Sun Oct 16 23:59:00 GMT 2011
On 10/16/11 14:31, jan.kolar wrote:
>> jc807j 2668 1 0 08:59 tty0 00:00:00 xterm -e ssh server
> 80x72+285+0 -e ssh server
>> jc807j 3004 1 0 08:59 tty0 00:00:00 xterm -e ssh server
>> 80x72-8+0 -e ssh server
>> jc807j 2928 5852 0 09:12 ? 00:00:00 xterm 20000 +tb
>> The actual command lines for the 3 xterm processes are:
>> C:\cygwin\bin\xterm.exe -sl 20000 +tb -geometry 80x72+285+0 -e ssh server
>> C:\cygwin\bin\xterm.exe -sl 20000 +tb -geometry 80x72-8+0 -e ssh server
>> C:\cygwin\bin\xterm.exe -sl 20000 +tb
> xterm calls XrmParseCommand() that
> "parses an (argc, argv) pair according to the specified option table ... and
> modifies the (argc, argv) pair to remove all recognized options."
> "-sl 20000 +tb -geometry 80x72+285+0"
> is properly removed
> and "-e ssh server" is moved to __argv[1 .. 3].
> Then __argv (respectively __argv for the shorter command) is assigned
> null pointer
> which results in the second "\0" in the od-output below.
> Either XrmParseCommand() does not update argc
> or the change does not propagate (how would that be possible?) to __argc.
> Therefore the command lines appear corrupted this particular way.
> /proc/*/cmdline uses a copy of __argc named __argc_safe
> which is hardly to be updated anyway.
> " for (int i = 0; i< __argc_safe; i++) "
> Funny enough, /proc/self/cmdline is likely to contain shortened version of
> " for (char **a = __argv; *a; a++)"
> [ pinfo.cc from cygwin 1.7.9-1 ]
Why wouldn't exec(1) be responsible for setting up /proc and therefore
fill in cmdline with effectively $0 *before* the program itself ever got
around to calling XrmParseCommand? (I'm not well versed in the
underlying mechanics here and I have not reviewed the code but I would
have thought that something like exec would have examined argv/argc
before the program was ever able to modify it).
Andrew DeFaria <http://defaria.com>
Chastity is curable if detected early.
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