posix man page for getprotobynumber

ENDPROTOENT(P)						     POSIX Programmer's Manual						    ENDPROTOENT(P)

NAME
       endprotoent, getprotobyname, getprotobynumber, getprotoent, setprotoent - network protocol database functions

SYNOPSIS
       #include <netdb.h>

       void endprotoent(void);
       struct protoent *getprotobyname(const char *name);
       struct protoent *getprotobynumber(int proto);
       struct protoent *getprotoent(void);
       void setprotoent(int stayopen);

DESCRIPTION
       These  functions shall retrieve information about protocols. This information is considered to be stored in a database that can be accessed
       sequentially or randomly. The implementation of this database is unspecified.

       The setprotoent() function shall open a connection to the database, and set the next entry to the first entry. If the stayopen argument	is
       non-zero,  the  connection to the network protocol database shall not be closed after each call to getprotoent() (either directly, or indi-
       rectly through one of the other getproto*() functions), and the implementation may maintain an open file descriptor for the database.

       The getprotobyname() function shall search the database from the beginning and find the first entry for which the protocol  name  specified
       by name matches the p_name member, opening and closing a connection to the database as necessary.

       The  getprotobynumber() function shall search the database from the beginning and find the first entry for which the protocol number speci-
       fied by proto matches the p_proto member, opening and closing a connection to the database as necessary.

       The getprotoent() function shall read the next entry of the database, opening and closing a connection to the database as necessary.

       The getprotobyname(), getprotobynumber(), and getprotoent() functions shall each return a pointer to a protoent structure, the  members	of
       which shall contain the fields of an entry in the network protocol database.

       The endprotoent() function shall close the connection to the database, releasing any open file descriptor.

       These functions need not be reentrant. A function that is not required to be reentrant is not required to be thread-safe.

RETURN VALUE
       Upon  successful  completion,  getprotobyname(),  getprotobynumber(),  and  getprotoent()  return  a pointer to a protoent structure if the
       requested entry was found, and a null pointer if the end of the database was reached or the requested entry was	not  found.  Otherwise,  a
       null pointer is returned.

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       The  getprotobyname(), getprotobynumber(), and getprotoent() functions may return pointers to static data, which may be overwritten by sub-
       sequent calls to any of these functions.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       The Base Definitions volume of IEEE Std 1003.1-2001, <netdb.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and  the  original  IEEE
       and  The  Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003							    ENDPROTOENT(P)