/*
 * Copyright 1993, 1995 Christopher Seiwald.
 *
 * This file is part of Jam - see jam.c for Copyright information.
 */

/*  This file is ALSO:
 *  Copyright 2001-2004 David Abrahams.
 *  Distributed under the Boost Software License, Version 1.0.
 *  (See accompanying file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
 */

/*
 * make.c - bring a target up to date, once rules are in place
 *
 * This modules controls the execution of rules to bring a target and
 * its dependencies up to date.  It is invoked after the targets, rules,
 * et. al. described in rules.h are created by the interpreting of the
 * jam files.
 *
 * This file contains the main make() entry point and the first pass
 * make0().  The second pass, make1(), which actually does the command
 * execution, is in make1.c.
 *
 * External routines:
 *	make() - make a target, given its name
 *
 * Internal routines:
 * 	make0() - bind and scan everything to make a TARGET
 * 	make0sort() - reorder TARGETS chain by their time (newest to oldest)
 *
 * 12/26/93 (seiwald) - allow NOTIME targets to be expanded via $(<), $(>)
 * 01/04/94 (seiwald) - print all targets, bounded, when tracing commands
 * 04/08/94 (seiwald) - progress report now reflects only targets with actions
 * 04/11/94 (seiwald) - Combined deps & headers into deps[2] in TARGET.
 * 12/20/94 (seiwald) - NOTIME renamed NOTFILE.
 * 12/20/94 (seiwald) - make0() headers after determining fate of target, so 
 *			that headers aren't seen as dependents on themselves.
 * 01/19/95 (seiwald) - distinguish between CANTFIND/CANTMAKE targets.
 * 02/02/95 (seiwald) - propagate leaf source time for new LEAVES rule.
 * 02/14/95 (seiwald) - NOUPDATE rule means don't update existing target.
 * 08/22/95 (seiwald) - NOUPDATE targets immune to anyhow (-a) flag.
 * 09/06/00 (seiwald) - NOCARE affects targets with sources/actions.
 * 03/02/01 (seiwald) - reverse NOCARE change.
 * 03/14/02 (seiwald) - TEMPORARY targets no longer take on parents age
 * 03/16/02 (seiwald) - support for -g (reorder builds by source time)
 */

# include "jam.h"

# include "lists.h"
# include "parse.h"
# include "variable.h"
# include "rules.h"

#ifdef OPT_HEADER_CACHE_EXT
# include "hcache.h"
#endif

# include "search.h"
# include "newstr.h"
# include "make.h"
# include "headers.h"
# include "command.h"
# include <assert.h>

# ifndef max
# define max( a,b ) ((a)>(b)?(a):(b))
# endif

static TARGETS *make0sort( TARGETS *c );

#ifdef OPT_GRAPH_DEBUG_EXT
static void dependGraphOutput( TARGET *t, int depth );
#endif

static const char *target_fate[] = 
{
	"init",		/* T_FATE_INIT */
	"making", 	/* T_FATE_MAKING */
	"stable", 	/* T_FATE_STABLE */
	"newer",	/* T_FATE_NEWER */
	"temp", 	/* T_FATE_ISTMP */
	"touched", 	/* T_FATE_TOUCHED */
	"rebuild", 	/* T_FATE_REBUILD */
	"missing", 	/* T_FATE_MISSING */
	"needtmp", 	/* T_FATE_NEEDTMP */
	"old", 		/* T_FATE_OUTDATED */
	"update", 	/* T_FATE_UPDATE */
	"nofind", 	/* T_FATE_CANTFIND */
	"nomake" 	/* T_FATE_CANTMAKE */
} ;

static const char *target_bind[] = 
{
	"unbound",
	"missing",
	"parents",
	"exists",
} ;

# define spaces(x) ( "                    " + ( x > 20 ? 0 : 20-x ) )

/*
 * make() - make a target, given its name
 */

int
make( 
	int		n_targets,
	const char	**targets,
	int		anyhow )
{
	int i;
	COUNTS counts[1];
	int status = 0;		/* 1 if anything fails */

#ifdef OPT_HEADER_CACHE_EXT
	hcache_init();
#endif

	memset( (char *)counts, 0, sizeof( *counts ) );

    /* First bind all targets with LOCATE_TARGET setting. This is
       needed to correctly handle dependencies to generated headers.       
    */
    bind_explicitly_located_targets();

