NAME¶
Win::Hivex::Regedit - Helper for reading and writing regedit format files
SYNOPSIS¶
use Win::Hivex;
use Win::Hivex::Regedit qw(reg_import reg_export);
$h = Win::Hivex->open ('SOFTWARE', write => 1);
open FILE, "updates.reg";
reg_import (\*FILE, $h);
$h->commit (undef);
reg_export ($h, "\\Microsoft\\Windows NT\\CurrentVersion", \*OUTFILE,
prefix => "HKEY_LOCAL_MACHINE\\SOFTWARE");
DESCRIPTION¶
Win::Hivex::Regedit is a helper library for reading and writing the Windows
regedit (or ".REG") file format. This is the textual format that is
commonly used on Windows for distributing groups of Windows Registry changes,
and this format is read and written by the proprietary "reg.exe" and
"regedit.exe" programs supplied with Windows. It is
not the
same as the binary "hive" format which the hivex library itself can
read and write. Note that the regedit format is not well-specified, and hence
deviations can occur between what the Windows program can read/write and what
we can read/write. (Please file bugs for any deviations found).
Win::Hivex::Regedit is the low-level Perl library. There is also a command line
tool for combining hive files and reg files (
hivexregedit(1)). If you
have a Windows virtual machine that you need to merge regedit-format changes
into, use the high-level
virt-win-reg(1) tool (part of libguestfs
tools).
FUNCTIONS¶
reg_import¶
reg_import ($fh, ($h|$map), [encoding => "UTF-16LE"]);
This function imports the registry keys from file handle $fh either into the
hive $h or via a map function.
The hive handle $h must have been opened for writing, ie. using the "write
=> 1" flag to "Win::Hivex->open".
In the binary hive file, the first part of the key name (eg.
"HKEY_LOCAL_MACHINE\SOFTWARE") is not stored. You just have to know
(somehow) that this maps to the "SOFTWARE" hive. Therefore if you
are given a file containing a mixture of keys that have to be added to
different hives, you have to have a way to map these to the hive handles. This
is outside the scope of the hivex library, but if the second argument is a
CODEREF (ie. reference to a function) then this $map function is called on
each key name:
map ($keyname)
==> ($h, $keyname)
As shown, the function should return a pair, hive handle, and the true key name
(with the prefix stripped off). For example:
sub map {
if ($_[0] =~ /^HKEY_LOCAL_MACHINE\\SOFTWARE(.*)/i) {
return ($software_h, $1);
} else ...
}
"encoding" is the encoding used by default for strings. If not
specified, this defaults to "UTF-16LE", however we highly advise you
to specify it. See "ENCODING STRINGS" below.
As with the regedit program, we merge the new registry keys with existing ones,
and new node values with old ones. You can use the "-" (minus)
character to delete individual keys and values. This is explained in detail in
the Wikipedia page on the Windows Registry.
Remember you need to call "$h->commit (undef)" on the hivex handle
before any changes are written to the hive file. See "WRITING TO HIVE
FILES" in
hivex(3).
reg_export¶
reg_export ($h, $key, $fh,
[prefix => $prefix],
[unsafe_printable_strings => 1]);
This function exports the registry keys starting at the root $key and
recursively downwards into the file handle $fh.
$key is a case-insensitive path of the node to start from, relative to the root
of the hive. It is an error if this path does not exist. Path elements should
be separated by backslash characters.
$prefix is prefixed to each key name. The usual use for this is to make key
names appear as they would on Windows. For example the key "\Foo" in
the SOFTWARE Registry, with $prefix "HKEY_LOCAL_MACHINE\SOFTWARE",
would be written as:
[HKEY_LOCAL_MACHINE\SOFTWARE\Foo]
"Key 1"=...
"Key 2"=...
If "unsafe_printable_strings" is not given or is false, then the
output is written as pure 7 bit ASCII, with line endings which are the default
for the local host. Strings are always encoded as hex bytes. This is safe
because it preserves the original content and encoding of strings. See
"ENCODING STRINGS" below.
If "unsafe_printable_strings" is true, then strings are assumed to be
UTF-16LE and are converted to UTF-8 for output. The final zero codepoint in
the string is removed if there is one. This is unsafe because it does not
preserve the fidelity of the strings in the Registry and because the content
type of strings is not always UTF-16LE. However it is useful if you just want
to display strings for quick hacking and debugging.
You may need to convert the file's encoding using
iconv(1) and line
endings using
unix2dos(1) if sending to a Windows user.
Nodes and keys are sorted alphabetically in the output.
This function does
not print a header. The real regedit program will
print a header like:
Windows Registry Editor Version 5.00
followed by a blank line. (Other headers are possible, see the Wikipedia page on
the Windows Registry). If you want a header, you need to write it out
yourself.
reg_export_node¶
reg_export_node ($h, $node, $fh, ...);
This is exactly the same as "reg_export" except that instead of
specifying the path to a key as a string, you pass a hivex library $node
handle.
ENCODING STRINGS¶
The situation with encoding strings in the Registry on Windows is very confused.
There are two main encodings that you would find in the binary (hive) file, 7
bit ASCII and UTF-16LE. (Other encodings are possible, it's also possible to
have arbitrary binary data incorrectly marked with a string type).
The hive file itself doesn't contain any indication of string encoding. Windows
probably guesses the encoding.
We think that regedit probably either guesses which encoding to use based on the
file encoding, or else has different defaults for different versions of
Windows. Neither choice is appropriate for a tool used in a real operating
system.
When using "reg_import", you should specify the default encoding for
strings using the "encoding" parameter. If not specified, it
defaults to UTF-16LE.
The file itself that is imported should be in the local encoding for files
(usually UTF-8 on modern Linux systems). This means if you receive a regedit
file from a Windows system, you may sometimes have to reencode it:
iconv -f utf-16le -t utf-8 < input.reg | dos2unix > output.reg
When writing regedit files ("reg_export") we bypass this madness
completely.
All strings (even pure ASCII) are written as hex bytes so
there is no doubt about how they should be encoded when they are read back in.
COPYRIGHT¶
Copyright (C) 2010-2011 Red Hat Inc.
LICENSE¶
Please see the file COPYING.LIB for the full license.
SEE ALSO¶
Win::Hivex(3),
hivexregedit(1),
virt-win-reg(1),
iconv(1),
dos2unix(1),
unix2dos(1),
hivex(3),
hivexsh(1), <
http://libguestfs.org>,
Sys::Guestfs(3).