First working version

[nsscash/nsscash.git] / nss / search.c

diff --git a/nss/search.c b/nss/search.c
new file mode 100644 (file)
index 0000000..d4f7106
--- /dev/null
+++ b/nss/search.c
@@ -0,0 +1,55 @@
+/*
+ * Search entries in nsscash files by using indices and binary search
+ *
+ * Copyright (C) 2019  Simon Ruderich
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "search.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+
+static int bsearch_callback(const void *x, const void *y) {
+    const struct search_key *key = x;
+
+    uint64_t offset = *(const uint64_t *)y;
+    const void *member = (const char *)key->data + offset + key->offset;
+
+    // Lookup by name
+    if (key->name != NULL) {
+        const char *name = member;
+        return strcmp(key->name, name);
+
+    // Lookup by ID
+    } else if (key->id != NULL) {
+        const uint64_t *id = member;
+        if (*key->id < *id) {
+            return -1;
+        } else if (*key->id == *id) {
+            return 0;
+        } else {
+            return +1;
+        }
+
+    } else {
+        abort();
+    }
+}
+
+uint64_t *search(struct search_key *key, const void *index, uint64_t count) {
+    return bsearch(key, index, count, sizeof(uint64_t), bsearch_callback);
+}