[Patch 3/5] Author: Frederick Grose <<a href="mailto:fgrose@sugarlabs.org">fgrose@sugarlabs.org</a>> Date: Thu Apr 14 10:37:13 2011 -0400 Support usage within a booted LiveOS instance. Provide functions to add loop devices and remove then on exit, a LiveImageMountError(Exception) class for better error handling, and random device mapper names. diff --git a/tools/liveimage-mount b/tools/liveimage-mount index 80d67d1..1ee5b16 100755 --- a/tools/liveimage-mount +++ b/tools/liveimage-mount @@ -23,10 +23,13 @@ import os import sys import stat +import time import getopt +import random import tempfile import subprocess +extra_loops = [] def usage(ecode): print """Usage: @@ -40,6 +43,18 @@ def usage(ecode): and [ARGS] = [arg1[ arg2[ ...]]]\n""" sys.exit(ecode) +class LiveImageMountError(Exception): + """An exception base class for all liveimage-mount errors.""" + def __init__(self, msg): + Exception.__init__(self, msg) + def __str__(self): + try: + return str(self.message) + except UnicodeEncodeError: + return repr(self.message) + + def __unicode__(self): + return unicode(self.message) def call(*popenargs, **kwargs): ''' @@ -62,43 +77,57 @@ def call(*popenargs, **kwargs): return rc -def rcall(args, env=None): +def rcall(args, stdin=None, stderr=True, env=None): + out, err, p, environ = None, None, None, None if env: environ = os.environ.copy() environ.update(env) - else: - environ = None try: - p = subprocess.Popen(args, stdout=subprocess.PIPE, - stderr=subprocess.PIPE, env=environ) - out, err = p.communicate() + p = subprocess.Popen(args, stdin=subprocess.PIPE, env=environ, + stdout=subprocess.PIPE, stderr=subprocess.PIPE) + out, err = p.communicate(stdin) except OSError, e: - raise CreatorError(u"Failed to execute:\n'%s'\n'%s'" % (args, e)) + raise LiveImageMountError(u"Failed executing:\n'%s'\n'%s'" % (args, e)) except: - raise CreatorError(u"""Failed to execute:\n'%s' - \renviron: '%s'\nstdout: '%s'\nstderr: '%s'\nreturncode: '%s'""" % - (args, environ, out, err, p.returncode)) + raise LiveImageMountError(u"""Failed to execute:\n'%s' + \renviron: '%s'\nstdout: '%s'\nstderr: '%s'""" % + (args, environ, out, err)) else: - if p.returncode != 0: - raise CreatorError(u"""Error in call:\n'%s'\nenviron: '%s' - \rstdout: '%s'\nstderr: '%s'\nreturncode: '%s'""" % - (args, environ, out, err, p.returncode)) + if p.returncode != 0 and stderr: + raise LiveImageMountError(u'''Error in call:\n'%s'\nenviron: '%s' + \rstdout: %s\nstderr: %sreturncode: %s''' % + (args, environ, out, err, p.returncode)) return out -def get_device_mountpoint(path): - """Return the device and mountpoint for a file or device path.""" +def get_loop(path): + """Return the loop device for a given mount point path.""" + + loopdevice = None + for loop in rcall(['/sbin/losetup', '-a']).splitlines(): + info = loop.split() + if path == info[2].strip('()'): + loopdevice = info[0].rstrip(':') + break + return loopdevice + + +def add_loop(n=8): + """Add a loop device.""" + + while os.path.exists('/dev/loop%s' % n): + n += 1 + os.mknod('/dev/loop%s' % n, 0660 | stat.S_IFBLK, os.makedev(7, n)) + extra_loops.extend(['/dev/loop%s' % n]) + return '/dev/loop%s' % n - info = list() - info[0:5] = [None] * 6 - if os.path.exists(path): - st_mode = os.stat(path).st_mode - if stat.S_ISBLK(st_mode) or os.path.ismount(path): - devinfo = rcall(['/bin/df', path]).splitlines() - info = devinfo[1].split(None) - if len(info) == 1: - info.extend(devinfo[2].split(None)) - return [info[0], info[5]] + +def loop_setup(path): + """Make and associate a loop device with an image file or device.""" + + loop = add_loop() + call(['/sbin/losetup', loop, path]) + return loop def main(): @@ -145,18 +174,16 @@ def main(): img_type = 'blk' imgloop = None overlayloop = None + liveosmnt = tempfile.mkdtemp(prefix='livemnt-device-') else: img_type = 'iso' - - if img_type is 'blk': - liveosmnt = tempfile.mkdtemp(prefix='livemnt-device-') - if img_type is 'iso': liveosmnt = tempfile.mkdtemp(prefix='livemnt-iso-') liveosdir = os.path.join(liveosmnt, 'LiveOS') homemnt = None dm_cow = None mntlive = None + rmmntdir = None command = args[2:] verbose = not command @@ -164,13 +191,12 @@ def main(): squashmnt = tempfile.mkdtemp(prefix='livemnt-squash-') squashloop = None imgloop = None - losetup_args = ['/sbin/losetup', '-f', '--show'] try: - if img_type is 'blk': + if img_type == 'blk': call(['/bin/mount', liveos, liveosmnt]) - elif img_type is 'iso': - liveosloop = rcall(losetup_args + [liveos]).rstrip() + elif img_type == 'iso': + liveosloop = loop_setup(liveos) call(['/bin/mount', '-o', 'ro', liveosloop, liveosmnt]) squash_img = os.path.join(liveosdir, 'squashfs.img') @@ -182,12 +208,12 @@ def main(): ecode = 1 return else: - squashloop = rcall(losetup_args + [squash_img]).rstrip() + squashloop = loop_setup(squash_img) call(['/bin/mount', '-o', 'ro', squashloop, squashmnt]) ext3_img = os.path.join(squashmnt, 'LiveOS', 'ext3fs.img') - if img_type is 'blk': - imgloop = rcall(losetup_args + [ext3_img]).rstrip() + if img_type == 'blk': + imgloop = loop_setup(ext3_img) imgsize = rcall(['/sbin/blockdev', '--getsz', imgloop]).rstrip() files = os.listdir(liveosdir) overlay = None @@ -195,18 +221,19 @@ def main(): if f.find('overlay-') == 0: overlay = f break - overlayloop = rcall(['/sbin/losetup', '-f']).rstrip() if overlay: - call(['/sbin/losetup', overlayloop, os.path.join(liveosdir, - overlay)]) - dm_cow = 'live-rw' + overlayloop = loop_setup(os.path.join(liveosdir, overlay)) + dm_cow = "live-rw-%d-%d" % (os.getpid(), + random.randint(0, 2**16)) + else: overlay = tempfile.NamedTemporaryFile(dir='/dev/shm') print "\npreparing temporary overlay..." call(['/bin/dd', 'if=/dev/null', 'of=%s' % <a href="http://overlay.name">overlay.name</a>, 'bs=1024', 'count=1', 'seek=%s' % (512 * 1024)]) - call(['/sbin/losetup', overlayloop, <a href="http://overlay.name">overlay.name</a>]) - dm_cow = 'live-ro' + overlayloop = loop_setup(<a href="http://overlay.name">overlay.name</a>) + dm_cow = "live-ro-%d-%d" % (os.getpid(), + random.randint(0, 2**16)) call(['/sbin/dmsetup', '--noudevrules', '--noudevsync', 'create', dm_cow, '--table=0 %s snapshot %s %s p 8' % (imgsize, imgloop, overlayloop)]) @@ -214,14 +241,15 @@ def main(): home_path = os.path.join(liveosdir, 'home.img') if os.path.exists(home_path): homemnt = os.path.join(destmnt, 'home') - homeloop = rcall(losetup_args + [home_path]).rstrip() + homeloop = loop_setup(home_path) call(['/bin/mount', homeloop, homemnt]) mntlive = os.path.join(destmnt, 'mnt', 'live') if not os.path.exists(mntlive): os.makedirs(mntlive) + rmmntdir = True call(['/bin/mount', '--bind', liveosmnt, mntlive]) - elif img_type is 'iso': - imgloop = rcall(losetup_args + [ext3_img]).rstrip() + elif img_type == 'iso': + imgloop = loop_setup(ext3_img) call(['/bin/mount', '-o', 'ro', imgloop, destmnt]) if mount_hacks: @@ -232,7 +260,7 @@ def main(): args = [] args.extend(command) live = '' - if img_type is 'blk': + if img_type == 'blk': live = 'live-' print """Starting process with this command line: \r%s\n %s is %smounted.""" % (' '.join(command), liveos, live) @@ -247,7 +275,7 @@ def main(): print "Starting subshell in chroot, press Ctrl-D to exit..." ecode = subprocess.call(['chroot', destmnt], stdin=sys.stdin, stdout=sys.stdout, stderr=sys.stderr) else: - if dm_cow == 'live-ro': + if img_type == 'blk' and dm_cow[:7] == 'live-ro': status = ' with NO LiveOS persistence,' else: status = '' @@ -268,11 +296,13 @@ def main(): if img_type is 'blk': if mntlive: call(['/bin/umount', mntlive]) - os.rmdir(mntlive) + if rmmntdir: + time.sleep(2) + os.rmdir(mntlive) if os.path.ismount(destmnt): call(['/bin/umount', destmnt]) if img_type is 'blk': - m_cow: + if dm_cow: call(['/sbin/dmsetup', '--noudevrules', '--noudevsync', 'remove', dm_cow]) if overlayloop: @@ -288,6 +318,10 @@ def main(): os.rmdir(squashmnt) if not os.path.ismount(liveosmnt): os.rmdir(liveosmnt) + time.sleep(2) + for loop in extra_loops: + if loop: + call(['/bin/rm', '-f', loop]) if verbose: print "Cleanup complete"