bsd/man/man2/getgroups.2

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  57 .\"     @(#)getgroups.2 8.2 (Berkeley) 4/16/94
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  59 .Dd September 17, 2010
  60 .Dt GETGROUPS 2
  61 .Os BSD 4.2
  62 .Sh NAME
  63 .Nm getgroups
  64 .Nd get group access list
  65 .Sh SYNOPSIS
  66 .Fd #include <unistd.h>
  67 .Ft int
  68 .Fo getgroups
  69 .Fa "int gidsetsize"
  70 .Fa "gid_t grouplist[]"
  71 .Fc
  72 .Sh DESCRIPTION
  73 .Fn getgroups
  74 gets the current group access list of the current user process
  75 and stores it in the array
  76 .Fa grouplist[] .
  77 The parameter
  78 .Fa gidsetsize
  79 indicates the number of entries that may be placed in
  80 .Fa grouplist[] .
  81 .Fn getgroups
  82 returns the actual number of groups returned in
  83 .Fa grouplist[] .
  84 However, no more than
  85 .Dv {NGROUPS_MAX}
  86 will be returned. If
  87 .Fa gidsetsize
  88 is 0,
  89 .Fn getgroups
  90 returns the number of groups without modifying the
  91 .Fa grouplist[]
  92 array.
  93 .Pp
  94 To provide compatibility with applications that use
  95 .Fn getgroups
  96 in environments where users may be in more than
  97 .Dv {NGROUPS_MAX}
  98 groups, a variant of
  99 .Fn getgroups ,
 100 obtained when compiling with either the macros
 101 .Dv _DARWIN_UNLIMITED_GETGROUPS
 102 or
 103 .Dv _DARWIN_C_SOURCE
 104 defined, can be used that is not limited to
 105 .Dv {NGROUPS_MAX}
 106 groups.
 107 However, this variant only returns the user's default group access list and
 108 not the group list modified by a call to
 109 .Xr setgroups 2
 110 (either in the current process or an ancestor process).
 111 Use of
 112 .Xr setgroups 2
 113 is highly discouraged, and there is no foolproof way to determine if it has
 114 been previously called.
 115 .Sh RETURN VALUES
 116 A successful call returns the number of groups in the group set.
 117 Otherwise, a value of -1 is returned and the global integer variable
 118 .Va errno
 119 is set to indicate the error.
 120 .Sh ERRORS
 121 The possible errors for
 122 .Fn getgroups
 123 are:
 124 .Bl -tag -width Er
 125 .\" ==========
 126 .It Bq Er EFAULT
 127 The argument
 128 .Fa grouplist
 129 specifies an invalid address.
 130 .\" ==========
 131 .It Bq Er EINVAL
 132 The argument
 133 .Fa gidsetsize ,
 134 although non-zero,
 135 is smaller than the number of groups in the group set.
 136 .El
 137 .Sh LEGACY SYNOPSIS
 138 .Fd #include <sys/param.h>
 139 .Fd #include <sys/types.h>
 140 .Fd #include <unistd.h>
 141 .Pp
 142 The include files
 143 .In sys/param.h
 144 and
 145 .In sys/types.h
 146 are necessary.
 147 .Sh SEE ALSO
 148 .Xr setgroups 2 ,
 149 .Xr initgroups 3 ,
 150 .Xr compat 5
 151 .Sh HISTORY
 152 The
 153 .Fn getgroups
 154 function call appeared in
 155 .Bx 4.2 .