[elbe-devel] [PATCH v3 3/8] Add save excursion in ChRootFilesystem context
dion at linutronix.de
dion at linutronix.de
Wed May 29 16:24:55 CEST 2019
From: Olivier Dion <dion at linutronix.de>
Instead of manually copying/moving/deleting files around,
the '__enter__' method of 'ChRootFilesystem' should save the
excursion into 'self.excursion'.
The excursion can be hardcoded directly at the top of the
'__enter__' method. Depending on the filesystem object,
other files can be add to the excursion as well dynamically.
To put a file into the excursion, 2 variables must be
provide and 1 optional.
* 'path' - file on the *host* to copy to the RFS.
* 'restore' - if to restore 'path' in the RFS on '__exit__'
* 'dst' (optional) - Copy 'path' to 'dst'
If 'dst' is not provided, then 'path' is copy to the same
place in the RFS.
Uppon exiting the 'ChrootFilesystem' context with '__exit__'
the excursion is restored according to the policies in it.
Finally, the excursion is deleted so it's reset in the next
context.
Examples
========
````````````````````````````````````````````````````````````
Excursion.add(self, "/usr/bin")
````````````````````````````````````````````````````````````
On '__enter__'
* Move "/rfs/usr/bin" to "/rfs/usr/bin.orig", even if it's a
broken link
* Copy "/usr/bin" to "/rfs/usr/bin"
On '__exit__'
* Remove "/rfs/usr/bin"
* Move "/rfs/usr/bin.orig" to "/rfs/usr/bin"
````````````````````````````````````````````````````````````
ui = "/usr/share/elbe/qemu-elbe/elbe"
Excursion.add(self, ui, False, "/usr/bin")
````````````````````````````````````````````````````````````
On '__enter__'
* Move "/usr/share/elbe/qemu-elbe/elbe" to "/rfs/usr/bin/elbe"
On '__exit__'
* Remove "/rfs/usr/bin/elbe"
Signed-off-by: Olivier Dion <dion at linutronix.de>
Reviewed-by: Torben Hohn <torben.hohn at linutronix.de>
---
elbepack/efilesystem.py | 99 ++++++++++++++++++++++++++++++++-----------------
1 file changed, 65 insertions(+), 34 deletions(-)
diff --git a/elbepack/efilesystem.py b/elbepack/efilesystem.py
index 1f6428e0..9181c89d 100644
--- a/elbepack/efilesystem.py
+++ b/elbepack/efilesystem.py
@@ -167,8 +167,61 @@ class ElbeFilesystem(Filesystem):
if xml_fname is not None:
licence_xml.write(xml_fname)
+class Excursion(object):
+
+ RFS = {}
+
+ @classmethod
+ def begin(cls, rfs):
+ cls.RFS[rfs.path] = []
+
+ @classmethod
+ def add(cls, rfs, path, restore=True, dst=None):
+ cls.RFS[rfs.path].append(Excursion(path, restore, dst))
+
+ @classmethod
+ def do(cls, rfs):
+ r = cls.RFS[rfs.path]
+ for tmp in r:
+ tmp._do_excursion(rfs)
+
+ @classmethod
+ def end(cls, rfs):
+ r = cls.RFS[rfs.path]
+ for tmp in r:
+ tmp._undo_excursion(rfs)
+ del r
+
+ def __init__(self, path, restore, dst):
+ self.origin = path
+ self.restore = restore
+ self.dst = dst
+
+
+ def _do_excursion(self, rfs):
+ if rfs.lexists(self.origin) and self.restore is True:
+ save_to = "%s.orig" % self.origin
+ os.system('mv %s %s' % (rfs.fname(self.origin), rfs.fname(save_to)))
+ if os.path.exists(self.origin):
+ if self.dst is not None:
+ dst = self.dst
+ else:
+ dst = self.origin
+ os.system('cp %s %s' % (self.origin, rfs.fname(dst)))
+
+ def _undo_excursion(self, rfs):
+ saved_to = "%s.orig" % self.origin
+ if rfs.lexists(self.origin):
+ flags = "-f"
+ if rfs.isdir(self.origin):
+ flags += "r"
+ os.system('rm %s %s' % (flags, rfs.fname(self.origin)))
+ if self.restore is True and rfs.lexists(saved_to):
+ os.system('mv %s %s' % (rfs.fname(saved_to), rfs.fname(self.origin)))
+
class ChRootFilesystem(ElbeFilesystem):
+
def __init__(self, path, interpreter=None, clean=False):
ElbeFilesystem.__init__(self, path, clean)
self.interpreter = interpreter
@@ -179,32 +232,27 @@ class ChRootFilesystem(ElbeFilesystem):
os.close(self.cwd)
def __enter__(self):
+ Excursion.begin(self)
+ Excursion.add(self, "/etc/resolv.conf")
+ Excursion.add(self, "/etc/apt/apt.conf")
+ Excursion.add(self, "/usr/sbin/policy-rc.d")
+
if self.interpreter:
if not self.exists("usr/bin"):
- self.mkdir("usr/bin")
+ if self.islink("usr/bin"):
+ Excursion.add(self, "/usr/bin")
ui = "/usr/share/elbe/qemu-elbe/" + self.interpreter
if not os.path.exists(ui):
ui = "/usr/bin/" + self.interpreter
- os.system('cp %s %s' % (ui, self.fname("usr/bin")))
- if self.exists("/etc/resolv.conf"):
- os.system('mv %s %s' % (self.fname("etc/resolv.conf"),
- self.fname("etc/resolv.conf.orig")))
- os.system('cp %s %s' % ("/etc/resolv.conf",
- self.fname("etc/resolv.conf")))
+ Excursion.add(self, ui, False, "/usr/bin")
- if self.exists("/etc/apt/apt.conf"):
- os.system('cp %s %s' % (self.fname("/etc/apt/apt.conf"),
- self.fname("/etc/apt/apt.conf.orig")))
- if os.path.exists("/etc/apt/apt.conf"):
- os.system('cp %s %s' % ("/etc/apt/apt.conf",
- self.fname("/etc/apt/")))
+ Excursion.do(self)
+ self.mkdir_p("usr/bin")
self.mkdir_p("usr/sbin")
- self.write_file("usr/sbin/policy-rc.d",
- 0o755, "#!/bin/sh\nexit 101\n")
-
+ self.write_file("usr/sbin/policy-rc.d", 0o755, "#!/bin/sh\nexit 101\n")
self.mount()
return self
@@ -212,25 +260,8 @@ class ChRootFilesystem(ElbeFilesystem):
if self.inchroot:
self.leave_chroot()
self.umount()
- if self.interpreter:
- os.system('rm -f %s' %
- os.path.join(self.path, "usr/bin/" + self.interpreter))
-
- os.system('rm -f %s' % (self.fname("etc/resolv.conf")))
-
- if self.exists("/etc/resolv.conf.orig"):
- os.system('mv %s %s' % (self.fname("etc/resolv.conf.orig"),
- self.fname("etc/resolv.conf")))
-
- if self.exists("/etc/apt/apt.conf"):
- os.system('rm -f %s' % (self.fname("etc/apt/apt.conf")))
-
- if self.exists("/etc/apt/apt.conf.orig"):
- os.system('mv %s %s' % (self.fname("etc/apt/apt.conf.orig"),
- self.fname("etc/apt/apt.conf")))
- if self.exists("/usr/sbin/policy-rc.d"):
- os.system('rm -f %s' % (self.fname("usr/sbin/policy-rc.d")))
+ Excursion.end(self)
def mount(self):
if self.path == '/':
--
2.11.0
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