    { PROFILE_ENTER(MAKE_MAKE0);
	for( i = 0; i < n_targets; i++ )
	{
	    TARGET *t = bindtarget( targets[i] );

	    make0( t, 0, 0, counts, anyhow );
	}
    PROFILE_EXIT(MAKE_MAKE0); }
        
#ifdef OPT_GRAPH_DEBUG_EXT
	if( DEBUG_GRAPH )
	{
	    for( i = 0; i < n_targets; i++ )
	    {
		TARGET *t = bindtarget( targets[i] );
		dependGraphOutput( t, 0 );
	    }
	}
#endif

	if( DEBUG_MAKE )
	{
	    if( counts->targets )
		printf( "...found %d target%s...\n", counts->targets,
		        counts->targets > 1 ? "s" : "" );
	    if( counts->temp )
		printf( "...using %d temp target%s...\n", counts->temp,
		        counts->temp > 1 ? "s" : "" );
	    if( counts->updating )
		printf( "...updating %d target%s...\n", counts->updating,
		        counts->updating > 1 ? "s" : "" );
	    if( counts->cantfind )
		printf( "...can't find %d target%s...\n", counts->cantfind,
		        counts->cantfind > 1 ? "s" : "" );
	    if( counts->cantmake )
		printf( "...can't make %d target%s...\n", counts->cantmake,
		        counts->cantmake > 1 ? "s" : "" );
	}

#ifdef OPT_HEADER_CACHE_EXT
	hcache_done();
#endif

	status = counts->cantfind || counts->cantmake;

    { PROFILE_ENTER(MAKE_MAKE1);
	for( i = 0; i < n_targets; i++ )
	    status |= make1( bindtarget( targets[i] ) );
    PROFILE_EXIT(MAKE_MAKE1); }

	return status;
}

/* Force any dependents of t that have already at least begun being
 * visited by make0 to be updated.
 */
static void update_dependents(TARGET* t)
{
    TARGETS *q;
    
    for (q = t->dependents; q; q = q->next)
    {
        TARGET* p = q->target;
        char fate0 = p->fate;

        /* If we've already at least begun visiting it and
         * we're not already rebuilding it for other reasons
         */
        if (fate0 != T_FATE_INIT && fate0 < T_FATE_BUILD)
        {
            p->fate = T_FATE_UPDATE;
            
            if (DEBUG_FATE)
            {
                printf( "fate change  %s from %s to %s (as dependent of %s)\n",
                        p->name, target_fate[fate0], target_fate[p->fate], t->name);
            }
    
            /* If we're done visiting it, go back and make sure its
             * dependents get rebuilt.
             */
            if (fate0 > T_FATE_MAKING)
                update_dependents(p);
        }
    }
}

/* Make sure that all of t's rebuilds get rebuilt */
static void force_rebuilds(TARGET* t)
{
    TARGETS* d;
    for (d = t->rebuilds; d; d = d->next)
    {
        TARGET* r = d->target;

        /* If it's not already being rebuilt for other reasons */
        if (r->fate < T_FATE_BUILD)
        {
            if (DEBUG_FATE)
                printf( "fate change  %s from %s to %s (by rebuild)\n",
                        r->name, target_fate[r->fate], target_fate[T_FATE_REBUILD]);
            
            /* Force rebuild it */
            r->fate = T_FATE_REBUILD;

            /* And make sure its dependents are updated too */
            update_dependents(r);
        }
    }
}
/*
 * make0() - bind and scan everything to make a TARGET
 *
 * Make0() recursively binds a target, searches for #included headers,
 * calls itself on those headers, and calls itself on any dependents.
 */

void
make0( 
	TARGET	*t,
	TARGET  *p,		/* parent */
	int	depth,		/* for display purposes */
	COUNTS	*counts,	/* for reporting */
	int	anyhow )	/* forcibly touch all (real) targets */
{
	TARGETS	*c, *d, *incs;
	TARGET 	*ptime = t;
	time_t	last, leaf, hlast;
	int	fate;
	const char *flag = "";
	SETTINGS *s;

#ifdef OPT_GRAPH_DEBUG_EXT
	int	savedFate, oldTimeStamp;
#endif

	if( DEBUG_MAKEPROG )
	    printf( "make\t--\t%s%s\n", spaces( depth ), t->name );

	/* 
	 * Step 1: initialize
	 */

	if( DEBUG_MAKEPROG )
	    printf( "make\t--\t%s%s\n", spaces( depth ), t->name );

	t->fate = T_FATE_MAKING;

