/*
 * Copyright 1993-2002 Christopher Seiwald and Perforce Software, Inc.
 *
 * 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)
 */

/*
 * make1.c - execute command to bring targets up to date
 *
 * This module contains make1(), the entry point called by make() to 
 * recursively decend the dependency graph executing update actions as
 * marked by make0().
 *
 * External routines:
 *
 *	make1() - execute commands to update a TARGET and all its dependents
 *
 * Internal routines, the recursive/asynchronous command executors:
 *
 *	make1a() - recursively traverse target tree, calling make1b()
 *	make1b() - dependents of target built, now build target with make1c()
 *	make1c() - launch target's next command, call make1b() when done
 *	make1d() - handle command execution completion and call back make1c()
 *
 * Internal support routines:
 *
 *	make1cmds() - turn ACTIONS into CMDs, grouping, splitting, etc
 *	make1list() - turn a list of targets into a LIST, for $(<) and $(>)
 * 	make1settings() - for vars that get bound values, build up replacement lists
 * 	make1bind() - bind targets that weren't bound in dependency analysis
 *
 * 04/16/94 (seiwald) - Split from make.c.
 * 04/21/94 (seiwald) - Handle empty "updated" actions.
 * 05/04/94 (seiwald) - async multiprocess (-j) support
 * 06/01/94 (seiwald) - new 'actions existing' does existing sources
 * 12/20/94 (seiwald) - NOTIME renamed NOTFILE.
 * 01/19/95 (seiwald) - distinguish between CANTFIND/CANTMAKE targets.
 * 01/22/94 (seiwald) - pass per-target JAMSHELL down to execcmd().
 * 02/28/95 (seiwald) - Handle empty "existing" actions.
 * 03/10/95 (seiwald) - Fancy counts.
 */

# include "jam.h"

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

# include "search.h"
# include "newstr.h"
# include "make.h"
# include "command.h"
# include "execcmd.h"
# include "compile.h"
# include "output.h"

# include <stdlib.h>

#if defined(sun) || defined(__sun)
#include <unistd.h> /* for unlink */
#endif

static CMD *make1cmds( TARGET *t );
static LIST *make1list( LIST *l, TARGETS *targets, int flags );
static SETTINGS *make1settings( LIST *vars );
static void make1bind( TARGET *t );

/* Ugly static - it's too hard to carry it through the callbacks. */

static struct {
	int	failed;
	int	skipped;
	int	total;
	int	made;
} counts[1] ;

/*
 * Target state - remove recursive calls by just keeping track of state target is in
 */
typedef struct _state
{
  struct _state *prev; /* previous state on stack */
  TARGET *t; /* current target */
  TARGET *parent; /* parent argument necessary for make1a() */
#define T_STATE_MAKE1A 0 /* make1a() should be called */
#define T_STATE_MAKE1ATAIL 1 /* make1atail() should be called */
#define T_STATE_MAKE1B 2 /* make1b() should be called */
#define T_STATE_MAKE1C 3 /* make1c() should be called */
#define T_STATE_MAKE1D 4 /* make1d() should be called */
  int curstate; /* current state */
  int status;
} state;

static void make1a( state *pState);
static void make1atail(state *pState);
static void make1b( state *pState );
static void make1c( state *pState );
static void make1d( state *pState );
static void make_closure(void *closure, int status, timing_info*, char *, char *);

typedef struct _stack
{
	state *stack;
} stack;

static stack state_stack = { NULL };

static state *state_freelist = NULL;

static state *alloc_state()
{
	if(state_freelist != NULL)
	{
		state *pState;

		pState = state_freelist;
		state_freelist = pState->prev;
		memset(pState, 0, sizeof(state));
		return pState;
	}
	else
	{
		return (state *)BJAM_MALLOC(sizeof(state));
	}
}

static void free_state(state *pState)
{
	pState->prev = state_freelist;
	state_freelist = pState;
}

