xref: /freebsd/contrib/bmake/make.c (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a)

/*	$NetBSD: make.c,v 1.264 2024/06/02 15:31:26 rillig Exp $	*/

/*
 * Copyright (c) 1988, 1989, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Copyright (c) 1989 by Berkeley Softworks
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Examination of targets and their suitability for creation.
 *
 * Interface:
 *	Make_Run	Initialize things for the module. Returns true if
 *			work was (or would have been) done.
 *
 *	Make_Update	After a target is made, update all its parents.
 *			Perform various bookkeeping chores like the updating
 *			of the youngestChild field of the parent, filling
 *			of the IMPSRC variable, etc. Place the parent on the
 *			toBeMade queue if it should be.
 *
 *	GNode_UpdateYoungestChild
 *			Update the node's youngestChild field based on the
 *			child's modification time.
 *
 *	GNode_SetLocalVars
 *			Set up the various local variables for a
 *			target, including the .ALLSRC variable, making
 *			sure that any variable that needs to exist
 *			at the very least has the empty value.
 *
 *	GNode_IsOODate	Determine if a target is out-of-date.
 *
 *	Make_HandleUse	See if a child is a .USE node for a parent
 *			and perform the .USE actions if so.
 *
 *	Make_ExpandUse	Expand .USE nodes
 */

#include "make.h"
#include "dir.h"
#include "job.h"

/*	"@(#)make.c	8.1 (Berkeley) 6/6/93"	*/
MAKE_RCSID("$NetBSD: make.c,v 1.264 2024/06/02 15:31:26 rillig Exp $");

/* Sequence # to detect recursion. */
static unsigned int checked_seqno = 1;

/*
 * The current fringe of the graph.
 * These are nodes which await examination by MakeOODate.
 * It is added to by Make_Update and subtracted from by MakeStartJobs
 */
static GNodeList toBeMade = LST_INIT;


void
debug_printf(const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	vfprintf(opts.debug_file, fmt, ap);
	va_end(ap);
}

static char *
GNodeType_ToString(GNodeType type)
{
	Buffer buf;

	Buf_Init(&buf);
#define ADD(flag) Buf_AddFlag(&buf, (type & (flag)) != OP_NONE, #flag)
	ADD(OP_DEPENDS);
	ADD(OP_FORCE);
	ADD(OP_DOUBLEDEP);
	ADD(OP_OPTIONAL);
	ADD(OP_USE);
	ADD(OP_EXEC);
	ADD(OP_IGNORE);
	ADD(OP_PRECIOUS);
	ADD(OP_SILENT);
	ADD(OP_MAKE);
	ADD(OP_JOIN);
	ADD(OP_MADE);
	ADD(OP_SPECIAL);
	ADD(OP_USEBEFORE);
	ADD(OP_INVISIBLE);
	ADD(OP_NOTMAIN);
	ADD(OP_PHONY);
	ADD(OP_NOPATH);
	ADD(OP_WAIT);
	ADD(OP_NOMETA);
	ADD(OP_META);
	ADD(OP_NOMETA_CMP);
	ADD(OP_SUBMAKE);
	ADD(OP_TRANSFORM);
	ADD(OP_MEMBER);
	ADD(OP_LIB);
	ADD(OP_ARCHV);
	ADD(OP_HAS_COMMANDS);
	ADD(OP_SAVE_CMDS);
	ADD(OP_DEPS_FOUND);
	ADD(OP_MARK);
#undef ADD
	if (buf.len == 0)
		Buf_AddStr(&buf, "none");
	return Buf_DoneData(&buf);
}

static char *
GNodeFlags_ToString(GNodeFlags flags)
{
	Buffer buf;

	Buf_Init(&buf);
	Buf_AddFlag(&buf, flags.remake, "REMAKE");
	Buf_AddFlag(&buf, flags.childMade, "CHILDMADE");
	Buf_AddFlag(&buf, flags.force, "FORCE");
	Buf_AddFlag(&buf, flags.doneWait, "DONE_WAIT");
	Buf_AddFlag(&buf, flags.doneOrder, "DONE_ORDER");
	Buf_AddFlag(&buf, flags.fromDepend, "FROM_DEPEND");
	Buf_AddFlag(&buf, flags.doneAllsrc, "DONE_ALLSRC");
	Buf_AddFlag(&buf, flags.cycle, "CYCLE");
	Buf_AddFlag(&buf, flags.doneCycle, "DONECYCLE");
	if (buf.len == 0)
		Buf_AddStr(&buf, "none");
	return Buf_DoneData(&buf);
}

void
GNode_FprintDetails(FILE *f, const char *prefix, const GNode *gn,
		    const char *suffix)
{
	char *type = GNodeType_ToString(gn->type);
	char *flags = GNodeFlags_ToString(gn->flags);

	fprintf(f, "%s%s, type %s, flags %s%s",
	    prefix, GNodeMade_Name(gn->made), type, flags, suffix);
	free(type);
	free(flags);
}

bool
GNode_ShouldExecute(GNode *gn)
{
	return !((gn->type & OP_MAKE)
	    ? opts.noRecursiveExecute
	    : opts.noExecute);
}

