MFC r1.12 (HEAD):

[dragonfly.git] / usr.bin / make / make.c

/*-
 * Copyright (c) 1988, 1989, 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 * 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.
 *
 * @(#)make.c   8.1 (Berkeley) 6/6/93
 * $FreeBSD: src/usr.bin/make/make.c,v 1.33 2005/02/04 12:38:57 harti Exp $
 * $DragonFly: src/usr.bin/make/make.c,v 1.33 2005/09/24 07:27:26 okumoto Exp $
 */

/*
 * make.c
 *      The functions which perform the examination of targets and
 *      their suitability for creation
 *
 * Interface:
 *      Make_Run        Initialize things for the module and recreate
 *                      whatever needs recreating. Returns true if
 *                      work was (or would have been) done and false
 *                      otherwise.
 *
 *      Make_Update     Update all parents of a given child. Performs
 *                      various bookkeeping chores like the updating
 *                      of the cmtime field of the parent, filling
 *                      of the IMPSRC context variable, etc. It will
 *                      place the parent on the toBeMade queue if it should be.
 *
 *      Make_TimeStamp  Function to set the parent's cmtime field
 *                      based on a child's modification time.
 *
 *      Make_DoAllVar   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.
 *
 *      Make_OODate     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.
 */

#include <stdlib.h>

#include "arch.h"
#include "config.h"
#include "dir.h"
#include "globals.h"
#include "GNode.h"
#include "job.h"
#include "make.h"
#include "parse.h"
#include "suff.h"
#include "targ.h"
#include "util.h"
#include "var.h"

/* 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 Lst toBeMade = Lst_Initializer(toBeMade);

/*
 * Number of nodes to be processed. If this is non-zero when Job_Empty()
 * returns true, there's a cycle in the graph.
 */
static int numNodes;

/**
 * Make_TimeStamp
 *      Set the cmtime field of a parent node based on the mtime stamp in its
 *      child. Called from MakeOODate via LST_FOREACH.
 *
 * Results:
 *      Always returns 0.
 *
 * Side Effects:
 *      The cmtime of the parent node will be changed if the mtime
 *      field of the child is greater than it.
 */
int
Make_TimeStamp(GNode *pgn, GNode *cgn)
{

        if (cgn->mtime > pgn->cmtime) {
                pgn->cmtime = cgn->mtime;
        }
        return (0);
}

/**
 * Make_OODate
 *      See if a given 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.
 *
 * Results:
 *      true if the node is out of date. false otherwise.
 *
 * Side Effects:
 *      The mtime field of the node and the cmtime field of its parents
 *      will/may be changed.
 */
bool
Make_OODate(GNode *gn)
{
        bool    oodate;
        LstNode *ln;

        /*
         * 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_EXEC)) == 0) {
                Dir_MTime(gn);
                if (gn->mtime != 0) {
                        DEBUGF(MAKE, ("modified %s...",
                            Targ_FmtTime(gn->mtime)));
                } else {
                        DEBUGF(MAKE, ("non-existent..."));
                }
        }

        /*
         * 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 type OP_NOP)
         *      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) {
                /*
                 * If the node is a USE node it is *never* out of date
                 * no matter *what*.
                 */
                DEBUGF(MAKE, (".USE node..."));
                oodate = false;

        } else if (gn->type & OP_LIB) {
                DEBUGF(MAKE, ("library..."));

                /*
                 * always out of date if no children and :: target
                 */
                oodate = Arch_LibOODate(gn) ||
                    ((gn->cmtime == 0) && (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.
                 */
                DEBUGF(MAKE, (".JOIN node..."));
                oodate = gn->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 (gn->type & OP_FORCE) {
                        DEBUGF(MAKE, ("! operator..."));
                } else if (gn->type & OP_PHONY) {
                        DEBUGF(MAKE, (".PHONY node..."));
                } else {
                        DEBUGF(MAKE, (".EXEC node..."));
                }
                oodate = true;

        } else if ((gn->mtime < gn->cmtime) ||
            ((gn->cmtime == 0) &&
            ((gn->mtime==0) || (gn->type & OP_DOUBLEDEP)))) {
                /*
                 * A node whose modification time is less than that of its
                 * youngest child or that has no children (cmtime == 0) and
                 * either doesn't exist (mtime == 0) or was the object of a
                 * :: operator is out-of-date. Why? Because that's the way
                 * Make does it.
                 */
                if (gn->mtime < gn->cmtime) {
                        DEBUGF(MAKE, ("modified before source..."));
                } else if (gn->mtime == 0) {
                        DEBUGF(MAKE, ("non-existent and no sources..."));
                } else {
                        DEBUGF(MAKE, (":: operator and no sources..."));
                }
                oodate = true;
        } else
                oodate = false;

