tools/patman/tools.py

# SPDX-License-Identifier: GPL-2.0+
#
# Copyright (c) 2016 Google, Inc
#

from __future__ import print_function

import command
import glob
import os
import shutil
import struct
import sys
import tempfile

import tout

# Output directly (generally this is temporary)
outdir = None

# True to keep the output directory around after exiting
preserve_outdir = False

# Path to the Chrome OS chroot, if we know it
chroot_path = None

# Search paths to use for Filename(), used to find files
search_paths = []

tool_search_paths = []

# Tools and the packages that contain them, on debian
packages = {
    'lz4': 'liblz4-tool',
    }

# List of paths to use when looking for an input file
indir = []

def PrepareOutputDir(dirname, preserve=False):
    """Select an output directory, ensuring it exists.

    This either creates a temporary directory or checks that the one supplied
    by the user is valid. For a temporary directory, it makes a note to
    remove it later if required.

    Args:
        dirname: a string, name of the output directory to use to store
                intermediate and output files. If is None - create a temporary
                directory.
        preserve: a Boolean. If outdir above is None and preserve is False, the
                created temporary directory will be destroyed on exit.

    Raises:
        OSError: If it cannot create the output directory.
    """
    global outdir, preserve_outdir

    preserve_outdir = dirname or preserve
    if dirname:
        outdir = dirname
        if not os.path.isdir(outdir):
            try:
                os.makedirs(outdir)
            except OSError as err:
                raise CmdError("Cannot make output directory '%s': '%s'" %
                                (outdir, err.strerror))
        tout.Debug("Using output directory '%s'" % outdir)
    else:
        outdir = tempfile.mkdtemp(prefix='binman.')
        tout.Debug("Using temporary directory '%s'" % outdir)

def _RemoveOutputDir():
    global outdir

    shutil.rmtree(outdir)
    tout.Debug("Deleted temporary directory '%s'" % outdir)
    outdir = None

def FinaliseOutputDir():
    global outdir, preserve_outdir

    """Tidy up: delete output directory if temporary and not preserved."""
    if outdir and not preserve_outdir:
        _RemoveOutputDir()
        outdir = None

def GetOutputFilename(fname):
    """Return a filename within the output directory.

    Args:
        fname: Filename to use for new file

    Returns:
        The full path of the filename, within the output directory
    """
    return os.path.join(outdir, fname)

def _FinaliseForTest():
    """Remove the output directory (for use by tests)"""
    global outdir

    if outdir:
        _RemoveOutputDir()
        outdir = None

def SetInputDirs(dirname):
    """Add a list of input directories, where input files are kept.

    Args:
        dirname: a list of paths to input directories to use for obtaining
                files needed by binman to place in the image.
    """
    global indir

    indir = dirname
    tout.Debug("Using input directories %s" % indir)

def GetInputFilename(fname):
    """Return a filename for use as input.

    Args:
        fname: Filename to use for new file

    Returns:
        The full path of the filename, within the input directory
    """
    if not indir:
        return fname
    for dirname in indir:
        pathname = os.path.join(dirname, fname)
        if os.path.exists(pathname):
            return pathname

    raise ValueError("Filename '%s' not found in input path (%s) (cwd='%s')" %
                     (fname, ','.join(indir), os.getcwd()))

def GetInputFilenameGlob(pattern):
    """Return a list of filenames for use as input.

    Args:
        pattern: Filename pattern to search for

    Returns:
        A list of matching files in all input directories
    """
    if not indir:
        return glob.glob(fname)
    files = []
    for dirname in indir:
        pathname = os.path.join(dirname, pattern)
        files += glob.glob(pathname)
    return sorted(files)

def Align(pos, align):
    if align:
        mask = align - 1
        pos = (pos + mask) & ~mask
    return pos

def NotPowerOfTwo(num):
    return num and (num & (num - 1))

def SetToolPaths(toolpaths):
    """Set the path to search for tools

    Args:
        toolpaths: List of paths to search for tools executed by Run()
    """
    global tool_search_paths

    tool_search_paths = toolpaths

def PathHasFile(path_spec, fname):
    """Check if a given filename is in the PATH

    Args:
        path_spec: Value of PATH variable to check
        fname: Filename to check

    Returns:
        True if found, False if not
    """
    for dir in path_spec.split(':'):
        if os.path.exists(os.path.join(dir, fname)):
            return True
    return False

def Run(name, *args):
    """Run a tool with some arguments

    This runs a 'tool', which is a program used by binman to process files and
    perhaps produce some output. Tools can be located on the PATH or in a
    search path.

