Fix malfunction of socket functions on HP-UX in 64-bit mode. * m4/socketlib.m4 (gl_SOCKETLIB): Add comment. * m4/extensions.m4 (AC_USE_SYSTEM_EXTENSIONS): Define _HPUX_ALT_XOPEN_SOCKET_API. * modules/accept (Depends-on): Add 'extensions'. * modules/getpeername (Depends-on): Likewise. * modules/getsockname (Depends-on): Likewise. * modules/getsockopt (Depends-on): Likewise. * modules/recvfrom (Depends-on): Likewise. * doc/posix-functions/accept.texi: Mention the HP-UX socklen_t problem. * doc/posix-functions/getpeername.texi: Likewise. * doc/posix-functions/getsockname.texi: Likewise. * doc/posix-functions/getsockopt.texi: Likewise. * doc/posix-functions/recvfrom.texi: Likewise.

--- a/doc/posix-functions/getpeername.texi	Sat Jan 27 08:52:31 2018 +0100
+++ b/doc/posix-functions/getpeername.texi	Sat Jan 27 10:57:59 2018 +0100
@@ -12,6 +12,11 @@
 On Windows platforms (excluding Cygwin), error codes from this function
 are not placed in @code{errno}, and @code{WSAGetLastError} must be used
 instead.
+@item
+On HP-UX 11, in 64-bit mode, when the macro @code{_HPUX_ALT_XOPEN_SOCKET_API}
+is not defined, this function behaves incorrectly because it is declared
+to take a pointer to a 64-bit wide @code{socklen_t} entity but in fact
+considers it as a pointer to a 32-bit wide @code{unsigned int} entity.
 @end itemize
 
 Portability problems not fixed by Gnulib: