December 2003 - Legacy - lists.gtalug.org

C considered harmful: was Debian attacker may have used new exploit
by henry-lqW1N6Cllo0sV2N9l4h3zg＠public.gmane.org 04 Dec '03

04 Dec '03

On Thu, 4 Dec 2003, Peter Hiscocks wrote: > Interesting examples. Given that any code can be executed by a Turing > machine (albeit somewhat slowly ;), I would bet that it is possible to do > all these things in a way that separates the code and the data (ie, without > generating code on the fly), but possibly not in a way that satisfies the > current speed requirements. Exactly. This is pure performance optimization. But it's a very powerful one which can make a huge difference. > ...it might even become more feasible to avoid what is effectively > 'self modifying code' as processors get faster and memory gets cheaper. Don't forget that the problems grow too. For example, considering the network-routing application, the networks are getting faster at about the same pace as the CPUs, so you don't *get* an advantage by waiting. Henry Spencer henry-lqW1N6Cllo0sV2N9l4h3zg at public.gmane.org -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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C considered harmful: was Debian attacker may have used new exploit
by phiscock-g851W1bGYuGnS0EtXVNi6w＠public.gmane.org 04 Dec '03

04 Dec '03

Interesting examples. Given that any code can be executed by a Turing machine (albeit somewhat slowly ;), I would bet that it is possible to do all these things in a way that separates the code and the data (ie, without generating code on the fly), but possibly not in a way that satisfies the current speed requirements. Or it might be that these approaches were taken at a time when this was the only way to get the necessary speed. So in the long run, it might even become more feasible to avoid what is effectively 'self modifying code' as processors get faster and memory gets cheaper. Peter On Thu, Dec 04, 2003 at 08:20:56PM -0500, Henry Spencer wrote: > It's highly desirable in cases where performance is critical and there are > too many different cases to just include one of each in a precompiled > binary. The classic example is Rob Pike's dynamically-compiled > implementation of RasterOp -- operations on one-bit-deep frame buffers -- > where the number of cases is the product of a dozen different variables > each with several values. Similar things can be done for applications > like network routing. > > Similarly, it's heavily used for implementing languages whose full > generality must be interpretive, but for which special cases can be > identified at run time and compiled into hard code. > > > Isn't it much safer to have a rigid demarcation between code generation and > > code execution? > > Safer, but less powerful. > > Henry Spencer > henry-lqW1N6Cllo0sV2N9l4h3zg at public.gmane.org > > -- > The Toronto Linux Users Group. Meetings: http://tlug.ss.org > TLUG requests: Linux topics, No HTML, wrap text below 80 columns > How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml -- Peter D. Hiscocks Department of Electrical and Computer Engineering Ryerson University, 350 Victoria Street, Toronto, Ontario, M5B 2K3, Canada Phone: (416) 979-5000 Ext 6109 Fax: (416) 979-5280 Email: phiscock-g851W1bGYuGnS0EtXVNi6w at public.gmane.org URL: http://www.ee.ryerson.ca/~phiscock -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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OOP, Was: C considered harmful: was Debian attacker may have used new exploit
by rgfranks-cmaem7PIVQT44Nm34jS7GywD8/FfD2ys＠public.gmane.org 04 Dec '03

04 Dec '03

>>>>> "Peter" == Peter L Peres <plp-ysDPMY98cNQDDBjDh4tngg at public.gmane.org> writes: Peter> On Thu, 4 Dec 2003, Greg Franks wrote: >> >>>>> "Marcus" == Marcus Brubaker <marcus.brubaker-H217xnMUJC0sA/PxXw9srA at public.gmane.org> >> writes: Marcus> To each their own opinion but if you want to do OOP then Marcus> there really isn't a better language out there than Java. >> You forgot Smalltalk. Everything is an object, even integers. Peter> Yes, and the processing overhead for an addition is about Peter> the same as for a square root extraction. You're thinking of an old smalltalk (or bad implementation perhaps...). The interpreter should do somthing like... if ( x & 8000000 ) { its an integer... } else { its an object... } Otoh, sqrt() isn't as pokey as it used to be either :-) -- __@ Greg Franks <| _~@ __O _`\<,_ Ottawa, Ontario, Canada |O\ -^\<;^\<, (*)/ (*) (*)--(*)%---/(*) "Where do you want to go today?" Outside. -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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C considered harmful: was Debian attacker may have used new exploit
by marcus.brubaker-H217xnMUJC0sA/PxXw9srA＠public.gmane.org 04 Dec '03

04 Dec '03

On Thu, 2003-12-04 at 19:36, Fraser Campbell wrote: > On December 4, 2003 12:56 pm, Marcus Brubaker wrote: > > > > You might find this article, by one of the LISP community's greats, both > > > interesting and on topic: > > > > > > http://www.paulgraham.com/javacover.html > > > > To each their own opinion but if you want to do OOP then there really > > isn't a better language out there than Java. > > Do people write real software with java or is still just web stuff? Absolutely. I've written a number of "real" projects in Java. Further, I use a number of applications that are written in Java. (E.G. PCGen) -- Marcus Brubaker <marcus.brubaker-H217xnMUJC0sA/PxXw9srA at public.gmane.org> -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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C considered harmful
by henry-lqW1N6Cllo0sV2N9l4h3zg＠public.gmane.org 04 Dec '03

04 Dec '03

On Thu, 4 Dec 2003, Peter Hiscocks wrote: > So, it is an interesting challenge to the language writers to create > something that has the power of the C language and still does (say) > automatic checking of array bounds. It's not that hard, if that is all you want. In particular, if you work in C++ and *always* use its library string and vector types (which have built-in bounds checks in many implementations) rather than C arrays, the problem is more or less solved. If one finds C++ unappealing, which is certainly a defensible position :-), then there's more of a problem. Henry Spencer henry-lqW1N6Cllo0sV2N9l4h3zg at public.gmane.org -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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C considered harmful: was Debian attacker may have used new exploit
by henry-lqW1N6Cllo0sV2N9l4h3zg＠public.gmane.org 04 Dec '03

04 Dec '03

On Thu, 4 Dec 2003, Peter Hiscocks wrote: > Dynamic code generation (program writes code then jumps to it) sounds like a > really useful facility for virus writers, trojan horses and worms. In what > circumstance is it necessary to have that capability? It's highly desirable in cases where performance is critical and there are too many different cases to just include one of each in a precompiled binary. The classic example is Rob Pike's dynamically-compiled implementation of RasterOp -- operations on one-bit-deep frame buffers -- where the number of cases is the product of a dozen different variables each with several values. Similar things can be done for applications like network routing. Similarly, it's heavily used for implementing languages whose full generality must be interpretive, but for which special cases can be identified at run time and compiled into hard code. > Isn't it much safer to have a rigid demarcation between code generation and > code execution? Safer, but less powerful. Henry Spencer henry-lqW1N6Cllo0sV2N9l4h3zg at public.gmane.org -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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C considered harmful: was Debian attacker may have used new exploit
by tim-s/rLXaiAEBtBDgjK7y7TUQ＠public.gmane.org 04 Dec '03

04 Dec '03

Jing Su <jingsu-26n5VD7DAF2Tm46uYYfjYg at public.gmane.org> writes: > > Dynamic code generation (program writes code then jumps to it) sounds like a > > really useful facility for virus writers, trojan horses and worms. In what > > circumstance is it necessary to have that capability? > > Dynamic run-time optimization. Hot field of research (though I know > nothing about it). That's one area. Decent LISP environments often blur the distinction between interpreted code, byte compiled code (to be executed by a virtual machine), and compiled code (i.e. machine language). Such environments allow you to integrate interpreted code with compiled code as well as compiling (with varying levels of optimization) individual functions. I'm sure other languages have similar environments. These tools can really enhance productivity as they facilitate rapid development by eliminating the compile/link/run cycle without sacrificing performance. And they tend to have great debugging facilities. Of course, you arguably don't need these facilities in "production code". So it wouldn't be too onerous to restrict this ability (to compile and execute code on-the-fly) to specific, privileged binaries via capabilities. -- tim writer <tim-s/rLXaiAEBtBDgjK7y7TUQ at public.gmane.org> starnix inc. 905.771.0017 ext. 225 thornhill, ontario, canada http://www.starnix.com professional linux services & products -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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C considered harmful: was Debian attacker may have used new exploit
by fraser-Txk5XLRqZ6CsTnJN9+BGXg＠public.gmane.org 04 Dec '03

04 Dec '03

On December 4, 2003 12:56 pm, Marcus Brubaker wrote: > > You might find this article, by one of the LISP community's greats, both > > interesting and on topic: > > > > http://www.paulgraham.com/javacover.html > > To each their own opinion but if you want to do OOP then there really > isn't a better language out there than Java. Do people write real software with java or is still just web stuff? -- Fraser Campbell <fraser-Txk5XLRqZ6CsTnJN9+BGXg at public.gmane.org> http://www.wehave.net/ Georgetown, Ontario, Canada Debian GNU/Linux -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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Multiple USB keyboards ?
by opengeometry-FFYn/CNdgSA＠public.gmane.org 04 Dec '03

04 Dec '03

On Thu, Dec 04, 2003 at 05:08:40AM -0500, Tim Writer wrote: > William Park <opengeometry-FFYn/CNdgSA at public.gmane.org> writes: > > > I have multiple video cards (agp, pci) and multiple mouses (serial, > > ps/2, usb) working independently. That is, I can choose which > > should be selected when bringing up X. > > > > But, multiple keyboards are all shared; so, you can press keys from > > any keyboard. How do you get them working independently? > > By having a separate XF86Config for each keyboard, mouse, and video > card combination. Each XF86Config would have its own InputDevice > sections for its respective keyboard and mouse. The trick is to know > which device (in /dev) represents which keyboard or mouse. This is > obviouse if you have say one PS/2 keyboard, one USB keyboard, one PS/2 > mouse, and one USB mouse. But it's tricky if you have multiple USB > keyboards and mice since they will be assigned entries in /dev/input > dynamically. As long as you keep them permanently plugged in, you > should be able to figure out what's what by trial and error. > > Note, while I have used USB keyboards and mice, I haven't tried this > type of setup so YMMV. Found it! -- http://cambuca.ldhs.cetuc.puc-rio.br/multiuser/ I got this working on my Slackware-9.1, kernel-2.4.23, and XFree86-4.3.0. Key insights are - modprobe -r keybdev - modprobe evdev -- William Park, Open Geometry Consulting, <opengeometry-FFYn/CNdgSA at public.gmane.org> Linux solution for data management and processing. -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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C considered harmful: was Debian attacker may have used new exploit
by jingsu-26n5VD7DAF2Tm46uYYfjYg＠public.gmane.org 04 Dec '03

04 Dec '03

> Dynamic code generation (program writes code then jumps to it) sounds like a > really useful facility for virus writers, trojan horses and worms. In what > circumstance is it necessary to have that capability? Dynamic run-time optimization. Hot field of research (though I know nothing about it). -- The Toronto Linux Users Group. Meetings: http://tlug.ss.org TLUG requests: Linux topics, No HTML, wrap text below 80 columns How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml

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