The program runs on ARM V7 platform and reports an error

[why5684784]

I have a program in mono termux 6.12.0.122-arm64-android24. tar. XZ works normally, but switch to mono termux 6.12.0.122-armv7a-android21. tar. XZ, report an error.

Error content:

Unhandled Exception:

System. EntryPointNotFoundException: getdomainname assembly: type: member:(null)

at (wrapper managed-to-native) System. Net. NetworkInformation. CommonUnixIPGlobalProperties. getdomainname(byte[],int)

at System. Net. NetworkInformation. CommonUnixIPGlobalProperties. get_ DomainName () [0x0000b] in <49b03f92059344cc840103fd28261b35>:0

at System. Net. CookieContainer.. ctor () [0x0003f] in <49b03f92059344cc840103fd28261b35>:0

Code used: System.Net.CookieContainer cookieContainer = new System.Net.CookieContainer();

How can I repair it?

[IanusInferus]

getdomainname is used by CommonUnixIPGlobalProperties. https://github.com/mono/mono/blob/main/mcs/class/System/System.Net.NetworkInformation/UnixIPGlobalProperties.cs

[DllImport ("libc")]
static extern int getdomainname ([MarshalAs (UnmanagedType.LPArray, SizeParamIndex = 1)] byte [] name, int len);

getdomainname is added to Android bionic on Android API Level 26. https://android.googlesource.com/platform/prebuilts/ndk/+/refs/tags/ndk-r25/platform/sysroot/usr/include/unistd.h

#if __ANDROID_API__ >= 26
int getdomainname(char* __buf, size_t __buf_size) __INTRODUCED_IN(26);
int setdomainname(const char* __name, size_t __n) __INTRODUCED_IN(26);
#endif /* __ANDROID_API__ >= 26 */

CookieContainer calls DomainName. https://github.com/mono/mono/blob/main/mcs/class/referencesource/System/net/System/Net/cookiecontainer.cs

public CookieContainer() {
#if !WASM        
    string domain = IPGlobalProperties.InternalGetIPGlobalProperties().DomainName;
    if (domain != null && domain.Length > 1)
    {
        m_fqdnMyDomain = '.' + domain;
    }
#endif            
    //Otherwise it will remain string.Empty
}

If you can not set minimum API Level to 26, I think you can remove the code in #if and recompile mscorlib.dll. You can do this on PC and copy mscorlib.dll to Android device.

[why5684784]

I have upgraded my mobile phone system from Android 7.1.1 to Android 9.0, and then it is normal.

[IanusInferus]

Android 7.1 is API Level 25. This explains the problem.