/* Update the youngest child of the node, according to the given child. */
void
GNode_UpdateYoungestChild(GNode *gn, GNode *cgn)
{
	if (gn->youngestChild == NULL || cgn->mtime > gn->youngestChild->mtime)
		gn->youngestChild = cgn;
}

static bool
IsOODateRegular(GNode *gn)
{
	/* These rules are inherited from the original Make. */

	if (gn->youngestChild != NULL) {
		if (gn->mtime < gn->youngestChild->mtime) {
			DEBUG1(MAKE, "modified before source \"%s\"...",
			    GNode_Path(gn->youngestChild));
			return true;
		}
		return false;
	}

	if (gn->mtime == 0 && !(gn->type & OP_OPTIONAL)) {
		DEBUG0(MAKE, "nonexistent and no sources...");
		return true;
	}

	if (gn->type & OP_DOUBLEDEP) {
		DEBUG0(MAKE, ":: operator and no sources...");
		return true;
	}

	return false;
}

/*
 * See if the node is out of date with respect to its sources.
 *
 * Used by Make_Run when deciding which nodes to place on the
 * toBeMade queue initially and by Make_Update to screen out .USE and
 * .EXEC nodes. In the latter case, however, any other sort of node
 * must be considered out-of-date since at least one of its children
 * will have been recreated.
 *
 * The mtime field of the node and the youngestChild field of its parents
 * may be changed.
 */
bool
GNode_IsOODate(GNode *gn)
{
	bool oodate;

	/*
	 * Certain types of targets needn't even be sought as their datedness
	 * doesn't depend on their modification time...
	 */
	if (!(gn->type & (OP_JOIN | OP_USE | OP_USEBEFORE | OP_EXEC))) {
		Dir_UpdateMTime(gn, true);
		if (DEBUG(MAKE)) {
			if (gn->mtime != 0)
				debug_printf("modified %s...",
				    Targ_FmtTime(gn->mtime));
			else
				debug_printf("nonexistent...");
		}
	}

	/*
	 * A target is remade in one of the following circumstances:
	 *
	 *	its modification time is smaller than that of its youngest
	 *	child and it would actually be run (has commands or is not
	 *	GNode_IsTarget)
	 *
	 *	it's the object of a force operator
	 *
	 *	it has no children, was on the lhs of an operator and doesn't
	 *	exist already.
	 *
	 * Libraries are only considered out-of-date if the archive module
	 * says they are.
	 *
	 * These weird rules are brought to you by Backward-Compatibility
	 * and the strange people who wrote 'Make'.
	 */
	if (gn->type & (OP_USE | OP_USEBEFORE)) {
		/*
		 * If the node is a USE node it is *never* out of date
		 * no matter *what*.
		 */
		DEBUG0(MAKE, ".USE node...");
		oodate = false;
	} else if ((gn->type & OP_LIB) && (gn->mtime == 0 || Arch_IsLib(gn))) {
		DEBUG0(MAKE, "library...");

		/*
		 * always out of date if no children and :: target
		 * or nonexistent.
		 */
		oodate = (gn->mtime == 0 || Arch_LibOODate(gn) ||
			  (gn->youngestChild == NULL &&
			   (gn->type & OP_DOUBLEDEP)));
	} else if (gn->type & OP_JOIN) {
		/*
		 * A target with the .JOIN attribute is only considered
		 * out-of-date if any of its children was out-of-date.
		 */
		DEBUG0(MAKE, ".JOIN node...");
		DEBUG1(MAKE, "source %smade...",
		    gn->flags.childMade ? "" : "not ");
		oodate = gn->flags.childMade;
	} else if (gn->type & (OP_FORCE | OP_EXEC | OP_PHONY)) {
		/*
		 * A node which is the object of the force (!) operator or
		 * which has the .EXEC attribute is always considered
		 * out-of-date.
		 */
		if (DEBUG(MAKE)) {
			if (gn->type & OP_FORCE)
				debug_printf("! operator...");
			else if (gn->type & OP_PHONY)
				debug_printf(".PHONY node...");
			else
				debug_printf(".EXEC node...");
		}
		oodate = true;
	} else if (IsOODateRegular(gn)) {
		oodate = true;
	} else {
		/*
		 * When a nonexistent child with no sources
		 * (such as a typically used FORCE source) has been made and
		 * the target of the child (usually a directory) has the same
		 * timestamp as the timestamp just given to the nonexistent
		 * child after it was considered made.
		 */
		if (DEBUG(MAKE)) {
			if (gn->flags.force)
				debug_printf("non existing child...");
		}
		oodate = gn->flags.force;
	}

#ifdef USE_META
	if (useMeta)
		oodate = meta_oodate(gn, oodate);
#endif

	/*
	 * If the target isn't out-of-date, the parents need to know its
	 * modification time. Note that targets that appear to be out-of-date
	 * but aren't, because they have no commands and are GNode_IsTarget,
	 * have their mtime stay below their children's mtime to keep parents
	 * from thinking they're out-of-date.
	 */
	if (!oodate) {
		GNodeListNode *ln;
		for (ln = gn->parents.first; ln != NULL; ln = ln->next)
			GNode_UpdateYoungestChild(ln->datum, gn);
	}

	return oodate;
}

static void
PretendAllChildrenAreMade(GNode *pgn)
{
	GNodeListNode *ln;

	for (ln = pgn->children.first; ln != NULL; ln = ln->next) {
		GNode *cgn = ln->datum;

		/* This may also update cgn->path. */
		Dir_UpdateMTime(cgn, false);
		GNode_UpdateYoungestChild(pgn, cgn);
		pgn->unmade--;
	}
}

/*
 * Called by Make_Run and SuffApplyTransform on the downward pass to handle
 * .USE and transformation nodes, by copying the child node's commands, type
 * flags and children to the parent node.
 *
 * A .USE node is much like an explicit transformation rule, except its
 * commands are always added to the target node, even if the target already
 * has commands.
 *
 * Input:
 *	cgn		The source node, which is either a .USE/.USEBEFORE
 *			node or a transformation node (OP_TRANSFORM).
 *	pgn		The target node
 */
void
Make_HandleUse(GNode *cgn, GNode *pgn)
{
	GNodeListNode *ln;	/* An element in the children list */

