GSOC: Introduction

Thu Mar 16 04:23:04 UTC 2017

On Wed, Mar 15, 2017 at 11:14 PM, Abhishek Tiwari
<erabhishektiwarics at gmail.com> wrote:
> On Tue, Mar 14, 2017 at 8:44 AM, Abhishek Tiwari
> <erabhishektiwarics at gmail.com> wrote:
>> On Tue, Mar 14, 2017 at 2:00 AM, Dmitry V. Levin <ldv at altlinux.org> wrote:
>>> On Tue, Mar 14, 2017 at 12:40:46AM +0530, Abhishek Tiwari wrote:
>>>> > Per-file summary is not in GNU change log format, please refer to
>>>> > https://www.gnu.org/prep/standards/html_node/Style-of-Change-Logs.html .
>>>> > Specifically, it lacks asterisks at the beginning of each new file
>>>> > description and has excess spaces between file part and description,
>>>> > otherwise looks fine.
>>>> >
>>>> > The patch wires up {,l}stat{,64}, fstatat/fstatat64 syscalls (used for obtaining
>>>> > file status), ustat syscall (which is a deprecated way to get some FS
>>>> > statistics) and some statfs syscalls (which are more contemporary way
>>>> > obtaining FS statistics information). On the other side, at least
>>>> > fstat/fstat64, fstatfs/fstatfs64, old{,f,l}stat, osf_{,f}statfs, and various
>>>> > (mostly unsupported) syscalls with osf_, svr4_, sysv_, bsd43_, and posix_
>>>> > prefixes, present on alpha and mips, are omitted. I'm not sure whether
>>>> > it was intended.
>>>> >
>>>> > There are minor tabulation irregularities introduced (at least) for
>>>> > newfstatat and fstatat64 syscall entries, it is better to avoid this.
>>>>
>>>> I have fixed the commit entries.
>>>> Now the patch includes all the stat-like syscalls that can be
>>>> displayed by following command->
>>>
>>> The idea is not to throw all syscalls that do some kind of stat into a
>>> single class, but to create a class of syscalls that could be useful.
>>> As Eugene already noted, there is little use of grouping syscalls that
>>> stat files with those that stat filesystems.
>>>
>>> Actually, there is a software project that could benefit from more
>>> fine-grained classes, e.g. oldstat+stat+stat64, oldlstat+lstat+lstat64,
>>> and newfstatat+fstatat64.
>>
>> Ok, so oldstat+stat+stat64 is one class that is to be grouped under
>> %stat, oldstat+lstat+lstat64 as another class and
>> fstatat+newfstatat+fstatat64 and some other class.
>>
>> I read in mailing list it is intended to group syscalls that perform
>> same action across different versions.
>>
>> But it is little confusing to decide what to group into one class.
>>
>>
>>> There may be some use of a class that groups all filesystem stat syscalls
>>> like ustat and *statfs*.  This might appear to be easier for you to
>>> implement, especially the part that tests it.
>>
>> I would be doing this part first. Grouping ustat and *statfs* under
>> %statfs. Is this class name fine?
>>
>>
>>>> grep -nr stat linux/*/syscallent*
>>>
>>> btw, why do you pass -nr to this grep command?
>>
>> This grep command is just to display the places where I have made the
>> change. The command actually used is mentioned in commit.
>>>> >> --- a/syscall.c
>>>> >> +++ b/syscall.c
>>>> >> @@ -77,6 +77,7 @@
>>>> >>  #define TS TRACE_SIGNAL
>>>> >>  #define TM TRACE_MEMORY
>>>> >>  #define TSC TRACE_SCHED
>>>> >> +#define TST  TRACE_STAT
>>>> > Tabulation is used for separating macro declaration and definition, but
>>>> > neighbouring lines utilise space for this purpose.
>>>>
>>>> Please elaborate, i don't get what correction is intended here?
>>>
>>> The rule of thumb is simple:
>>> when patching a piece of code, follow its coding style.
>>>
>>> If the code uses spaces, use spaces.  If it uses tabs, use tabs.
>>> strace has a long history with a lot of contributors so the style
>>> used in different parts might differ slightly.
>>
>> Sorry, that space was not intensional.
>>
>>>> >> +++ b/tests/stat_like.test
>>>> >> @@ -0,0 +1,58 @@
>>>> >> +#!/bin/sh
>>>> >> +
>>>> >> +# Check how stat-like syscalls are traced.
>>>> >> +#
>>>> >> +# Copyright (c) 2017 The strace developers.
>>>> >> +# All rights reserved.
>>>> >> +#
>>>> >> +# Redistribution and use in source and binary forms, with or without
>>>> >> +# modification, are permitted provided that the following conditions
>>>> >> +# are met:
>>>> >> +# 1. Redistributions of source code must retain the above copyright
>>>> >> +#    notice, this list of conditions and the following disclaimer.
>>>> >> +# 2. Redistributions in binary form must reproduce the above copyright
>>>> >> +#    notice, this list of conditions and the following disclaimer in the
>>>> >> +#    documentation and/or other materials provided with the distribution.
>>>> >> +# 3. The name of the author may not be used to endorse or promote products
>>>> >> +#    derived from this software without specific prior written permission.
>>>> >> +#
>>>> >> +# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
>>>> >> +# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
>>>> >> +# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
>>>> >> +# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
>>>> >> +# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
>>>> >> +# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
>>>> >> +# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
>>>> >> +# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
>>>> >> +# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
>>>> >> +# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
>>>> >> +
>>>> >> +STAT_TESTS='21 fstat
>>>> >> +33 ustat
>>>> >> +32 statx
>>>> >> +17 statfs
>>>> >> +21 oldfstat'
>>>> >> +
>>>> >> +NON_STAT_TESTS='11 fchdir
>>>> >> +27 futex
>>>> >> +10 fsync'
>>>> >> +
>>>> >> +. "${srcdir=.}/init.sh"
>>>> >> +
>>>> >> +echo "$STAT_TESTS" | while read w i
>>>> >> +do
>>>> >> +     run_prog ./$i > /dev/null
>>>> >> +     run_strace -a$w -e%stat ./$i > "$EXP"
>>>> >> +     match_diff "$LOG" "$EXP"
>>>> >> +done
>>>> >> +
>>>> >> +echo '+++ exited with 0 +++' > "$EXP"
>>>> >> +
>>>> >> +echo "$NON_STAT_TESTS" | while read w i
>>>> >> +do
>>>> >> +     run_prog ./$i > /dev/null
>>>> >> +     run_strace -a$w -e%stat ./$i > /dev/null
>>>> >> +     match_diff "$LOG" "$EXP"
>>>> >> +done
>>>> >> +
>>>> >> +rm "$EXP"
>>>> > This test produces the following diagnostics:
>>>> >
>>>> >     1,2c1,2
>>>> >     < fstat(0, 0x7f4dc9b2ffe0) = -1 EFAULT (Bad address)
>>>> >     < fstat(0, {st_dev=makedev(9, 1), st_ino=8761399, st_mode=S_IFREG|0640, st_nlink=1, st_uid=1000, st_gid=1000, st_blksize=4096, st_blocks=0, st_size=43147718418, st_atime=1969-12-31T21:59:17+0100.000000135, st_mtime=1969-12-31T21:59:19+0100.000000246, st_ctime=2017-03-13T07:03:55+0100.962268762}) = 0
>>>> >     ---
>>>> >     > stat("/etc/localtime", {st_mode=S_IFREG|0644, st_size=2246, ...}) = 0
>>>> >     > stat("/etc/localtime", {st_mode=S_IFREG|0644, st_size=2246, ...}) = 0
>>>> >     stat_like.test: failed test: ../strace -a21 -e%stat ./fstat output mismatch
>>>> >
>>>> > It exits with status 0, however.
>>>>
>>>> Please help me with this part, how can I run this test on my machine.
>>>
>>> Do you ask about running this particular test?  I think it's as simple as
>>> $ make check TESTS=stat_like VERBOSE=1
>>
>> Thank you, I just never did testing this way and I am new to this part.
>>>
>>> --
>>> ldv
>>>
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>>>
>
>
> Is it fine to group statfs+ statfs64+ fstatfs + fstatfs64 + ustat  as
> %statfs or it should be (statfs+statfs64 + ustat) and
> (fstatfs+ftsatfs64) i.e. two different classes ?

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