static void clear_state_freelist()
{
	while(state_freelist != NULL)
	{
		state *pState = state_freelist;
		state_freelist = state_freelist->prev;
		BJAM_FREE(pState);
	}
}

static state *current_state(stack *pStack)
{
	return pStack->stack;
}

static void pop_state(stack *pStack)
{
	state *pState;

	if(pStack->stack != NULL)
	{
		pState = pStack->stack->prev;
		free_state(pStack->stack);
		pStack->stack = pState;
	}
}

static state *push_state(stack *pStack, TARGET *t, TARGET *parent, int curstate)
{
	state *pState;

	pState = alloc_state();

	pState->t = t;
	pState->parent = parent;
	pState->prev = pStack->stack;
	pState->curstate = curstate;

	pStack->stack = pState;

	return pStack->stack;
}

/* pushes a stack onto another stack, effectively reversing the order */
static void push_stack_on_stack(stack *pDest, stack *pSrc)
{
	while(pSrc->stack != NULL)
	{
		state *pState;

		pState = pSrc->stack;
		pSrc->stack = pSrc->stack->prev;
		pState->prev = pDest->stack;
		pDest->stack = pState;
	}
}

/*
 * make1() - execute commands to update a TARGET and all its dependents
 */

static int intr = 0;

int
make1( TARGET *t )
{
	state *pState;

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

	/* Recursively make the target and its dependents */
	push_state(&state_stack, t, NULL, T_STATE_MAKE1A);

	do
	{
		while((pState = current_state(&state_stack)) != NULL)
		{
            if (intr) 
                pop_state(&state_stack);

			switch(pState->curstate)
			{
			case T_STATE_MAKE1A:
				make1a(pState);
				break;
			case T_STATE_MAKE1ATAIL:
				make1atail(pState);
				break;
			case T_STATE_MAKE1B:
				make1b(pState);
				break;
			case T_STATE_MAKE1C:
				make1c(pState);
				break;
			case T_STATE_MAKE1D:
				make1d(pState);
				break;
			default:
				break;
			}
		}
	

	/* Wait for any outstanding commands to finish running. */
	} while( execwait() );

	clear_state_freelist();

	/* Talk about it */
	if( counts->failed )
	    printf( "...failed updating %d target%s...\n", counts->failed,
		        counts->failed > 1 ? "s" : "" );

	if( DEBUG_MAKE && counts->skipped )
	    printf( "...skipped %d target%s...\n", counts->skipped,
		        counts->skipped > 1 ? "s" : "" );

	if( DEBUG_MAKE && counts->made )
	    printf( "...updated %d target%s...\n", counts->made,
		        counts->made > 1 ? "s" : "" );

	return counts->total != counts->made;
}

/*
 * make1a() - recursively traverse target tree, calling make1b()
 */

static void
make1a( state *pState)
{
    TARGET* t = pState->t;
	TARGETS	*c;
    TARGETS   *inc;

	/* If the parent is the first to try to build this target */
	/* or this target is in the make1c() quagmire, arrange for the */
	/* parent to be notified when this target is built. */

	if( pState->parent )
	    switch( pState->t->progress )
	{
	case T_MAKE_INIT:
	case T_MAKE_ACTIVE:
	case T_MAKE_RUNNING:
	    pState->t->parents = targetentry( pState->t->parents, pState->parent );
	    pState->parent->asynccnt++;
	}

	if( pState->t->progress != T_MAKE_INIT )
	{
		pop_state(&state_stack);
		return;
	}

	/* Asynccnt counts the dependents preventing this target from */
	/* proceeding to make1b() for actual building.  We start off with */
	/* a count of 1 to prevent anything from happening until we can */
	/* call all dependents.  This 1 is accounted for when we call */
	/* make1b() ourselves, below. */

	pState->t->asynccnt = 1;

    /* Add header node that was created during building process. */

    inc = 0;
    for (c = t->depends; c; c = c->next) {        
        if (c->target->rescanned && c->target->includes)
            inc = targetentry(inc, c->target->includes);           
    }
    t->depends = targetchain(t->depends, inc);

