lyx_mirror/lib/scripts/lyxpreview_tools.py

#! /usr/bin/env python

# file lyxpreview_tools.py
# This file is part of LyX, the document processor.
# Licence details can be found in the file COPYING.

# author Angus Leeming
# Full author contact details are available in file CREDITS

# and with much help testing the code under Windows from
#   Paul A. Rubin, rubin@msu.edu.

# A repository of the following functions, used by the lyxpreview2xyz scripts.
# copyfileobj, error, find_exe, find_exe_or_terminate, mkstemp,
# run_command, warning

import os, re, string, sys, tempfile

# compatibility with python 2.2
if sys.version_info[:2] == (2, 2):
    __builtins__.True = (1 == 1)
    __builtins__.False = (1 == 0)
    def bool(value):
        """Demote a value to 0 or 1, depending on its truth value

        This is not to be confused with types.BooleanType, which is
        way too hard to duplicate in 2.1 to be worth the trouble.
        """
        return not not value
    __builtins__.bool = bool
    del bool
# end compatibility chunk

use_win32_modules = 0
if os.name == "nt":
    use_win32_modules = 1
    try:
        import pywintypes
        import win32con
        import win32event
        import win32file
        import win32pipe
        import win32process
        import win32security
        import winerror
    except:
        sys.stderr.write("Consider installing the PyWin extension modules "\
                         "if you're irritated by windows appearing briefly.\n")
        use_win32_modules = 0


def warning(message):
    sys.stderr.write(message + '\n')


def error(message):
    sys.stderr.write(message + '\n')
    sys.exit(1)


def find_exe(candidates, path):
    for prog in candidates:
        for directory in path:
            if os.name == "nt":
                full_path = os.path.join(directory, prog + ".exe")
            else:
                full_path = os.path.join(directory, prog)

            if os.access(full_path, os.X_OK):
                # The thing is in the PATH already (or we wouldn't
                # have found it). Return just the basename to avoid
                # problems when the path to the executable contains
                # spaces.
                return os.path.basename(full_path)

    return None


def find_exe_or_terminate(candidates, path):
    exe = find_exe(candidates, path)
    if exe == None:
        error("Unable to find executable from '%s'" % string.join(candidates))

    return exe


def run_command_popen(cmd):
    handle = os.popen(cmd, 'r')
    cmd_stdout = handle.read()
    cmd_status = handle.close()

    return cmd_status, cmd_stdout


def run_command_win32(cmd):
    sa = win32security.SECURITY_ATTRIBUTES()
    sa.bInheritHandle = True
    stdout_r, stdout_w = win32pipe.CreatePipe(sa, 0)

    si = win32process.STARTUPINFO()
    si.dwFlags = (win32process.STARTF_USESTDHANDLES
                  | win32process.STARTF_USESHOWWINDOW)
    si.wShowWindow = win32con.SW_HIDE
    si.hStdOutput = stdout_w

    process, thread, pid, tid = \
             win32process.CreateProcess(None, cmd, None, None, True,
                                        0, None, None, si)
    if process == None:
        return -1, ""

    # Must close the write handle in this process, or ReadFile will hang.
    stdout_w.Close()

    # Read the pipe until we get an error (including ERROR_BROKEN_PIPE,
    # which is okay because it happens when child process ends).
    data = ""
    error = 0
    while 1:
        try:
            hr, buffer = win32file.ReadFile(stdout_r, 4096)
            if hr != winerror.ERROR_IO_PENDING:
                data = data + buffer

        except pywintypes.error, e:
            if e.args[0] != winerror.ERROR_BROKEN_PIPE:
                error = 1
            break

    if error:
        return -2, ""

    # Everything is okay --- the called process has closed the pipe.
    # For safety, check that the process ended, then pick up its exit code.
    win32event.WaitForSingleObject(process, win32event.INFINITE)
    if win32process.GetExitCodeProcess(process):
        return -3, ""

    return None, data


def run_command(cmd):
    if use_win32_modules:
        return run_command_win32(cmd)
    else:
        return run_command_popen(cmd)


def get_version_info():
    version_re = re.compile("([0-9])\.([0-9])")

    match = version_re.match(sys.version)
    if match == None:
        error("Unable to extract version info from 'sys.version'")

    return string.atoi(match.group(1)), string.atoi(match.group(2))


def copyfileobj(fsrc, fdst, rewind=0, length=16*1024):
    """copy data from file-like object fsrc to file-like object fdst"""
    if rewind:
        fsrc.flush()
        fsrc.seek(0)

    while 1:
        buf = fsrc.read(length)
        if not buf:
            break
        fdst.write(buf)


class TempFile:
    """clone of tempfile.TemporaryFile to use with python < 2.0."""
    # Cache the unlinker so we don't get spurious errors at shutdown
    # when the module-level "os" is None'd out.  Note that this must
    # be referenced as self.unlink, because the name TempFile
    # may also get None'd out before __del__ is called.
    unlink = os.unlink

    def __init__(self):
        self.filename = tempfile.mktemp()
        self.file = open(self.filename,"w+b")
        self.close_called = 0

    def close(self):
        if not self.close_called:
            self.close_called = 1
            self.file.close()
            self.unlink(self.filename)

    def __del__(self):
        self.close()

    def read(self, size = -1):
        return self.file.read(size)

    def write(self, line):
        return self.file.write(line)

    def seek(self, offset):
        return self.file.seek(offset)

    def flush(self):
        return self.file.flush()


def mkstemp():
    """create a secure temporary file and return its object-like file"""
    major, minor = get_version_info()

    if major >= 2 and minor >= 0:
        return tempfile.TemporaryFile()
    else:
        return TempFile()