chroot: accept new options --userspec=U:G and --groups=G1,G2,G3

* NEWS: Note chroot's new options.
* doc/coreutils.texi: Document them.
* src/chroot.c (main): Add support for --userspec and --groups.
* tests/Makefile.am (root-tests): Add chroot/credentials.
* tests/chroot/credentials: New file.
* tests/test-lib.sh: Define NON_ROOT_GROUP to a default value.

1 files changed, 20 insertions, 3 deletions

diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 1a3075ffe..97ea830e1 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -14144,7 +14144,7 @@ underlying function is non-privileged due to lack of support in MS-Windows.}
 Synopses:
 
 @example
-chroot @var{newroot} [@var{command} [@var{args}]@dots{}]
+chroot @var{option} @var{newroot} [@var{command} [@var{args}]@dots{}]
 chroot @var{option}
 @end example
 
@@ -14157,8 +14157,25 @@ variable or @command{/bin/sh} if not set, invoked with the @option{-i} option.
 @var{command} must not be a special built-in utility
 (@pxref{Special built-in utilities}).
 
-The only options are @option{--help} and @option{--version}.  @xref{Common
-options}.  Options must precede operands.
+The program accepts the following options.  Also see @ref{Common options}.
+Options must precede operands.
+
+@table @samp
+
+@itemx --userspec=@var{user}[:@var{group}]
+@opindex --userspec
+By default, @var{command} is run with the same credentials
+as the invoking process.
+Use this option to run it as a different @var{user} and/or with a
+different primary @var{group}.
+
+@itemx --groups=@var{groups}
+@opindex --groups
+Use this option to specify the supplementary @var{groups} to be
+used by the new process.
+The items in the list (names or numeric IDs) must be separated by commas.
+
+@end table
 
 Here are a few tips to help avoid common problems in using chroot.
 To start with a simple example, make @var{command} refer to a statically