	/* against circular dependency. */

	pState->t->progress = T_MAKE_ONSTACK;

	{
		stack temp_stack = { NULL };
        for( c = t->depends; c && !intr; c = c->next )            
            push_state(&temp_stack, c->target, pState->t, T_STATE_MAKE1A);

		/* using stacks reverses the order of execution. Reverse it back */
		push_stack_on_stack(&state_stack, &temp_stack);
	}

	pState->curstate = T_STATE_MAKE1ATAIL;
}

static void make1atail(state *pState)
{
	pState->t->progress = T_MAKE_ACTIVE;

	/* Now that all dependents have bumped asynccnt, we now allow */
	/* decrement our reference to asynccnt. */ 
	pState->curstate = T_STATE_MAKE1B;
}

/*
 * make1b() - dependents of target built, now build target with make1c()
 */

static void
make1b( state *pState )
{
    TARGET      *t = pState->t;
    TARGETS     *c;
    TARGET      *failed = 0;
    char* failed_name = "dependencies";

    /* If any dependents are still outstanding, wait until they */
    /* call make1b() to signal their completion. */

    if( --(pState->t->asynccnt) )
	{
		pop_state(&state_stack);
		return;
	}
    
    /* Try to aquire a semaphore. If it's locked, wait until the target
       that locked it is build and signals completition. */
#ifdef OPT_SEMAPHORE
	if( t->semaphore && t->semaphore->asynccnt )
	{
        /* Append 't' to the list of targets waiting on semaphore. */
	    t->semaphore->parents = targetentry( t->semaphore->parents, t );
	    t->asynccnt++;

	    if( DEBUG_EXECCMD )
		printf( "SEM: %s is busy, delaying launch of %s\n",
			t->semaphore->name, t->name);
		pop_state(&state_stack);
	    return;
	}
#endif


    /* Now ready to build target 't'... if dependents built ok. */

    /* Collect status from dependents */


    for( c = t->depends; c; c = c->next )
        if( c->target->status > t->status && !( c->target->flags & T_FLAG_NOCARE ))
        {
            failed = c->target;
            pState->t->status = c->target->status;
        }
    /* If a internal header node failed to build, we'd want to output the 
       target that it failed on. */
    if (failed && (failed->flags & T_FLAG_INTERNAL)) {
        failed_name = failed->failed;
    } else if (failed) {
        failed_name = failed->name;
    }
    t->failed = failed_name;

    /* If actions on deps have failed, bail. */
    /* Otherwise, execute all actions to make target */

    if( pState->t->status == EXEC_CMD_FAIL && pState->t->actions )
    {
        ++counts->skipped;
        if ( ( pState->t->flags & ( T_FLAG_RMOLD | T_FLAG_NOTFILE ) ) == T_FLAG_RMOLD )
        {
            if( !unlink( pState->t->boundname ) )
                printf( "...removing outdated %s\n", pState->t->boundname );
        }
        else {
            printf( "...skipped %s for lack of %s...\n", pState->t->name, failed_name );
        }
    }

    if( pState->t->status == EXEC_CMD_OK )
        switch( pState->t->fate )
        {
            /* These are handled by the default case below now
        case T_FATE_INIT:
        case T_FATE_MAKING:
            */

        case T_FATE_STABLE:
        case T_FATE_NEWER:
            break;

        case T_FATE_CANTFIND:
        case T_FATE_CANTMAKE:
            pState->t->status = EXEC_CMD_FAIL;
            break;

        case T_FATE_ISTMP:
            if( DEBUG_MAKE )
                printf( "...using %s...\n", pState->t->name );
            break;

        case T_FATE_TOUCHED:
        case T_FATE_MISSING:
        case T_FATE_NEEDTMP:
        case T_FATE_OUTDATED:
        case T_FATE_UPDATE:
        case T_FATE_REBUILD:

