Relationship to the XSH Specification

 Error Numbers

Some functions provide an error number in errno, which is either a variable or macro defined in <errno.h>; the macro expands to a modifiable lvalue of type int.

A list of valid values for errno and advice to application writers on the use of errno appears in the XSH specification.

 Thread Safety

All interfaces defined by this document will be thread-safe, except for the following interfaces which need not be thread-safe:

gethostbyaddr()
gethostbyname()
gethostent()
getnetbyaddr()
getnetbyname()
getnetent()
getprotobynumber()
getprotobyname()
getprotoent()
getservbyname()
getservbyport()
getservent()
inet_ntoa()

 Thread Cancellation Points

Cancellation points will occur when a thread is executing any of the following functions:

accept()
connect()
recv()
recvfrom()
recvmsg()
send()
sendmsg()
sendto()
t_close()
t_connect()
t_listen()
t_rcv()
t_rcvconnect()
t_rcvrel()
t_rcvreldata()
t_rcvudata()
t_rcvv()
t_rcvvudata()
t_snd()
t_sndrel()
t_sndreldata()
t_sndudata()
t_sndv()
t_sndvudata()

A cancellation point may also occur when a thread is executing any of the following functions:

endhostent()
endnetent()
endprotoent()
endservent()
gethostbyaddr()
gethostbyname()
gethostent()
gethostname()
getnetbyaddr()
getnetbyname()
getnetent()
getprotobynumber()
getprotobyname()
getprotoent()
getservbyport()
getservbyname()
getservent()
sethostent()
setnetent()
setprotoent()
setservent()

An implementation will not introduce cancellation points into any other function specified in this document.

See the XSH, Section 2.8 for further information.

 Relationship to Emerging Formal Standards

The IEEE 1003.1g standards committee is also developing interfaces to XTI and Sockets. X/Open is actively involved in the work of this committee.