#ifdef DEBUG_SRC
	if (!(cgn->type & (OP_USE | OP_USEBEFORE | OP_TRANSFORM))) {
		debug_printf("Make_HandleUse: called for plain node %s\n",
		    cgn->name);
		/* XXX: debug mode should not affect control flow */
		return;
	}
#endif

	if ((cgn->type & (OP_USE | OP_USEBEFORE)) ||
	    Lst_IsEmpty(&pgn->commands)) {
		if (cgn->type & OP_USEBEFORE) {
			/* .USEBEFORE */
			Lst_PrependAll(&pgn->commands, &cgn->commands);
		} else {
			/* .USE, or target has no commands */
			Lst_AppendAll(&pgn->commands, &cgn->commands);
		}
	}

	for (ln = cgn->children.first; ln != NULL; ln = ln->next) {
		GNode *gn = ln->datum;

		/*
		 * Expand variables in the .USE node's name
		 * and save the unexpanded form.
		 * We don't need to do this for commands.
		 * They get expanded properly when we execute.
		 */
		if (gn->uname == NULL)
			gn->uname = gn->name;
		else
			free(gn->name);
		gn->name = Var_Subst(gn->uname, pgn, VARE_EVAL);
		/* TODO: handle errors */
		if (gn->uname != NULL && strcmp(gn->name, gn->uname) != 0) {
			/* See if we have a target for this node. */
			GNode *tgn = Targ_FindNode(gn->name);
			if (tgn != NULL)
				gn = tgn;
		}

		Lst_Append(&pgn->children, gn);
		Lst_Append(&gn->parents, pgn);
		pgn->unmade++;
	}

	pgn->type |=
	    cgn->type & (unsigned)~(OP_OPMASK | OP_USE | OP_USEBEFORE | OP_TRANSFORM);
}

/*
 * Used by Make_Run on the downward pass to handle .USE nodes. Should be
 * called before the children are enqueued to be looked at by MakeAddChild.
 *
 * For a .USE child, the commands, type flags and children are copied to the
 * parent node, and since the relation to the .USE node is then no longer
 * needed, that relation is removed.
 *
 * Input:
 *	cgn		the child, which may be a .USE node
 *	pgn		the current parent
 */
static void
MakeHandleUse(GNode *cgn, GNode *pgn, GNodeListNode *ln)
{
	bool unmarked;

	unmarked = !(cgn->type & OP_MARK);
	cgn->type |= OP_MARK;

	if (!(cgn->type & (OP_USE | OP_USEBEFORE)))
		return;

	if (unmarked)
		Make_HandleUse(cgn, pgn);

	/*
	 * This child node is now "made", so we decrement the count of
	 * unmade children in the parent... We also remove the child
	 * from the parent's list to accurately reflect the number of decent
	 * children the parent has. This is used by Make_Run to decide
	 * whether to queue the parent or examine its children...
	 */
	Lst_Remove(&pgn->children, ln);
	pgn->unmade--;
}

static void
HandleUseNodes(GNode *gn)
{
	GNodeListNode *ln, *nln;
	for (ln = gn->children.first; ln != NULL; ln = nln) {
		nln = ln->next;
		MakeHandleUse(ln->datum, gn, ln);
	}
}


/*
 * Check the modification time of a gnode, and update it if necessary.
 * Return 0 if the gnode does not exist, or its filesystem time if it does.
 */
time_t
Make_Recheck(GNode *gn)
{
	time_t mtime;

	Dir_UpdateMTime(gn, true);
	mtime = gn->mtime;

#ifndef RECHECK
	/*
	 * We can't re-stat the thing, but we can at least take care of rules
	 * where a target depends on a source that actually creates the
	 * target, but only if it has changed, e.g.
	 *
	 * parse.h : parse.o
	 *
	 * parse.o : parse.y
	 *		yacc -d parse.y
	 *		cc -c y.tab.c
	 *		mv y.tab.o parse.o
	 *		cmp -s y.tab.h parse.h || mv y.tab.h parse.h
	 *
	 * In this case, if the definitions produced by yacc haven't changed
	 * from before, parse.h won't have been updated and gn->mtime will
	 * reflect the current modification time for parse.h. This is
	 * something of a kludge, I admit, but it's a useful one.
	 *
	 * XXX: People like to use a rule like "FRC:" to force things that
	 * depend on FRC to be made, so we have to check for gn->children
	 * being empty as well.
	 */
	if (!Lst_IsEmpty(gn->commands) || Lst_IsEmpty(gn->children))
		gn->mtime = now;
#else
	/*
	 * This is what Make does and it's actually a good thing, as it
	 * allows rules like
	 *
	 *	cmp -s y.tab.h parse.h || cp y.tab.h parse.h
	 *
	 * to function as intended. Unfortunately, thanks to the stateless
	 * nature of NFS (by which I mean the loose coupling of two clients
	 * using the same file from a common server), there are times when
	 * the modification time of a file created on a remote machine
	 * will not be modified before the local stat() implied by the
	 * Dir_UpdateMTime occurs, thus leading us to believe that the file
	 * is unchanged, wreaking havoc with files that depend on this one.
	 *
	 * I have decided it is better to make too much than to make too
	 * little, so this stuff is commented out unless you're sure it's ok.
	 * -- ardeb 1/12/88
	 */
	/*
	 * Christos, 4/9/92: If we are saving commands, pretend that
	 * the target is made now. Otherwise archives with '...' rules
	 * don't work!
	 */
	if (!GNode_ShouldExecute(gn) || (gn->type & OP_SAVE_CMDS) ||
	    (mtime == 0 && !(gn->type & OP_WAIT))) {
		DEBUG2(MAKE, " recheck(%s): update time from %s to now\n",
		    gn->name,
		    gn->mtime == 0 ? "nonexistent" : Targ_FmtTime(gn->mtime));
		gn->mtime = now;
	} else {
		DEBUG2(MAKE, " recheck(%s): current update time: %s\n",
		    gn->name, Targ_FmtTime(gn->mtime));
	}
#endif