            /* Set "on target" vars, build actions, unset vars */
            /* Set "progress" so that make1c() counts this target among */
            /* the successes/failures. */

            if( pState->t->actions )
            {
                ++counts->total;
                if( DEBUG_MAKE && !( counts->total % 100 ) )
                    printf( "...on %dth target...\n", counts->total );

                pState->t->cmds = (char *)make1cmds( pState->t );
                pState->t->progress = T_MAKE_RUNNING;
            }

            break;
            
            /* All possible fates should have been accounted for by now */
        default:
            printf("ERROR: %s has bad fate %d", pState->t->name, pState->t->fate);
            abort();
        }

		/* Call make1c() to begin the execution of the chain of commands */
		/* needed to build target.  If we're not going to build target */
		/* (because of dependency failures or because no commands need to */
		/* be run) the chain will be empty and make1c() will directly */
		/* signal the completion of target. */

	/* Recurse on our dependents, manipulating progress to guard */

#ifdef OPT_SEMAPHORE
	/* If there is a semaphore, indicate that its in use */
	if( pState->t->semaphore )
	{
	    ++(pState->t->semaphore->asynccnt);

	    if( DEBUG_EXECCMD )
		printf( "SEM: %s now used by %s\n", pState->t->semaphore->name,
		       pState->t->name );
	}
#endif

	pState->curstate = T_STATE_MAKE1C;
}

/*
 * make1c() - launch target's next command, call make1b() when done
 */

static void
make1c( state *pState )
{
	CMD	*cmd = (CMD *)pState->t->cmds;

	/* If there are (more) commands to run to build this target */
	/* (and we haven't hit an error running earlier comands) we */
	/* launch the command with execcmd(). */
	
	/* If there are no more commands to run, we collect the status */
	/* from all the actions then report our completion to all the */
	/* parents. */

	if( cmd && pState->t->status == EXEC_CMD_OK )
	{
            char *rule_name = 0;
            char *target = 0;
		if( DEBUG_MAKEQ || 
            ! ( cmd->rule->actions->flags & RULE_QUIETLY ) && DEBUG_MAKE)
	    {
            rule_name = cmd->rule->name;
            target = lol_get(&cmd->args, 0)->string;
            if ( globs.noexec )
            {
                out_action(rule_name,target,cmd->buf,"","",EXIT_OK);
            }
	    }

	    if( globs.noexec )
	    {
			pState->curstate = T_STATE_MAKE1D;
			pState->status = EXEC_CMD_OK;
	    } 
	    else
	    {
			TARGET *t = pState->t;

			pop_state(&state_stack); /* pop state first because execcmd could push state */
			execcmd( cmd->buf, make_closure, t, cmd->shell, rule_name, target );
	    }
	}
	else
	{
	    TARGETS	*c;
	    ACTIONS	*actions;

	    /* Collect status from actions, and distribute it as well */

	    for( actions = pState->t->actions; actions; actions = actions->next )
		if( actions->action->status > pState->t->status )
		    pState->t->status = actions->action->status;

	    for( actions = pState->t->actions; actions; actions = actions->next )
		if( pState->t->status > actions->action->status )
		    actions->action->status = pState->t->status;

	    /* Tally success/failure for those we tried to update. */

	    if( pState->t->progress == T_MAKE_RUNNING )
		switch( pState->t->status )
	    {
	    case EXEC_CMD_OK:
		++counts->made;
		break;
	    case EXEC_CMD_FAIL:
		++counts->failed;
		break;
	    }

	    /* Tell parents dependent has been built */
		{
			stack temp_stack = { NULL };
			TARGET *t = pState->t;            
            TARGET* additional_includes = NULL;

			t->progress = T_MAKE_DONE;

            /* Target was updated. Rescan dependencies. */
            if (t->fate >= T_FATE_MISSING &&
                t->status == EXEC_CMD_OK &&
                !t->rescanned) {

