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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 17:09:30 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 17:09:30 +0000
commit81749f1fe87e489c4e2e7408a0fae9370c3810b3 (patch)
tree2d1345a5762855b6577495d90ac134c4e92d7ff8 /src/hash.c
parentInitial commit. (diff)
downloadlibseccomp-81749f1fe87e489c4e2e7408a0fae9370c3810b3.tar.xz
libseccomp-81749f1fe87e489c4e2e7408a0fae9370c3810b3.zip
Adding upstream version 2.5.5.upstream/2.5.5upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/hash.c')
-rw-r--r--src/hash.c90
1 files changed, 90 insertions, 0 deletions
diff --git a/src/hash.c b/src/hash.c
new file mode 100644
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--- /dev/null
+++ b/src/hash.c
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+/**
+ * Seccomp Library hash code
+ *
+ */
+
+/*
+ * This code is based on MurmurHash3.cpp from Austin Appleby and is placed in
+ * the public domain.
+ *
+ * https://github.com/aappleby/smhasher
+ *
+ */
+
+#include <stdlib.h>
+#include <inttypes.h>
+
+#include "hash.h"
+
+static inline uint32_t getblock32(const uint32_t *p, int i)
+{
+ return p[i];
+}
+
+static inline uint32_t rotl32(uint32_t x, int8_t r)
+{
+ return (x << r) | (x >> (32 - r));
+}
+
+static inline uint32_t fmix32(uint32_t h)
+{
+ h ^= h >> 16;
+ h *= 0x85ebca6b;
+ h ^= h >> 13;
+ h *= 0xc2b2ae35;
+ h ^= h >> 16;
+
+ return h;
+}
+
+/* NOTE: this is an implementation of MurmurHash3_x86_32 */
+uint32_t hash(const void *key, size_t length)
+{
+ const uint8_t *data = (const uint8_t *)key;
+ const uint32_t *blocks;
+ const uint8_t *tail;
+ const int nblocks = length / 4;
+ const uint32_t c1 = 0xcc9e2d51;
+ const uint32_t c2 = 0x1b873593;
+ uint32_t k1;
+ uint32_t k2 = 0;
+ int i;
+
+ /* NOTE: we always force a seed of 0 */
+ uint32_t h1 = 0;
+
+ /* body */
+ blocks = (const uint32_t *)(data + nblocks * 4);
+ for(i = -nblocks; i; i++) {
+ k1 = getblock32(blocks, i);
+
+ k1 *= c1;
+ k1 = rotl32(k1, 15);
+ k1 *= c2;
+
+ h1 ^= k1;
+ h1 = rotl32(h1, 13);
+ h1 = h1 * 5 + 0xe6546b64;
+ }
+
+ /* tail */
+ tail = (const uint8_t *)(data + nblocks * 4);
+ switch(length & 3) {
+ case 3:
+ k2 ^= tail[2] << 16;
+ case 2:
+ k2 ^= tail[1] << 8;
+ case 1:
+ k2 ^= tail[0];
+ k2 *= c1;
+ k2 = rotl32(k2, 15);
+ k2 *= c2;
+ h1 ^= k2;
+ };
+
+ /* finalization */
+ h1 ^= length;
+ h1 = fmix32(h1);
+
+ return h1;
+}