gem5/util/gem5img.py
Gabe Black 947a5ba9a5 Util: Replace mkblankimage.sh with the new gem5img.py.
This change replaces the mkblankimage.sh script, used for creating new disk
images, with a new gem5img.py script. The new version is written in python
instead of bash, takes its parameters from command line arguments instead of
prompting for them, and finds a free loopback device dynamically instead of
hardcoding /dev/loop1. The file system used is now optionally configurable,
and the blank image is filled by a "hole" left by lseek and write instead of
literally filling it with zeroes.

The functionality of the new script is broken into subcommands "init",
"mount", "umount", "new", "partition", and "format". "init" creates a new file
of the appropriate size, partitions it, and then formats the first (and only)
new parition. "mount" attaches a new loopback device to the first parition of
the image file and mounts it to the specified mount point. "umount" unmounts
the specified mount point and identifies and cleans up the underlying loopback
device. "new", "partition", and "format" are the individual stages of "init"
but broken out so they can be run individually. That's so an image can be
reinitialized in place if needed.

Two features of the original script are being dropped. The first is the
ability to specify a source directory to copy into the new file system. The
second is the ability to specify a list of commands to run which are expected
to (but not required to) update the permissions of the files in the new fs.
Both of these seem easy enough to do manually, especially given the "mount"
and "umount" commands, that removing them would meaningfully simplify the
script without making it less useful.
2011-04-29 04:46:19 -04:00

372 lines
11 KiB
Python
Executable file

#!/usr/bin/python
#
# gem5img.py
# Script for managing a gem5 disk image.
#
from optparse import OptionParser
import os
from os import environ as env
import string
from subprocess import CalledProcessError, Popen, PIPE, STDOUT
from sys import exit, argv
# Some constants.
MaxLBACylinders = 16383
MaxLBAHeads = 16
MaxLBASectors = 63
MaxLBABlocks = MaxLBACylinders * MaxLBAHeads * MaxLBASectors
BlockSize = 512
MB = 1024 * 1024
# Setup PATH to look in the sbins.
env['PATH'] += ':/sbin:/usr/sbin'
# Whether to print debug output.
debug = False
# Figure out cylinders, heads and sectors from a size in blocks.
def chsFromSize(sizeInBlocks):
if sizeInBlocks >= MaxLBABlocks:
sizeInMBs = (sizeInBlocks * BlockSize) / MB
print '%d MB is too big for LBA, truncating file.' % sizeInMBs
return (MaxLBACylinders, MaxLBAHeads, MaxLBASectors)
sectors = sizeInBlocks
if sizeInBlocks > 63:
sectors = 63
headSize = sizeInBlocks / sectors
heads = 16
if headSize < 16:
heads = sizeInBlocks
cylinders = sizeInBlocks / (sectors * heads)
return (cylinders, heads, sectors)
# Figure out if we should use sudo.
def needSudo():
if not hasattr(needSudo, 'notRoot'):
needSudo.notRoot = (os.geteuid() != 0)
if needSudo.notRoot:
print 'You are not root. Using sudo.'
return needSudo.notRoot
# Run an external command.
def runCommand(command, inputVal=''):
print "%>", ' '.join(command)
proc = Popen(command, stdin=PIPE)
proc.communicate(inputVal)
return proc.returncode
# Run an external command and capture its output. This is intended to be
# used with non-interactive commands where the output is for internal use.
def getOutput(command, inputVal=''):
global debug
if debug:
print "%>", ' '.join(command)
proc = Popen(command, stderr=STDOUT,
stdin=PIPE, stdout=PIPE)
(out, err) = proc.communicate(inputVal)
return (out, proc.returncode)
# Run a command as root, using sudo if necessary.
def runPriv(command, inputVal=''):
realCommand = command
if needSudo():
realCommand = [findProg('sudo')] + command
return runCommand(realCommand, inputVal)
def privOutput(command, inputVal=''):
realCommand = command
if needSudo():
realCommand = [findProg('sudo')] + command
return getOutput(realCommand, inputVal)
