Re: [Tarantool-patches] [PATCH luajit] Fix os.date() for wider libc strftime() compatibility.

[Maxim Kokryashkin via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

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Hi!
Thanks for the fixes!
LGTM.
--
Best regards,
Maxim Kokryashkin
 
 
> 
>>Hi, Maxim!
>>
>>Thanks for the review!
>>
>>Fixed your comments, branch is force-pushed.
>>
>>On 02.02.23, Maxim Kokryashkin wrote:
>>>
>>> Hi, Sergey!
>>> Thanks for the patch!
>>> LGTM, except for a few nits below.
>>> > 
>>> >>From: Mike Pall <mike>
>>> >>
>>> >>Thanks to Jesper Lundgren.
>>> >>
>>> >>(cherry picked from commit fc63c938b522e147ea728b75f385728bf4a8fc35)
>>> >>
>>> >>When `strftime()` returns empty result (for example, for "%p" on some
>>> >>locales or when LuaJIT is built with musl's `strftime()` and format
>>> >>string is invalid), the `os.date()` endless retries to format result
>>> >Typo: s/endless/endlessly/
>>> >Typo: s/format result/format the result/
>>
>>Fixed, thanks!
>>
>>> >>and reallocates buffer for resulting string. This leads to OOM.
>>> >Typo: s/buffer for resulting/the buffer for the resulting/
>>
>>Fixed, thanks!
>>
>>> >>
>>> >>This patch limits amount of retries by 4.
>>> >Typo: s/amount/the amount/
>>
>>Fixed, thanks!
>>
>>> >Side note: Why is it exactly 4?
>>
>>That's what she said:)
>>
>>> >>
>>> >>Sergey Kaplun:
>>> >>* added the description and the test for the problem
>>> >>
>>> >>Part of tarantool/tarantool#8069
>>> >>---
>>> >>
>>> >>PR:  https://github.com/tarantool/tarantool/pull/8237
>>> >>Issues:
>>> >>*  https://github.com/LuaJIT/LuaJIT/issues/463
>>> >>*  https://github.com/tarantool/tarantool/issues/8069
>>> >>Branch:  https://github.com/tarantool/luajit/tree/skaplun/lj-463-os-date-oom-full-ci
>>> >>
>>> >> src/lib_os.c | 4 ++--
>>> >> .../lj-463-os-date-oom.test.lua | 19 +++++++++++++++++++
>>> >> 2 files changed, 21 insertions(+), 2 deletions(-)
>>> >> create mode 100644 test/tarantool-tests/lj-463-os-date-oom.test.lua
>>> >>
>>> >>diff --git a/src/lib_os.c b/src/lib_os.c
>>> >>index 9e78d49a..ffbc3fdc 100644
>>> >>--- a/src/lib_os.c
>>> >>+++ b/src/lib_os.c
>>> >>@@ -205,12 +205,12 @@ LJLIB_CF(os_date)
>>> >>     setboolfield(L, "isdst", stm->tm_isdst);
>>> >>   } else if (*s) {
>>> >>     SBuf *sb = &G(L)->tmpbuf;
>>> >>- MSize sz = 0;
>>> >>+ MSize sz = 0, retry = 4;
>>> >>     const char *q;
>>> >>     for (q = s; *q; q++)
>>> >>       sz += (*q == '%') ? 30 : 1; /* Overflow doesn't matter. */
>>> >>     setsbufL(sb, L);
>>> >>- for (;;) {
>>> >>+ while (retry--) { /* Limit growth for invalid format or empty result. */
>>> >>       char *buf = lj_buf_need(sb, sz);
>>> >>       size_t len = strftime(buf, sbufsz(sb), s, stm);
>>> >>       if (len) {
>>> >>diff --git a/test/tarantool-tests/lj-463-os-date-oom.test.lua b/test/tarantool-tests/lj-463-os-date-oom.test.lua
>>> >>new file mode 100644
>>> >>index 00000000..cce78b6e
>>> >>--- /dev/null
>>> >>+++ b/test/tarantool-tests/lj-463-os-date-oom.test.lua
>>> >>@@ -0,0 +1,19 @@
>>> >>+local tap = require('tap')
>>> >>+
>>> >>+-- See also  https://github.com/LuaJIT/LuaJIT/issues/463 .
>>> >>+local test = tap.test('lj-463-os-date-oom')
>>> >>+test:plan(1)
>>> >>+
>>> >>+-- The ru_RU.utf8 locale is chosen as one that will be set on a
>>> >>+-- developer's PC with high possibility. It may be unavailable at
>>> >Typo: s/with high possibility/with a high probability/
>>
>>Fixed.
>>
>>> >>+-- CI, so don't check the status and result of function calls.
>>> >>+-- If it's unavailable `os.setlocale()` does nothing.
>>> >>+-- Before the patch, the call to `os.date('%p')` on non-standard
>>> >>+-- locale may lead to OOM.
>>> >>+
>>> >>+os.setlocale('ru_RU.utf8')
>>> >>+os.date('%p')
>>> >>+
>>> >>+test:ok(true, 'os.date() finished without OOM')
>>> >>+
>>> >>+os.exit(test:check() and 0 or 1)
>>> >>--
>>> >>2.34.1
>>> >--
>>> >Best regards,
>>> >Maxim Kokryashkin
>>> > 
>>
>>--
>>Best regards,
>>Sergey Kaplun
> 

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