🚀 go-pugleaf

The ATC source I posted on Friday assumed that kernel file locking
was available.  While this is true of System V Release 2 systems
from AT&T, it is not included in all versions of System V.

To get around the problem, I've introduced another compile option in
the top level Makefile.  If you have /usr/group standard record and
file locking (check for the presence of /usr/include/unistd.h),
leave the makefile as is.  Otherwise, comment out the line that
says "UNISTD = -DUNISTD".

The new locking scheme is based on exclusive creation of a
temporary file.  It's hardly bullet-proof, but it should suffice
in a friendly environment.  Anybody who wants to beef it up
should feel free to do so.

Five files are affected by this change:  Makefile, src/Makefile,
src/include.h, src/log.c, and src/graphics.c.  Vanilla diff's appear
below.  Sorry for the inconvenience.


Diff for Makefile:
14a15,17
> # for System V with kernel locking, use the following line
> UNISTD = -DUNISTD
> 
47,49c50,52
< 		( cd $(SRC); \
< 		make OSVER=$(OSVER) DEST='"$(DESTINATION)"' \
< 			$(CURSESLIBR) USETERML=$(USETERML) )
---
> 		(cd $(SRC); \
> 		make OSVER=$(OSVER) UNISTD=$(UNISTD) \
> 		DEST='"$(DESTINATION)"' $(CURSESLIBR) USETERML=$(USETERML) )


Diff for src/Makefile:
10c10
< CFLAGS        = -O -D$(OSVER) -DDEST='$(DEST)'
---
> CFLAGS        = $(UNISTD) -O -D$(OSVER) -DDEST='$(DEST)'


Diff for src/include.h:
24a25
> #ifdef UNISTD
25a27
> #endif
27a30
> #include <errno.h>


Diff for src/log.c:
82a83
> #ifdef UNISTD
83a85,100
> #else
> #define	LOCKNAME	"/tmp/atc.lock"
> 	/* locking scheme for those without kernel file locking */
> 	for (i=0; i < 10; i++)
> 	{
> 		if (open(LOCKNAME, O_WRONLY|O_CREAT|O_EXCL, 0200) != -1)
> 			break;		/* success */
> 		if (errno != EEXIST)	/* some other error */
> 		{
> 			i = 10;
> 			break;
> 		}
> 		sleep(2);
> 	}
> 
> 	if (i == 10) /* hit loop end, bomb out */
84a102
> #endif
190c208,210
< 	/* lock will evaporate upon close */
---
> 	/* kernel lock will evaporate upon close */
> #ifndef UNISTD
> 	unlink(LOCKNAME);	/* remove lock file */


Diffs for src/graphics.c:
11,13d10
< #ifdef SYSV
< #include <errno.h>
< #endif
-- 
						Regards,
						DJ Molny, N9609U
						ihnp4!cuae2!djmolny