[Debian-science-sagemath] Bug#844789: Bug#844789: iS: issue related to compressed manual.six
Jerome BENOIT
calculus at rezozer.net
Tue Nov 29 17:37:44 UTC 2016
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Hello All, a quick email just to say that I am working a a patch that may resolve the issue.
Thanks, Jerome
On 24/11/16 17:45, Jerome BENOIT wrote:
> Hello for your reply,
>
> On 24/11/16 17:02, Bill Allombert wrote:
>> On Thu, Nov 24, 2016 at 04:43:16PM +0000, Jerome BENOIT wrote:
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>>>
>>> Hello Bill, thanks for your reply.
>>>
>>> On 24/11/16 10:26, Bill Allombert wrote:
>>>> On Thu, Nov 24, 2016 at 10:34:28AM +0100, Bill Allombert wrote:
>>>>> On Thu, Nov 24, 2016 at 04:55:28AM +0000, Jerome BENOIT wrote:
>>>>>> -----BEGIN PGP SIGNED MESSAGE-----
>>>>>> Hash: SHA512
>>>>>>
>>>>>> Hello Again,
>>>>>>
>>>>>> On 24/11/16 02:52, Jerome BENOIT wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 23/11/16 09:59, Bill Allombert wrote:
>>>>>>>> Can you generate a full strace dump ?
>>>>>>>
>>>>>>> Yes. Unfortunately I have not yet succeeded to decipher them.
>>>>>>>
>>>>>>> There is a `Broken pipe' somewhere.
>>>>>>> The piping seems to be related to the uncompresion of a `manual.siz.gx'.
>>>>>>
>>>>>> There are a myriad of processes: the messages around the `Broken pipe' are:
>>>>>>
>>>>>> execve("/bin/gunzip", ["gunzip"], [/* 90 vars */]) = 0
>>>>>> [...]
>>>>>> rt_sigaction(SIGINT, NULL, {SIG_DFL, [], 0}, 8) = 0
>>>>>> rt_sigaction(SIGHUP, NULL, {SIG_IGN, [], 0}, 8) = 0
>>>>>> rt_sigaction(SIGPIPE, NULL, {SIG_IGN, [], 0}, 8) = 0
>>>>>> rt_sigaction(SIGTERM, NULL, {SIG_DFL, [], 0}, 8) = 0
>>>>>> rt_sigaction(SIGXCPU, NULL, {SIG_DFL, [], 0}, 8) = 0
>>>>>> rt_sigaction(SIGXFSZ, NULL, {SIG_IGN, [], 0}, 8) = 0
>>>>>> rt_sigaction(SIGINT, {0x4035c0, [INT TERM XCPU], SA_RESTORER, 0x7eff302e1040}, NULL, 8) = 0
>>>>>> rt_sigaction(SIGTERM, {0x4035c0, [INT TERM XCPU], SA_RESTORER, 0x7eff302e1040}, NULL, 8) = 0
>>>>>> rt_sigaction(SIGXCPU, {0x4035c0, [INT TERM XCPU], SA_RESTORER, 0x7eff302e1040}, NULL, 8) = 0
>>>>>> ioctl(0, TCGETS, 0x7ffef9ddf1c0) = -1 ENOTTY (Inappropriate ioctl for device)
>>>>>> fstat(0, {st_mode=S_IFREG|0644, st_size=171476, ...}) = 0
>>>>>> read(0, "\37\213\10\0\0\0\0\0\2\3\244\\\331\222\324H\226}\317\257\220\345\274T\233\1\346\3732c\363\240"..., 32768) = 32768
>>>>>> brk(NULL) = 0x669000
>>>>>> brk(0x68a000) = 0x68a000
>>>>>> write(1, "#SIXFORMAT GapDocGAP\nHELPBOOKIN"..., 32768) = 32768
>>>>>> write(1, ".4-1\", [ 20, 4, 1 ], 98, 246, \"l"..., 32768) = 32768
>>>>>> write(1, " \"35.3-5\", [ 35, 3, 5 ], 310, 46"..., 32768) = 16384
>>>>>> - --- SIGPIPE {si_signo=SIGPIPE, si_code=SI_USER, si_pid=9643, si_uid=1000} ---
>>>>>> write(1, "033[101X\", \"41.10-2\", \n [ 4"..., 16384) = -1 EPIPE (Broken pipe)
>>>>>> - --- SIGPIPE {si_signo=SIGPIPE, si_code=SI_USER, si_pid=9643, si_uid=1000} ---
>>>>>> write(2, "\ngzip: ", 7) = 7
>>>>>> write(2, "stdout: Broken pipe\n", 20) = 20
>>>>>> rt_sigprocmask(SIG_BLOCK, [INT TERM XCPU], [], 8) = 0
>>>>>> rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
>>>>>> lseek(0, 0, SEEK_CUR) = 32768
>>>>>> close(0) = 0
>>>>>> close(1) = 0
>>>>>> close(2) = 0
>>>>>> exit_group(1) = ?
>>>>>> +++ exited with 1 +++
>>>>>>
>>>>>> [[/bin/gunzip is in fact a shell script that wraps `gzip -d' ]]
>>>>>>
>>>>>> It looks like that it happens what is described in the following link:
>>>>>>
>>>>>> https://blog.nelhage.com/2010/02/a-very-subtle-bug/
>>>>>>
>>>>>> that is to say, python/sage manipulates SIGPIPE in such a way that any gzip piping
>>>>>> becomes hazardous.
>>>>>
>>>>> Can you confirm that 'CloseStream(stream);' is the call that trigger the
>>>>> SIGPIPE ? In which case this can be worked around.
>>>>
>>>> Please find a patch that make sure the stream is empty before calling
>>>> CloseStream(stream).
>>>
>>> This patch does not fix the issue.
>
>> There should still be a difference in the strace. Did you observe it ?
>
> I observe a minor difference: for one of the two Broken pipe event (EPIPE), the raise seems to be postponed:
>
>
> write(1, "#SIXFORMAT GapDocGAP\nHELPBOOKIN"..., 32768) = 32768
> write(1, ".4-1\", [ 20, 4, 1 ], 98, 246, \"l"..., 32768) = 32768
> write(1, " \"35.3-5\", [ 35, 3, 5 ], 310, 46"..., 32768) = 16384
> --- SIGPIPE {si_signo=SIGPIPE, si_code=SI_USER, si_pid=29824, si_uid=1000} ---
> write(1, "033[101X\", \"41.10-2\", \n [ 4"..., 16384) = -1 EPIPE (Broken pipe)
> --- SIGPIPE {si_signo=SIGPIPE, si_code=SI_USER, si_pid=29824, si_uid=1000} ---
> write(2, "\ngzip: ", 7)
> write(2, "stdout: Broken pipe\n", 20) = 20
>
> instead of
>
> write(1, "#SIXFORMAT GapDocGAP\nHELPBOOKIN"..., 32768) = 32768
> write(1, ".4-1\", [ 20, 4, 1 ], 98, 246, \"l"..., 32768) = -1 EPIPE (Broken pipe)
> --- SIGPIPE {si_signo=SIGPIPE, si_code=SI_USER, si_pid=29620, si_uid=1000} ---
> write(2, "\ngzip: ", 7) = 7
> write(2, "stdout: Broken pipe\n", 20) = 20
>
>
>
>
>
>>> In other words, GAP exposes itself to this kind of bug because it compresses and
>>> decompresses thought pipes, what I would not consider as good behaviour.
>
>> This is the UNIX way to do this.
>
> More exactly, this is one of the UNIX ways to do this.
> Using zlib is an other way, and a safer way.
> zlib is also a lazy way to do so because the zlib
> library is designed to manage compressed files as uncompressed file
> (of course here we are not dealing with high level zlib functons).
>
> Thanks,
> Jerome
>
>
>> Cheers,
>
>
>
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>
- --
Jerome BENOIT, Ph.D. | jgmbenoit-at+rezozer*dot_net
http://www.rezozer.net/
- --
Jerome BENOIT | calculus+at-rezozer^dot*net
https://qa.debian.org/developer.php?login=calculus@rezozer.net
AE28 AE15 710D FF1D 87E5 A762 3F92 19A6 7F36 C68B
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