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 connection 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.

SEE ALSO

       getnetent(3), getprotoent_r(3), getservent(3), protocols(5)

COLOPHON

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