SQLite search backend

scripts/sqlite_extension.c

@@ -0,0 +1,84 @@
+#include <sqlite3ext.h>
+#include <string.h>
+#include <stdlib.h>
+
+SQLITE_EXTENSION_INIT1
+
+static int sep_rfind(const char *str) {
+    for (int i = (int) strlen(str); i >= 0; i--) {
+        if (str[i] == '/') {
+            return i;
+        }
+    }
+    return -1;
+}
+
+void path_parent_func(sqlite3_context *ctx, int argc, sqlite3_value **argv) {
+    if (argc != 1 || sqlite3_value_type(argv[0]) != SQLITE_TEXT) {
+        sqlite3_result_error(ctx, "Invalid parameters", -1);
+    }
+
+    const char *value = (const char *) sqlite3_value_text(argv[0]);
+
+    int stop = sep_rfind(value);
+    if (stop == -1) {
+        sqlite3_result_null(ctx);
+        return;
+    }
+    char parent[4096 * 3];
+    strncpy(parent, value, stop);
+
+    sqlite3_result_text(ctx, parent, stop, SQLITE_TRANSIENT);
+}
+
+void random_func(sqlite3_context *ctx, int argc, sqlite3_value **argv) {
+    if (argc != 1 || sqlite3_value_type(argv[0]) != SQLITE_INTEGER) {
+        sqlite3_result_error(ctx, "Invalid parameters", -1);
+    }
+
+    char state_buf[32] = {0,};
+    struct random_data buf;
+    int result;
+
+    long seed = sqlite3_value_int64(argv[0]);
+
+    initstate_r((int) seed, state_buf, sizeof(state_buf), &buf);
+
+    random_r(&buf, &result);
+
+    sqlite3_result_int(ctx, result);
+}
+
+
+int sqlite3_extension_init(
+        sqlite3 *db,
+        char **pzErrMsg,
+        const sqlite3_api_routines *pApi
+) {
+    SQLITE_EXTENSION_INIT2(pApi);
+
+
+    sqlite3_create_function(
+            db,
+            "path_parent",
+            1,
+            SQLITE_UTF8,
+            NULL,
+            path_parent_func,
+            NULL,
+            NULL
+    );
+
+    sqlite3_create_function(
+            db,
+            "random_seeded",
+            1,
+            SQLITE_UTF8,
+            NULL,
+            random_func,
+            NULL,
+            NULL
+    );
+
+    return SQLITE_OK;
+}