Skip to main content.
home | support | download

Back to List Archive

RE: Spidering on Windows

From: David Norris <kg9ae(at)not-real.geocities.com>
Date: Mon Oct 26 1998 - 20:57:14 GMT
> The stack trace I am interested in shows the exact calling context.
> There are 16 different places where fgets() is called.  The first thing
> I'd need to know is which of those 16 places is the call that fails.

I can't get a useful stack trace when the debugger faults while reading the
stack.  I need to install Softice and set it to the default debugger in VS
97.

Well, when in doubt...  Start hacking the code to pieces.  It is definitely
in the http.c file.  I am almost certain that it is related to the PERL
helper.  I get the message "Bad Command Or File Name" printed to the console
just before the crash.  (Some glitch in the error handling, I presume ;)

Here is the only thing that I can figure:

Some code between line 404 to about 427 of http.c seems to be causing the
error.

I can comment out the below line and the debugger starts behaving.  Mark
seems correct, the stack appears to be trashed by a buffer overflow.

This seems to corrupt the stack and kills my debugger;
http.c line 411:
	fgets(buffer, sizeof(buffer), fp);

The real problem is possibly (or related expressions):
http.c line 404-406:
    command = (char *)emalloc(strlen(spiderdirectory) + strlen(url) +
		strlen(tmpdir) + strlen(commandline) + strlen(spiderprog) + 32);
    sprintf(command, commandline, spiderdirectory, spiderprog, tmpdir,
lgetpid(), url);

I don't think that one could call the PERL helper in this manner on Windows.
Any ideas?  Am I doing something stupid?  What would it take to make this
work?

BTW, I have no major need for the functionality, I am merely interested in
seeing it work.  So, I am in no hurry to fix it.  I am sure that I would
make some use it if it worked, though.

,David Norris

World Wide Web - http://www.geocities.com/CapeCanaveral/Lab/1652/
Illusionary Web - http://illusionary.dyn.ml.org/ <-- 02:00 - 10:00 GMT
Video/Audio Phone - callto:illusionary.dyn.ml.org
Page via mail - 412039@pager.mirabilis.com
ICQ Universal Internet Number - 412039
E-Mail - kg9ae@geocities.com
Received on Mon Oct 26 13:07:54 1998