gen.subproj/getservent.3

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  28 .\"     From: @(#)getservent.3  8.3 (Berkeley) 1/12/94
  29 .\" $FreeBSD: src/lib/libc/net/getservent.3,v 1.15 2007/01/09 00:28:02 imp Exp $
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  31 .Dd July 9, 1995
  32 .Dt GETSERVENT 3
  33 .Os
  34 .Sh NAME
  35 .Nm getservent ,
  36 .Nm getservbyport ,
  37 .Nm getservbyname ,
  38 .Nm setservent ,
  39 .Nm endservent
  40 .Nd get service entry
  41 .Sh LIBRARY
  42 .Lb libc
  43 .Sh SYNOPSIS
  44 .In netdb.h
  45 .Ft struct servent *
  46 .Fn getservent
  47 .Ft struct servent *
  48 .Fn getservbyname "const char *name" "const char *proto"
  49 .Ft struct servent *
  50 .Fn getservbyport "int port" "const char *proto"
  51 .Ft void
  52 .Fn setservent "int stayopen"
  53 .Ft void
  54 .Fn endservent void
  55 .Sh DESCRIPTION
  56 The
  57 .Fn getservent ,
  58 .Fn getservbyname ,
  59 and
  60 .Fn getservbyport
  61 functions
  62 each return a pointer to an object with the
  63 following structure
  64 containing the broken-out
  65 fields of a line in the network services data base,
  66 .Pa /etc/services .
  67 .Bd -literal -offset indent
  68 struct  servent {
  69         char    *s_name;        /* official name of service */
  70         char    **s_aliases;    /* alias list */
  71         int     s_port;         /* port service resides at */
  72         char    *s_proto;       /* protocol to use */
  73 };
  74 .Ed
  75 .Pp
  76 The members of this structure are:
  77 .Bl -tag -width s_aliases
  78 .It Fa s_name
  79 The official name of the service.
  80 .It Fa s_aliases
  81 A zero terminated list of alternate names for the service.
  82 .It Fa s_port
  83 The port number at which the service resides.
  84 Port numbers are returned in network byte order.
  85 .It Fa s_proto
  86 The name of the protocol to use when contacting the
  87 service.
  88 .El
  89 .Pp
  90 The
  91 .Fn getservent
  92 function
  93 reads the next line of the file, opening the file if necessary.
  94 .Pp
  95 The
  96 .Fn setservent
  97 function
  98 opens and rewinds the file.
  99 If the
 100 .Fa stayopen
 101 flag is non-zero,
 102 the net data base will not be closed after each call to
 103 .Fn getservbyname
 104 or
 105 .Fn getservbyport .
 106 .Pp
 107 The
 108 .Fn endservent
 109 function
 110 closes the file.
 111 .Pp
 112 The
 113 .Fn getservbyname
 114 and
 115 .Fn getservbyport
 116 functions
 117 sequentially search from the beginning
 118 of the file until a matching
 119 protocol name or
 120 port number (which must be specified in
 121 network byte order) is found,
 122 or until
 123 .Dv EOF
 124 is encountered.
 125 If a protocol name is also supplied (non-
 126 .Dv NULL ) ,
 127 searches must also match the protocol.
 128 .Sh FILES
 129 .Bl -tag -width /etc/services -compact
 130 .It Pa /etc/services
 131 .El
 132 .Sh DIAGNOSTICS
 133 Null pointer
 134 (0) returned on
 135 .Dv EOF
 136 or error.
 137 .Sh SEE ALSO
 138 .Xr getprotoent 3 ,
 139 .Xr services 5
 140 .Sh HISTORY
 141 The
 142 .Fn getservent ,
 143 .Fn getservbyport ,
 144 .Fn getservbyname ,
 145 .Fn setservent ,
 146 and
 147 .Fn endservent
 148 functions appeared in
 149 .Bx 4.2 .
 150 .Sh BUGS
 151 These functions use a thread-specific data storage;
 152 if the data is needed for future use, it should be
 153 copied before any subsequent calls overwrite it.
 154 Expecting port numbers to fit in a 32 bit
 155 quantity is probably naive.