man3/setnetgrent.3

   1 .\"  Copyright 2002 walter harms (walter.harms@informatik.uni-oldenburg.de)
   2 .\"
   3 .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
   4 .\" Distributed under GPL
   5 .\" %%%LICENSE_END
   6 .\"
   7 .\"  based on glibc infopages
   8 .\" polished - aeb
   9 .\"
  10 .TH SETNETGRENT 3 2015-04-19 "GNU" "Linux Programmer's Manual"
  11 .SH NAME
  12 setnetgrent, endnetgrent, getnetgrent, getnetgrent_r, innetgr \-
  13 handle network group entries
  14 .SH SYNOPSIS
  15 .nf
  16 .B #include <netdb.h>
  17
  18 .BI "int setnetgrent(const char *" netgroup );
  19
  20 .B "void endnetgrent(void);"
  21
  22 .BI "int getnetgrent(char **" host ", char **" user ", char **" domain );
  23
  24 .BI "int getnetgrent_r(char **" host ", char **" user ","
  25 .BI "                  char **" domain ", char *" buf ", size_t " buflen );
  26
  27 .BI "int innetgr(const char *" netgroup ", const char *" host ","
  28 .BI "            const char *" user ", const char *" domain );
  29 .fi
  30 .sp
  31 .in -4n
  32 Feature Test Macro Requirements for glibc (see
  33 .BR feature_test_macros (7)):
  34 .in
  35 .sp
  36 .ad l
  37 .BR setnetgrent (),
  38 .BR endnetgrent (),
  39 .BR getnetgrent (),
  40 .BR getnetgrent_r (),
  41 .BR innetgr ():
  42 _BSD_SOURCE || _SVID_SOURCE
  43 .ad b
  44 .SH DESCRIPTION
  45 The
  46 .I netgroup
  47 is a SunOS invention.
  48 A netgroup database is a list of string triples
  49 .RI ( hostname ", " username ", " domainname )
  50 or other netgroup names.
  51 Any of the elements in a triple can be empty,
  52 which means that anything matches.
  53 The functions described here allow access to the netgroup databases.
  54 The file
  55 .I /etc/nsswitch.conf
  56 defines what database is searched.
  57 .PP
  58 The
  59 .BR setnetgrent ()
  60 call defines the netgroup that will be searched by subsequent
  61 .BR getnetgrent ()
  62 calls.
  63 The
  64 .BR getnetgrent ()
  65 function retrieves the next netgroup entry, and returns pointers in
  66 .IR host ,
  67 .IR user ,
  68 .IR domain .
  69 A null pointer means that the corresponding entry matches any string.
  70 The pointers are valid only as long as there is no call to other
  71 netgroup-related functions.
  72 To avoid this problem you can use the GNU function
  73 .BR getnetgrent_r ()
  74 that stores the strings in the supplied buffer.
  75 To free all allocated buffers use
  76 .BR endnetgrent ().
  77 .PP
  78 In most cases you want to check only if the triplet
  79 .RI ( hostname ", " username ", " domainname )
  80 is a member of a netgroup.
  81 The function
  82 .BR innetgr ()
  83 can be used for this without calling the above three functions.
  84 Again, a null pointer is a wildcard and matches any string.
  85 The function is thread-safe.
  86 .SH RETURN VALUE
  87 These functions return 1 on success and 0 for failure.
  88 .SH FILES
  89 .I /etc/netgroup
  90 .br
  91 .I /etc/nsswitch.conf
  92 .SH ATTRIBUTES
  93 For an explanation of the terms used in this section, see
  94 .BR attributes (7).
  95 .TS
  96 allbox;
  97 lbw16 lb lbw23
  98 l l l.
  99 Interface       Attribute       Value
 100 T{
 101 .BR setnetgrent (),
 102 .br
 103 .BR getnetgrent_r (),
 104 .br
 105 .BR innetgr ()
 106 T}      Thread safety   T{
 107 MT-Unsafe race:netgrent
 108 .br
 109 locale
 110 T}
 111 T{
 112 .BR endnetgrent ()
 113 T}      Thread safety   MT-Unsafe race:netgrent
 114 T{
 115 .BR getnetgrent ()
 116 T}      Thread safety   T{
 117 MT-Unsafe race:netgrent
 118 .br
 119 race:netgrentbuf locale
 120 T}
 121 .TE
 122
 123 In the above table,
 124 .I netgrent
 125 in
 126 .I race:netgrent
 127 signifies that if any of the functions
 128 .BR setnetgrent (3),
 129 .BR getnetgrent_r (3),
 130 .BR innetgr (3),
 131 .BR getnetgrent (3),
 132 or
 133 .BR endnetgrent (3)
 134 are used in parallel in different threads of a program,
 135 then data races could occur.
 136 .SH CONFORMING TO
 137 These functions are not in POSIX.1, but
 138 .BR setnetgrent (),
 139 .BR endnetgrent (),
 140 .BR getnetgrent (),
 141 and
 142 .BR innetgr ()
 143 are available on most UNIX systems.
 144 .BR getnetgrent_r ()
 145 is not widely available on other systems.
 146 .\" getnetgrent_r() is on Solaris 8 and AIX 5.1, but not the BSDs.
 147 .SH NOTES
 148 In the BSD implementation,
 149 .BR setnetgrent ()
 150 returns void.
 151 .SH SEE ALSO
 152 .BR sethostent (3),
 153 .BR setprotoent (3),
 154 .BR setservent (3)