2002/1222/port/dev.c (diff list | history)

2002/0925/sys/src/9/port/dev.c:50,57 – 2002/1222/sys/src/9/port/dev.c:50,88 (short | long | prev | next)
Add comment explaining use of devgen. Add devdebug. rsc Fri Mar 4 12:44:25 2005
1990/0227		}
2001/0527		/*
2002/1222		* (here, Devgen is the prototype; devgen is the function in dev.c.) * * a Devgen is expected to return the directory entry for ".." * if you pass it s==DEVDOTDOT (-1). otherwise... * * there are two contradictory rules. * * (i) if c is a directory, a Devgen is expected to list its children * as you iterate s. * * (ii) whether or not c is a directory, a Devgen is expected to list * its siblings as you iterate s. * * devgen always returns the list of children in the root * directory. thus it follows (i) when c is the root and (ii) otherwise. * many other Devgens follow (i) when c is a directory and (ii) otherwise. * * devwalk assumes (i). it knows that devgen breaks (i) * for children that are themselves directories, and explicitly catches them. * * devstat assumes (ii). if the Devgen in question follows (i) * for this particular c, devstat will not find the necessary info. * with our particular Devgen functions, this happens only for * directories, so devstat makes something up, assuming * c->name, c->qid, eve, DMDIR|0555. * * devdirread assumes (i). the callers have to make sure * that the Devgen satisfies (i) for the chan being read. */ /*
2001/0527		* the zeroth element of the table MUST be the directory itself for .. */
2002/1222		int devdebug;
1990/0227		int
2001/0527		devgen(Chan *c, char*, Dirtab *tab, int ntab, int i, Dir *dp)
1990/0227		{