        /*
         * 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 aren't of type OP_NOP,
         * have their mtime stay below their children's mtime to keep parents
         * from thinking they're out-of-date.
         */
        if (!oodate) {
                LST_FOREACH(ln, &gn->parents)
                        if (Make_TimeStamp(Lst_Datum(ln), gn))
                                break;
        }

        return (oodate);
}

/**
 * Make_HandleUse
 *      Function called by Make_Run and SuffApplyTransform on the downward
 *      pass to handle .USE and transformation nodes. A callback function
 *      for LST_FOREACH, it implements the .USE and transformation
 *      functionality by copying the node's commands, type flags
 *      and children to the parent node. Should be called before the
 *      children are enqueued to be looked at.
 *
 *      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.
 *
 * Results:
 *      returns 0.
 *
 * Side Effects:
 *      Children and commands may be added to the parent and the parent's
 *      type may be changed.
 */
int
Make_HandleUse(GNode *cgn, GNode *pgn)
{
        GNode   *gn;    /* A child of the .USE node */
        LstNode *ln;    /* An element in the children list */

        if (cgn->type & (OP_USE | OP_TRANSFORM)) {
                if ((cgn->type & OP_USE) || Lst_IsEmpty(&pgn->commands)) {
                        /*
                         * .USE or transformation and target has no commands --
                         * append the child's commands to the parent.
                         */
                        Lst_Concat(&pgn->commands, &cgn->commands, LST_CONCNEW);
                }

                for (ln = Lst_First(&cgn->children); ln != NULL;
                    ln = Lst_Succ(ln)) {
                        gn = Lst_Datum(ln);

                        if (Lst_Member(&pgn->children, gn) == NULL) {
                                Lst_AtEnd(&pgn->children, gn);
                                Lst_AtEnd(&gn->parents, pgn);
                                pgn->unmade += 1;
                        }
                }

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

                /*
                 * 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...
                 */
                if (cgn->type & OP_USE) {
                        pgn->unmade--;
                }
        }
        return (0);
}

/**
 * Make_Update
 *      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.
 *
 * Results:
 *      Always returns 0
 *
 * Side Effects:
 *      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 childMade field will be set true
 *      and its cmtime set to now.
 *
 *      If the child wasn't made, the cmtime 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)
{
        GNode           *pgn;   /* the parent node */
        const char      *cname; /* the child's name */
        LstNode         *ln;    /* Element in parents and iParents lists */
        const char      *cpref;

        cname = Var_Value(TARGET, cgn);

        /*
         * 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) {
#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
                 * cgn->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(&cgn->commands) ||
                    Lst_IsEmpty(&cgn->children)) {
                        cgn->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_MTime 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 (noExecute || (cgn->type & OP_SAVE_CMDS) ||
                    Dir_MTime(cgn) == 0) {
                        cgn->mtime = now;
                }
                DEBUGF(MAKE, ("update time: %s\n", Targ_FmtTime(cgn->mtime)));
#endif
        }

        for (ln = Lst_First(&cgn->parents); ln != NULL; ln = Lst_Succ(ln)) {
                pgn = Lst_Datum(ln);
                if (pgn->make) {
                        pgn->unmade -= 1;

                        if (!(cgn->type & (OP_EXEC | OP_USE))) {
                                if (cgn->made == MADE) {
                                        pgn->childMade = true;
                                        if (pgn->cmtime < cgn->mtime) {
                                                pgn->cmtime = cgn->mtime;
                                        }
                                } else {
                                        Make_TimeStamp(pgn, cgn);
                                }
                        }
                        if (pgn->unmade == 0) {
                                /*
                                 * Queue the node up -- any unmade predecessors
                                 * will be dealt with in MakeStartJobs.
                                 */
                                Lst_EnQueue(&toBeMade, pgn);
                        } else if (pgn->unmade < 0) {
                                Error("Graph cycles through %s", pgn->name);
                        }
                }
        }

