net/getprotoent.3

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  32 .\"     @(#)getprotoent.3       8.1 (Berkeley) 6/4/93
  33 .\" $FreeBSD: src/lib/libc/net/getprotoent.3,v 1.8 2001/10/01 16:08:55 ru Exp $
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  35 .Dd June 4, 1993
  36 .Dt GETPROTOENT 3
  37 .Os
  38 .Sh NAME
  39 .Nm getprotoent ,
  40 .Nm getprotobynumber ,
  41 .Nm getprotobyname ,
  42 .Nm setprotoent ,
  43 .Nm endprotoent
  44 .Nd get protocol entry
  45 .Sh LIBRARY
  46 .Lb libc
  47 .Sh SYNOPSIS
  48 .In netdb.h
  49 .Ft struct protoent *
  50 .Fn getprotoent void
  51 .Ft struct protoent *
  52 .Fn getprotobyname "const char *name"
  53 .Ft struct protoent *
  54 .Fn getprotobynumber "int proto"
  55 .Ft void
  56 .Fn setprotoent "int stayopen"
  57 .Ft void
  58 .Fn endprotoent void
  59 .Sh DESCRIPTION
  60 The
  61 .Fn getprotoent ,
  62 .Fn getprotobyname ,
  63 and
  64 .Fn getprotobynumber
  65 functions
  66 each return a pointer to an object with the
  67 following structure
  68 containing the broken-out
  69 fields of a line in the network protocol data base,
  70 .Pa /etc/protocols .
  71 .Bd -literal -offset indent
  72 .Pp
  73 struct  protoent {
  74         char    *p_name;        /* official name of protocol */
  75         char    **p_aliases;    /* alias list */
  76         int     p_proto;        /* protocol number */
  77 };
  78 .Ed
  79 .Pp
  80 The members of this structure are:
  81 .Bl -tag -width p_aliases
  82 .It Fa p_name
  83 The official name of the protocol.
  84 .It Fa p_aliases
  85 A zero terminated list of alternate names for the protocol.
  86 .It Fa p_proto
  87 The protocol number.
  88 .El
  89 .Pp
  90 The
  91 .Fn getprotoent
  92 function
  93 reads the next line of the file, opening the file if necessary.
  94 .Pp
  95 The
  96 .Fn setprotoent
  97 function
  98 opens and rewinds the file.  If the
  99 .Fa stayopen
 100 flag is non-zero,
 101 the net data base will not be closed after each call to
 102 .Fn getprotobyname
 103 or
 104 .Fn getprotobynumber .
 105 .Pp
 106 The
 107 .Fn endprotoent
 108 function
 109 closes the file.
 110 .Pp
 111 The
 112 .Fn getprotobyname
 113 function
 114 and
 115 .Fn getprotobynumber
 116 sequentially search from the beginning
 117 of the file until a matching
 118 protocol name or
 119 protocol number is found,
 120 or until
 121 .Dv EOF
 122 is encountered.
 123 .Sh RETURN VALUES
 124 Null pointer
 125 (0) returned on
 126 .Dv EOF
 127 or error.
 128 .Sh FILES
 129 .Bl -tag -width /etc/protocols -compact
 130 .It Pa /etc/protocols
 131 .El
 132 .Sh SEE ALSO
 133 .Xr protocols 5
 134 .Sh HISTORY
 135 The
 136 .Fn getprotoent ,
 137 .Fn getprotobynumber ,
 138 .Fn getprotobyname ,
 139 .Fn setprotoent ,
 140 and
 141 .Fn endprotoent
 142 functions appeared in
 143 .Bx 4.2 .
 144 .Sh BUGS
 145 These functions use a static data space;
 146 if the data is needed for future use, it should be
 147 copied before any subsequent calls overwrite it.
 148 Only the Internet
 149 protocols are currently understood.