    Args:
        name: Command name to run
        args: Arguments to the tool

    Returns:
        CommandResult object
    """
    try:
        env = None
        if tool_search_paths:
            env = dict(os.environ)
            env['PATH'] = ':'.join(tool_search_paths) + ':' + env['PATH']
        all_args = (name,) + args
        result = command.RunPipe([all_args], capture=True, capture_stderr=True,
                                 env=env, raise_on_error=False)
        if result.return_code:
            raise Exception("Error %d running '%s': %s" %
               (result.return_code,' '.join(all_args),
                result.stderr))
        return result.stdout
    except:
        if env and not PathHasFile(env['PATH'], name):
            msg = "Please install tool '%s'" % name
            package = packages.get(name)
            if package:
                 msg += " (e.g. from package '%s')" % package
            raise ValueError(msg)
        raise

def Filename(fname):
    """Resolve a file path to an absolute path.

    If fname starts with ##/ and chroot is available, ##/ gets replaced with
    the chroot path. If chroot is not available, this file name can not be
    resolved, `None' is returned.

    If fname is not prepended with the above prefix, and is not an existing
    file, the actual file name is retrieved from the passed in string and the
    search_paths directories (if any) are searched to for the file. If found -
    the path to the found file is returned, `None' is returned otherwise.

    Args:
      fname: a string,  the path to resolve.

    Returns:
      Absolute path to the file or None if not found.
    """
    if fname.startswith('##/'):
      if chroot_path:
        fname = os.path.join(chroot_path, fname[3:])
      else:
        return None

    # Search for a pathname that exists, and return it if found
    if fname and not os.path.exists(fname):
        for path in search_paths:
            pathname = os.path.join(path, os.path.basename(fname))
            if os.path.exists(pathname):
                return pathname

    # If not found, just return the standard, unchanged path
    return fname

def ReadFile(fname, binary=True):
    """Read and return the contents of a file.

    Args:
      fname: path to filename to read, where ## signifiies the chroot.

    Returns:
      data read from file, as a string.
    """
    with open(Filename(fname), binary and 'rb' or 'r') as fd:
        data = fd.read()
    #self._out.Info("Read file '%s' size %d (%#0x)" %
                   #(fname, len(data), len(data)))
    return data

def WriteFile(fname, data):
    """Write data into a file.

    Args:
        fname: path to filename to write
        data: data to write to file, as a string
    """
    #self._out.Info("Write file '%s' size %d (%#0x)" %
                   #(fname, len(data), len(data)))
    with open(Filename(fname), 'wb') as fd:
        fd.write(data)

def GetBytes(byte, size):
    """Get a string of bytes of a given size

    This handles the unfortunate different between Python 2 and Python 2.

    Args:
        byte: Numeric byte value to use
        size: Size of bytes/string to return

    Returns:
        A bytes type with 'byte' repeated 'size' times
    """
    if sys.version_info[0] >= 3:
        data = bytes([byte]) * size
    else:
        data = chr(byte) * size
    return data

def ToUnicode(val):
    """Make sure a value is a unicode string

    This allows some amount of compatibility between Python 2 and Python3. For
    the former, it returns a unicode object.

    Args:
        val: string or unicode object

    Returns:
        unicode version of val
    """
    if sys.version_info[0] >= 3:
        return val
    return val if isinstance(val, unicode) else val.decode('utf-8')

def FromUnicode(val):
    """Make sure a value is a non-unicode string

    This allows some amount of compatibility between Python 2 and Python3. For
    the former, it converts a unicode object to a string.

    Args:
        val: string or unicode object

    Returns:
        non-unicode version of val
    """
    if sys.version_info[0] >= 3:
        return val
    return val if isinstance(val, str) else val.encode('utf-8')

def ToByte(ch):
    """Convert a character to an ASCII value

    This is useful because in Python 2 bytes is an alias for str, but in
    Python 3 they are separate types. This function converts the argument to
    an ASCII value in either case.

    Args:
        ch: A string (Python 2) or byte (Python 3) value

    Returns:
        integer ASCII value for ch
    """
    return ord(ch) if type(ch) == str else ch

def ToChar(byte):
    """Convert a byte to a character

    This is useful because in Python 2 bytes is an alias for str, but in
    Python 3 they are separate types. This function converts an ASCII value to
    a value with the appropriate type in either case.

