[Tarantool-patches] [PATCH luajit 2/3] Fix potential file descriptor leak in luaL_loadfile*().

[Sergey Kaplun]

From: Mike Pall <mike>

Reported by Assumeru.

(cherry picked from commit 19db4e9b7c5e19398286adb4d953a4874cc39ae0)

`loadfile()` doesn't close the fd in case when `fopen()` results
successfully, but the call `lua_pushfstring()` raises the "not enough
memory" error on creation of the filename string (started with @).

This patch fixes that behaviour by moving the string creation before the
`fopen()` call to avoid descriptor leak.

Sergey Kaplun:
* added the description and the test for the problem

Part of tarantool/tarantool#11278
---
 src/lj_load.c                                 |  3 ++-
 .../lj-1249-loadfile-fd-leak.test.lua         | 27 +++++++++++++++++++
 test/tarantool-tests/utils/CMakeLists.txt     |  1 +
 3 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 test/tarantool-tests/lj-1249-loadfile-fd-leak.test.lua

diff --git a/src/lj_load.c b/src/lj_load.c
index 19ac6ba2..a6d0b464 100644
--- a/src/lj_load.c
+++ b/src/lj_load.c
@@ -88,12 +88,13 @@ LUALIB_API int luaL_loadfilex(lua_State *L, const char *filename,
   int status;
   const char *chunkname;
   if (filename) {
+    chunkname = lua_pushfstring(L, "@%s", filename);
     ctx.fp = fopen(filename, "rb");
     if (ctx.fp == NULL) {
+      L->top--;
       lua_pushfstring(L, "cannot open %s: %s", filename, strerror(errno));
       return LUA_ERRFILE;
     }
-    chunkname = lua_pushfstring(L, "@%s", filename);
   } else {
     ctx.fp = stdin;
     chunkname = "=stdin";
diff --git a/test/tarantool-tests/lj-1249-loadfile-fd-leak.test.lua b/test/tarantool-tests/lj-1249-loadfile-fd-leak.test.lua
new file mode 100644
index 00000000..c1a45724
--- /dev/null
+++ b/test/tarantool-tests/lj-1249-loadfile-fd-leak.test.lua
@@ -0,0 +1,27 @@
+local tap = require('tap')
+
+-- Test file to demonstrate fd leakage in case of OOM during the
+-- `loadfile()` call. The test fails before the patch when run
+-- under Valgrind with the `--track-fds=yes` option.
+-- See also, https://github.com/LuaJIT/LuaJIT/issues/1249.
+local test = tap.test('lj-1249-loadfile-fd-leak')
+
+test:plan(2)
+
+local allocinject = require('allocinject')
+
+allocinject.enable_null_alloc()
+
+-- Just use the /dev/null as the surely available file.
+-- OOM is due to the creation of the string "@/dev/null" as the
+-- filename to be stored.
+local res, errmsg = pcall(loadfile, '/dev/null')
+
+allocinject.disable()
+
+-- Sanity checks.
+test:ok(not res, 'correct status, OOM on filename creation')
+test:like(errmsg, 'not enough memory',
+          'correct error message, OOM on filename creation')
+
+test:done(true)
diff --git a/test/tarantool-tests/utils/CMakeLists.txt b/test/tarantool-tests/utils/CMakeLists.txt
index 15871934..d44a8802 100644
--- a/test/tarantool-tests/utils/CMakeLists.txt
+++ b/test/tarantool-tests/utils/CMakeLists.txt
@@ -2,6 +2,7 @@ list(APPEND tests
   lj-1166-error-stitch-oom-ir-buff.test.lua
   lj-1166-error-stitch-oom-snap-buff.test.lua
   lj-1247-fin-tab-rehashing-on-trace.test.lua
+  lj-1249-loadfile-fd-leak.test.lua
   lj-1298-oom-on-concat-recording.test.lua
 )
 BuildTestCLib(allocinject allocinject.c "${tests}")
-- 
2.49.0