The Regents of the University of California. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
4. Neither the name of the University nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
From: @(#)getgrent.3 8.2 (Berkeley) 4/19/94
$FreeBSD: releng/10.2/lib/libc/gen/getgrent.3 165903 2007-01-09 00:28:16Z imp $
.Dd April 16, 2003 .Dt GETGRENT 3 .Os .Sh NAME .Nm getgrent , .Nm getgrent_r , .Nm getgrnam , .Nm getgrnam_r , .Nm getgrgid , .Nm getgrgid_r , .Nm setgroupent , .Nm setgrent , .Nm endgrent .Nd group database operations .Sh LIBRARY .Lb libc .Sh SYNOPSIS n grp.h .Ft struct group * .Fn getgrent void .Ft int .Fn getgrent_r "struct group *grp" "char *buffer" "size_t bufsize" "struct group **result" .Ft struct group * .Fn getgrnam "const char *name" .Ft int .Fn getgrnam_r "const char *name" "struct group *grp" "char *buffer" "size_t bufsize" "struct group **result" .Ft struct group * .Fn getgrgid "gid_t gid" .Ft int .Fn getgrgid_r "gid_t gid" "struct group *grp" "char *buffer" "size_t bufsize" "struct group **result" .Ft int .Fn setgroupent "int stayopen" .Ft int .Fn setgrent void .Ft void .Fn endgrent void .Sh DESCRIPTION These functions operate on the group database file
a /etc/group which is described in .Xr group 5 . Each line of the database is defined by the structure .Vt group found in the include file n grp.h : d -literal -offset indent struct group { char *gr_name; /* group name */ char *gr_passwd; /* group password */ gid_t gr_gid; /* group id */ char **gr_mem; /* group members */ }; .Ed
p The functions .Fn getgrnam and .Fn getgrgid search the group database for the given group name pointed to by .Fa name or the group id pointed to by .Fa gid , respectively, returning the first one encountered. Identical group names or group gids may result in undefined behavior.
p The .Fn getgrent function sequentially reads the group database and is intended for programs that wish to step through the complete list of groups.
p The functions .Fn getgrent_r , .Fn getgrnam_r , and .Fn getgrgid_r are thread-safe versions of .Fn getgrent , .Fn getgrnam , and .Fn getgrgid , respectively. The caller must provide storage for the results of the search in the .Fa grp , .Fa buffer , .Fa bufsize , and .Fa result arguments. When these functions are successful, the .Fa grp argument will be filled-in, and a pointer to that argument will be stored in .Fa result . If an entry is not found or an error occurs, .Fa result will be set to .Dv NULL .
p These functions will open the group file for reading, if necessary.
p The .Fn setgroupent function opens the file, or rewinds it if it is already open. If .Fa stayopen is non-zero, file descriptors are left open, significantly speeding functions subsequent calls. This functionality is unnecessary for .Fn getgrent as it does not close its file descriptors by default. It should also be noted that it is dangerous for long-running programs to use this functionality as the group file may be updated.
p The .Fn setgrent function is identical to .Fn setgroupent with an argument of zero.
p The .Fn endgrent function closes any open files. .Sh RETURN VALUES The functions .Fn getgrent , .Fn getgrnam , and .Fn getgrgid , return a pointer to a group structure on success or .Dv NULL if the entry is not found or if an error occurs. If an error does occur, .Va errno will be set. Note that programs must explicitly set .Va errno to zero before calling any of these functions if they need to distinguish between a non-existent entry and an error. The functions .Fn getgrent_r , .Fn getgrnam_r , and .Fn getgrgid_r return 0 if no error occurred, or an error number to indicate failure. It is not an error if a matching entry is not found. (Thus, if .Fa result is set to .Dv NULL and the return value is 0, no matching entry exists.)
p The functions .Fn setgroupent and .Fn setgrent return the value 1 if successful, otherwise the value 0 is returned. The functions .Fn endgrent and .Fn setgrfile have no return value. .Sh FILES l -tag -width /etc/group -compact t Pa /etc/group group database file .El .Sh COMPATIBILITY The historic function .Fn setgrfile , which allowed the specification of alternate password databases, has been deprecated and is no longer available. .Sh SEE ALSO .Xr getpwent 3 , .Xr group 5 , .Xr nsswitch.conf 5 , .Xr yp 8 .Sh STANDARDS The .Fn getgrent , .Fn getgrnam , .Fn getgrnam_r , .Fn getgrgid , .Fn getgrgid_r and .Fn endgrent functions conform to .St -p1003.1-96 . The .Fn setgrent function differs from that standard in that its return type is .Vt int rather than .Vt void . .Sh HISTORY The functions .Fn endgrent , .Fn getgrent , .Fn getgrnam , .Fn getgrgid , and .Fn setgrent appeared in .At v7 . The functions .Fn setgrfile and .Fn setgroupent appeared in x 4.3 Reno . The functions .Fn getgrent_r , .Fn getgrnam_r , and .Fn getgrgid_r appeared in .Fx 5.1 . .Sh BUGS The functions .Fn getgrent , .Fn getgrnam , .Fn getgrgid , .Fn setgroupent and .Fn setgrent leave their results in an internal static object and return a pointer to that object. Subsequent calls to the same function will modify the same object.
p The functions .Fn getgrent , .Fn getgrent_r , .Fn endgrent , .Fn setgroupent , and .Fn setgrent are fairly useless in a networked environment and should be avoided, if possible. The .Fn getgrent and .Fn getgrent_r functions make no attempt to suppress duplicate information if multiple sources are specified in .Xr nsswitch.conf 5 .