	/*
	 * XXX: The returned mtime may differ from gn->mtime. Intentionally?
	 */
	return mtime;
}

/*
 * Set the .PREFIX and .IMPSRC variables for all the implied parents
 * of this node.
 */
static void
UpdateImplicitParentsVars(GNode *cgn, const char *cname)
{
	GNodeListNode *ln;
	const char *cpref = GNode_VarPrefix(cgn);

	for (ln = cgn->implicitParents.first; ln != NULL; ln = ln->next) {
		GNode *pgn = ln->datum;
		if (pgn->flags.remake) {
			Var_Set(pgn, IMPSRC, cname);
			if (cpref != NULL)
				Var_Set(pgn, PREFIX, cpref);
		}
	}
}

/* See if a .ORDER rule stops us from building this node. */
static bool
IsWaitingForOrder(GNode *gn)
{
	GNodeListNode *ln;

	for (ln = gn->order_pred.first; ln != NULL; ln = ln->next) {
		GNode *ogn = ln->datum;

		if (GNode_IsDone(ogn) || !ogn->flags.remake)
			continue;

		DEBUG2(MAKE,
		    "IsWaitingForOrder: Waiting for .ORDER node \"%s%s\"\n",
		    ogn->name, ogn->cohort_num);
		return true;
	}
	return false;
}

static bool MakeBuildChild(GNode *, GNodeListNode *);

static void
ScheduleOrderSuccessors(GNode *gn)
{
	GNodeListNode *toBeMadeNext = toBeMade.first;
	GNodeListNode *ln;

	for (ln = gn->order_succ.first; ln != NULL; ln = ln->next) {
		GNode *succ = ln->datum;

		if (succ->made == DEFERRED &&
		    !MakeBuildChild(succ, toBeMadeNext))
			succ->flags.doneOrder = true;
	}
}

/*
 * Perform update on the parents of a node. Used by JobFinish once
 * a node has been dealt with and by MakeStartJobs if it finds an
 * up-to-date node.
 *
 * The unmade field of pgn is decremented and pgn may be placed on
 * the toBeMade queue if this field becomes 0.
 *
 * If the child was made, the parent's flag CHILDMADE field will be
 * set true.
 *
 * If the child is not up-to-date and still does not exist,
 * set the FORCE flag on the parents.
 *
 * If the child wasn't made, the youngestChild field of the parent will be
 * altered if the child's mtime is big enough.
 *
 * Finally, if the child is the implied source for the parent, the
 * parent's IMPSRC variable is set appropriately.
 */
void
Make_Update(GNode *cgn)
{
	const char *cname;	/* the child's name */
	time_t mtime = -1;
	GNodeList *parents;
	GNodeListNode *ln;
	GNode *centurion;

	/* It is save to re-examine any nodes again */
	checked_seqno++;

	cname = GNode_VarTarget(cgn);

	DEBUG2(MAKE, "Make_Update: %s%s\n", cgn->name, cgn->cohort_num);

	/*
	 * If the child was actually made, see what its modification time is
	 * now -- some rules won't actually update the file. If the file
	 * still doesn't exist, make its mtime now.
	 */
	if (cgn->made != UPTODATE)
		mtime = Make_Recheck(cgn);

	/*
	 * If this is a `::' node, we must consult its first instance
	 * which is where all parents are linked.
	 */
	if ((centurion = cgn->centurion) != NULL) {
		if (!Lst_IsEmpty(&cgn->parents))
			Punt("%s%s: cohort has parents", cgn->name,
			    cgn->cohort_num);
		centurion->unmade_cohorts--;
		if (centurion->unmade_cohorts < 0)
			Error("Graph cycles through centurion %s",
			    centurion->name);
	} else {
		centurion = cgn;
	}
	parents = &centurion->parents;

	/* If this was a .ORDER node, schedule the RHS */
	ScheduleOrderSuccessors(centurion);

	/* Now mark all the parents as having one less unmade child */
	for (ln = parents->first; ln != NULL; ln = ln->next) {
		GNode *pgn = ln->datum;

		if (DEBUG(MAKE)) {
			debug_printf("inspect parent %s%s: ", pgn->name,
			    pgn->cohort_num);
			GNode_FprintDetails(opts.debug_file, "", pgn, "");
			debug_printf(", unmade %d ", pgn->unmade - 1);
		}

		if (!pgn->flags.remake) {
			/* This parent isn't needed */
			DEBUG0(MAKE, "- not needed\n");
			continue;
		}
		if (mtime == 0 && !(cgn->type & OP_WAIT))
			pgn->flags.force = true;

		/*
		 * If the parent has the .MADE attribute, its timestamp got
		 * updated to that of its newest child, and its unmade
		 * child count got set to zero in Make_ExpandUse().
		 * However other things might cause us to build one of its
		 * children - and so we mustn't do any processing here when
		 * the child build finishes.
		 */
		if (pgn->type & OP_MADE) {
			DEBUG0(MAKE, "- .MADE\n");
			continue;
		}

		if (!(cgn->type & (OP_EXEC | OP_USE | OP_USEBEFORE))) {
			if (cgn->made == MADE)
				pgn->flags.childMade = true;
			GNode_UpdateYoungestChild(pgn, cgn);
		}

		/*
		 * A parent must wait for the completion of all instances
		 * of a `::' dependency.
		 */
		if (centurion->unmade_cohorts != 0 ||
		    !GNode_IsDone(centurion)) {
			DEBUG2(MAKE,
			    "- centurion made %d, %d unmade cohorts\n",
			    centurion->made, centurion->unmade_cohorts);
			continue;
		}

