man3/setnetgrent.3

   1 .\"  Copyright 2002 walter harms (walter.harms@informatik.uni-oldenburg.de)
   2 .\"
   3 .\" SPDX-License-Identifier: GPL-1.0-or-later
   4 .\"
   5 .\"  based on glibc infopages
   6 .\" polished - aeb
   7 .\"
   8 .TH setnetgrent 3 (date) "Linux man-pages (unreleased)"
   9 .SH NAME
  10 setnetgrent, endnetgrent, getnetgrent, getnetgrent_r, innetgr \-
  11 handle network group entries
  12 .SH LIBRARY
  13 Standard C library
  14 .RI ( libc ", " \-lc )
  15 .SH SYNOPSIS
  16 .nf
  17 .B #include <netdb.h>
  18 .PP
  19 .BI "int setnetgrent(const char *" netgroup );
  20 .B "void endnetgrent(void);"
  21 .PP
  22 .BI "int getnetgrent(char **restrict " host ,
  23 .BI "            char **restrict " user ", char **restrict " domain );
  24 .BI "int getnetgrent_r(char **restrict " host ,
  25 .BI "            char **restrict " user ", char **restrict " domain ,
  26 .BI "            char *restrict " buf ", size_t " buflen );
  27 .PP
  28 .BI "int innetgr(const char *" netgroup ", const char *" host ,
  29 .BI "            const char *" user ", const char *" domain );
  30 .fi
  31 .PP
  32 .RS -4
  33 Feature Test Macro Requirements for glibc (see
  34 .BR feature_test_macros (7)):
  35 .RE
  36 .ad l
  37 .PP
  38 .nh
  39 .BR setnetgrent (),
  40 .BR endnetgrent (),
  41 .BR getnetgrent (),
  42 .BR getnetgrent_r (),
  43 .BR innetgr ():
  44 .hy
  45 .nf
  46     Since glibc 2.19:
  47         _DEFAULT_SOURCE
  48     Glibc 2.19 and earlier:
  49         _BSD_SOURCE || _SVID_SOURCE
  50 .fi
  51 .ad
  52 .SH DESCRIPTION
  53 The
  54 .I netgroup
  55 is a SunOS invention.
  56 A netgroup database is a list of string triples
  57 .RI ( hostname ", " username ", " domainname )
  58 or other netgroup names.
  59 Any of the elements in a triple can be empty,
  60 which means that anything matches.
  61 The functions described here allow access to the netgroup databases.
  62 The file
  63 .I /etc/nsswitch.conf
  64 defines what database is searched.
  65 .PP
  66 The
  67 .BR setnetgrent ()
  68 call defines the netgroup that will be searched by subsequent
  69 .BR getnetgrent ()
  70 calls.
  71 The
  72 .BR getnetgrent ()
  73 function retrieves the next netgroup entry, and returns pointers in
  74 .IR host ,
  75 .IR user ,
  76 .IR domain .
  77 A null pointer means that the corresponding entry matches any string.
  78 The pointers are valid only as long as there is no call to other
  79 netgroup-related functions.
  80 To avoid this problem you can use the GNU function
  81 .BR getnetgrent_r ()
  82 that stores the strings in the supplied buffer.
  83 To free all allocated buffers use
  84 .BR endnetgrent ().
  85 .PP
  86 In most cases you want to check only if the triplet
  87 .RI ( hostname ", " username ", " domainname )
  88 is a member of a netgroup.
  89 The function
  90 .BR innetgr ()
  91 can be used for this without calling the above three functions.
  92 Again, a null pointer is a wildcard and matches any string.
  93 The function is thread-safe.
  94 .SH RETURN VALUE
  95 These functions return 1 on success and 0 for failure.
  96 .SH FILES
  97 .I /etc/netgroup
  98 .br
  99 .I /etc/nsswitch.conf
 100 .SH ATTRIBUTES
 101 For an explanation of the terms used in this section, see
 102 .BR attributes (7).
 103 .ad l
 104 .nh
 105 .TS
 106 allbox;
 107 lb lb lbx
 108 l l l.
 109 Interface       Attribute       Value
 110 T{
 111 .BR setnetgrent (),
 112 .BR getnetgrent_r (),
 113 .BR innetgr ()
 114 T}      Thread safety   T{
 115 MT-Unsafe race:netgrent
 116 locale
 117 T}
 118 T{
 119 .BR endnetgrent ()
 120 T}      Thread safety   T{
 121 MT-Unsafe race:netgrent
 122 T}
 123 T{
 124 .BR getnetgrent ()
 125 T}      Thread safety   T{
 126 MT-Unsafe race:netgrent
 127 race:netgrentbuf locale
 128 T}
 129 .TE
 130 .hy
 131 .ad
 132 .sp 1
 133 In the above table,
 134 .I netgrent
 135 in
 136 .I race:netgrent
 137 signifies that if any of the functions
 138 .BR setnetgrent (),
 139 .BR getnetgrent_r (),
 140 .BR innetgr (),
 141 .BR getnetgrent (),
 142 or
 143 .BR endnetgrent ()
 144 are used in parallel in different threads of a program,
 145 then data races could occur.
 146 .SH STANDARDS
 147 These functions are not in POSIX.1, but
 148 .BR setnetgrent (),
 149 .BR endnetgrent (),
 150 .BR getnetgrent (),
 151 and
 152 .BR innetgr ()
 153 are available on most UNIX systems.
 154 .BR getnetgrent_r ()
 155 is not widely available on other systems.
 156 .\" getnetgrent_r() is on Solaris 8 and AIX 5.1, but not the BSDs.
 157 .SH NOTES
 158 In the BSD implementation,
 159 .BR setnetgrent ()
 160 returns void.
 161 .SH SEE ALSO
 162 .BR sethostent (3),
 163 .BR setprotoent (3),
 164 .BR setservent (3)