[arch-general] adb backup broken named pipe

[Pascal]

does anyone have any idea what should be added/removed at the end of the
data to properly complete the tgz archive ?

regards, lacsaP.

Le jeu. 16 mai 2019 à 16:00, Pascal <patatetom at gmail.com> a écrit :

> when I looked a little closer at what adb backup was doing, I realized
> that it was communicating with an adb server running in parallel and, by
> mimicking the conversation with python, I managed to get what I wanted.
> *(note that a small error was present in the question : the string to use
> with printf is "\x1f\x8b\x08\x00\x00\x00\x00\x00").*
>
> I still have a slight problem because the tar command ends with an error :
> *(the same error is also present with adb, printf and tail).*
>
> $ adb devices
> List of devices attached
> CB5A2B0M9R    device
> $ python3 adbackup.py > /tmp/mybackup.tgz
> $ tar tvzf /tmp/mybackup.tgz
> ... all my files are here :-)
> gzip: stdin: unexpected end of file
> tar: Child returned status 1
> tar: Error is not recoverable: exiting now
>
> adbackup.py :
>
> #!/usr/bin/python3
>
> # strace adb backup -all -f /tmp/backup.ab
> #    ...
> #    unlink("/tmp/backup.ab")                = 0
> #    creat("/tmp/backup.ab", 0640)           = 3
> #    ...
> #    socket(AF_INET, SOCK_STREAM, IPPROTO_IP) = 4
> #    bind(4, {sa_family=AF_INET, sin_port=htons(0),
> sin_addr=inet_addr("127.0.0.1")}, 16) = 0
> #    connect(4, {sa_family=AF_INET, sin_port=htons(5037),
> sin_addr=inet_addr("127.0.0.1")}, 16) = 0
> #    setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0
> #    write(4, "0012host:transport-any", 22)  = 22
> #    read(4, "OKAY", 4)                      = 4
> #    write(4, "000ebackup: '-all'", 18)      = 18
> #    read(4, "OKAY", 4)                      = 4
> #    fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(0x88, 0x1), ...}) = 0
> #    write(1, "Now unlock your device and confi"..., 59) = 59
> #    read(4, "ANDROID BACKUP\n4\n1\nnone\n", 32768) = 24
> #    write(3, "ANDROID BACKUP\n4\n1\nnone\n", 24) = 24
> #    read(4, "x\332", 32768)                 = 2
> #    write(3, "x\332", 2)                    = 2
> #    read(4, "\344VY\256\35E\f}\337o\25\254
> \361\\U\253A\256\301(\37$Q\22\366\317\251\233\274(\240"..., 32768) = 967
>
> import socket, sys
> s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
> s.connect(("localhost", 5037))
> s.sendall(b"0012host:transport-any")
> data = s.recv(4)        # b"OKAY"
> s.sendall(b"000ebackup: '-all'")
> data = s.recv(4)        # b"OKAY"
> data = s.recv(32768)    # b"ANDROID BACKUP\n4\n1\nnone\n"
> sys.stdout.buffer.write(b"\x1f\x8b\x08\x00\x00\x00\x00\x00")
> data = s.recv(32768)
> while data:
>     sys.stdout.buffer.write(data)
>     data = s.recv(32768)
>
> regards, lacsaP.
>
> Le jeu. 16 mai 2019 à 10:57, Pascal <patatetom at gmail.com> a écrit :
>
>> hello,
>>
>> I'm looking for a solution for the problem below : all leads are welcome !
>>
>> the adb tool is able to make a backup of a smartphone in a file:
>> adb backup -all -f mybackup.ab
>>
>> however, the file mybackup.ab has a particular format that prevents it
>> from being used "simply".
>> to convert it into a tgz archive, it is possible to do this:
>> ( printf "\x1f\x8b\x08\x08\x00\x00\x00\x00\x00\x00\x00"; tail -c +25
>> mybackup.ab ) > mybackup.tgz
>>
>> but in this case, I can easily end up with two files of 16Gb or more...
>> to avoid this volume problem, I tried to do this:
>> mkfifo backup.fifo
>> adb backup -all -f backup.fifo &
>> ( printf "\x1f\x8b\x08\x08\x00\x00\x00\x00\x00\x00" ; tail -c +25
>> backup.fifo) > mybackup.tgz
>>
>> but adb systematically breaks my named pipe and my code doesn't work as
>> expected.
>> how to prevent adb from breaking the named pipe ?
>> I'm considering using fuse but there may be a simpler way...
>>
>> regards, lacsaP.
>>
>