From 790d75cf6edf1f17601bad711ee281c89167ae9e Mon Sep 17 00:00:00 2001
From: "Eason(G Ray)" <30045503+Eason0729@users.noreply.github.com>
Date: Sun, 18 Aug 2024 21:31:17 +0800
Subject: [PATCH] Fix unhandled negative offset

---
 .../src/m20231207_000001_create_table.rs      |  8 ++++
 backend/src/entity/util/helper.rs             | 20 +++++++++-
 backend/src/entity/util/paginator.rs          | 39 ++++++++++++-------
 backend/src/server/db.rs                      |  4 +-
 backend/src/util/bound.rs                     | 23 ++++++++---
 5 files changed, 74 insertions(+), 20 deletions(-)

diff --git a/backend/migration/src/m20231207_000001_create_table.rs b/backend/migration/src/m20231207_000001_create_table.rs
index b7d2519..bd95c52 100644
--- a/backend/migration/src/m20231207_000001_create_table.rs
+++ b/backend/migration/src/m20231207_000001_create_table.rs
@@ -668,17 +668,25 @@ impl MigrationTrait for Migration {
         index!(manager, Problem, AcceptCount);
         index!(manager, Problem, Difficulty);
         index!(manager, Problem, Order);
+        index!(manager, Problem, Content);
+        index!(manager, Problem, Title);
+
         index!(manager, Submit, Committed);
         index!(manager, Submit, Time);
         index!(manager, Submit, Memory);
+        index!(manager, Submit, UserId);
+
         index!(manager, Contest, Hoster);
         index!(manager, Contest, Public);
         index!(manager, Contest, End);
         index!(manager, Contest, Begin);
+
         index!(manager, User, Score);
         index!(manager, User, Username);
+
         index!(manager, Token, Rand);
         index!(manager, Token, Expiry);
+
         index!(manager, Chat, CreateAt);
 
         manager
diff --git a/backend/src/entity/util/helper.rs b/backend/src/entity/util/helper.rs
index b199553..5d69f9b 100644
--- a/backend/src/entity/util/helper.rs
+++ b/backend/src/entity/util/helper.rs
@@ -4,8 +4,8 @@
 
 use std::ops::Deref;
 
-use sea_orm::*;
 use sea_orm::sea_query::*;
+use sea_orm::*;
 use tracing::instrument;
 
 use crate::util::error::Error;
@@ -190,3 +190,21 @@ impl<E: EntityTrait> MaxCount<E> {
         })
     }
 }
+
+/// convert sized span to single-direction span
+///
+/// Return None if span cannot be converted(cross boundary).
+///
+/// It panics if overflow(u64 to i64).
+///
+/// See `dev.md` for sized span and single-direction span.
+pub(super) fn to_inner_size_offset(size: u64, offset: i64) -> Option<(i64, u64)> {
+    // cross boundary
+    if offset.is_negative() && size > offset.unsigned_abs() {
+        return None;
+    }
+    match offset.is_negative() {
+        true => Some((-(size as i64), offset.unsigned_abs() - size)),
+        false => Some((size as i64, offset as u64)),
+    }
+}
diff --git a/backend/src/entity/util/paginator.rs b/backend/src/entity/util/paginator.rs
index ff47389..7af82bb 100644
--- a/backend/src/entity/util/paginator.rs
+++ b/backend/src/entity/util/paginator.rs
@@ -20,7 +20,7 @@ use std::marker::PhantomData;
 
 use crate::util::error::Error;
 
-const PAGINATE_GUARANTEE: u64 = 96;
+const PAGINATE_GUARANTEE: u64 = 256;
 
 #[async_trait]
 pub trait PaginateRaw
@@ -362,6 +362,14 @@ impl<S: SortSource<R>, R: Reflect<S::Entity>> PaginateRaw for ColumnPaginator<S,
     }
 }
 
+/// A paginator that may be initialized
+///
+/// Key-set Paginator requires information from last fetched column
+/// (sometimes called trailing information) to be initialized.
+///
+/// **Can only be serialized or deserialized when initialized.**
+///
+/// **Calling fetch with size 0 doesn't initialize it!**
 #[derive(Serialize, Default)]
 pub enum UninitPaginator<P: PaginateRaw> {
     #[serde(skip)]
@@ -390,9 +398,15 @@ impl<'de, P: PaginateRaw> Deserialize<'de> for UninitPaginator<P> {
 }
 
