where is apr_sendfile() implementation?

[Albert Yu]

Hi,

I am debugging httpd 2.0.45, I found a problem to read files
on QStar repository.

I found sendfile_it_all() in core.c calls apr_sendfile()

I searched the whole source code in the source package, I
just could not find its implementation. I added printf() to
all apr_socket_sendfile(),
they seem not being called.

Could somebody tell me where the apr_sendfile()
implementation is, or how it works

Thanks.

Best regards,

Albert