		/* One more child of this parent is now made */
		pgn->unmade--;
		if (pgn->unmade < 0) {
			if (DEBUG(MAKE)) {
				debug_printf("Graph cycles through %s%s\n",
				    pgn->name, pgn->cohort_num);
				Targ_PrintGraph(2);
			}
			Error("Graph cycles through %s%s", pgn->name,
			    pgn->cohort_num);
		}

		/*
		 * We must always rescan the parents of .WAIT and .ORDER
		 * nodes.
		 */
		if (pgn->unmade != 0 && !(centurion->type & OP_WAIT)
		    && !centurion->flags.doneOrder) {
			DEBUG0(MAKE, "- unmade children\n");
			continue;
		}
		if (pgn->made != DEFERRED) {
			/*
			 * Either this parent is on a different branch of
			 * the tree, or it on the RHS of a .WAIT directive
			 * or it is already on the toBeMade list.
			 */
			DEBUG0(MAKE, "- not deferred\n");
			continue;
		}

		if (IsWaitingForOrder(pgn))
			continue;

		if (DEBUG(MAKE)) {
			debug_printf("- %s%s made, schedule %s%s (made %d)\n",
			    cgn->name, cgn->cohort_num,
			    pgn->name, pgn->cohort_num, pgn->made);
			Targ_PrintNode(pgn, 2);
		}
		/* Ok, we can schedule the parent again */
		pgn->made = REQUESTED;
		Lst_Enqueue(&toBeMade, pgn);
	}

	UpdateImplicitParentsVars(cgn, cname);
}

static void
UnmarkChildren(GNode *gn)
{
	GNodeListNode *ln;

	for (ln = gn->children.first; ln != NULL; ln = ln->next) {
		GNode *child = ln->datum;
		child->type &= (unsigned)~OP_MARK;
	}
}

/*
 * Add a child's name to the ALLSRC and OODATE variables of the given
 * node, but only if it has not been given the .EXEC, .USE or .INVISIBLE
 * attributes. .EXEC and .USE children are very rarely going to be files,
 * so...
 *
 * If the child is a .JOIN node, its ALLSRC is propagated to the parent.
 *
 * A child is added to the OODATE variable if its modification time is
 * later than that of its parent, as defined by Make, except if the
 * parent is a .JOIN node. In that case, it is only added to the OODATE
 * variable if it was actually made (since .JOIN nodes don't have
 * modification times, the comparison is rather unfair...)..
 *
 * Input:
 *	cgn		The child to add
 *	pgn		The parent to whose ALLSRC variable it should
 *			be added
 */
static void
MakeAddAllSrc(GNode *cgn, GNode *pgn)
{
	const char *child, *allsrc;

	if (cgn->type & OP_MARK)
		return;
	cgn->type |= OP_MARK;

	if (cgn->type & (OP_EXEC | OP_USE | OP_USEBEFORE | OP_INVISIBLE))
		return;

	if (cgn->type & OP_ARCHV)
		child = GNode_VarMember(cgn);
	else
		child = GNode_Path(cgn);

	if (cgn->type & OP_JOIN)
		allsrc = GNode_VarAllsrc(cgn);
	else
		allsrc = child;

	if (allsrc != NULL)
		Var_Append(pgn, ALLSRC, allsrc);

	if (pgn->type & OP_JOIN) {
		if (cgn->made == MADE)
			Var_Append(pgn, OODATE, child);

	} else if ((pgn->mtime < cgn->mtime) ||
		   (cgn->mtime >= now && cgn->made == MADE)) {
		/*
		 * It goes in the OODATE variable if the parent is
		 * younger than the child or if the child has been
		 * modified more recently than the start of the make.
		 * This is to keep pmake from getting confused if
		 * something else updates the parent after the make
		 * starts (shouldn't happen, I know, but sometimes it
		 * does). In such a case, if we've updated the child,
		 * the parent is likely to have a modification time
		 * later than that of the child and anything that
		 * relies on the OODATE variable will be hosed.
		 *
		 * XXX: This will cause all made children to go in
		 * the OODATE variable, even if they're not touched,
		 * if RECHECK isn't defined, since cgn->mtime is set
		 * to now in Make_Update. According to some people,
		 * this is good...
		 */
		Var_Append(pgn, OODATE, child);
	}
}

/*
 * Set up the ALLSRC and OODATE variables. Sad to say, it must be
 * done separately, rather than while traversing the graph. This is
 * because Make defined OODATE to contain all sources whose modification
 * times were later than that of the target, *not* those sources that
 * were out-of-date. Since in both compatibility and native modes,
 * the modification time of the parent isn't found until the child
 * has been dealt with, we have to wait until now to fill in the
 * variable. As for ALLSRC, the ordering is important and not
 * guaranteed when in native mode, so it must be set here, too.
 *
 * If the node is a .JOIN node, its TARGET variable will be set to
 * match its ALLSRC variable.
 */
void
GNode_SetLocalVars(GNode *gn)
{
	GNodeListNode *ln;

	if (gn->flags.doneAllsrc)
		return;

	UnmarkChildren(gn);
	for (ln = gn->children.first; ln != NULL; ln = ln->next)
		MakeAddAllSrc(ln->datum, gn);

	if (!Var_Exists(gn, OODATE))
		Var_Set(gn, OODATE, "");
	if (!Var_Exists(gn, ALLSRC))
		Var_Set(gn, ALLSRC, "");

	if (gn->type & OP_JOIN)
		Var_Set(gn, TARGET, GNode_VarAllsrc(gn));
	gn->flags.doneAllsrc = true;
}

static void
ScheduleRandomly(GNode *gn)
{
	GNodeListNode *ln;
	size_t i, n;

	n = 0;
	for (ln = toBeMade.first; ln != NULL; ln = ln->next)
		n++;
	i = n > 0 ? (size_t)random() % (n + 1) : 0;

	if (i == 0) {
		Lst_Append(&toBeMade, gn);
		return;
	}
	i--;

	for (ln = toBeMade.first; i > 0; ln = ln->next)
		i--;
	Lst_InsertBefore(&toBeMade, ln, gn);
}

static bool
MakeBuildChild(GNode *cn, GNodeListNode *toBeMadeNext)
{

	if (DEBUG(MAKE)) {
		debug_printf("MakeBuildChild: inspect %s%s, ",
		    cn->name, cn->cohort_num);
		GNode_FprintDetails(opts.debug_file, "", cn, "\n");
	}
	if (GNode_IsReady(cn))
		return false;

	/* If this node is on the RHS of a .ORDER, check LHSs. */
	if (IsWaitingForOrder(cn)) {
		/*
		 * Can't build this (or anything else in this child list) yet
		 */
		cn->made = DEFERRED;
		return false;	/* but keep looking */
	}

	DEBUG2(MAKE, "MakeBuildChild: schedule %s%s\n",
	    cn->name, cn->cohort_num);

	cn->made = REQUESTED;
	if (opts.randomizeTargets && !(cn->type & OP_WAIT))
		ScheduleRandomly(cn);
	else if (toBeMadeNext == NULL)
		Lst_Append(&toBeMade, cn);
	else
		Lst_InsertBefore(&toBeMade, toBeMadeNext, cn);

	if (cn->unmade_cohorts != 0) {
		ListNode *ln;

		for (ln = cn->cohorts.first; ln != NULL; ln = ln->next)
			if (MakeBuildChild(ln->datum, toBeMadeNext))
				break;
	}

	/*
	 * If this node is a .WAIT node with unmade children
	 * then don't add the next sibling.
	 */
	return cn->type & OP_WAIT && cn->unmade > 0;
}

static void
MakeChildren(GNode *gn)
{
	GNodeListNode *toBeMadeNext = toBeMade.first;
	GNodeListNode *ln;

	for (ln = gn->children.first; ln != NULL; ln = ln->next)
		if (MakeBuildChild(ln->datum, toBeMadeNext))
			break;
}

/*
 * Start as many jobs as possible, taking them from the toBeMade queue.
 *
 * If the -q option was given, no job will be started,
 * but as soon as an out-of-date target is found, this function
 * returns true. In all other cases, this function returns false.
 */
static bool
MakeStartJobs(void)
{
	GNode *gn;
	bool have_token = false;

	while (!Lst_IsEmpty(&toBeMade)) {
		/*
		 * Get token now to avoid cycling job-list when we only
		 * have 1 token
		 */
		if (!have_token && !Job_TokenWithdraw())
			break;
		have_token = true;

		gn = Lst_Dequeue(&toBeMade);
		DEBUG2(MAKE, "Examining %s%s...\n", gn->name, gn->cohort_num);

		if (gn->made != REQUESTED) {
			debug_printf("internal error: made = %s\n",
			    GNodeMade_Name(gn->made));
			Targ_PrintNode(gn, 2);
			Targ_PrintNodes(&toBeMade, 2);
			Targ_PrintGraph(3);
			abort();
		}

		if (gn->checked_seqno == checked_seqno) {
			/*
			 * We've already looked at this node since a job
			 * finished...
			 */
			DEBUG2(MAKE, "already checked %s%s\n", gn->name,
			    gn->cohort_num);
			gn->made = DEFERRED;
			continue;
		}
		gn->checked_seqno = checked_seqno;

		if (gn->unmade != 0) {
			/*
			 * We can't build this yet, add all unmade children
			 * to toBeMade, just before the current first element.
			 */
			gn->made = DEFERRED;

			MakeChildren(gn);

			/* and drop this node on the floor */
			DEBUG2(MAKE, "dropped %s%s\n", gn->name,
			    gn->cohort_num);
			continue;
		}

		gn->made = BEINGMADE;
		if (GNode_IsOODate(gn)) {
			DEBUG0(MAKE, "out-of-date\n");
			if (opts.query)
				return strcmp(gn->name, ".MAIN") != 0;
			GNode_SetLocalVars(gn);
			Job_Make(gn);
			have_token = false;
		} else {
			DEBUG0(MAKE, "up-to-date\n");
			gn->made = UPTODATE;
			if (gn->type & OP_JOIN) {
				/*
				 * Even for an up-to-date .JOIN node, we
				 * need it to have its local variables so
				 * references to it get the correct value
				 * for .TARGET when building up the local
				 * variables of its parent(s)...
				 */
				GNode_SetLocalVars(gn);
			}
			Make_Update(gn);
		}
	}

	if (have_token)
		Job_TokenReturn();

	return false;
}

/* Print the status of a .ORDER node. */
static void
MakePrintStatusOrderNode(GNode *ogn, GNode *gn)
{
	if (!GNode_IsWaitingFor(ogn))
		return;

	printf("    `%s%s' has .ORDER dependency against %s%s ",
	    gn->name, gn->cohort_num, ogn->name, ogn->cohort_num);
	GNode_FprintDetails(stdout, "(", ogn, ")\n");

	if (DEBUG(MAKE) && opts.debug_file != stdout) {
		debug_printf("    `%s%s' has .ORDER dependency against %s%s ",
		    gn->name, gn->cohort_num, ogn->name, ogn->cohort_num);
		GNode_FprintDetails(opts.debug_file, "(", ogn, ")\n");
	}
}

static void
MakePrintStatusOrder(GNode *gn)
{
	GNodeListNode *ln;
	for (ln = gn->order_pred.first; ln != NULL; ln = ln->next)
		MakePrintStatusOrderNode(ln->datum, gn);
}

static void MakePrintStatusList(GNodeList *, int *);

/*
 * Print the status of a top-level node, viz. it being up-to-date already
 * or not created due to an error in a lower level.
 */
static bool
MakePrintStatus(GNode *gn, int *errors)
{
	if (gn->flags.doneCycle) {
		/*
		 * We've completely processed this node before, don't do
		 * it again.
		 */
		return false;
	}

	if (gn->unmade == 0) {
		gn->flags.doneCycle = true;
		switch (gn->made) {
		case UPTODATE:
			printf("`%s%s' is up to date.\n", gn->name,
			    gn->cohort_num);
			break;
		case MADE:
			break;
		case UNMADE:
		case DEFERRED:
		case REQUESTED:
		case BEINGMADE:
			(*errors)++;
			printf("`%s%s' was not built", gn->name,
			    gn->cohort_num);
			GNode_FprintDetails(stdout, " (", gn, ")!\n");
			if (DEBUG(MAKE) && opts.debug_file != stdout) {
				debug_printf("`%s%s' was not built", gn->name,
				    gn->cohort_num);
				GNode_FprintDetails(opts.debug_file, " (", gn,
				    ")!\n");
			}
			/* Most likely problem is actually caused by .ORDER */
			MakePrintStatusOrder(gn);
			break;
		default:
			/* Errors - already counted */
			printf("`%s%s' not remade because of errors.\n",
			    gn->name, gn->cohort_num);
			if (DEBUG(MAKE) && opts.debug_file != stdout)
				debug_printf(
				    "`%s%s' not remade because of errors.\n",
				    gn->name, gn->cohort_num);
			break;
		}
		return false;
	}

	DEBUG3(MAKE, "MakePrintStatus: %s%s has %d unmade children\n",
	    gn->name, gn->cohort_num, gn->unmade);
	/*
	 * If printing cycles and came to one that has unmade children,
	 * print out the cycle by recursing on its children.
	 */
	if (!gn->flags.cycle) {
		/* First time we've seen this node, check all children */
		gn->flags.cycle = true;
		MakePrintStatusList(&gn->children, errors);
		/* Mark that this node needn't be processed again */
		gn->flags.doneCycle = true;
		return false;
	}

	/* Only output the error once per node */
	gn->flags.doneCycle = true;
	Error("Graph cycles through `%s%s'", gn->name, gn->cohort_num);
	if ((*errors)++ > 100)
		/* Abandon the whole error report */
		return true;

	/* Reporting for our children will give the rest of the loop */
	MakePrintStatusList(&gn->children, errors);
	return false;
}

static void
MakePrintStatusList(GNodeList *gnodes, int *errors)
{
	GNodeListNode *ln;

	for (ln = gnodes->first; ln != NULL; ln = ln->next)
		if (MakePrintStatus(ln->datum, errors))
			break;
}

static void
ExamineLater(GNodeList *examine, GNodeList *toBeExamined)
{
	GNodeListNode *ln;

	for (ln = toBeExamined->first; ln != NULL; ln = ln->next) {
		GNode *gn = ln->datum;

		if (gn->flags.remake)
			continue;
		if (gn->type & (OP_USE | OP_USEBEFORE))
			continue;

		DEBUG2(MAKE, "ExamineLater: need to examine \"%s%s\"\n",
		    gn->name, gn->cohort_num);
		Lst_Enqueue(examine, gn);
	}
}

/*
 * Expand .USE nodes and create a new targets list.
 *
 * Input:
 *	targs		the initial list of targets
 */
void
Make_ExpandUse(GNodeList *targs)
{
	GNodeList examine = LST_INIT;	/* Queue of targets to examine */
	Lst_AppendAll(&examine, targs);

	/*
	 * Make an initial downward pass over the graph, marking nodes to
	 * be made as we go down.
	 *
	 * We call Suff_FindDeps to find where a node is and to get some
	 * children for it if it has none and also has no commands. If the
	 * node is a leaf, we stick it on the toBeMade queue to be looked
	 * at in a minute, otherwise we add its children to our queue and
	 * go on about our business.
	 */
	while (!Lst_IsEmpty(&examine)) {
		GNode *gn = Lst_Dequeue(&examine);

		if (gn->flags.remake)
			/* We've looked at this one already */
			continue;
		gn->flags.remake = true;
		DEBUG2(MAKE, "Make_ExpandUse: examine %s%s\n",
		    gn->name, gn->cohort_num);

		if (gn->type & OP_DOUBLEDEP)
			Lst_PrependAll(&examine, &gn->cohorts);

		/*
		 * Apply any .USE rules before looking for implicit
		 * dependencies to make sure everything has commands that
		 * should.
		 *
		 * Make sure that the TARGET is set, so that we can make
		 * expansions.
		 */
		if (gn->type & OP_ARCHV) {
			char *eoa = strchr(gn->name, '(');
			char *eon = strchr(gn->name, ')');
			if (eoa == NULL || eon == NULL)
				continue;
			*eoa = '\0';
			*eon = '\0';
			Var_Set(gn, MEMBER, eoa + 1);
			Var_Set(gn, ARCHIVE, gn->name);
			*eoa = '(';
			*eon = ')';
		}

