From e6330986d0c8d638e20cc1cd7d443689268078f0 Mon Sep 17 00:00:00 2001
From: Dennis Shen <dzshen@google.com>
Date: Wed, 20 Dec 2023 19:27:19 +0000
Subject: [PATCH] aconfig: add whole table serialization test

1, Add whole table serialization test to also lock down how the buckets
are serialized. Before this change, we are only locking down the header
and nodes serialization.

2, Switch over to the absolute offset in the file instead of relative
offset. Before we are using relative offset. For example, if a bucket is
Some(10), it means that it is pointing to 10 bytes over the start of the
node region of the table. Now it will be the absolute byte offset with
respect to the start of the table.

Bug: b/312243587
Test: atest aconfig.test
Change-Id: If7abc8c6b6687c0bc0c40bbfc6afbe0e46ece770
---
 tools/aconfig/src/storage/package_table.rs | 54 +++++++++++++++++-----
 1 file changed, 43 insertions(+), 11 deletions(-)

diff --git a/tools/aconfig/src/storage/package_table.rs b/tools/aconfig/src/storage/package_table.rs
index a6ce013309..940c5b2f64 100644
--- a/tools/aconfig/src/storage/package_table.rs
+++ b/tools/aconfig/src/storage/package_table.rs
@@ -87,6 +87,7 @@ impl PackageTableNode {
     }
 }
 
+#[derive(PartialEq, Debug)]
 pub struct PackageTable {
     pub header: PackageTableHeader,
     pub buckets: Vec<Option<u32>>,
@@ -104,11 +105,17 @@ impl PackageTable {
             nodes: packages.iter().map(|pkg| PackageTableNode::new(pkg, num_buckets)).collect(),
         };
 
+        // initialize all header fields
+        table.header.bucket_offset = table.header.as_bytes().len() as u32;
+        table.header.node_offset = table.header.bucket_offset + num_buckets * 4;
+        table.header.file_size = table.header.node_offset
+            + table.nodes.iter().map(|x| x.as_bytes().len()).sum::<usize>() as u32;
+
         // sort nodes by bucket index for efficiency
         table.nodes.sort_by(|a, b| a.bucket_index.cmp(&b.bucket_index));
 
         // fill all node offset
-        let mut offset = 0;
+        let mut offset = table.header.node_offset;
         for i in 0..table.nodes.len() {
             let node_bucket_idx = table.nodes[i].bucket_index;
             let next_node_bucket_idx = if i + 1 < table.nodes.len() {
@@ -129,12 +136,6 @@ impl PackageTable {
             }
         }
 
-        // fill table region offset
-        table.header.bucket_offset = table.header.as_bytes().len() as u32;
-        table.header.node_offset = table.header.bucket_offset + num_buckets * 4;
-        table.header.file_size = table.header.node_offset
-            + table.nodes.iter().map(|x| x.as_bytes().len()).sum::<usize>() as u32;
-
         Ok(table)
     }
 
@@ -190,6 +191,32 @@ mod tests {
         }
     }
 
+    impl PackageTable {
+        // test only method to deserialize back into the table struct
+        fn from_bytes(bytes: &[u8]) -> Result<Self> {
+            let header = PackageTableHeader::from_bytes(bytes)?;
+            let num_packages = header.num_packages;
+            let num_buckets = storage::get_table_size(num_packages)?;
+            let mut head = header.as_bytes().len();
+            let buckets = (0..num_buckets)
+                .map(|_| match read_u32_from_bytes(bytes, &mut head).unwrap() {
+                    0 => None,
+                    val => Some(val),
+                })
+                .collect();
+            let nodes = (0..num_packages)
+                .map(|_| {
+                    let node = PackageTableNode::from_bytes(&bytes[head..], num_buckets).unwrap();
+                    head += node.as_bytes().len();
+                    node
+                })
+                .collect();
+
+            let table = Self { header, buckets, nodes };
+            Ok(table)
+        }
+    }
+
     pub fn create_test_package_table() -> Result<PackageTable> {
         let caches = parse_all_test_flags();
         let packages = group_flags_by_package(caches.iter());
@@ -214,7 +241,7 @@ mod tests {
         assert_eq!(header, &expected_header);
 
         let buckets: &Vec<Option<u32>> = &package_table.as_ref().unwrap().buckets;
-        let expected: Vec<Option<u32>> = vec![Some(0), None, None, Some(50), None, None, None];
+        let expected: Vec<Option<u32>> = vec![Some(58), None, None, Some(108), None, None, None];
         assert_eq!(buckets, &expected);
 
         let nodes: &Vec<PackageTableNode> = &package_table.as_ref().unwrap().nodes;
@@ -231,7 +258,7 @@ mod tests {
             package_name: String::from("com.android.aconfig.storage.test_1"),
             package_id: 0,
             boolean_offset: 0,
-            next_offset: Some(100),
+            next_offset: Some(158),
             bucket_index: 3,
         };
         assert_eq!(nodes[1], second_node_expected);
@@ -250,18 +277,23 @@ mod tests {
     fn test_serialization() {
         let package_table = create_test_package_table();
         assert!(package_table.is_ok());
+        let package_table = package_table.unwrap();
 
-        let header: &PackageTableHeader = &package_table.as_ref().unwrap().header;
+        let header: &PackageTableHeader = &package_table.header;
         let reinterpreted_header = PackageTableHeader::from_bytes(&header.as_bytes());
         assert!(reinterpreted_header.is_ok());
         assert_eq!(header, &reinterpreted_header.unwrap());
 
-        let nodes: &Vec<PackageTableNode> = &package_table.as_ref().unwrap().nodes;
+        let nodes: &Vec<PackageTableNode> = &package_table.nodes;
         let num_buckets = storage::get_table_size(header.num_packages).unwrap();
         for node in nodes.iter() {
             let reinterpreted_node = PackageTableNode::from_bytes(&node.as_bytes(), num_buckets);
             assert!(reinterpreted_node.is_ok());
             assert_eq!(node, &reinterpreted_node.unwrap());
         }
+
+        let reinterpreted_table = PackageTable::from_bytes(&package_table.as_bytes());
+        assert!(reinterpreted_table.is_ok());
+        assert_eq!(&package_table, &reinterpreted_table.unwrap());
     }
 }