	/*
	 * Step 2: under the influence of "on target" variables,
	 * bind the target and search for headers.
	 */

	/* Step 2a: set "on target" variables. */

	s = copysettings( t->settings );
	pushsettings( s );

	/* Step 2b: find and timestamp the target file (if it's a file). */

	if( t->binding == T_BIND_UNBOUND && !( t->flags & T_FLAG_NOTFILE ) )
	{
            char* another_target;
            t->boundname = search( t->name, &t->time, &another_target );
            /* If it was detected that this target refers to an already
               existing and bound one, we add include dependency, so that
               every target which depends on us will depend on that other 
               target. */
            if( another_target )
            {
                TARGET* includes;
                if (!t->includes) {
                    t->includes = copytarget(t);
                    t->includes->original_target = t;
                }
                includes = t->includes;
                includes->depends = targetlist( includes->depends,
                                              list_new( L0, another_target ) );
            }
        
	    t->binding = t->time ? T_BIND_EXISTS : T_BIND_MISSING;
	}

	/* INTERNAL, NOTFILE header nodes have the time of their parents */

	if( p && t->flags & T_FLAG_INTERNAL )
	    ptime = p;

	/* If temp file doesn't exist but parent does, use parent */
	if( p && t->flags & T_FLAG_TEMP && 
	    t->binding == T_BIND_MISSING && 
	    p->binding != T_BIND_MISSING )
    {
	    t->binding = T_BIND_PARENTS;
	    ptime = p;
    }

#ifdef OPT_SEMAPHORE
	{
	    LIST *var = var_get( "JAM_SEMAPHORE" );
	    if( var )
	    {
		TARGET *semaphore = bindtarget( var->string );

		semaphore->progress = T_MAKE_SEMAPHORE;
		t->semaphore = semaphore;
	    }
	}
#endif

	/* Step 2c: If its a file, search for headers. */

	if( t->binding == T_BIND_EXISTS )
	    headers( t );

	/* Step 2d: reset "on target" variables */

	popsettings( s );
	freesettings( s );

	/* 
	 * Pause for a little progress reporting 
	 */

	if( DEBUG_BIND )

	{
	    if( strcmp( t->name, t->boundname ) )
	    {
		printf( "bind\t--\t%s%s: %s\n",
			spaces( depth ), t->name, t->boundname );
	    }

	    switch( t->binding )
	    {
	    case T_BIND_UNBOUND:
	    case T_BIND_MISSING:
	    case T_BIND_PARENTS:
		printf( "time\t--\t%s%s: %s\n",
			spaces( depth ), t->name, target_bind[ t->binding ] );
		break;

	    case T_BIND_EXISTS:
		printf( "time\t--\t%s%s: %s",
			spaces( depth ), t->name, ctime( &t->time ) );
		break;
	    }
	}

	/* 
	 * Step 3: recursively make0() dependents & headers
	 */

	/* Step 3a: recursively make0() dependents */

	for( c = t->depends; c; c = c->next )
	{
	    int internal = t->flags & T_FLAG_INTERNAL;
/* Seems like it's not relevant for us....
	    if( DEBUG_DEPENDS )
		printf( "%s \"%s\" : \"%s\" ;\n", 
		    internal ? "Includes" : "Depends",
		    t->name, c->target->name );
*/

	    /* Warn about circular deps, except for includes, */
	    /* which include each other alot. */

	    if( c->target->fate == T_FATE_INIT )
		make0( c->target, ptime, depth + 1, counts, anyhow );
	    else if( c->target->fate == T_FATE_MAKING && !internal )
		printf( "warning: %s depends on itself\n", c->target->name );
	}

	/* Step 3b: recursively make0() internal includes node */

	if( t->includes )
	    make0( t->includes, p, depth + 1, counts, anyhow );

	/* Step 3c: add dependents' includes to our direct dependencies */

	incs = 0;

	for( c = t->depends; c; c = c->next )
	    if( c->target->includes )
		incs = targetentry( incs, c->target->includes );

	t->depends = targetchain( t->depends, incs );

	/*
	 * Step 4: compute time & fate 
	 */

	/* Step 4a: pick up dependents' time and fate */


	last = 0;
	leaf = 0;
    fate = T_FATE_STABLE;

	for( c = t->depends; c; c = c->next )
	{
	    /* If LEAVES has been applied, we only heed the timestamps of */
	    /* the leaf source nodes. */

	    leaf = max( leaf, c->target->leaf );

	    if( t->flags & T_FLAG_LEAVES )
	    {
		last = leaf;
		continue;
	    }

	    last = max( last, c->target->time );
	    fate = max( fate, c->target->fate );

