recipe.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include	"mk.h"

int
dorecipe(Node *node)
{
	char buf[BIGBLOCK];
	register Node *n;
	Rule *r = 0;
	Arc *a, *aa;
	Word head, ahead, lp, ln, *w, *ww, *aw;
	Symtab *s;
	int did = 0;
	char cwd[128];

	aa = 0;
	/*
		pick up the rule
	*/
	for(a = node->prereqs; a; a = a->next)
		if(*a->r->recipe)
			r = (aa = a)->r;
	/*
		no recipe? go to buggery!
	*/
	if(r == 0){
		if(!(node->flags&VIRTUAL) && !(node->flags&NORECIPE)){
			if(getwd(cwd, sizeof cwd))
				fprint(2, "mk: no recipe to make '%s' in directory %s\n", node->name, cwd);
			else
				fprint(2, "mk: no recipe to make '%s'\n", node->name);
			Exit();
		}
		if(strchr(node->name, '(') && node->time == 0)
			MADESET(node, MADE);
		else
			update(0, node);
		if(tflag){
			if(!(node->flags&VIRTUAL))
				touch(node->name);
			else if(explain)
				Bprint(&bout, "no touch of virtual '%s'\n", node->name);
		}
		return(did);
	}
	/*
		build the node list
	*/
	node->next = 0;
	head.next = 0;
	ww = &head;
	ahead.next = 0;
	aw = &ahead;
	if(r->attr&REGEXP){
		ww->next = newword(node->name);
		aw->next = newword(node->name);
	} else {
		for(w = r->alltargets; w; w = w->next){
			if(r->attr&META)
				subst(aa->stem, w->s, buf, sizeof(buf));
			else
				strcpy(buf, w->s);
			aw->next = newword(buf);
			aw = aw->next;
			if((s = symlook(buf, S_NODE, 0)) == 0)
				continue;	/* not a node we are interested in */
			n = s->u.ptr;
			if(aflag == 0 && n->time) {
				for(a = n->prereqs; a; a = a->next)
					if(a->n && outofdate(n, a, 0))
						break;
				if(a == 0)
					continue;
			}
			ww->next = newword(buf);
			ww = ww->next;
			if(n == node) continue;
			n->next = node->next;
			node->next = n;
		}
	}
	for(n = node; n; n = n->next)
		if((n->flags&READY) == 0)
			return(did);
	/*
		gather the params for the job
	*/
	lp.next = ln.next = 0;
	for(n = node; n; n = n->next){
		for(a = n->prereqs; a; a = a->next){
			if(a->n){
				addw(&lp, a->n->name);
				if(outofdate(n, a, 0)){
					addw(&ln, a->n->name);
					if(explain)
						fprint(1, "%s(%ld) < %s(%ld)\n",
							n->name, n->time, a->n->name, a->n->time);
				}
			} else {
				if(explain)
					fprint(1, "%s has no prerequisites\n",
							n->name);
			}
		}
		MADESET(n, BEINGMADE);
	}
/*	print("lt=%s ln=%s lp=%s\n",wtos(head.next, ' '),wtos(ln.next, ' '),wtos(lp.next, ' '));/**/
	run(newjob(r, node, aa->stem, aa->match, lp.next, ln.next, head.next, ahead.next));
	return(1);
}

void
addw(Word *w, char *s)
{
	Word *lw;

	for(lw = w; w = w->next; lw = w){
		if(strcmp(s, w->s) == 0)
			return;
	}
	lw->next = newword(s);
}