		Dir_UpdateMTime(gn, false);
		Var_Set(gn, TARGET, GNode_Path(gn));
		UnmarkChildren(gn);
		HandleUseNodes(gn);

		if (!(gn->type & OP_MADE))
			Suff_FindDeps(gn);
		else {
			PretendAllChildrenAreMade(gn);
			if (gn->unmade != 0) {
				printf(
				    "Warning: "
				    "%s%s still has %d unmade children\n",
				    gn->name, gn->cohort_num, gn->unmade);
			}
		}

		if (gn->unmade != 0)
			ExamineLater(&examine, &gn->children);
	}

	Lst_Done(&examine);
}

/* Make the .WAIT node depend on the previous children */
static void
add_wait_dependency(GNodeListNode *owln, GNode *wn)
{
	GNodeListNode *cln;
	GNode *cn;

	for (cln = owln; (cn = cln->datum) != wn; cln = cln->next) {
		DEBUG3(MAKE, ".WAIT: add dependency %s%s -> %s\n",
		    cn->name, cn->cohort_num, wn->name);

		/*
		 * XXX: This pattern should be factored out, it repeats often
		 */
		Lst_Append(&wn->children, cn);
		wn->unmade++;
		Lst_Append(&cn->parents, wn);
	}
}

/* Convert .WAIT nodes into dependencies. */
static void
Make_ProcessWait(GNodeList *targs)
{
	GNode *pgn;		/* 'parent' node we are examining */
	GNodeListNode *owln;	/* Previous .WAIT node */
	GNodeList examine;	/* List of targets to examine */

	/*
	 * We need all the nodes to have a common parent in order for the
	 * .WAIT and .ORDER scheduling to work.
	 * Perhaps this should be done earlier...
	 */

	pgn = GNode_New(".MAIN");
	pgn->flags.remake = true;
	pgn->type = OP_PHONY | OP_DEPENDS;
	/* Get it displayed in the diag dumps */
	Lst_Prepend(Targ_List(), pgn);

	{
		GNodeListNode *ln;
		for (ln = targs->first; ln != NULL; ln = ln->next) {
			GNode *cgn = ln->datum;

			Lst_Append(&pgn->children, cgn);
			Lst_Append(&cgn->parents, pgn);
			pgn->unmade++;
		}
	}

	/* Start building with the 'dummy' .MAIN' node */
	MakeBuildChild(pgn, NULL);

	Lst_Init(&examine);
	Lst_Append(&examine, pgn);

	while (!Lst_IsEmpty(&examine)) {
		GNodeListNode *ln;

		pgn = Lst_Dequeue(&examine);

		/* We only want to process each child-list once */
		if (pgn->flags.doneWait)
			continue;
		pgn->flags.doneWait = true;
		DEBUG1(MAKE, "Make_ProcessWait: examine %s\n", pgn->name);

		if (pgn->type & OP_DOUBLEDEP)
			Lst_PrependAll(&examine, &pgn->cohorts);

		owln = pgn->children.first;
		for (ln = pgn->children.first; ln != NULL; ln = ln->next) {
			GNode *cgn = ln->datum;
			if (cgn->type & OP_WAIT) {
				add_wait_dependency(owln, cgn);
				owln = ln;
			} else {
				Lst_Append(&examine, cgn);
			}
		}
	}

	Lst_Done(&examine);
}

/*
 * Initialize the nodes to remake and the list of nodes which are ready to
 * be made by doing a breadth-first traversal of the graph starting from the
 * nodes in the given list. Once this traversal is finished, all the 'leaves'
 * of the graph are in the toBeMade queue.
 *
 * Using this queue and the Job module, work back up the graph, calling on
 * MakeStartJobs to keep the job table as full as possible.
 *
 * Input:
 *	targs		the initial list of targets
 *
 * Results:
 *	True if work was done, false otherwise.
 *
 * Side Effects:
 *	The make field of all nodes involved in the creation of the given
 *	targets is set to 1. The toBeMade list is set to contain all the
 *	'leaves' of these subgraphs.
 */
bool
Make_Run(GNodeList *targs)
{
	int errors;		/* Number of errors the Job module reports */

	/* Start trying to make the current targets... */
	Lst_Init(&toBeMade);

	Make_ExpandUse(targs);
	Make_ProcessWait(targs);

	if (DEBUG(MAKE)) {
		debug_printf("#***# full graph\n");
		Targ_PrintGraph(1);
	}

	if (opts.query) {
		/*
		 * We wouldn't do any work unless we could start some jobs
		 * in the next loop... (we won't actually start any, of
		 * course, this is just to see if any of the targets was out
		 * of date)
		 */
		return MakeStartJobs();
	}
	/*
	 * Initialization. At the moment, no jobs are running and until some
	 * get started, nothing will happen since the remaining upward
	 * traversal of the graph is performed by the routines in job.c upon
	 * the finishing of a job. So we fill the Job table as much as we can
	 * before going into our loop.
	 */
	(void)MakeStartJobs();

	/*
	 * Main Loop: The idea here is that the ending of jobs will take
	 * care of the maintenance of data structures and the waiting for
	 * output will cause us to be idle most of the time while our
	 * children run as much as possible. Because the job table is kept
	 * as full as possible, the only time when it will be empty is when
	 * all the jobs which need running have been run, so that is the end
	 * condition of this loop. Note that the Job module will exit if
	 * there were any errors unless the keepgoing flag was given.
	 */
	while (!Lst_IsEmpty(&toBeMade) || jobTokensRunning > 0) {
		Job_CatchOutput();
		(void)MakeStartJobs();
	}

	errors = Job_Finish();

	/*
	 * Print the final status of each target. E.g. if it wasn't made
	 * because some inferior reported an error.
	 */
	DEBUG1(MAKE, "done: errors %d\n", errors);
	if (errors == 0) {
		MakePrintStatusList(targs, &errors);
		if (DEBUG(MAKE)) {
			debug_printf("done: errors %d\n", errors);
			if (errors > 0)
				Targ_PrintGraph(4);
		}
	}
	return errors > 0;
}