                TARGET *target_to_rescan = t;
                SETTINGS *s;               

                target_to_rescan->rescanned = 1;

                if (target_to_rescan->flags & T_FLAG_INTERNAL) {
                    target_to_rescan = t->original_target;                    
                }

                /* Clean current includes */
                if (target_to_rescan->includes) {
                    target_to_rescan->includes = 0;
                }

                s = copysettings( target_to_rescan->settings );
                pushsettings( s );
                headers(target_to_rescan);
                popsettings( s );
                freesettings( s );

                if (target_to_rescan->includes) {
                    target_to_rescan->includes->rescanned = 1;
                    /* Tricky. The parents were already processed, but they
                       did not seen the internal node, because it was just 
                       created. We need to make the calls to make1a that would
                       have been done by parents here, and also make sure all
                       unprocessed parents will pick up the includes. We must
                       make sure processing of the additional make1a invocations
                       is done before make1b which means this target is built,
                       otherwise the parent will be considered built before this
                       make1a processing is even started.
                    */
                    make0(target_to_rescan->includes, target_to_rescan->parents->target, 0, 0, 0);
                    for( c = target_to_rescan->parents; c; c = c->next) {
                        c->target->depends = targetentry( c->target->depends, 
                                                          target_to_rescan->includes );
                    }
                    /* Will be processed below. */
                    additional_includes = target_to_rescan->includes;
                }                
            }

            if (additional_includes)
                for ( c = t->parents; c; c = c->next ) {                            
                    push_state(&temp_stack, additional_includes, c->target, T_STATE_MAKE1A);
                    
                }

			for( c = t->parents; c; c = c->next ) {
				push_state(&temp_stack, c->target, NULL, T_STATE_MAKE1B);
            }
             


#ifdef OPT_SEMAPHORE
	    /* If there is a semaphore, its now free */
	    if( t->semaphore )
	    {
		assert( t->semaphore->asynccnt == 1 );
		--(t->semaphore->asynccnt);

		if( DEBUG_EXECCMD )
		    printf( "SEM: %s is now free\n", t->semaphore->name);

		/* If anything is waiting, notify the next target. There's no
            point in notifying all waiting targets, since they'll be
            serialized again. */
		if( t->semaphore->parents )
		{
		    TARGETS *first = t->semaphore->parents;
		    if( first->next )
			first->next->tail = first->tail;
		    t->semaphore->parents = first->next;

		    if( DEBUG_EXECCMD )
			printf( "SEM: placing %s on stack\n", first->target->name);
            push_state(&temp_stack, first->target, NULL, T_STATE_MAKE1B);
		    BJAM_FREE( first );
		}
	    }
#endif

		
			/* must pop state before pushing any more */
			pop_state(&state_stack);
		
			/* using stacks reverses the order of execution. Reverse it back */
			push_stack_on_stack(&state_stack, &temp_stack);

		}
	}
}

/* Look up the __TIMING_RULE__ variable on the given target, and if
 * non-empty, invoke the rule it names, passing the given
 * timing_info
 */
static void call_timing_rule(TARGET* target, timing_info* time)
{
    LIST* timing_rule;
    
    pushsettings(target->settings);
    timing_rule = var_get( "__TIMING_RULE__" );
    popsettings(target->settings);

    if (timing_rule)
    {
        /* rule timing-rule (
            args * :
            target :
            start end user system ) */

        /* Prepare the argument list */
        FRAME frame[1];
        frame_init( frame );

        /* args * :: $(__ACTION_RULE__[2-]) */
        lol_add( frame->args, list_copy( L0, timing_rule->next ) );

        /* target :: the name of the target */
        lol_add( frame->args, list_new( L0, target->name ) );

        /* start end user system :: info about the action command */
        lol_add( frame->args,
            list_new( list_new( list_new( list_new( L0,
                outf_time(time->start) ),
                outf_time(time->end) ),
                outf_double(time->user) ),
                outf_double(time->system) ) );

