【Consultation】getservbyname alaways return NULL

[ZhongYi-LinuxDriverDev]

I'm having some problems with the ftplib library and would like to ask you for advice.
I failed to call Connect() in initramfs to log in to the FTP server.
I checked the code of ftplib.cpp and found that getservbyname() returned a failure.

if ((pse = getservbyname("ftp","tcp")) == NULL)
	{
		perror("getservbyname");
		free(lhost);
		return 0;
	}

However,Connect in romfs can successfully login to the ftp server
I tried to copy /etc/services from romfs to initramfs , but it still failed to log in.
I do not know what is wrong, Can you give me some suggestions?

[mkulke]

in initramfs there might not be a libc implementation to resolve the hostname?