 impl<P: PaginateRaw> UninitPaginator<P> {
+    /// construct a paginator with its initial query argument.
     pub fn new(data: <P::Source as PagerData>::Data, start_from_end: bool) -> Self {
         Self::Uninit(data, start_from_end)
     }
+    /// fetch some entries
+    ///
+    /// Return `Error::BadArgument` when
+    /// 1. offset is when paginator has yet to be initialized and offset is negative
+    /// 2. span crosses the boundary,
     pub async fn fetch(
         &mut self,
         size: u64,
@@ -401,17 +415,8 @@ impl<P: PaginateRaw> UninitPaginator<P> {
         db: &DatabaseConnection,
     ) -> Result<Vec<P::Reflect>, Error> {
         if let UninitPaginator::Init(x) = self {
-            let size = size.min((i64::MAX - 1) as u64) as i64;
-            let offset = offset.max(i64::MIN + 1);
-            let (size, offset) = match offset < 0 {
-                true => (
-                    -size,
-                    (-offset)
-                        .checked_sub(size)
-                        .ok_or(Error::BadArgument("size"))? as u64,
-                ),
-                false => (size, offset as u64),
-            };
+            let (size, offset) =
+                to_inner_size_offset(size, offset).ok_or(Error::BadArgument("size"))?;
             x.fetch(auth, size, offset, db).await.map(|mut x| {
                 if size.is_negative() {
                     x.reverse();
@@ -419,14 +424,22 @@ impl<P: PaginateRaw> UninitPaginator<P> {
                 x
             })
         } else if let UninitPaginator::Uninit(x, start_from_end) = std::mem::take(self) {
+            if offset.is_negative() {
+                return Err(Error::BadArgument("offset"));
+            }
             let (paginator, list) =
-                P::new_fetch(x, auth, size, offset.max(0) as u64, start_from_end, db).await?;
+                P::new_fetch(x, auth, size, offset as u64, start_from_end, db).await?;
             *self = UninitPaginator::Init(paginator);
             Ok(list)
         } else {
             unreachable!("Cannot in middle state")
         }
     }
+    /// get how many column are remaining the **absolute forward** direction of paginator
+    ///
+    /// If more than [`PAGINATE_GUARANTEE`], it returns [`PAGINATE_GUARANTEE`].
+    ///
+    /// It passes [`sea_orm::DbErr`] to the callee.
     pub async fn remain(&self, auth: &Auth, db: &DatabaseConnection) -> Result<u64, Error>
     where
         P: Remain,
diff --git a/backend/src/server/db.rs b/backend/src/server/db.rs
index e4b426c..4d1c20b 100644
--- a/backend/src/server/db.rs
+++ b/backend/src/server/db.rs
@@ -48,7 +48,9 @@ pub async fn init(
 #[cfg(feature = "standalone")]
 /// Run migration
 async fn migrate(db: &DatabaseConnection) -> super::Result<()> {
-    <::migration::Migrator as migration::MigratorTrait>::up(db,None).await.map_err(InitError::AutoMigrate)
+    <::migration::Migrator as migration::MigratorTrait>::up(db, None)
+        .await
+        .map_err(InitError::AutoMigrate)
 }
 
 #[instrument(skip_all, name = "construct_admin")]
diff --git a/backend/src/util/bound.rs b/backend/src/util/bound.rs
index 845a0fb..2c46a87 100644
--- a/backend/src/util/bound.rs
+++ b/backend/src/util/bound.rs
@@ -53,7 +53,7 @@ macro_rules! list_paginator_request {
         paste::paste! {
             impl BoundCheck for [<List $n Request>] {
                 fn check(&self) -> bool {
-                    if self.size==0{
+                    if self.size == 0 || self.size >= i32::MAX as u64 || self.offset.unsigned_abs() >= i32::MAX as u64{
                         true
                     }else if let Some(x) = &self.request {
                         (match x {
@@ -82,7 +82,12 @@ list_paginator_request!(User);
 
 impl BoundCheck for ListTokenRequest {
     fn check(&self) -> bool {
-        if let Some(list_token_request::Request::Paginator(x)) = &self.request {
+        if self.size == 0
+            || self.size >= i32::MAX as u64
+            || self.offset.unsigned_abs() >= i32::MAX as u64
+        {
+            true
+        } else if let Some(list_token_request::Request::Paginator(x)) = &self.request {
             x.len() > 512
         } else {
             false
@@ -92,12 +97,15 @@ impl BoundCheck for ListTokenRequest {
 
 impl BoundCheck for ListChatRequest {
     fn check(&self) -> bool {
-        self.offset == 0 || self.offset > 4096 || self.size > 128
+        self.offset == 0 || self.offset.unsigned_abs() > 4096 || self.size > 128
     }
 }
 impl BoundCheck for ListSubmitRequest {
     fn check(&self) -> bool {
-        if self.offset == 0 {
+        if self.size == 0
+            || self.size >= i32::MAX as u64
+            || self.offset.unsigned_abs() >= i32::MAX as u64
+        {
             true
         } else if let Some(list_submit_request::Request::Paginator(x)) = &self.request {
             x.len() > 512
@@ -108,7 +116,12 @@ impl BoundCheck for ListSubmitRequest {
 }
 impl BoundCheck for ListTestcaseRequest {
     fn check(&self) -> bool {
-        if let Some(list_testcase_request::Request::Paginator(x)) = &self.request {
+        if self.size == 0
+            || self.size >= i32::MAX as u64
+            || self.offset.unsigned_abs() >= i32::MAX as u64
+        {
+            true
+        } else if let Some(list_testcase_request::Request::Paginator(x)) = &self.request {
             x.len() > 512
         } else {
             false