fix: preserve B-tree result semantics in table API

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;

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";
     }

src/database.c

@@ -93,7 +93,17 @@ 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;
+        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 +232,16 @@ 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)

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);