# Find the path to a program.
def findProg(program, cleanupDev=None):
(out, returncode) = getOutput(['which', program])
if returncode != 0:
if cleanupDev:
cleanupDev.destroy()
exit("Unable to find program %s, check your PATH variable." % program)
return string.strip(out)
class LoopbackDevice(object):
def __init__(self, devFile=None):
self.devFile = devFile
def __str__(self):
return str(self.devFile)
def setup(self, fileName, offset=False):
assert not self.devFile
(out, returncode) = privOutput([findProg('losetup'), '-f'])
if returncode != 0:
print out
return returncode
self.devFile = string.strip(out)
command = [findProg('losetup'), self.devFile, fileName]
if offset:
off = findPartOffset(self.devFile, fileName, 0)
command = command[:1] + \
["-o", "%d" % off] + \
command[1:]
return runPriv(command)
def destroy(self):
assert self.devFile
returncode = runPriv([findProg('losetup'), '-d', self.devFile])
self.devFile = None
return returncode
def findPartOffset(devFile, fileName, partition):
# Attach a loopback device to the file so we can use sfdisk on it.
dev = LoopbackDevice()
dev.setup(fileName)
# Dump the partition information.
command = [findProg('sfdisk'), '-d', dev.devFile]
(out, returncode) = privOutput(command)
if returncode != 0:
print out
exit(returncode)
lines = out.splitlines()
# Make sure the first few lines of the output look like what we expect.
assert(lines[0][0] == '#')
assert(lines[1] == 'unit: sectors')
assert(lines[2] == '')
# This line has information about the first partition.
chunks = lines[3].split()
# The fourth chunk is the offset of the partition in sectors followed by
# a comma. We drop the comma and convert that to an integer.
sectors = string.atoi(chunks[3][:-1])
# Free the loopback device and return an answer.
dev.destroy()
return sectors * BlockSize
def mountPointToDev(mountPoint):
(mountTable, returncode) = getOutput([findProg('mount')])
if returncode != 0:
print mountTable
exit(returncode)
mountTable = mountTable.splitlines()
for line in mountTable:
chunks = line.split()
if os.path.samefile(chunks[2], mountPoint):
return LoopbackDevice(chunks[0])
return None
# Commands for the gem5img.py script
commands = {}
commandOrder = []
class Command(object):
def addOption(self, *args, **kargs):
self.parser.add_option(*args, **kargs)
def __init__(self, name, description, posArgs):
self.name = name
self.description = description
self.func = None
self.posArgs = posArgs
commands[self.name] = self
commandOrder.append(self.name)
usage = 'usage: %prog [options]'
posUsage = ''
for posArg in posArgs:
(argName, argDesc) = posArg
usage += ' %s' % argName
posUsage += '\n %s: %s' % posArg
usage += posUsage
self.parser = OptionParser(usage=usage, description=description)
self.addOption('-d', '--debug', dest='debug', action='store_true',
help='Verbose output.')
def parseArgs(self, argv):
(self.options, self.args) = self.parser.parse_args(argv[2:])
if len(self.args) != len(self.posArgs):
self.parser.error('Incorrect number of arguments')
global debug
if self.options.debug:
debug = True
def runCom(self):
if not self.func:
exit('Unimplemented command %s!' % self.name)
self.func(self.options, self.args)
# A command which prepares an image with an partition table and an empty file
# system.
initCom = Command('init', 'Create an image with an empty file system.',
[('file', 'Name of the image file.'),
('mb', 'Size of the file in MB.')])
initCom.addOption('-t', '--type', dest='fstype', action='store',
default='ext2',
help='Type of file system to use. Appended to mkfs.')