#ifdef OPT_GRAPH_DEBUG_EXT
	    if( DEBUG_FATE )
		if( fate < c->target->fate )
		    printf( "fate change  %s from %s to %s by dependency %s\n",
			    t->name,
			    target_fate[fate], target_fate[c->target->fate],
			    c->target->name);
#endif

	}

	/* Step 4b: pick up included headers time */

	/* 
	 * If a header is newer than a temp source that includes it, 
	 * the temp source will need building.   
	 */

	hlast = t->includes ? t->includes->time : 0;

	/* Step 4c: handle NOUPDATE oddity */

	/*
	 * If a NOUPDATE file exists, make dependents eternally old.
	 * Don't inherit our fate from our dependents.  Decide fate
	 * based only upon other flags and our binding (done later).
	 */

	if( t->flags & T_FLAG_NOUPDATE )
	{
#ifdef OPT_GRAPH_DEBUG_EXT
	    if( DEBUG_FATE )
		if( fate != T_FATE_STABLE )
		    printf( "fate change  %s back to stable, NOUPDATE.\n",
			   t->name);
#endif

	    last = 0;
	    t->time = 0;


	    /*
	     * Don't inherit our fate from our dependents.  Decide fate
	     * based only upon other flags and our binding (done later).
	     */

	    fate = T_FATE_STABLE;
	}

	/* Step 4d: determine fate: rebuild target or what? */

	/* 
	    In English:
		If can't find or make child, can't make target.
		If children changed, make target.
		If target missing, make it.
		If children newer, make target.
		If temp's children newer than parent, make temp.
		If temp's headers newer than parent, make temp.
		If deliberately touched, make it.
		If up-to-date temp file present, use it.
		If target newer than non-notfile parent, mark target newer.
		Otherwise, stable!

		Note this block runs from least to most stable:
		as we make it further down the list, the target's
		fate is getting stabler.
	*/

#ifdef OPT_GRAPH_DEBUG_EXT
	savedFate = fate;
	oldTimeStamp = 0;
#endif

	if( fate >= T_FATE_BROKEN )
	{
	    fate = T_FATE_CANTMAKE;
	}
	else if( fate >= T_FATE_SPOIL )
	{
	    fate = T_FATE_UPDATE;
	}
	else if( t->binding == T_BIND_MISSING )
	{
	    fate = T_FATE_MISSING;
	}
	else if( t->binding == T_BIND_EXISTS && last > t->time )
	{
#ifdef OPT_GRAPH_DEBUG_EXT
	    oldTimeStamp = 1;
#endif
	    fate = T_FATE_OUTDATED;
	}
	else if( t->binding == T_BIND_PARENTS && last > p->time )
	{
#ifdef OPT_GRAPH_DEBUG_EXT
	    oldTimeStamp = 1;
#endif
	    fate = T_FATE_NEEDTMP;
	}
	else if( t->binding == T_BIND_PARENTS && hlast > p->time )
	{
	    fate = T_FATE_NEEDTMP;
	}
	else if( t->flags & T_FLAG_TOUCHED )
	{
	    fate = T_FATE_TOUCHED;
	}
	else if( anyhow && !( t->flags & T_FLAG_NOUPDATE ) )
	{
	    fate = T_FATE_TOUCHED;
	}
	else if( t->binding == T_BIND_EXISTS && t->flags & T_FLAG_TEMP )
	{
	    fate = T_FATE_ISTMP;
	}
	else if( t->binding == T_BIND_EXISTS && p && 
		 p->binding != T_BIND_UNBOUND && t->time > p->time )
	{
#ifdef OPT_GRAPH_DEBUG_EXT
	    oldTimeStamp = 1;
#endif
	    fate = T_FATE_NEWER;
	}
	else
	{
	    fate = T_FATE_STABLE;
	}
#ifdef OPT_GRAPH_DEBUG_EXT
	if( DEBUG_FATE && fate != savedFate )
	    if( savedFate == T_FATE_STABLE )
		printf( "fate change  %s set to %s%s\n",
		       t->name, target_fate[fate],
		       oldTimeStamp ? " (by timestamp)" : "" );
	    else
		printf( "fate change  %s from %s to %s%s\n",
		       t->name, target_fate[savedFate], target_fate[fate],
		       oldTimeStamp ? " (by timestamp)" : "" );
#endif

	/* Step 4e: handle missing files */
	/* If it's missing and there are no actions to create it, boom. */
	/* If we can't make a target we don't care about, 'sokay */
	/* We could insist that there are updating actions for all missing */
	/* files, but if they have dependents we just pretend it's NOTFILE. */

	if( fate == T_FATE_MISSING && !t->actions && !t->depends )
	{
	    if( t->flags & T_FLAG_NOCARE )
	    {
#ifdef OPT_GRAPH_DEBUG_EXT
		if( DEBUG_FATE )
		    printf( "fate change  %s to STABLE from %s, "
			    "no actions, no dependents and don't care\n",
			    t->name, target_fate[fate]);
#endif
		fate = T_FATE_STABLE;
	    }
	    else
	    {
		printf( "don't know how to make %s\n", t->name );

		fate = T_FATE_CANTFIND;
	    }
	}

	/* Step 4f: propagate dependents' time & fate. */
	/* Set leaf time to be our time only if this is a leaf. */

	t->time = max( t->time, last );
	t->leaf = leaf ? leaf : t->time ;
    /* This target's fate may have been updated by virtue of following
     * some target's rebuilds list, so only allow it to be increased
     * to the fate we've calculated.  Otherwise, grab its new fate.
     */
    if (fate > t->fate)
        t->fate = fate;
    else
        fate = t->fate;

    /* Step 4g: if this target needs to be built, force rebuild
     * everything in this target's rebuilds list */
    if (fate >= T_FATE_BUILD && fate < T_FATE_BROKEN)
        force_rebuilds(t);
	/* 
	 * Step 5: sort dependents by their update time. 
	 */

	if( globs.newestfirst )
	    t->depends = make0sort( t->depends );

	/* 
	 * Step 6: a little harmless tabulating for tracing purposes 
	 */

	/* Don't count or report interal includes nodes. */

	if( t->flags & T_FLAG_INTERNAL )
	    return;

    if (counts) {
#ifdef OPT_IMPROVED_PATIENCE_EXT
        ++counts->targets;
#else	
        if( !( ++counts->targets % 1000 ) && DEBUG_MAKE )
            printf( "...patience...\n" );
#endif

        if( fate == T_FATE_ISTMP )
            counts->temp++;
        else if( fate == T_FATE_CANTFIND )
            counts->cantfind++;
        else if( fate == T_FATE_CANTMAKE && t->actions )
            counts->cantmake++;
        else if( fate >= T_FATE_BUILD && fate < T_FATE_BROKEN && t->actions )
            counts->updating++;
    }

	if( !( t->flags & T_FLAG_NOTFILE ) && fate >= T_FATE_SPOIL )
	    flag = "+";
	else if( t->binding == T_BIND_EXISTS && p && t->time > p->time )
	    flag = "*";

	if( DEBUG_MAKEPROG )
	    printf( "made%s\t%s\t%s%s\n", 
		flag, target_fate[ t->fate ], 
		spaces( depth ), t->name );

/* We don't have DEBUG_CAUSES. 
	if( DEBUG_CAUSES && 
	    t->fate >= T_FATE_NEWER && 
	    t->fate <= T_FATE_MISSING )
		printf( "%s %s\n", target_fate[ t->fate ], t->name );
*/
}

#ifdef OPT_GRAPH_DEBUG_EXT

static const char* target_name( TARGET* t )
{
    static char buf[1000];
    if (t->flags & T_FLAG_INTERNAL) {
        sprintf(buf, "%s (internal node)", t->name);
        return buf;
    } else {
        return t->name;
    }
}

/*
 * dependGraphOutput() - output the DG after make0 has run
 */

static void
dependGraphOutput( TARGET *t, int depth )
{
    TARGETS	*c;

    if (   (t->flags & T_FLAG_VISITED) != 0
	|| !t->name
	|| !t->boundname)
	return;

    t->flags |= T_FLAG_VISITED;

    switch (t->fate)
    {
      case T_FATE_TOUCHED:
      case T_FATE_MISSING:
      case T_FATE_OUTDATED:
      case T_FATE_UPDATE:
	printf( "->%s%2d Name: %s\n", spaces(depth), depth, target_name(t) );
	break;
      default:
	printf( "  %s%2d Name: %s\n", spaces(depth), depth, target_name(t) );
	break;
    }

    if( strcmp (t->name, t->boundname) )
    {
	printf( "  %s    Loc: %s\n", spaces(depth), t->boundname );
    }

    switch( t->fate )
    {
      case T_FATE_STABLE:
	printf( "  %s       : Stable\n", spaces(depth) );
	break;
      case T_FATE_NEWER:
	printf( "  %s       : Newer\n", spaces(depth) );
	break;
      case T_FATE_ISTMP:
	printf( "  %s       : Up to date temp file\n", spaces(depth) );
      case T_FATE_NEEDTMP:
	printf( "  %s       : Temporary file, to be updated\n", spaces(depth) );
	break;
      case T_FATE_TOUCHED:
        printf( "  %s       : Been touched, updating it\n", spaces(depth) );
	break;
      case T_FATE_MISSING:
	printf( "  %s       : Missing, creating it\n", spaces(depth) );
	break;
      case T_FATE_OUTDATED:
	printf( "  %s       : Outdated, updating it\n", spaces(depth) );
	break;
      case T_FATE_REBUILD:
	printf( "  %s       : Rebuild, Updating it\n", spaces(depth) );
	break;
      case T_FATE_UPDATE:
	printf( "  %s       : Updating it\n", spaces(depth) );
	break;
      case T_FATE_CANTFIND:
	printf( "  %s       : Can't find it\n", spaces(depth) );
	break;
      case T_FATE_CANTMAKE:
	printf( "  %s       : Can't make it\n", spaces(depth) );
	break;
    }

    if( t->flags & ~T_FLAG_VISITED )
    {
	printf( "  %s       : ", spaces(depth) );
	if( t->flags & T_FLAG_TEMP ) printf ("TEMPORARY ");
	if( t->flags & T_FLAG_NOCARE ) printf ("NOCARE ");
	if( t->flags & T_FLAG_NOTFILE ) printf ("NOTFILE ");
	if( t->flags & T_FLAG_TOUCHED ) printf ("TOUCHED ");
	if( t->flags & T_FLAG_LEAVES ) printf ("LEAVES ");
	if( t->flags & T_FLAG_NOUPDATE ) printf ("NOUPDATE ");
	printf( "\n" );
    }

    for( c = t->depends; c; c = c->next )
    {
	printf( "  %s       : Depends on %s (%s)", spaces(depth),
	       target_name(c->target), target_fate[ c->target->fate ] );
    if (c->target->time == t->time)
        printf( " (max time)");
    printf("\n");
    
    }


    for( c = t->depends; c; c = c->next )
    {

	dependGraphOutput( c->target, depth + 1 );
    }
}

#endif
/*
 * make0sort() - reorder TARGETS chain by their time (newest to oldest)
 */

static TARGETS *
make0sort( TARGETS *chain )
{
    PROFILE_ENTER(MAKE_MAKE0SORT);
	TARGETS *result = 0;

	/* We walk chain, taking each item and inserting it on the */
	/* sorted result, with newest items at the front.  This involves */
	/* updating each TARGETS' c->next and c->tail.  Note that we */
	/* make c->tail a valid prev pointer for every entry.  Normally, */
	/* it is only valid at the head, where prev == tail.  Note also */
	/* that while tail is a loop, next ends at the end of the chain. */

	/* Walk current target list */

	while( chain )
	{
	    TARGETS *c = chain;
	    TARGETS *s = result;

	    chain = chain->next;

	    /* Find point s in result for c */

	    while( s && s->target->time > c->target->time )
		s = s->next;

	    /* Insert c in front of s (might be 0). */
	    /* Don't even think of deciphering this. */

	    c->next = s;			/* good even if s = 0 */
	    if( result == s ) result = c;	/* new head of chain? */
	    if( !s ) s = result;		/* wrap to ensure a next */
	    if( result != c ) s->tail->next = c; /* not head? be prev's next */
	    c->tail = s->tail;			/* take on next's prev */
	    s->tail = c;			/* make next's prev us */
	}

    PROFILE_EXIT(MAKE_MAKE0SORT);
	return result;
}

static LIST *targets_to_update_ = 0;

void mark_target_for_updating(char *target)
{
    targets_to_update_ = list_new( targets_to_update_, target );
}

LIST *targets_to_update()
{
    return targets_to_update_;
}

void clear_targets_to_update()
{
    list_free(targets_to_update_);
    targets_to_update_ = 0;
}
