diff options
Diffstat (limited to 'rdiff-backup/src/rdiff.py')
| -rw-r--r-- | rdiff-backup/src/rdiff.py | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/rdiff-backup/src/rdiff.py b/rdiff-backup/src/rdiff.py new file mode 100644 index 0000000..c27d4f2 --- /dev/null +++ b/rdiff-backup/src/rdiff.py @@ -0,0 +1,175 @@ +execfile("rlist.py") +import os, popen2 + +####################################################################### +# +# rdiff - Invoke rdiff utility to make signatures, deltas, or patch +# + +class RdiffException(Exception): pass + +class Rdiff: + """Contains static methods for rdiff operations + + All these operations should be done in a relatively safe manner + using RobustAction and the like. + + """ + def get_signature(rp): + """Take signature of rpin file and return in file object""" + Log("Getting signature of %s" % rp.path, 7) + return rp.conn.RdiffPopen(['rdiff', 'signature', rp.path]) + + def get_delta_sigfileobj(sig_fileobj, rp_new): + """Like get_delta but signature is in a file object""" + sig_tf = TempFileManager.new(rp_new, None) + sig_tf.write_from_fileobj(sig_fileobj) + rdiff_popen_obj = Rdiff.get_delta(sig_tf, rp_new) + rdiff_popen_obj.set_thunk(sig_tf.delete) + return rdiff_popen_obj + + def get_delta(rp_signature, rp_new): + """Take signature rp and new rp, return delta file object""" + assert rp_signature.conn is rp_new.conn + Log("Getting delta of %s with signature %s" % + (rp_new.path, rp_signature.path), 7) + return rp_new.conn.RdiffPopen(['rdiff', 'delta', + rp_signature.path, rp_new.path]) + + def write_delta_action(basis, new, delta): + """Return action writing delta which brings basis to new""" + sig_tf = TempFileManager.new(new, None) + delta_tf = TempFileManager.new(delta) + def init(): + Log("Writing delta %s from %s -> %s" % + (basis.path, new.path, delta.path), 7) + sig_tf.write_from_fileobj(Rdiff.get_signature(basis)) + delta_tf.write_from_fileobj(Rdiff.get_delta(sig_tf, new)) + sig_tf.delete() + return Robust.make_tf_robustaction(init, (sig_tf, delta_tf), + (None, delta)) + + def write_delta(basis, new, delta): + """Write rdiff delta which brings basis to new""" + Rdiff.write_delta_action(basis, new, delta).execute() + + def patch_action(rp_basis, rp_delta, rp_out = None, out_tf = None): + """Return RobustAction which patches rp_basis with rp_delta + + If rp_out is None, put output in rp_basis. Will use TempFile + out_tf it is specified. + + """ + if not rp_out: rp_out = rp_basis + else: assert rp_out.conn is rp_basis.conn + if not (isinstance(rp_delta, RPath) and isinstance(rp_basis, RPath) + and rp_basis.conn is rp_delta.conn): + return Rdiff.patch_fileobj_action(rp_basis, rp_delta.open('rb'), + rp_out, out_tf) + + if out_tf is None: out_tf = TempFileManager.new(rp_out) + def init(): + Log("Patching %s using %s to %s via %s" % + (rp_basis.path, rp_delta.path, rp_out.path, out_tf.path), 7) + cmdlist = ["rdiff", "patch", rp_basis.path, + rp_delta.path, out_tf.path] + return_val = rp_basis.conn.os.spawnvp(os.P_WAIT, 'rdiff', cmdlist) + out_tf.setdata() + if return_val != 0 or not out_tf.lstat(): + RdiffException("Error running %s" % cmdlist) + return Robust.make_tf_robustaction(init, (out_tf,), (rp_out,)) + + def patch_fileobj_action(rp_basis, delta_fileobj, + rp_out = None, out_tf = None): + """Like patch_action but diff is given in fileobj form + + Nest a writing of a tempfile with the actual patching to + create a new action. We have to nest so that the tempfile + will be around until the patching finishes. + + """ + if not rp_out: rp_out = rp_basis + delta_tf = TempFileManager.new(rp_out, None) + def init(): delta_tf.write_from_fileobj(delta_fileobj) + return Robust.chain_nested([RobustAction(init, delta_tf.delete, + lambda exp: delta_tf.delete), + Rdiff.patch_action(rp_basis, delta_tf, + rp_out, out_tf)]) + + def patch_with_attribs_action(rp_basis, rp_delta, rp_out = None): + """Like patch_action, but also transfers attributs from rp_delta""" + if not rp_out: rp_out = rp_basis + tf = TempFileManager.new(rp_out) + return Robust.chain_nested( + [Rdiff.patch_action(rp_basis, rp_delta, rp_out, tf), + Robust.copy_attribs_action(rp_delta, tf)]) + + def copy_action(rpin, rpout): + """Use rdiff to copy rpin to rpout, conserving bandwidth""" + if not rpin.isreg() or not rpout.isreg() or rpin.conn is rpout.conn: + # rdiff not applicable, fallback to regular copying + return Robust.copy_action(rpin, rpout) + + Log("Rdiff copying %s to %s" % (rpin.path, rpout.path), 6) + delta_tf = TempFileManager.new(rpout, None) + return Robust.chain(Rdiff.write_delta_action(rpout, rpin, delta_tf), + Rdiff.patch_action(rpout, delta_tf), + RobustAction(lambda: None, delta_tf.delete, + lambda exp: delta_tf.delete)) + +MakeStatic(Rdiff) + + +class RdiffPopen: + """Spawn process and treat stdout as file object + + Instead of using popen, which evaluates arguments with the shell + and thus may lead to security holes (thanks to Jamie Heilman for + this point), use the popen2 class and discard stdin. + + When closed, this object checks to make sure the process exited + cleanly, and executes closing_thunk. + + """ + def __init__(self, cmdlist, closing_thunk = None): + """RdiffFilehook initializer + + fileobj is the file we are emulating + thunk is called with no parameters right after the file is closed + + """ + assert type(cmdlist) is types.ListType + self.p3obj = popen2.Popen3(cmdlist) + self.fileobj = self.p3obj.fromchild + self.closing_thunk = closing_thunk + self.cmdlist = cmdlist + + def set_thunk(self, closing_thunk): + """Set closing_thunk if not already""" + assert not self.closing_thunk + self.closing_thunk = closing_thunk + + def read(self, length = -1): return self.fileobj.read(length) + + def close(self): + closeval = self.fileobj.close() + if self.closing_thunk: self.closing_thunk() + exitval = self.p3obj.poll() + if exitval == 0: return closeval + elif exitval == 256: + Log("Failure probably because %s couldn't be found in PATH." + % self.cmdlist[0], 2) + assert 0, "rdiff not found" + elif exitval == -1: + # There may a race condition where a process closes + # but doesn't provide its exitval fast enough. + Log("Waiting for process to close", 8) + time.sleep(0.2) + exitval = self.p3obj.poll() + if exitval == 0: return closeval + raise RdiffException("%s exited with non-zero value %d" % + (self.cmdlist, exitval)) + + + + |