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Date: Tue, 6 Dec 2005 20:47:47 -0500
From: Christopher Faylor <cgf-no-personal-reply-please AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: [PATCH] cygcheck bug when listing services (Was Re: Parallel  writes to a single FIFO do not queue, and deadlock cygwin)
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On Tue, Dec 06, 2005 at 08:41:24PM -0500, Igor Pechtchanski wrote:
>On Tue, 6 Dec 2005, Yitzchak Scott-Thoennes wrote:
>
>> On Mon, Dec 05, 2005 at 09:40:01AM -0500, Igor Pechtchanski wrote:
>> > Running cygcheck under strace shows that after listing all the available
>> > services, it invokes "cygrunsrv --query grunsrv.exe --list", which results
>> > in the above message.  I think this may be because the output of
>> > "cygrunsrv --list" doesn't contain a trailing '\n', and so strtok gets
>> > confused.  The following patch (against a slightly older cygcheck) fixes
>> > it for me, but I haven't had the time to test it extensively:
>> > [snip]
>> > -      buf[nchars] = 0;
>> > +      buf[nchars] = buf[nchars+1] = 0;
>>
>> That needs a comment in the code.
>
>Fair enough:
>
>Index: cygcheck.cc
>===================================================================
>RCS file: /cvs/src/src/winsup/utils/cygcheck.cc,v
>retrieving revision 1.77
>diff -u -p -r1.77 cygcheck.cc
>--- cygcheck.cc 17 Aug 2005 00:52:43 -0000      1.77
>+++ cygcheck.cc 7 Dec 2005 01:38:07 -0000
>@@ -950,8 +950,10 @@ dump_sysinfo_services ()
>   else
>     {
>       /* read the output of --list, and then run --query for each service */
>-      size_t nchars = fread ((void *) buf, 1, sizeof (buf) - 1, f);
>-      buf[nchars] = 0;
>+      size_t nchars = fread ((void *) buf, 1, sizeof (buf) - 2, f);
>+      /* Add two nulls to avoid confusing strtok() when the trailing separator
>+         is missing */
>+      buf[nchars] = buf[nchars+1] = 0;
>       pclose (f);
>
>       if (nchars > 0)
>
>I'll even add a ChangeLog of sorts :-)
>
>2005-12-06  Igor Pechtchanski  <pechtcha AT cs DOT nyu DOT edu>
>
>	* cygcheck.cc (dump_sysinfo_services): Add an extra NUL to mollify
>	strtok() when the trailing newline is missing.

How about a testcase which shows that the MSVCRT strtok needs two
trailing NUL bytes to work around problems when there is no trailing
separator?  I would find that much more interesting than a comment which
simply asserts that behavior.

cgf

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