        /*
         * Deal with successor nodes. If any is marked for making and has an
         * unmade count of 0, has not been made and isn't in the examination
         * queue, it means we need to place it in the queue as it restrained
         * itself before.
         */
        for (ln = Lst_First(&cgn->successors); ln != NULL; ln = Lst_Succ(ln)) {
                GNode   *succ = Lst_Datum(ln);

                if (succ->make && succ->unmade == 0 && succ->made == UNMADE &&
                    Lst_Member(&toBeMade, succ) == NULL) {
                        Lst_EnQueue(&toBeMade, succ);
                }
        }

        /*
         * Set the .PREFIX and .IMPSRC variables for all the implied parents
         * of this node.
         */
        cpref = Var_Value(PREFIX, cgn);
        for (ln = Lst_First(&cgn->iParents); ln != NULL; ln = Lst_Succ(ln)) {
                pgn = Lst_Datum(ln);
                if (pgn->make) {
                        Var_Set(IMPSRC, cname, pgn);
                        Var_Set(PREFIX, cpref, pgn);
                }
        }
}

/**
 * Make_DoAllVar
 *      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.
 *
 * Side Effects:
 *      The ALLSRC and OODATE variables of the given node is filled in.
 *      If the node is a .JOIN node, its TARGET variable will be set to
 *      match its ALLSRC variable.
 */
void
Make_DoAllVar(GNode *gn)
{
        LstNode *ln;

        LST_FOREACH(ln, &gn->children) {
                /*
                 * Add the child's name to the ALLSRC and OODATE variables of
                 * the given node. The child is added 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...
                 *
                 * 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...).
                 */
                GNode   *cgn = Lst_Datum(ln);

                if ((cgn->type & (OP_EXEC | OP_USE | OP_INVISIBLE)) == 0) {
                        const char      *child;

                        if (OP_NOP(cgn->type)) {
                                /*
                                 * this node is only source; use the specific
                                 * pathname for it
                                 */
                                child = cgn->path ? cgn->path : cgn->name;
                        } else {
                                child = Var_Value(TARGET, cgn);
                        }

                        Var_Append(ALLSRC, child, gn);
                        if (gn->type & OP_JOIN) {
                                if (cgn->made == MADE) {
                                        Var_Append(OODATE, child, gn);
                                }
                        } else if (gn->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 kid, the parent is
                                 * likely to have a modification time later than
                                 * that of the kid 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(OODATE, child, gn);
                        }
                }
        }

        if (Var_Value(OODATE, gn) == NULL) {
                Var_Set(OODATE, "", gn);
        }
        if (Var_Value(ALLSRC, gn) == NULL) {
                Var_Set(ALLSRC, "", gn);
        }

        if (gn->type & OP_JOIN) {
                Var_Set(TARGET, Var_Value(ALLSRC, gn), gn);
        }
}

/**
 * MakeStartJobs
 *      Start as many jobs as possible.
 *
 * Results:
 *      If the query flag was given to pmake, no job will be started,
 *      but as soon as an out-of-date target is found, this function
 *      returns 1. At all other times, this function returns 0.
 *
 * Side Effects:
 *      Nodes are removed from the toBeMade queue and job table slots
 *      are filled.
 */
static int
MakeStartJobs(bool queryFlag)
{
        GNode   *gn;

        while (!Lst_IsEmpty(&toBeMade) && !Job_Full()) {
                gn = Lst_DeQueue(&toBeMade);
                DEBUGF(MAKE, ("Examining %s...", gn->name));

                /*
                 * Make sure any and all predecessors that are going to be made,
                 * have been.
                 */
                if (!Lst_IsEmpty(&gn->preds)) {
                        LstNode *ln;

                        for (ln = Lst_First(&gn->preds); ln != NULL;
                            ln = Lst_Succ(ln)){
                                GNode   *pgn = Lst_Datum(ln);

                                if (pgn->make && pgn->made == UNMADE) {
                                        DEBUGF(MAKE, ("predecessor %s not made "
                                            "yet.\n", pgn->name));
                                        break;
                                }
                        }
                        /*
                         * If ln isn't NULL, there's a predecessor as yet
                         * unmade, so we just drop this node on the floor.
                         * When the node in question has been made, it will
                         * notice this node as being ready to make but as yet
                         * unmade and will place the node on the queue.
                         */
                        if (ln != NULL) {
                                continue;
                        }
                }

                numNodes--;
                if (Make_OODate(gn)) {
                        DEBUGF(MAKE, ("out-of-date\n"));
                        if (queryFlag) {
                                return (1);     /* target was not up-to-date */
                        }
                        Make_DoAllVar(gn);
                        Job_Make(gn);
                } else {
                        DEBUGF(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 context variables so
                                 * references to it get the correct value for
                                 * .TARGET when building up the context
                                 * variables of its parent(s)...
                                 */
                                Make_DoAllVar(gn);
                        }

