From 91c17baf6b7a7df2baaafea36c3f956a15ceaa10 Mon Sep 17 00:00:00 2001
From: All Asmaul Husnain <2263081025@uttarauniversity.edu.bd>
Date: Wed, 4 Nov 2026 03:17:54 +0600
Subject: [PATCH 1/5] refactor: distinguish B-tree lookup misses

---
 include/btree.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/btree.h b/include/btree.h
index 3e02583..cdcb1c9 100644
--- a/include/btree.h
+++ b/include/btree.h
@@ -12,7 +12,8 @@ typedef enum {
     BTREE_IO_ERROR,
     BTREE_DUPLICATE_KEY,
     BTREE_TABLE_FULL,
-    BTREE_CORRUPT
+    BTREE_CORRUPT,
+    BTREE_ROW_NOT_FOUND
 } BTreeResult;
 
 typedef struct BTree BTree;

From c66aa73aa55e9a673533fe3fac71e591ac11b4e9 Mon Sep 17 00:00:00 2001
From: All Asmaul Husnain <2263081025@uttarauniversity.edu.bd>
Date: Wed, 4 Nov 2026 03:17:59 +0600
Subject: [PATCH 2/5] fix: preserve B-tree lookup result semantics

---
 src/btree.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/btree.c b/src/btree.c
index bec39d2..8a1f144 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -779,7 +779,7 @@ BTreeResult btree_find(const BTree *tree, int id, Row *row)
                 deserialize_row(row, const_leaf_cell(page, index));
                 return BTREE_OK;
             }
-            return BTREE_INVALID_ARGUMENT;
+            return BTREE_ROW_NOT_FOUND;
         }
 
         page_number = child_page_at(page, internal_child_index(page, id));
@@ -899,6 +899,8 @@ const char *btree_result_string(BTreeResult result)
         return "database capacity reached";
     case BTREE_CORRUPT:
         return "database file is corrupt";
+    case BTREE_ROW_NOT_FOUND:
+        return "row not found";
     default:
         return "unknown error";
     }

From aa4e4503fb3b89da932adcdb660d29f67bb857b5 Mon Sep 17 00:00:00 2001
From: All Asmaul Husnain <2263081025@uttarauniversity.edu.bd>
Date: Wed, 4 Nov 2026 03:18:03 +0600
Subject: [PATCH 3/5] fix: propagate B-tree open read errors

---
 src/database.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/database.c b/src/database.c
index e4319a6..701dcf6 100644
--- a/src/database.c
+++ b/src/database.c
@@ -93,7 +93,18 @@ Table *table_open(const char *filename, SqliteResult *result)
         btree_read_all(tree, table->rows, TABLE_ROW_CAPACITY, &table->size);
     if (read_result != BTREE_OK) {
         table_destroy(table);
-        *result = SQLITE_IO_ERROR;
+        table_destroy(table);
+        switch (read_result) {
+        case BTREE_CORRUPT:
+            *result = SQLITE_CORRUPT;
+            break;
+        case BTREE_TABLE_FULL:
+            *result = SQLITE_TABLE_FULL;
+            break;
+        default:
+            *result = SQLITE_IO_ERROR;
+            break;
+        }
         return NULL;
     }
 
@@ -222,11 +233,16 @@ SqliteResult table_find(const Table *table, int id, Row *row)
         return SQLITE_OK;
     }
 
-    if (result == BTREE_INVALID_ARGUMENT) {
+    switch (result) {
+    case BTREE_ROW_NOT_FOUND:
         return SQLITE_ROW_NOT_FOUND;
+    case BTREE_CORRUPT:
+        return SQLITE_CORRUPT;
+    case BTREE_TABLE_FULL:
+        return SQLITE_TABLE_FULL;
+    default:
+        return SQLITE_IO_ERROR;
     }
-
-    return SQLITE_IO_ERROR;
 }
 
 const char *sqlite_result_string(SqliteResult result)

From aeef3962612d20a9b2774715e907a7d28425dbff Mon Sep 17 00:00:00 2001
From: All Asmaul Husnain <2263081025@uttarauniversity.edu.bd>
Date: Wed, 4 Nov 2026 03:18:07 +0600
Subject: [PATCH 4/5] test: assert exact missing-row result

---
 tests/test_database.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/test_database.c b/tests/test_database.c
index 04c5103..7b35f14 100644
--- a/tests/test_database.c
+++ b/tests/test_database.c
@@ -143,7 +143,7 @@ static void test_lookup(void)
     assert(found.id == 23);
     assert(strcmp(found.username, "user23") == 0);
 
-    assert(table_find(table, 99, &found) != SQLITE_OK);
+    assert(table_find(table, 99, &found) == SQLITE_ROW_NOT_FOUND);
 
     table_destroy(table);
     remove(filename);

From e94d350821f5f08928087340745713fc567b8948 Mon Sep 17 00:00:00 2001
From: All Asmaul Husnain <2263081025@uttarauniversity.edu.bd>
Date: Wed, 4 Nov 2026 03:18:33 +0600
Subject: [PATCH 5/5] fix: avoid duplicate table cleanup on open failure

---
 src/database.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/database.c b/src/database.c
index 701dcf6..81eb884 100644
--- a/src/database.c
+++ b/src/database.c
@@ -92,7 +92,6 @@ Table *table_open(const char *filename, SqliteResult *result)
     BTreeResult read_result =
         btree_read_all(tree, table->rows, TABLE_ROW_CAPACITY, &table->size);
     if (read_result != BTREE_OK) {
-        table_destroy(table);
         table_destroy(table);
         switch (read_result) {
         case BTREE_CORRUPT: