GSOC: Introduction

Wed Mar 15 17:44:29 UTC 2017

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 ?