                        Make_Update(gn);
                }
        }
        return (0);     /* Successful completion */
}

/**
 * MakePrintStatus
 *      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.
 *      Callback function for Make_Run via LST_FOREACH.  If gn->unmade is
 *      nonzero and that is meant to imply a cycle in the graph, then
 *      cycle is true.
 *
 * Side Effects:
 *      A message may be printed.
 */
static void
MakePrintStatus(GNode *gn, bool cycle)
{
        LstNode *ln;

        if (gn->made == UPTODATE) {
                printf("`%s' is up to date.\n", gn->name);

        } else if (gn->unmade != 0) {
                if (cycle) {
                        /*
                         * If printing cycles and came to one that has unmade
                         * children, print out the cycle by recursing on its
                         * children. Note a cycle like:
                         *      a : b
                         *      b : c
                         *      c : b
                         * will cause this to erroneously complain about a
                         * being in the cycle, but this is a good approximation.
                         */
                        if (gn->made == CYCLE) {
                                Error("Graph cycles through `%s'", gn->name);
                                gn->made = ENDCYCLE;
                                LST_FOREACH(ln, &gn->children)
                                        MakePrintStatus(Lst_Datum(ln), true);
                                gn->made = UNMADE;
                        } else if (gn->made != ENDCYCLE) {
                                gn->made = CYCLE;
                                LST_FOREACH(ln, &gn->children)
                                        MakePrintStatus(Lst_Datum(ln), true);
                        }
                } else {
                        printf("`%s' not remade because of errors.\n",
                            gn->name);
                }
        }
}

/**
 * Make_Run
 *      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.
 *
 * Results:
 *      Exit status of make.
 *
 * 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(Lst *targs, bool queryFlag)
{
        GNode   *gn;            /* a temporary pointer */
        GNode   *cgn;
        Lst     examine;        /* List of targets to examine */
        int     errors;         /* Number of errors the Job module reports */
        LstNode *ln;

        /*
         * Initialize job module before traversing
         * the graph, now that any .BEGIN and .END
         * targets have been read.  This is done
         * only if the -q flag wasn't given (to
         * prevent the .BEGIN from being executed
         * should it exist).
         */
        if (!queryFlag) {
                Job_Init(jobLimit);
                jobsRunning = true;
        }

        Lst_Init(&examine);
        Lst_Duplicate(&examine, targs, NOCOPY);
        numNodes = 0;

        /*
         * 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)) {
                gn = Lst_DeQueue(&examine);

                if (!gn->make) {
                        gn->make = true;
                        numNodes++;

                        /*
                         * Apply any .USE rules before looking for implicit
                         * dependencies to make sure everything has commands
                         * that should...
                         */
                        LST_FOREACH(ln, &gn->children)
                                if (Make_HandleUse(Lst_Datum(ln), gn))
                                        break;

                        Suff_FindDeps(gn);

                        if (gn->unmade != 0) {
                                LST_FOREACH(ln, &gn->children) {
                                        cgn = Lst_Datum(ln);
                                        if (!cgn->make && !(cgn->type & OP_USE))
                                                Lst_EnQueue(&examine, cgn);
                                }
                        } else {
                                Lst_EnQueue(&toBeMade, gn);
                        }
                }
        }

        if (queryFlag) {
                /*
                 * 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(true);
        }

        /*
         * 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.
         */
        MakeStartJobs(false);

        /*
         * 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 (!Job_Empty()) {
                Job_CatchOutput(!Lst_IsEmpty(&toBeMade));
                Job_CatchChildren(!usePipes);
                MakeStartJobs(false);
        }

        errors = Job_Finish();

        /*
         * Print the final status of each target. E.g. if it wasn't made
         * because some inferior reported an error.
         */
        errors = ((errors == 0) && (numNodes != 0));
        LST_FOREACH(ln, targs)
                MakePrintStatus(Lst_Datum(ln), errors);

        return 0;       /* Successful completion */
}