Re: [Chicken-users] daemonize egg: redirect I/O?
um, why not just use (duplicate-fileno (portfileno port)) ? or if its only stdin/stdout/stderr that youre worried about, calling (current-[input|output|error]-port) with an argument should change the value. the above three procs are parameters (re: the daemon question, i would just use (foreign-lambda int daemon int int) , but thats just me.) -elf On Fri, 26 Oct 2007, Thomas Christian Chust wrote: Ozzi wrote: I am working on for creating unix daemons. Can anyone tell me how to redirect stdout and stderr? I want to redirect them to /dev/null by default. Hello, such an egg would indeed be a useful addition :-) To redirect the standard file descriptors I would suggest to use the same technique as if one wanted to achieve this from C: (require-extension posix) (let ((null-device (file-open /dev/null (bitwise-ior open/read open/write (duplicate-fileno null-device fileno/stdin) (duplicate-fileno null-device fileno/stdout) (duplicate-fileno null-device fileno/stderr) (file-close null-device)) I would also be interested in comments on my plans for the egg in general. Presently, the interface is as follows: daemonize is a function that takes a daemon proc of one argument, that argument being a cleanup proc which the daemon proc should call before it exits. I wonder why one would want to pass this cleanup argument to the daemon procedure -- why should the spawned process simply perform cleanup once the daemon procedure returns? [...] Let me know what you think, and if you have any other ideas or suggestions. Apart from redirecting I/O, don't forget to also place your daemon process into its own process group so it doesn't get terminated when the parent process' group leader dies (see setsid(2) and daemon(3) in your system's manpages). [...] cu, Thomas ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] daemonize egg: redirect I/O?
Elf wrote: um, why not just use (duplicate-fileno (portfileno port)) ? [...] Because not the file descriptor of a given port should be duplicated but rather the file descriptor of a given port should be replaced by a duplicate of another one. Of course one could use (portfileno ...) instead of the fileno/... constants in my example, but it wouldn't make much of a difference, unless the ports were already set to something different from the standard -- but in that case it may not be such a good idea to redirect them. I think it makes much more sense to redirect those descriptors which are, by default, connected to the controlling terminal of the process, because they usually become useless after detaching from the original process group. (re: the daemon question, i would just use (foreign-lambda int daemon int int) , but thats just me.) Isn't daemon(3) a BSD C library function? I don't know whether it is available everywhere -- and besides that, an implementation in Scheme is not a lot of work but could offer a great deal of added flexibility in addition to what deamon(3) can do. [...] cu, Thomas ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] daemonize egg: redirect I/O?
grok that. im trying to get chicken working in visual studio. this does not rate amongst the 'fun' things i have done. yay work requiring ms os. -elf On Fri, 26 Oct 2007, Alex Queiroz wrote: Hallo, On 10/26/07, Elf [EMAIL PROTECTED] wrote: heh, none of these are going to work everywhere. all posix extensions are custom. the only i/o procs in the standard are call-with-[input|output]file, with-[input|output]-to-file, current-[input|output]-port, [input|output]-file?, [open|close]-[input|output]-file, write, display, read, load, eof-object?, newline, and the lovely and never implemented transcript-[on|off]. i know im missing some (character one, prolly), but the point is that the standard basically only says 'you need to be able to interact with the system' in terms of its i/o specification. there has never been a general posix.1003 or posix.2 srfi submitted (or at least there has never been one posted). Yes, that's why a low-level egg is needed that uses POSIX where available and (sigh) the Win32 API in Windows systems. In the ideal world I would use only POSIX OSes, but unfortunately I can't and I'd rather use scheme everywhere. Cheers, ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] daemonize egg: redirect I/O?
Hallo, On 10/26/07, Elf [EMAIL PROTECTED] wrote: heh, none of these are going to work everywhere. all posix extensions are custom. the only i/o procs in the standard are call-with-[input|output]file, with-[input|output]-to-file, current-[input|output]-port, [input|output]-file?, [open|close]-[input|output]-file, write, display, read, load, eof-object?, newline, and the lovely and never implemented transcript-[on|off]. i know im missing some (character one, prolly), but the point is that the standard basically only says 'you need to be able to interact with the system' in terms of its i/o specification. there has never been a general posix.1003 or posix.2 srfi submitted (or at least there has never been one posted). Yes, that's why a low-level egg is needed that uses POSIX where available and (sigh) the Win32 API in Windows systems. In the ideal world I would use only POSIX OSes, but unfortunately I can't and I'd rather use scheme everywhere. Cheers, -- -alex http://www.ventonegro.org/ ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] daemonize egg: redirect I/O?
Hallo, On 10/26/07, Elf [EMAIL PROTECTED] wrote: (re: the daemon question, i would just use (foreign-lambda int daemon int int) , but thats just me.) A very nice solution... If it worked (everywhere). Cheers, -- -alex http://www.ventonegro.org/ ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] daemonize egg: redirect I/O?
On Fri, 26 Oct 2007, Thomas Christian Chust wrote: Elf wrote: um, why not just use (duplicate-fileno (portfileno port)) ? [...] Because not the file descriptor of a given port should be duplicated but rather the file descriptor of a given port should be replaced by a duplicate of another one. Of course one could use (portfileno ...) instead of the fileno/... constants in my example, but it wouldn't make much of a difference, unless the ports were already set to something different from the standard -- but in that case it may not be such a good idea to redirect them. I think it makes much more sense to redirect those descriptors which are, by default, connected to the controlling terminal of the process, because they usually become useless after detaching from the original process group. yes, i understood that. hence the comment regarding the (current-input/output/error-port) procedures being parameters that take an argument for automatic replacement. they need to be replaced WITH something, though, hence the portfileno remark. (re: the daemon question, i would just use (foreign-lambda int daemon int int) , but thats just me.) Isn't daemon(3) a BSD C library function? I don't know whether it is available everywhere -- and besides that, an implementation in Scheme is not a lot of work but could offer a great deal of added flexibility in addition to what deamon(3) can do. [...] daemon() has been standard in libc since around 1995. the only machines that wont have it are windows boxen. the direct chicken code for daemon() (without type or validity checking), and with an explicit continuation since return values mean very little in this context, is: (define (daemon nochdir noclose cnt) (call-with-current-continuation (lambda (k) (process-fork (lambda () (k #t))) (exit 0))) (create-session) (call-with-current-continuation (lambda (k) (process-fork (lambda () (k #t))) (exit 0))) (and (= 0 nochdir) (change-directory /)) (and-let* ((cls (= 0 noclose)) (ipt (open-input-file /dev/null)) (opt (open-output-file /dev/null))) (current-input-port ipt) (current-output-port opt) (current-error-port opt) (cnt))) the call/cc's i believe are necessary because process-fork automatically calls (_exit 0) after evaling the lambda for the child procs. -elf ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] daemonize egg: redirect I/O?
heh, none of these are going to work everywhere. all posix extensions are custom. the only i/o procs in the standard are call-with-[input|output]file, with-[input|output]-to-file, current-[input|output]-port, [input|output]-file?, [open|close]-[input|output]-file, write, display, read, load, eof-object?, newline, and the lovely and never implemented transcript-[on|off]. i know im missing some (character one, prolly), but the point is that the standard basically only says 'you need to be able to interact with the system' in terms of its i/o specification. there has never been a general posix.1003 or posix.2 srfi submitted (or at least there has never been one posted). rant in my experiences amongst the various distributions, this is the area in which the greatest incompatabilities are found. furthermore, unlike 95% or more of the other incompats, its hard/impossible to write wrappers to allow lowlev crosscompat, because everyone has different views on how to schemeify posix, and instead of agreeing on something thats fairly ugly (straight c wrapping or whatnot) that everyone can build their nice extensions with (which could then be wrapped), the implementations are almost entirely divergent. if r6rs had actually been a real attempt at standardisation, it would have tackled posix(ish) constructs, regular expressions, and networking, as its useful to both academic and nonacademic coders, is divergent between the distributions, is a major hook for potential converts, and has the highest visibility for ALL distributions. (go to the page for any given distrib, and some subset of the above will be displayed most prominently under 'features', along with whatever library/module system they use.) /rant sorry. :) -elf On Fri, 26 Oct 2007, Alex Queiroz wrote: Hallo, On 10/26/07, Elf [EMAIL PROTECTED] wrote: (re: the daemon question, i would just use (foreign-lambda int daemon int int) , but thats just me.) A very nice solution... If it worked (everywhere). Cheers, ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] daemonize egg: redirect I/O?
Thomas Christian Chust wrote: I wonder why one would want to pass this cleanup argument to the daemon procedure -- why should the spawned process simply perform cleanup once the daemon procedure returns? The problem with that, as I see it, is that sometimes daemons don't get to return normally, i.e. if they get killed. Of course any proper daemon will implement signal handlers and such so that it will clean up after itself and exit gracefully. With my implementation you can implement that sort of stuff anyway you like, and just call the additional (cleanup) proc to take care of whatever you had daemonize set up for you, i.e. the PID file. Of course, it might be nice to have daemonize take care of everything, including signal handlers and such. I would see that as a further abstraction. (define (super-daemonize proc) (daemonize (lambda (cleanup) (set-signal-handler! ...) ; Call cleanup if we get killed. (proc) (cleanup ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
[Chicken-users] RFC: web-unity egg
Hi all, I just made a new egg called web-unity. Its purpose is pretty simple: it allows you to create web applications which can run via CGI, SCGI, FCGI or Spiffy without having to change the code. All that's needed is a server-specific dispatcher procedure which hands off the request to a generic procedure that does the work. Have a look at its wiki page and try out the egg (available through svn only right now), let me know where it can be improved. Cheers, Peter -- http://sjamaan.ath.cx -- The process of preparing programs for a digital computer is especially attractive, not only because it can be economically and scientifically rewarding, but also because it can be an aesthetic experience much like composing poetry or music. -- Donald Knuth pgpYGXWscFWCU.pgp Description: PGP signature ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
