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backup: fix race condition with inner tar process

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Do not assume that tar will finish quickly - explicitly wait for either
process termination or request for the next archive part.
This commit is contained in:
Marek Marczykowski-Górecki 2013-11-09 17:09:44 +01:00
parent 89b6069bda
commit 54f08e00b9
1 changed files with 9 additions and 7 deletions
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16
core/qubesutils.py
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@ -1342,6 +1342,7 @@ def restore_vm_dirs (backup_dir, backup_tmpdir, passphrase, vms_dirs, vms, vms_s
self.print_callback("Extracting file "+filename+" to "+system_path["qubes_base_dir"]) self.print_callback("Extracting file "+filename+" to "+system_path["qubes_base_dir"])
pipe = open(self.restore_pipe,'r+b')
if self.tar2_command == None: if self.tar2_command == None:
# FIXME: Make the extraction safer by avoiding to erase other vms: # FIXME: Make the extraction safer by avoiding to erase other vms:
# - extracting directly to the target directory (based on the vm name and by using the --strip=2). # - extracting directly to the target directory (based on the vm name and by using the --strip=2).
@ -1349,9 +1350,8 @@ def restore_vm_dirs (backup_dir, backup_tmpdir, passphrase, vms_dirs, vms, vms_s
# marmarek: use other (local) variable for command line # marmarek: use other (local) variable for command line
self.tar2_command = ['tar', '--tape-length','1000000', '-C', system_path["qubes_base_dir"], '-xvf', self.restore_pipe] self.tar2_command = ['tar', '--tape-length','1000000', '-C', system_path["qubes_base_dir"], '-xvf', self.restore_pipe]
self.print_callback("Running command "+str(self.tar2_command)) self.print_callback("Running command "+str(self.tar2_command))
self.tar2_command = subprocess.Popen(self.tar2_command,stdin=subprocess.PIPE) self.tar2_command = subprocess.Popen(self.tar2_command, stdin=subprocess.PIPE, stderr=subprocess.PIPE)
pipe = open(self.restore_pipe,'r+b')
if self.encrypted: if self.encrypted:
# Start decrypt # Start decrypt
encryptor = subprocess.Popen (["openssl", "enc", "-d", "-aes-256-cbc", "-pass", "pass:"+passphrase], stdin=open(filename,'rb'), stdout=subprocess.PIPE) encryptor = subprocess.Popen (["openssl", "enc", "-d", "-aes-256-cbc", "-pass", "pass:"+passphrase], stdin=open(filename,'rb'), stdout=subprocess.PIPE)
@ -1364,11 +1364,13 @@ def restore_vm_dirs (backup_dir, backup_tmpdir, passphrase, vms_dirs, vms, vms_s
pipe.close() pipe.close()
self.print_callback("Run error:"+run_error) # tar2 input closed, wait for either it finishes, or prompt for the next
self.print_callback(str(self.tar2_command.poll())) # file part; in both cases we can use read() on stderr - in the former case
# it will return "" (EOF)
if self.tar2_command.poll() != None: tar2_stderr=self.tar2_command.stderr.readline()
if self.tar2_command.poll() != 0: if tar2_stderr == "":
# EOF, so collect process exit status
if self.tar2_command.wait() != 0:
raise QubesException("ERROR: unable to extract files for {0}.".format(filename)) raise QubesException("ERROR: unable to extract files for {0}.".format(filename))
else: else:
# Finished extracting the tar file # Finished extracting the tar file