Introduction

[Rishi Bhatt]

The output we see when we run lets say strace -e trace=open <program> which
will list all the open syscalls performed in the program. Now as per
README-linux-ptrace (if i interpreted it correctly) when tracee is
ptrace-stop the necessary information which we are getting as output is
extracted by ptrace(PTRACE_*,pid,...,...)  and this extracted information
is somehow directed towards its specific decoder in this example open.c and
then the decoders in the open.c are responsible for printing out the
information.Am i correct with the flow?

On Mon, Mar 6, 2017 at 8:32 PM, Rishi Bhatt <bhatt.rishi062 at gmail.com>
wrote:

> Thanks,
> It helped me to where to look for answers i got a better idea now how a -e
> trace=option works,And i see many *.c files which have these SYS_FUNC() in
> them what are these files for?
>
> Thanks,
> Rishi
>
> On Sat, Mar 4, 2017 at 10:58 PM, Eugene Syromyatnikov <evgsyr at gmail.com>
> wrote:
>
>> On Sat, Mar 4, 2017 at 5:15 PM, Rishi Bhatt <bhatt.rishi062 at gmail.com>
>> wrote:
>> > Thanks ldv,
>> > I have read the man pages and got basic idea about strace.Now where
>> should i
>> > start understanding the code?The codebase is so big i dont know where to
>> > start.
>> The core is strace.c and syscall.c (mostly). Take a look at some
>> simple (umask.c, readahead.c, mount.c) and not so simple (time.c,
>> ioctl.c, net.c, signal.c, ipc.c) decoders. You can look at some tests
>> then, like umask, or aio, or sendmmsg, or btrfs. util.c contains
>> various utility functions, defs.h contains various utility macros and
>> inlines. linux directory contains various (mostly
>> architecture-specific) system definitions which are preferred to be
>> part of strace codebase. linux/*/syscallent.h contains wirings for
>> syscalls. xlat directory contains sources for generation of symbolic
>> constant headers.
>>
>> > On Sat, Mar 4, 2017 at 4:25 AM, Dmitry V. Levin <ldv at altlinux.org>
>> wrote:
>> >>
>> >> Hi,
>> >>
>> >> On Fri, Mar 03, 2017 at 11:55:33PM +0530, Rishi Bhatt wrote:
>> >> > Hi ldv,
>> >> > thanks for the reply i have build the strace  source-code and when i
>> >> > was building it it skipped 50 test cases. So do you know why that
>> >> > happened? or is it the  matter that i should look into?
>> >>
>> >> Why skipped or why 50?
>> >>
>> >> A test can be skipped if
>> >> - it is not applicable for the architecture being tested, for example,
>> >>   the test is for a syscall that is not inplemented for this
>> architecture;
>> >> - the test framework doesn't support the test, for example, a kernel
>> >>   module is not loaded, or the filesystem is not capable, etc.
>> >>
>> >> Currently there are two architectures where exactly 50 tests are
>> skipped:
>> >> - native x86_64;
>> >> - native sparc64.
>> >>
>> >> I bet sparc64 is not your case, so you must be running the test suite
>> >> natively on x86_64.
>> >>
>> >> > And can you guide me where should i start to know about -e
>> trace=class?
>> >>
>> >> I think the best is to start with reading the manual page, then look
>> >> at the code to understand how it's implemented.  As soon as you've
>> >> understood the implementation, it's easy to extend.
>> >>
>> >
>> >>
>> >> --
>> >> ldv
>> >>
>> >>
>> >> ------------------------------------------------------------
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>> >>
>> >
>> >
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>>
>>
>>
>> --
>> Eugene Syromyatnikov
>> mailto:evgsyr at gmail.com
>> xmpp:esyr at jabber.{ru|org}
>>
>> ------------------------------------------------------------
>> ------------------
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>>
>
>
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