# A command to mount the first partition in the image.
mountCom = Command('mount', 'Mount the first partition in the disk image.',
[('file', 'Name of the image file.'),
('mount point', 'Where to mount the image.')])
def mountComFunc(options, args):
(path, mountPoint) = args
if not os.path.isdir(mountPoint):
print "Mount point %s is not a directory." % mountPoint
dev = LoopbackDevice()
if dev.setup(path, offset=True) != 0:
exit(1)
if runPriv([findProg('mount'), str(dev), mountPoint]) != 0:
dev.destroy()
exit(1)
mountCom.func = mountComFunc
# A command to unmount the first partition in the image.
umountCom = Command('umount', 'Unmount the first partition in the disk image.',
[('mount point', 'What mount point to unmount.')])
def umountComFunc(options, args):
(mountPoint,) = args
if not os.path.isdir(mountPoint):
print "Mount point %s is not a directory." % mountPoint
exit(1)
dev = mountPointToDev(mountPoint)
if not dev:
print "Unable to find mount information for %s." % mountPoint
# Unmount the loopback device.
if runPriv([findProg('umount'), mountPoint]) != 0:
exit(1)
# Destroy the loopback device.
dev.destroy()
umountCom.func = umountComFunc
# A command to create an empty file to hold the image.
newCom = Command('new', 'File creation part of "init".',
[('file', 'Name of the image file.'),
('mb', 'Size of the file in MB.')])
def newImage(file, mb):
(cylinders, heads, sectors) = chsFromSize((mb * MB) / BlockSize)
size = cylinders * heads * sectors * BlockSize
# We lseek to the end of the file and only write one byte there. This
# leaves a "hole" which many file systems are smart enough not to actually
# store to disk and which is defined to read as zero.
fd = os.open(file, os.O_WRONLY | os.O_CREAT)
os.lseek(fd, size - 1, os.SEEK_SET)
os.write(fd, '\0')
def newComFunc(options, args):
(file, mb) = args
mb = string.atoi(mb)
newImage(file, mb)
newCom.func = newComFunc
# A command to partition the image file like a raw disk device.
partitionCom = Command('partition', 'Partition part of "init".',
[('file', 'Name of the image file.')])
def partition(dev, cylinders, heads, sectors):
# Use fdisk to partition the device
comStr = '0,\n;\n;\n;\n'
return runPriv([findProg('sfdisk'), '--no-reread', '-D', \
'-C', "%d" % cylinders, \
'-H', "%d" % heads, \
'-S', "%d" % sectors, \
str(dev)], inputVal=comStr)
def partitionComFunc(options, args):
(path,) = args
dev = LoopbackDevice()
if dev.setup(path) != 0:
exit(1)
# Figure out the dimensions of the file.
size = os.path.getsize(path)
if partition(dev, *chsFromSize(size / BlockSize)) != 0:
dev.destroy()
exit(1)
dev.destroy()
partitionCom.func = partitionComFunc
# A command to format the first partition in the image.
formatCom = Command('format', 'Formatting part of "init".',
[('file', 'Name of the image file.')])
formatCom.addOption('-t', '--type', dest='fstype', action='store',
default='ext2',
help='Type of file system to use. Appended to mkfs.')
def formatImage(dev, fsType):
return runPriv([findProg('mkfs.%s' % fsType, dev), str(dev)])
def formatComFunc(options, args):
(path,) = args
dev = LoopbackDevice()
if dev.setup(path, offset=True) != 0:
exit(1)
# Format the device.
if formatImage(dev, options.fstype) != 0:
dev.destroy()
exit(1)
dev.destroy()
formatCom.func = formatComFunc
def initComFunc(options, args):
(path, mb) = args
mb = string.atoi(mb)
newImage(path, mb)
dev = LoopbackDevice()
if dev.setup(path) != 0:
exit(1)
size = os.path.getsize(path)
if partition(dev, *chsFromSize((mb * MB) / BlockSize)) != 0:
dev.destroy()
exit(1)
dev.destroy()
if dev.setup(path, offset=True) != 0:
exit(1)
if formatImage(dev, options.fstype) != 0:
dev.destroy()
exit(1)
dev.destroy()
initCom.func = initComFunc
# Figure out what command was requested and execute it.
if len(argv) < 2 or argv[1] not in commands:
print 'Usage: %s [command] <command arguments>'
print 'where [command] is one of '
for name in commandOrder:
command = commands[name]
print ' %s: %s' % (command.name, command.description)
print 'Watch for orphaned loopback devices and delete them with'
print 'losetup -d. Mounted images will belong to root, so you may need'
print 'to use sudo to modify their contents.'
exit(1)
command = commands[argv[1]]
command.parseArgs(argv)
command.runCom()