        /* Call the rule. */
        evaluate_rule( timing_rule->string, frame );

        /* Clean up */
        frame_free( frame );
    }
}

/* Look up the __ACTION_RULE__ variable on the given target, and if
 * non-empty, invoke the rule it names, passing the given info, 
 * timing_info, executed command and command output
 */
static void call_action_rule(TARGET* target, int status, timing_info* time,
    char *executed_command, char *command_output)
{
    LIST* action_rule;

    pushsettings(target->settings);
    action_rule = var_get( "__ACTION_RULE__" );
    popsettings(target->settings);

    if (action_rule)
    {
        /* rule action-rule (
            args * :
            target :
            command status start end user system :
            output ? ) */

        /* Prepare the argument list */
        FRAME frame[1];
        frame_init( frame );

        /* args * :: $(__ACTION_RULE__[2-]) */
        lol_add( frame->args, list_copy( L0, action_rule->next ) );

        /* target :: the name of the target */
        lol_add( frame->args, list_new( L0, target->name ) );

        /* command status start end user system :: info about the action command */
        lol_add( frame->args,
            list_new( list_new( list_new( list_new( list_new( list_new( L0,
                newstr(executed_command) ),
                outf_int(status) ),
                outf_time(time->start) ),
                outf_time(time->end) ),
                outf_double(time->user) ),
                outf_double(time->system) ) );

        /* output ? :: the output of the action command */
        if (command_output)
            lol_add(frame->args, list_new(L0, newstr(command_output)));
        else
            lol_add(frame->args, L0);

        /* Call the rule. */
        evaluate_rule( action_rule->string, frame );

        /* Clean up */
        frame_free( frame );
    }
}


static void make_closure(
    void *closure, int status, timing_info* time, char *executed_command,
    char *command_output)
{
    TARGET* built = (TARGET*)closure;

    call_timing_rule(built, time);
    if (DEBUG_EXECCMD)
        printf("%f sec system; %f sec user\n", time->system, time->user);

    call_action_rule(built, status, time, executed_command, command_output);
    
    push_state(&state_stack, built, NULL, T_STATE_MAKE1D)->status = status;
}

/*
 * make1d() - handle command execution completion and call back make1c()
 */

static void
make1d(state *pState)
{
	TARGET	*t = pState->t;
	CMD	*cmd = (CMD *)t->cmds;
	int status = pState->status;

	/* Execcmd() has completed.  All we need to do is fiddle with the */
	/* status and signal our completion so make1c() can run the next */
	/* command.  On interrupts, we bail heavily. */

        if ( t->flags & T_FLAG_FAIL_EXPECTED )
        {
          /* invert execution result when FAIL_EXPECTED was applied */
          switch (status)
          {
            case EXEC_CMD_FAIL: status = EXEC_CMD_OK; break;
            case EXEC_CMD_OK:   status = EXEC_CMD_FAIL; break;
            default:
              ;
          }
        }
        
	if( status == EXEC_CMD_FAIL && ( cmd->rule->actions->flags & RULE_IGNORE ) )
	    status = EXEC_CMD_OK;

	/* On interrupt, set intr so _everything_ fails */

	if( status == EXEC_CMD_INTR )
	    ++intr;

	if( status == EXEC_CMD_FAIL && DEBUG_MAKE )
	{
	    /* Print command text on failure */

	    if( !DEBUG_EXEC )
		printf( "%s\n", cmd->buf );

	    printf( "...failed %s ", cmd->rule->name );
	    list_print( lol_get( &cmd->args, 0 ) );
	    printf( "...\n" );
	}

	if (status == EXEC_CMD_FAIL)
		if( globs.quitquick ) ++intr;

	/* If the command was interrupted or failed and the target */
	/* is not "precious", remove the targets */

	if( status != EXEC_CMD_OK && !( cmd->rule->actions->flags & RULE_TOGETHER ) )
	{
	    LIST *targets = lol_get( &cmd->args, 0 );

	    for( ; targets; targets = list_next( targets ) )
		if( !unlink( targets->string ) )
		    printf( "...removing %s\n", targets->string );
	}

