summaryrefslogtreecommitdiffstats
path: root/src/basic/hash-funcs.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/basic/hash-funcs.c')
-rw-r--r--src/basic/hash-funcs.c91
1 files changed, 91 insertions, 0 deletions
diff --git a/src/basic/hash-funcs.c b/src/basic/hash-funcs.c
new file mode 100644
index 0000000..1be43d4
--- /dev/null
+++ b/src/basic/hash-funcs.c
@@ -0,0 +1,91 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <string.h>
+
+#include "hash-funcs.h"
+#include "path-util.h"
+
+void string_hash_func(const char *p, struct siphash *state) {
+ siphash24_compress(p, strlen(p) + 1, state);
+}
+
+DEFINE_HASH_OPS(string_hash_ops, char, string_hash_func, string_compare_func);
+
+void path_hash_func(const char *q, struct siphash *state) {
+ size_t n;
+
+ assert(q);
+ assert(state);
+
+ /* Calculates a hash for a path in a way this duplicate inner slashes don't make a differences, and also
+ * whether there's a trailing slash or not. This fits well with the semantics of path_compare(), which does
+ * similar checks and also doesn't care for trailing slashes. Note that relative and absolute paths (i.e. those
+ * which begin in a slash or not) will hash differently though. */
+
+ n = strspn(q, "/");
+ if (n > 0) { /* Eat up initial slashes, and add one "/" to the hash for all of them */
+ siphash24_compress(q, 1, state);
+ q += n;
+ }
+
+ for (;;) {
+ /* Determine length of next component */
+ n = strcspn(q, "/");
+ if (n == 0) /* Reached the end? */
+ break;
+
+ /* Add this component to the hash and skip over it */
+ siphash24_compress(q, n, state);
+ q += n;
+
+ /* How many slashes follow this component? */
+ n = strspn(q, "/");
+ if (q[n] == 0) /* Is this a trailing slash? If so, we are at the end, and don't care about the slashes anymore */
+ break;
+
+ /* We are not add the end yet. Hash exactly one slash for all of the ones we just encountered. */
+ siphash24_compress(q, 1, state);
+ q += n;
+ }
+}
+
+int path_compare_func(const char *a, const char *b) {
+ return path_compare(a, b);
+}
+
+DEFINE_HASH_OPS(path_hash_ops, char, path_hash_func, path_compare_func);
+
+void trivial_hash_func(const void *p, struct siphash *state) {
+ siphash24_compress(&p, sizeof(p), state);
+}
+
+int trivial_compare_func(const void *a, const void *b) {
+ return CMP(a, b);
+}
+
+const struct hash_ops trivial_hash_ops = {
+ .hash = trivial_hash_func,
+ .compare = trivial_compare_func,
+};
+
+void uint64_hash_func(const uint64_t *p, struct siphash *state) {
+ siphash24_compress(p, sizeof(uint64_t), state);
+}
+
+int uint64_compare_func(const uint64_t *a, const uint64_t *b) {
+ return CMP(*a, *b);
+}
+
+DEFINE_HASH_OPS(uint64_hash_ops, uint64_t, uint64_hash_func, uint64_compare_func);
+
+#if SIZEOF_DEV_T != 8
+void devt_hash_func(const dev_t *p, struct siphash *state) {
+ siphash24_compress(p, sizeof(dev_t), state);
+}
+
+int devt_compare_func(const dev_t *a, const dev_t *b) {
+ return CMP(*a, *b);
+}
+
+DEFINE_HASH_OPS(devt_hash_ops, dev_t, devt_hash_func, devt_compare_func);
+#endif