http://www.nnseek.com/e/comp.unix.programmer/ Posts for comp.unix.programmer Tue, 19 Aug 2008 18:24:24 PDT http://www.nnseek.com/ http://www.nnseek.com/img/64.png 64 64 NNSeek http://www.nnseek.com/e/comp.unix.programmer/can_a_program_make_itself_immune_to_an_interposer_134185103t.html http://www.nnseek.com/e/comp.unix.programmer/can_a_program_make_itself_immune_to_an_interposer_134185103t.html for a way to make my program immune. However, in fact, I'm looking at
it the other way - I have written an interposer, but somehow it is not
working (in one case).

Longer version: I have written an interposer for the POSIX open()
function. This is not at all the first interposer I've written, and it
works fine with a little test program that I have written. However, it
does not work (that is, I can tell that my interposer is not called),
when used with GAWK.

I am invoking gawk as:

LD_PRELOAD=./libopen_fix.so gawk '{print FILENAME,$0}' "$@"

and yet the interposer never gets called. GAWK *is* dynamically linked:

(output of "ldd gawk")
linux-gate.so.1 => (0xb7ee8000)
libdl.so.2 => /lib/libdl.so.2 (0xb7ed2000)
libm.so.6 => /lib/libm.so.6 (0xb7ead000)
libc.so.6 => /lib/libc.so.6 (0xb7d74000)
/lib/ld-linux.so.2 (0xb7ee9000)

Any ideas?

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]]> Tue, 19 Aug 2008 18:24:24 PDT http://www.nnseek.com/e/comp.unix.programmer/handling_multiple_sigchlds_reliably_134162575t.html http://www.nnseek.com/e/comp.unix.programmer/handling_multiple_sigchlds_reliably_134162575t.html Hi all,

My program seems to not handle multiple SIGCHLDs reliably; some
SIGCHLDs seem to be getting "lost". I've googled the manual several
times, and looked for other resources, but seem to be at a loss still.

Here is the signal handler

void catcher ( int signo, siginfo_t *psig, void *ctx)
{
pid_t pid;
int status;

pid = -1;
status = 0;
pid = waitpid( -1, &status, WNOHANG);
printf(" catcher: caught signal %%d around process %%d\n", signo,
pid );
}

and here is the main program that sets up the catcher

struct sigaction handler_action;

sigemptyset( & (handler_action.sa_mask) );
sigaddset( & (handler_action.sa_mask), SIGINT );
sigaddset( & (handler_action.sa_mask), SIGQUIT );
sigaddset( & (handler_action.sa_mask), SIGCHLD ); /* reliably block
SIGCHLDs in handler */
handler_action.sa_flags = SA_SIGINFO|SA_NOCLDWAIT;
handler_action.sa_sigaction = catcher;

sigaction ( SIGCHLD, &handler_action, (struct sigaction *)0 );

/* remaining part of main program */
i = atoi(argv[1]); /* this is usually 4 or 5 */

while (i > 0)
{
if ((pid = fork()) == 0) { /* forks i children */

printf(" running command in background \n");
execv(argv[2], &argv[2]); perror("The execl() call must have
failed"); exit(255);

} else {

printf (" child pid = %%d\n", pid);
}
i--;
}

for(;;) /* main program continues to do this waiting for Ctl-C
*/
{
printf (" zzz \n");
sleep(3);
}
My questions:

1. I've set up the sa_mask to block SIGCHLDs so that means each time
the handler runs, it should block other SIGCHLDs i.e. handler should
be invoked 5 times. But my handler is called only once or twice at
most. What happens to the other SIGCHLDs? (This is an AIX 5.3 system,
BTW)
2. I don't see any zombies so I assume the children did exit properly,
fair assumption?
3. I am relying on the waitpid() in the handler to return the pid of
the child that was most likely responsible for the SIGCHLD. But the
waitpid always returns -1. Can anyone explain this?
4. Is there a different/better way to do this? My basic requirement is
to start a child process in the background and for the main program to
get notified when the child exits. My manual-and-google-reading seems
to indicate sigaction() + waitpid() as the best way so far. Any other
ideas?

Thanks in advance
Sam

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]]> Tue, 19 Aug 2008 15:08:53 PDT http://www.nnseek.com/e/comp.unix.programmer/closing_socket_without_sending_fin_134134415t.html http://www.nnseek.com/e/comp.unix.programmer/closing_socket_without_sending_fin_134134415t.html be notified about the fact? I'm writing a server program and would
like to test such behaviour, but unpluging the network cable is
tedious or impossible if you'd like to test several clients at once.

