From 49edbb003a0aef0fd864e5f2a12228807618a175 Mon Sep 17 00:00:00 2001
From: rsiddharth <s@ricketyspace.net>
Date: Sat, 11 Apr 2020 11:27:21 -0400
Subject: nserver: Add db_load.

* nserver/src/db.c (db_load): New function definition.
* nserver/src/db.h (db_load): New function declaration.
* nserver/tests/db_tests.c (test_db_load): New test.
---
 nserver/src/db.c         | 40 +++++++++++++++++++++++++++++++++++++---
 nserver/src/db.h         |  1 +
 nserver/tests/db_tests.c | 17 +++++++++++++++++
 3 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/nserver/src/db.c b/nserver/src/db.c
index 156ec01..32701b6 100644
--- a/nserver/src/db.c
+++ b/nserver/src/db.c
@@ -22,13 +22,11 @@ datum *mk_datum(char *data)
     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.
@@ -44,7 +42,6 @@ int db_init()
     return -1;
 }
 
-
 int db_store(char *key, char *value)
 {
     datum *k_datum = NULL, *v_datum = NULL;
@@ -93,3 +90,40 @@ int db_store(char *key, char *value)
     }
     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");
+
+    // clean up.
+    free(k_datum);
+
+    return v_datum.dptr;
+ error:
+    if (k_datum) {
+        free(k_datum);
+    }
+    if (gf) {
+        gdbm_close(gf);
+    }
+    return NULL;
+}
diff --git a/nserver/src/db.h b/nserver/src/db.h
index 68af98e..1a9c243 100644
--- a/nserver/src/db.h
+++ b/nserver/src/db.h
@@ -9,6 +9,7 @@
 
 int db_init();
 int db_store(char *key, char *value);
+char *db_load(char *key);
 
 #endif
 
diff --git a/nserver/tests/db_tests.c b/nserver/tests/db_tests.c
index 33821bb..de93262 100644
--- a/nserver/tests/db_tests.c
+++ b/nserver/tests/db_tests.c
@@ -20,12 +20,29 @@ char *test_db_store()
     return NULL;
 }
 
+char *test_db_load()
+{
+    char *k = "hello";
+    char *expected_v = "kirk";
+
+    char *v = db_load(k);
+    mu_assert(v != NULL, "key not found");
+    mu_assert(strncmp(v, expected_v, strlen(expected_v)) == 0,
+              "incorrect value for key");
+
+    // cleanup.
+    free(v);
+
+    return NULL;
+}
+
 char *all_tests()
 {
     mu_suite_start();
 
     mu_run_test(test_db_init);
     mu_run_test(test_db_store);
+    mu_run_test(test_db_load);
 
     return NULL;
 }
-- 
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