No description
Rongsong Shen
bc3f76b42e
User-reported live crash: xce_scheduler SIGSEGV in fcfs_cursor_enter_queue (builtin_fcfs.c), called from builtin_fcfs_next_job <- sched_job_picker (picker thread). priv->cursor/priv->job_cursor (fcfs_plugin_data_t) are raw ordq_item_t* pointers that persist across SEPARATE next_job() calls, each with its own independent priv->lock acquisition/release. The existing mutual-exclusion fix (task 2.4) correctly protects the cursor walk from corruption DURING one locked call, but does nothing to stop a LATER call from dereferencing a node a properly-locked, INTERVENING call already freed. on_queue_update()'s re-sort (remove old ordq_item_t node, insert a fresh one via ordq_put) is exactly such a free -- with only one queue in the deployment, the picker's cursor is essentially always parked on it between calls (sched_queue_is_ready/sched_job_is_ready are unconditional true stubs today, so the cursor never advances away while jobs remain), making a queue config update land in that window trivially reachable. Fixed by invalidating (NULLing) whichever cursor points at a node right before that node is freed, at all three sites that can free a node the cursors might reference: on_queue_update's reuse-and-resort path (priv->cursor + priv->job_cursor in lockstep), builtin_fcfs_on_job_state_change's !JOB_IS_PEND removal, and fcfs_remove_job_everywhere's cross-queue removal loop (both job_cursor only, via an ordq_peek-then-invalidate-then-delete pattern). Always safe: next_job() treats a NULL cursor as "no more candidates this round", and begin_session() resets both cursors fresh every round regardless -- worst case is a bounded one-round delay, never a crash or a permanently lost job. New test_builtin_fcfs_cursor_uaf.c reproduces the bug fully single-threaded (next_job() releases the lock between calls, so no real concurrency is needed to hit the window). RED-phase independently confirmed a real ASAN heap-use-after-free with the exact same call chain as the live crash (freed by on_queue_update, read by next_job()); GREEN confirms 0 failures and no job permanently lost across the invalidation. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01AgYRU3zDTqNGV5Jk8aiKLg |
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| .claude | ||
| .kiro | ||
| .wolf | ||
| docs/superpowers/plans | ||
| raft | ||
| reports | ||
| scripts | ||
| src | ||
| .clang-format | ||
| .gitignore | ||
| .mcp.json | ||
| .opencode.json | ||
| CLAUDE.md | ||
| README.md | ||
1. commit 规则
- 每个人 fork 自己的 branch， 从自己的 branch 做 PR，review 完再 commit
2. code format
2.1. C
推荐使用 clang-format，公共配置放在源码里面 xce/.clang-format
（理论上直接使用源码里面 xce/.clang-format 文件格式不会变）
2.1.1. vscode 可以在配置中加上如下内容
"C_Cpp.clang_format_style": "WebKit",
"C_Cpp.clang_format_fallbackStyle": "WebKit",
2.1.2. vim & emacs
clang-format -style="{BasedOnStyle: webkit}" -i XX.c
2.2. golang
使用默认 gofmt
3. build environment and build (example of ubuntu)
3.1 build environment
- Install nix package management tool
sh <(curl -L https://nixos.org/nix/install) --daemon
- Edit /etc/nix/nix.conf to make sure
experimental-features = nix-command flakes
sandbox = true
sandbox-fallback = false
substituters = https://mirrors.ustc.edu.cn/nix-channels/store https://cache.nixos.org https://cache.nixos.org/
trusted-users = root <your account>
make sure that you have restarted nix-daemon service after you have changed /etc/nix/nix.conf
- Install socat and config ssh (for clone by ssh protocol)
nix profile add nixpkgs#socat
.ssh/config
Host gitea.shenrs.eu
HostName gitea.shenrs.eu
IdentityFile ~/.ssh/id_ed25519
ProxyCommand socat - openssl-connect:gitea.shenrs.eu:2022,snihost=gitea.shenrs.eu,verify=0
3.2 checkout source code
3.3 build (for package and release)
cd xce/src
# for build debug version
nix build --option sandbox false .#xcecore_debug
# for normal build
nix build --option sandbox false .#xcecore
You can find the generated binaries at =result= directory
3.4 build (for daily develop)
cd xce/src
nix develop
# using meson to generated build configuration (debug and address sanitize)
meson setup build --buildtype=debug -Db_sanitize=address
# run meson to build
meson compile -C build
# The generated files will be in build/
3.5 build AppImage package
cd xce/src
nix bundle --bundler github:ralismark/nix-appimage --option sandbox false .#xce
This will create all in one AppImage file which contains everything for package delivery.
4. misc
4.1. Windows remap ctrl and alt key
create a reg file, e.g. remapkey.reg
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Keyboard Layout]
"Scancode Map"=hex:00,00,00,00,00,00,00,00,05,00,00,00,38,00,1d,00,1d,00,38,00,38,e0,1d,e0,1d,e0,38,e0,00,00,00,00
then double click remapkey.reg to import it. Restart OS.