formatcvt/android-ndk-vsnprintf-issue

android ndk vsnprintf issue

Description

On some Android devices vsprintf returns -1 with any buffer size inside separated thread for non-english languages.

Steps to reproduce:

1. Take any format function (i've tried many). For example this one https://github.com/cocos2d/cocos2d-x/blob/cocos2d-x-3.17/cocos/base/ccUTF8.cpp#L43
2. Call format function in separated thread twice with delay (1-2 sec) with non-english language text.

Example code:

std::thread _thread = std::thread([](){
    std::string test1 = format("Any text here. Language doesn't matter %d", 1);
    // sleep is important. vsnprint stop working (returns -1) after some delay, not immediately
    sleep(2);
    // non-english language is important
    std::string test2 = format("运送%d个乘客！电工、防火员和警察不算", 1);
});
_thread.detach();

Or use this test case

Environment Details

• NDK Version: staring from r15c (with r14b everything is fine)
• Build system: cmake/ndk-build
• Host OS: MacOS 10.13.6/Linux Ubuntu 16.04
• Compiler: clang
• ABI: armeabi-v7a
• STL: c++_static
• NDK API level: 16
• Device API level: 24, 26

Non-affected devices (tested)

• Samsung GT-I9082 (Android 4.2.2, API 17)
• Xiaomi Mi A1 (Android 8.1.0, API 27)
• DIGMA VOX S501 3G VS5002PG (Android 5.1, API 22)
• TCL 5065D (Android 5.1.1, API 22)
• Sony E5303 (Android 6.0 API 23)
• Google Pixel XL (Android 9, API 28)
• Google Pixel 3 XL (Android 9, API 28)

Affected devices (tested):

• Xiaomi Mi PAD 3 (Android 7.0.0, API 24)

Affected devices (according to top devices from crashlytics issue):

• TCT (Alcatel) Alcatel 1X (U5A_PLUS_4G), Android 8.1
• Xiaomi Redmi 6A (cactus), Android 8.1
• Xiaomi Redmi 6 (cereus), Android 8.1
• Huawei Honor 7A (HWDUA-M), Android 8.1

Screenshots: