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Re: Using 'flock' in GNU Pascal.
by Frank Heckenbach 10 Jan '99

10 Jan '99

Chris Wood wrote: > I am in the process of developing a CGI program using GNU Pascal. The = > CGI program is to be used in a Linux environment. It is a database CGI = > script and I would like to have one running process of the CGI script = > have exclusive write access. I was hoping that someone could provide me = > with an example, or a place where I can find further (detailed) = > information, of using the flock() function from the C library in a GNU = > Pascal program. I also need to know how to detect when a file is = > locked. A million thanks for your time and help. The best way (WRT portability and security for future versions) is currently to write a small C wrapper. This is because "constants" (i.e., #defines) from a C header cannot be easily made available in Pascal. (I hope one day GPC will have a C header translator which would solve the problem more elegantly.) What you need to know from the Pascal side is that `GetFile' returns a C file (i.e., a `FILE *') for a Pascal file. The file handle (integer), which is needed by flock(), can then be obtained by the libc function fileno(). So, here's an example. First the C wrapper (fileno.c): #include <stdio.h> #include <sys/file.h> typedef unsigned char Boolean; int filelock (FILE*, Boolean, Boolean); int filelock (FILE* f, Boolean Exclusive, Boolean NoBlock) { return flock (fileno (f), (Exclusive ? LOCK_EX : LOCK_SH) | (NoBlock ? LOCK_NB : 0)); } int fileunlock (FILE*); int fileunlock (FILE* f) { return flock (fileno (f), LOCK_UN); } Now a test program: program FileLockDemo; uses GPC; {$L fileno.c} function FileLock (f : CFilePtr; Exclusive, NoBlock : Boolean) : Integer; C; function FileUnlock (f : CFilePtr) : Integer; C; var a, b : Text; begin Rewrite (a, 'foo.bar'); Reset (b, 'foo.bar'); { Non-exclusive locks, succeed } Writeln (FileLock (GetFile (a), False, True)); Writeln (FileLock (GetFile (b), False, True)); { Exclusive lock, fails } Writeln (FileLock (GetFile (a), True, True)); { Remove the non-exclusive locks, succeed } Writeln (FileUnLock (GetFile (a))); Writeln (FileUnLock (GetFile (b))); { Exclusive lock, succeeds } Writeln (FileLock (GetFile (a), True, True)); { Another exclusive lock, fails } Writeln (FileLock (GetFile (b), True, True)); { An exclusive lock *with* blocking, will block the program forever! } Writeln (FileLock (GetFile (b), True, False)); end. As the example shows, you can find out if a file is locked, by trying to lock it without blocking (and removing the lock again if not needed). I don't know if there's another way to check... Frank -- Frank Heckenbach, frank(a)fjf.gnu.de http://fjf.gnu.de/ PGP and GPG keys: http://fjf.gnu.de/plan

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Using 'flock' in GNU Pascal.
by Chris Wood 10 Jan '99

10 Jan '99

I am in the process of developing a CGI program using GNU Pascal. The CGI program is to be used in a Linux environment. It is a database CGI script and I would like to have one running process of the CGI script have exclusive write access. I was hoping that someone could provide me with an example, or a place where I can find further (detailed) information, of using the flock() function from the C library in a GNU Pascal program. I also need to know how to detect when a file is locked. A million thanks for your time and help. Sincerely, Chris Wood

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Some help building GPC-19980830
by Ken Linder 09 Jan '99

09 Jan '99

Ok, Oh GPC & make masters... I was a good little boy & spent the best part of a day downloading GCC-2.8.1 and GPC-19980830. This is what I did & the error I got... Background Info: RH Linux 4.2 with GCC 2.7.2.1 1) gunzip GCC & GPC 2) untar GCC into /usr/src/gcc-2.8.1 3) untar gpc into /tmp/gpc 4) in the gcc source dir make a link ln -s p /tmp/gpc/p 5) apply the patch patch -p -s1 < p/gcc-2.8.1.diff 6) do in the gcc source dir configure -prefix=/usr 7) compile the thing in gcc source dir make LANGUAGES=pascal OK... problem... This is what I get... make[1]: entering directory '/tmp/gpc/p' make[1]: *** No rule to make target '../configure', needed by 'Makefile', stop. make[1]: leaving directory '/tmp/gpc/p' make: ***[gpc1] Error 2 Ok, oh mighty GPC wizards... What did I do wrong? Did I miss something? TNX... Ken Linder kc7rad(a)vegasnet.net

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Re: Some help building GPC-19980830
by Frank Heckenbach 09 Jan '99

09 Jan '99

Ken Linder wrote: > Ok, Oh GPC & make masters... > > I was a good little boy & spent the best part of a day downloading > GCC-2.8.1 and GPC-19980830. This is what I did & the error I got... > > Background Info: RH Linux 4.2 with GCC 2.7.2.1 > > 1) gunzip GCC & GPC > 2) untar GCC into /usr/src/gcc-2.8.1 > 3) untar gpc into /tmp/gpc > 4) in the gcc source dir make a link ln -s p /tmp/gpc/p > > [...] > > make[1]: entering directory '/tmp/gpc/p' > make[1]: *** No rule to make target '../configure', needed by 'Makefile', > stop. I'm not sure, but ISTR that building GPC doesn't work with a symlink, because then `..' points to the wrong directory, and the GPC Makefiles use `..' a lot. So you might want to try moving the GPC directory below the GCC directory. Frank -- Frank Heckenbach, frank(a)fjf.gnu.de http://fjf.gnu.de/ PGP and GPG keys: http://fjf.gnu.de/plan

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Re: enum definition bug
by Frank Heckenbach 09 Jan '99

09 Jan '99

Miguel Lobo wrote: > By the way, it would be nice if an updated "known > bugs" list was put in GPC's web page. That way, when > a program doesn't do what I expected, I would > know if it's GPC's fault or mine. It is already there. Please look at: http://agnes.dida.physik.uni-essen.de/~gnu-pascal/todo.html Hmmm... perhaps we should post a short FAQ here regularly that mentions the most important URLs and other stuff. Your bug was indeed already known and listed there (`enum types do not properly survive transport through two interfaces (russell2.pas, baby2.pas)'), but unfortunately not fixed yet. > And finally, if there is a beta release, would you > please build some binaries? (Compiling GCC is too much > for my computer and me; last time I tried I ran out > of disk space after about two hours of compilation). Which platform please? > Well, that was all by now. Happy new year, and good luck > fixing the bug :) Thanks. Happy New Year, Frank -- Frank Heckenbach, frank(a)fjf.gnu.de http://fjf.gnu.de/ PGP and GPG keys: http://fjf.gnu.de/plan

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enum definition bug
by Miguel Lobo 03 Jan '99

03 Jan '99

This bug appears when you use an enumerated type, defined in a unit, in the "interface" of another unit which is used by the first (complicated, eh? :) ). Well, better look at the attached example to see what I mean. I compiled the main program with "--automake" and got "incompatible type" errors. By the way, it would be nice if an updated "known bugs" list was put in GPC's web page. That way, when a program doesn't do what I expected, I would know if it's GPC's fault or mine. And finally, if there is a beta release, would you please build some binaries? (Compiling GCC is too much for my computer and me; last time I tried I ran out of disk space after about two hours of compilation). Well, that was all by now. Happy new year, and good luck fixing the bug :) Miguel. uses bugenum1,bugenum2; begin q(e1); end. unit bugenum1; interface type enum = (e1,e2,e3,e4); function q(v: enum): boolean; implementation uses bugenum2; function q(v: enum): boolean; begin q :=p(v,e1); end; end. unit bugenum2; interface uses bugenum1; function p(v1,v2: enum): boolean; implementation function p(v1,v2: enum): boolean; begin p :=(v1=v2); end; end.

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None
by The Magician 31 Dec '98

31 Dec '98

I study in the University of Coruña I.S.Informatica and we use the G.N.U. compiler. I need your help, please. I need the font codig ('codigo fuente' en español) of a function to Append like append of Turbo Pascal. Please, hurry up. Thanks. ================================================== Obtenga GRATIS su E-Mail permanente en http://www.mixmail.com

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gpc bug?
by Miguel Lobo 31 Dec '98

31 Dec '98

I wrote a week ago about some 'Internal compiler error' message. Unfortunately I was using gpc 2.0 and, as Peter Gerwinsky pointed, that was the cause of the error; I downloaded gpc-19981124 from debian.org and now that bug has disappeared. I am glad to see that the compiler is now much better (although compiling a file with errors often causes strange messages), but I think that I might have found a new bug. The problem arises when calling a destructor inside a dispose statement. I send a program which manifests the problem attached to this message. Specifically, when the list.done method is called, it should dispose all the items in the list by calling their 'done' destructor. But apparently sometimes this does not happen. When I run the program I get: descend-init: 1 descend-init: 2 descend-init: 3 descend-init: 4 extracting: descend: 1 descend-done: 1 extracting: descend: 2 extracting: descend: 3 descend-done: 3 extracting: descend: 4 So items 2 and 4 are not freed (or at least their destructors are not called). Changing the line "dispose(extfirst, done);" to "item :=extfirst; dispose(item,done);" solves the problem. I have checked the program in Borland Pascal and it works, so I think is a GPC bug. BTW, although I plan to join the mailing list in the future I haven't done so yet, so please mail me any answer. Thank you. type pitem = ^item; item = object prev,next: pitem; constructor init; destructor done; virtual; procedure write; virtual; end; pdescend = ^descend; descend = object(item) i: integer; constructor init(ii: integer); destructor done; virtual; procedure write; virtual; end; plist = ^list; list = object first,last: pitem; constructor init; destructor done; function extfirst: pitem; procedure add(l: pitem); procedure adddesc(i: integer); end; constructor item.init; begin prev :=nil; next :=nil; end; destructor item.done; begin end; procedure item.write; begin writeln('item'); end; constructor descend.init(ii: integer); begin inherited init; i :=ii; writeln('descend-init: ',i); end; destructor descend.done; begin writeln('descend-done: ',i); inherited done; end; procedure descend.write; begin writeln('descend: ',i); end; constructor list.init; begin first :=nil; last :=nil; end; destructor list.done; begin while (first<>nil) do dispose(extfirst,done); end; function list.extfirst: pitem; var item: pitem; begin write('extracting: '); first^.write; extfirst :=first; if (first=nil) then exit; item :=first; first :=first^.next; item^.next :=nil; if (first<>nil) then first^.prev :=nil else last :=nil; end; procedure list.add(l: pitem); begin if (first=nil) then first :=l else last^.next :=l; l^.prev :=last; last :=l; end; procedure list.adddesc(i: integer); begin add(new(pdescend,init(i))); end; var alist: plist; begin new(alist,init); alist^.adddesc(1); alist^.adddesc(2); alist^.adddesc(3); alist^.adddesc(4); dispose(alist,done); end.

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Re: Help for G.N.U.
by Peter Gerwinski 31 Dec '98

31 Dec '98

Hello, "The Magician"! (I'd prefer to know to whom I speak. Also, your other, identical email came without subject.)-: > I study in the University of CoruÃ±a I.S.Informatica and we > use the G.N.U. compiler. Which version? (Run `gpc -v' if you are not sure.) > I need your help, please. I need > the font codig ('codigo fuente' en espaÃ±ol) of a function > to Append like append of Turbo Pascal. I do not understand what you mean with "font codig", but recent versions of GNU Pascal have a built-in `Append' procedure; all versions of GNU Pascal have an `Extend' procedure (according to ISO-10206 Extended Pascal) which does the same. > Please, hurry up. Please be aware that I am giving you this help in my free time without being paid for it. (Of course if you want that I assign a high priority to your specific problems, you can pay me for that.;-) Hope this helps, Peter -- Peter Gerwinski, Essen, Germany, http://home.pages.de/~Peter.Gerwinski/ Maintainer GNU Pascal - http://home.pages.de/~GNU-Pascal/ - gpc-980830 PGP key on request - 6C 94 45 BE 28 A4 96 - 0E CC E9 12 47 25 82 75 Fight the SPAM and UBE! - http://spam.abuse.net/ - http://maps.vix.com/

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Re: "keypressed" from TP/BP?
by Frank Heckenbach 31 Dec '98

31 Dec '98

Peter Gerwinski wrote: > GRX? If so, your `KeyPressed' problem can easily be solved; see > the `MouseEvent'-related functions of GRX. (Although they are > named `MouseEvent', they cover the keyboard as well and in a > more flexible way than `KeyPressed' and `ReadKey' do.) > > > I'm now hung up on a little side issue. In TP and BP, there > > was a useful Boolean function "keypressed". This let you > > do things like: [...] > > The next (beta) release of GPC (scheduled for ... er ... last > week #-) will come with a portable standard unit that will cover > this. Yes, a BP compatible CRT unit. However, it does not (yet?) work well together with graphics under all circumstances. So you can try it on your own risk (and perhaps improve the unit's ability to work together with graphics), but when working with GRX, it might be easier to use the GRX keyboard functions (at least for now). Frank -- Frank Heckenbach, frank(a)fjf.gnu.de http://fjf.gnu.de/ PGP and GPG keys: http://fjf.gnu.de/plan

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