    Args:
        byte: A byte or str value
    """
    return chr(byte) if type(byte) != str else byte

def ToChars(byte_list):
    """Convert a list of bytes to a str/bytes type

    Args:
        byte_list: List of ASCII values representing the string

    Returns:
        string made by concatenating all the ASCII values
    """
    return ''.join([chr(byte) for byte in byte_list])

def ToBytes(string):
    """Convert a str type into a bytes type

    Args:
        string: string to convert value

    Returns:
        Python 3: A bytes type
        Python 2: A string type
    """
    if sys.version_info[0] >= 3:
        return string.encode('utf-8')
    return string

def Compress(indata, algo, with_header=True):
    """Compress some data using a given algorithm

    Note that for lzma this uses an old version of the algorithm, not that
    provided by xz.

    This requires 'lz4' and 'lzma_alone' tools. It also requires an output
    directory to be previously set up, by calling PrepareOutputDir().

    Args:
        indata: Input data to compress
        algo: Algorithm to use ('none', 'gzip', 'lz4' or 'lzma')

    Returns:
        Compressed data
    """
    if algo == 'none':
        return indata
    fname = GetOutputFilename('%s.comp.tmp' % algo)
    WriteFile(fname, indata)
    if algo == 'lz4':
        data = Run('lz4', '--no-frame-crc', '-c', fname)
    # cbfstool uses a very old version of lzma
    elif algo == 'lzma':
        outfname = GetOutputFilename('%s.comp.otmp' % algo)
        Run('lzma_alone', 'e', fname, outfname, '-lc1', '-lp0', '-pb0', '-d8')
        data = ReadFile(outfname)
    elif algo == 'gzip':
        data = Run('gzip', '-c', fname)
    else:
        raise ValueError("Unknown algorithm '%s'" % algo)
    if with_header:
        hdr = struct.pack('<I', len(data))
        data = hdr + data
    return data

def Decompress(indata, algo, with_header=True):
    """Decompress some data using a given algorithm

    Note that for lzma this uses an old version of the algorithm, not that
    provided by xz.

    This requires 'lz4' and 'lzma_alone' tools. It also requires an output
    directory to be previously set up, by calling PrepareOutputDir().

    Args:
        indata: Input data to decompress
        algo: Algorithm to use ('none', 'gzip', 'lz4' or 'lzma')

    Returns:
        Compressed data
    """
    if algo == 'none':
        return indata
    if with_header:
        data_len = struct.unpack('<I', indata[:4])[0]
        indata = indata[4:4 + data_len]
    fname = GetOutputFilename('%s.decomp.tmp' % algo)
    with open(fname, 'wb') as fd:
        fd.write(indata)
    if algo == 'lz4':
        data = Run('lz4', '-dc', fname)
    elif algo == 'lzma':
        outfname = GetOutputFilename('%s.decomp.otmp' % algo)
        Run('lzma_alone', 'd', fname, outfname)
        data = ReadFile(outfname)
    elif algo == 'gzip':
        data = Run('gzip', '-cd', fname)
    else:
        raise ValueError("Unknown algorithm '%s'" % algo)
    return data

CMD_CREATE, CMD_DELETE, CMD_ADD, CMD_REPLACE, CMD_EXTRACT = range(5)

IFWITOOL_CMDS = {
    CMD_CREATE: 'create',
    CMD_DELETE: 'delete',
    CMD_ADD: 'add',
    CMD_REPLACE: 'replace',
    CMD_EXTRACT: 'extract',
    }

def RunIfwiTool(ifwi_file, cmd, fname=None, subpart=None, entry_name=None):
    """Run ifwitool with the given arguments:

    Args:
        ifwi_file: IFWI file to operation on
        cmd: Command to execute (CMD_...)
        fname: Filename of file to add/replace/extract/create (None for
            CMD_DELETE)
        subpart: Name of sub-partition to operation on (None for CMD_CREATE)
        entry_name: Name of directory entry to operate on, or None if none
    """
    args = ['ifwitool', ifwi_file]
    args.append(IFWITOOL_CMDS[cmd])
    if fname:
        args += ['-f', fname]
    if subpart:
        args += ['-n', subpart]
    if entry_name:
        args += ['-d', '-e', entry_name]
    Run(*args)

def ToHex(val):
    """Convert an integer value (or None) to a string

    Returns:
        hex value, or 'None' if the value is None
    """
    return 'None' if val is None else '%#x' % val

def ToHexSize(val):
    """Return the size of an object in hex

    Returns:
        hex value of size, or 'None' if the value is None
    """
    return 'None' if val is None else '%#x' % len(val)