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]]> Tue, 19 Aug 2008 12:02:55 PDT http://www.nnseek.com/e/comp.unix.programmer/entry_point_134083215t.html http://www.nnseek.com/e/comp.unix.programmer/entry_point_134083215t.html mean analog to WinMainCRTStartup for executable on Windows? Is it
possible to overwrite entry point? Does linker have this option? I
assume this entry point besides other stuff contains calls to all
static instances constructors and destructors and actually calls main.

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]]> Tue, 19 Aug 2008 07:37:02 PDT http://www.nnseek.com/e/comp.unix.programmer/free_sex_moves_download_free_134048143t.html http://www.nnseek.com/e/comp.unix.programmer/free_sex_moves_download_free_134048143t.html



http://kumaripud.blogspot.com/

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]]> Tue, 19 Aug 2008 02:49:50 PDT http://www.nnseek.com/e/comp.unix.programmer/what_binary_manipulation_tools_are_there_133992847t.html http://www.nnseek.com/e/comp.unix.programmer/what_binary_manipulation_tools_are_there_133992847t.html activity to develop them
I have utterly failed to produce a tool that can convert small strings
into unsigned chars
of their binary equivalents.
For example a file containing (in ASCII):

1 1010
111 10

would become a file containing (as numeric values): 1 10 7 2

I've tried oktata and it required anding, oring and xoring everything
instead of straight
forward editing. It also suggested in the manual that that was the
traditional technique.


So what tools (if any are there) for editing a binary by just...
editing it rather
than doing a heap of maths on all but the correct byte?

*These connect the regions of the brain and in my case run very
slowly.
Every thing except lexical analysis (remembering words and word
patterns)
and logic (grammar) are stuffed without working with everything else
non-stop.

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]]> Mon, 18 Aug 2008 15:28:51 PDT http://www.nnseek.com/e/comp.unix.programmer/kernel_user_communication_133873807t.html http://www.nnseek.com/e/comp.unix.programmer/kernel_user_communication_133873807t.html
I have to communicate a user program and a kernel module in two-way.
What are the methods available ?
What is the best method to implement?? Please help me.

Thanks and regards
VASU

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]]> Mon, 18 Aug 2008 01:22:23 PDT http://www.nnseek.com/e/comp.unix.programmer/buffer_limits_for_ipc_using_named_pipe_133859471t.html http://www.nnseek.com/e/comp.unix.programmer/buffer_limits_for_ipc_using_named_pipe_133859471t.html on the Solaris box. One process keeps pumping in huge amount of data,
and the other server process receives this data and performs further
processing.

As huge amount of data is sent over the named pipe, I'm just concerned
whether there will be a buffer limit problem(at sender & receiver
sides) due to that. Can anybody tell me how I can find out the
limitation by Solaris, and how exactly I can increase tune this limit?

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]]> Sun, 17 Aug 2008 23:22:39 PDT http://www.nnseek.com/e/comp.unix.programmer/ann_seed7_release_2008_08_17_133805455t.html http://www.nnseek.com/e/comp.unix.programmer/ann_seed7_release_2008_08_17_133805455t.html
I have released a new version of Seed7: seed7_05_20080817.tgz

In the Seed7 programming language new statements and operators
can be declared easily. Types are first class objects and therefore
templates/generics need no special syntax. Object orientation is
used when it brings advantages and not in places when other
solutions are more obvious.

Seed7 is covered by the GPL (and LGPL for the Seed7 runtime library).

Changelog:
- The FAQ about static type checking was improved and an FAQ about
development speed and type checking was added.
- A chapter about the type 'category' was added to the manual.
- The chapters about boolean, string, set and reference in the
manual, were improved.
- The functions toUuencoded and fromUuencoded were added to the
encoding.s7i library.
- The html entity 'ang' and several comments were added to the
html_ent.s7i library.
- The error management of the chkint.sd7 program was improved.
- The 'configValue' function was improved to support values for
TWOS_COMPLEMENT_INTTYPE, INTTYPE_64BIT and INTTYPE_LITERAL_SUFFIX.
- The function growStri was improved to work correctly in out of
memory situations.
- The makefiles makefile, mk_cygw.mak, mk_linux.mak, mk_mingw.mak,
mk_msvc.mak, mk_msys.mak and mk_nmake.mak were improved to define
TWOS_COMPLEMENT_INTTYPE when appropriate.
- The file setlib.c was improved to work correctly with bitsettype's
of different sizes.

Greetings Thomas Mertes

Seed7 Homepage: http://seed7.sourceforge.net
Seed7 - The extensible programming language: User defined statements
and operators, abstract data types, templates without special
syntax, OO with interfaces and multiple dispatch, statically typed,
interpreted or compiled, portable, runs under linux/unix/windows.

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]]> Sun, 17 Aug 2008 11:10:28 PDT