1 files changed, 138 insertions, 0 deletions
diff --git a/src/db.c b/src/db.c
new file mode 100644
index 0000000..a0443c9
--- /dev/null
+++ b/src/db.c
@@ -0,0 +1,138 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Copyright © 2020 rsiddharth <s@ricketyspace.net>
+ */
+
+#include <db.h>
+
+static const char *DB_FILE = "nserver.db";
+
+datum *mk_datum(char *data)
+{
+    datum *d = NULL;
+
+    check(data != NULL, "data invalid");
+
+    d = calloc(1, sizeof(datum));
+    check(d != NULL, "datum mem alloc failed");
+
+    d->dptr = data;
+    d->dsize = strlen(data);
+
+    return d;
+ error:
+    if (d) {
+        free(d);
+    }
+    return NULL;
+}
+
+GDBM_FILE db_open(int flags)
+{
+   return gdbm_open(DB_FILE, 0,flags, S_IRUSR|S_IWUSR, NULL);
+}
+
+int db_init()
+{
+    // Create DB if it's not already created.
+    GDBM_FILE  gf = db_open(GDBM_WRCREAT);
+    check(gf != NULL, "unable to init db");
+
+    // Close the DB.
+    int rc = gdbm_close(gf);
+    check(rc == 0,  "error closing db after init");
+
+    return 0;
+ error:
+    return -1;
+}
+
+int db_store(char *key, char *value)
+{
+    datum *k_datum = NULL, *v_datum = NULL;
+    GDBM_FILE gf = NULL;
+
+    check(key != NULL && strlen(key) > 0, "key invalid");
+    check(value != NULL && strlen(value) > 0, "data invalid");
+
+    // make key value datum
+    k_datum = mk_datum(key);
+    check(k_datum != NULL, "key datum init failed");
+
+    v_datum = mk_datum(value);
+    check(v_datum != NULL, "value datum init failed");
+
+    // init db.
+    int rc = db_init();
+    check(rc == 0, "db init failed");
+
+    // open the gdbm data in write mode
+    gf = db_open(GDBM_WRITER|GDBM_SYNC);
+    check(gf != NULL, "unable to open db in write  mode");
+
+    // write key -> data to db.
+    rc = gdbm_store(gf, *k_datum, *v_datum, GDBM_REPLACE);
+    check(rc == 0, "gdbm store failed");
+
+    // close db
+    rc = gdbm_close(gf);
+    check(rc == 0, "gdbm close failed");
+
+    // cleanup.
+    free(k_datum);
+    free(v_datum);
+
+    return 0;
+ error:
+    if (k_datum) {
+        free(k_datum);
+    }
+    if (v_datum)  {
+        free(v_datum);
+    }
+    if (gf) {
+        gdbm_close(gf);
+    }
+    return -1;
+}
+
+char *db_load(char *key)
+{
+    datum *k_datum = NULL;
+    GDBM_FILE gf = NULL;
+
+    check(key != NULL && strlen(key) > 0, "key invalid");
+
+    // make key datum
+    k_datum = mk_datum(key);
+    check(k_datum != NULL, "key datum init failed");
+
+    // init db.
+    int rc = db_init();
+    check(rc == 0, "db init failed");
+
+    // open the gdbm data in read mode
+    gf = db_open(GDBM_READER|GDBM_SYNC);
+    check(gf != NULL, "unable to open db in read  mode");
+
+    // try to fetch value for key.
+    datum v_datum = gdbm_fetch(gf, *k_datum);
+    check(v_datum.dptr != NULL, "key not found");
+
+    // close db
+    rc = gdbm_close(gf);
+    check(rc == 0, "gdbm close failed");
+
+    // clean up.
+    free(k_datum);
+
+    return v_datum.dptr;
+ error:
+    if (k_datum) {
+        free(k_datum);
+    }
+    if (gf) {
+        gdbm_close(gf);
+    }
+    return NULL;
+}