getprotoent(3) — Linux manual page

getprotoent(3)          Library Functions Manual          getprotoent(3)

NAME

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

LIBRARY

       Standard C library (libc, -lc)

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.

STANDARDS

       POSIX.1-2008.

HISTORY

       POSIX.1-2001, 4.3BSD.

SEE ALSO

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

COLOPHON

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Linux man-pages 6.9.1          2024-05-02                 getprotoent(3)

Pages that refer to this page: getent(1), getsockopt(2), socket(2), getnetent(3), getprotoent_r(3), getservent(3), setnetgrent(3), nsswitch.conf(5), protocols(5), raw(7)

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