[Tarantool-patches] [PATCH luajit] Add stricter check for print() vs. tostring() shortcut.
Sergey Kaplun
skaplun at tarantool.org
Mon Dec 27 13:25:24 MSK 2021
From: Mike Pall <mike>
(cherry picked from 46a1b268eb0534182eda0447303c344a071632fe)
`print()` function uses tostring to convert all incoming values to the
strings. So, if element to convert has `__tostring` metamethod it must
be used. In LuaJIT `print()` base library function has a shortcut to
detect fast path for strings and numbers. This shortcut doesn't check
metatable presence for numbers, so `__tostring` metamethod is ignored.
This patch adds the corresponding check for metatable on base number
type, when the aforementioned shortcut is set.
Sergey Kaplun:
* added the description and the test for the problem
Part of tarantool/tarantool#6548
---
Issue: https://github.com/tarantool/tarantool/issues/6548
Related issue: https://github.com/tarantool/tarantool/issues/6746
Branch: https://github.com/tarantool/luajit/tree/skaplun/gh-noticket-print-tostring-number-mt-full-ci
Tarantool branch: https://github.com/tarantool/tarantool/tree/skaplun/gh-noticket-print-tostring-number-mt-full-ci
CI is red due to integration tests failes (same as on master) or due to
connection errors.
src/lib_base.c | 3 +-
.../print-tostring-number.test.lua | 45 +++++++++++++++++++
2 files changed, 47 insertions(+), 1 deletion(-)
create mode 100644 test/tarantool-tests/print-tostring-number.test.lua
diff --git a/src/lib_base.c b/src/lib_base.c
index 3a757870..d58de10b 100644
--- a/src/lib_base.c
+++ b/src/lib_base.c
@@ -493,7 +493,8 @@ LJLIB_CF(print)
lua_gettable(L, LUA_GLOBALSINDEX);
tv = L->top-1;
}
- shortcut = (tvisfunc(tv) && funcV(tv)->c.ffid == FF_tostring);
+ shortcut = (tvisfunc(tv) && funcV(tv)->c.ffid == FF_tostring)
+ && !gcrefu(basemt_it(G(L), LJ_TNUMX));
for (i = 0; i < nargs; i++) {
cTValue *o = &L->base[i];
const char *str;
diff --git a/test/tarantool-tests/print-tostring-number.test.lua b/test/tarantool-tests/print-tostring-number.test.lua
new file mode 100644
index 00000000..862bd0f9
--- /dev/null
+++ b/test/tarantool-tests/print-tostring-number.test.lua
@@ -0,0 +1,45 @@
+local tap = require('tap')
+
+local test = tap.test('print-tostring-number')
+
+-- First field is type, second -- content of cmd.
+local test_data = {
+ {'nil', 'nil'},
+ {'boolean', 'true'},
+ {'userdata', 'newproxy()'},
+ {'number', '42'},
+ -- FIXME: This test case is disabled, because __tostring
+ -- metamethod isn't checked for string base metatable.
+ -- See also https://github.com/tarantool/tarantool/issues/6746.
+ -- {'string', '"teststr"'},
+ {'table', '{}'},
+ {'function', 'function() end'},
+ {'thread', 'coroutine.create(function() end)'},
+}
+
+local NTEST = #test_data
+test:plan(NTEST)
+
+local i = 0
+while arg[i] do i = i - 1 end
+local luabin = arg[i + 1]
+
+for j = 1, NTEST do
+ local prefix = '__tostring reloaded for '
+ local datatype = test_data[j][1]
+ local expected = prefix .. datatype
+
+ local cmd = luabin .. ([[ -e '
+ local testvar = %s
+ debug.setmetatable(testvar, {__tostring = function(a)
+ return "%s" .. type(a)
+ end})
+ print(testvar)
+ ']]):format(test_data[j][2], prefix)
+
+ local proc = io.popen(cmd)
+ local res = proc:read('*all'):gsub('%s+$', '')
+ test:ok(res == expected, expected)
+end
+
+os.exit(test:check() and 0 or 1)
--
2.34.1
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