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GETPROTOENT(3) Linux Programmer's Manual GETPROTOENT(3)

NAME

     getprotoent, getprotobyname, getprotobynumber, setprotoent, endprotoent
     - get protocol entry

SYNOPSIS

     #include <netdb.h>

     struct protoent *getprotoent(void);

     struct protoent *getprotobyname(const char *name);

     struct protoent *getprotobynumber(int proto);

     void setprotoent(int stayopen);

     void endprotoent(void);

DESCRIPTION

     The getprotoent() function reads the  next  entry  from  the  protocols
     database (see protocols(5)) and returns a protoent structure containing
     the broken-out fields from the entry.  A connection is  opened  to  the
     database if necessary.

     The  getprotobyname()  function  returns  a  protoent structure for the
     entry from the database that matches the protocol name name.  A connec-
     tion is opened to the database if necessary.

     The  getprotobynumber()  function  returns a protoent structure for the
     entry from the database that matches the  protocol  number  number.   A
     connection is opened to the database if necessary.

     The setprotoent() function opens a connection to the database, and sets
     the next entry to the first entry.  If stayopen is  nonzero,  then  the
     connection  to  the database will not be closed between calls to one of
     the getproto*() functions.

     The endprotoent() function closes the connection to the database.

     The protoent structure is defined in <netdb.h> as follows:

         struct protoent {
             char  *p_name;       /* official protocol name */
             char **p_aliases;    /* alias list */
             int    p_proto;      /* protocol number */ }

     The members of the protoent structure are:

     p_name The official name of the protocol.

     p_aliases
            A NULL-terminated list of alternative names for the protocol.

     p_proto
            The protocol number.

RETURN VALUE

     The getprotoent(), getprotobyname()  and  getprotobynumber()  functions
     return  a  pointer  to  a statically allocated protoent structure, or a
     null pointer if an error occurs or the end of the file is reached.

FILES

     /etc/protocols
            protocol database file

ATTRIBUTES

     For  an  explanation  of  the  terms  used   in   this   section,   see
     attributes(7).

     +-------------------+---------------+------------------------------+
     |Interface          | Attribute     | Value                        |
     +-------------------+---------------+------------------------------+
     |getprotoent()      | Thread safety | MT-Unsafe race:protoent      |
     |                   |               | race:protoentbuf locale      |
     +-------------------+---------------+------------------------------+
     |getprotobyname()   | Thread safety | MT-Unsafe race:protobyname   |
     |                   |               | locale                       |
     +-------------------+---------------+------------------------------+
     |getprotobynumber() | Thread safety | MT-Unsafe race:protobynumber |
     |                   |               | locale                       |
     +-------------------+---------------+------------------------------+
     |setprotoent(),     | Thread safety | MT-Unsafe race:protoent      |
     |endprotoent()      |               | locale                       |
     +-------------------+---------------+------------------------------+
     In  the above table, protoent in race:protoent signifies that if any of
     the functions setprotoent(), getprotoent(), or endprotoent()  are  used
     in  parallel  in  different threads of a program, then data races could
     occur.

CONFORMING TO

     POSIX.1-2001, POSIX.1-2008, 4.3BSD.