+
+uint32_t jenkins_hashword(const uint32_t *k, size_t length, uint32_t initval);
+void jenkins_hashword2(const uint32_t *k, size_t length, uint32_t *pc, uint32_t *pb);
+
+uint32_t jenkins_hashlittle(const void *key, size_t length, uint32_t initval);
+void jenkins_hashlittle2(const void *key, size_t length, uint32_t *pc, uint32_t *pb);
+
+uint32_t jenkins_hashbig(const void *key, size_t length, uint32_t initval);
+
+static inline uint64_t jenkins_hash64(const void *data, size_t length) {
+        uint32_t a = 0, b = 0;
+
+        jenkins_hashlittle2(data, length, &a, &b);
+
+        return ((uint64_t) a << 32ULL) | (uint64_t) b;
+}