	/* Free this command and call make1c() to move onto next command. */

	t->status = status;
	t->cmds = (char *)cmd_next( cmd );

	cmd_free( cmd );

	pState->curstate = T_STATE_MAKE1C;
}

/*
 * swap_settings() - replace the settings from the current module and
 *                   target with those from the new module and target
 */
static void swap_settings(
    module_t** current_module
    , TARGET** current_target
    , module_t* new_module
    , TARGET* new_target)
{
    if (new_module == root_module())
        new_module = 0;
    
    if (new_target == *current_target && new_module == *current_module)
        return;

    if (*current_target)
        popsettings( (*current_target)->settings );
        
    if (new_module != *current_module)
    {
        if (*current_module)
            exit_module( *current_module );

        *current_module = new_module;
        
        if (new_module)
            enter_module( new_module );
    }

    *current_target = new_target;
    if (new_target)
        pushsettings( new_target->settings );
}

/*
 * make1cmds() - turn ACTIONS into CMDs, grouping, splitting, etc
 *
 * Essentially copies a chain of ACTIONs to a chain of CMDs, 
 * grouping RULE_TOGETHER actions, splitting RULE_PIECEMEAL actions,
 * and handling RULE_NEWSRCS actions.  The result is a chain of
 * CMDs which can be expanded by var_string() and executed with
 * execcmd().
 */

static CMD *
make1cmds( TARGET *t )
{
	CMD *cmds = 0;
	LIST *shell = 0;
        
        module_t *settings_module = 0;
        TARGET *settings_target = 0;
        
	/* Step through actions */
	/* Actions may be shared with other targets or grouped with */
	/* RULE_TOGETHER, so actions already seen are skipped. */
        
        ACTIONS* a0;
	for(a0 = t->actions ; a0; a0 = a0->next )
	{
	    RULE    *rule = a0->action->rule;
            rule_actions *actions = rule->actions;
	    SETTINGS *boundvars;
	    LIST    *nt, *ns;
	    ACTIONS *a1;
	    int	    start, chunk, length;

	    /* Only do rules with commands to execute. */
	    /* If this action has already been executed, use saved status */

	    if( !actions || a0->action->running )
		continue;

	    a0->action->running = 1;
	    
	    /* Make LISTS of targets and sources */
	    /* If `execute together` has been specified for this rule, tack */
	    /* on sources from each instance of this rule for this target. */

	    nt = make1list( L0, a0->action->targets, 0 );
	    ns = make1list( L0, a0->action->sources, actions->flags );

	    if( actions->flags & RULE_TOGETHER )
		for( a1 = a0->next; a1; a1 = a1->next )
		    if( a1->action->rule == rule && !a1->action->running )
	    {
		ns = make1list( ns, a1->action->sources, actions->flags );
		a1->action->running = 1;
	    }

	    /* If doing only updated (or existing) sources, but none have */
	    /* been updated (or exist), skip this action. */

	    if( !ns && ( actions->flags & ( RULE_NEWSRCS | RULE_EXISTING ) ) )
	    {
		list_free( nt );
		continue;
	    }

            swap_settings( &settings_module, &settings_target, rule->module, t );
            if (!shell)
                shell = var_get( "JAMSHELL" );	/* shell is per-target */
                
	    /* If we had 'actions xxx bind vars' we bind the vars now */

	    boundvars = make1settings( actions->bindlist );
	    pushsettings( boundvars );

	    /*
	     * Build command, starting with all source args. 
	     *
	     * If cmd_new returns 0, it's because the resulting command
	     * length is > MAXLINE.  In this case, we'll slowly reduce
	     * the number of source arguments presented until it does
	     * fit.  This only applies to actions that allow PIECEMEAL 
	     * commands.
	     *
	     * While reducing slowly takes a bit of compute time to get
	     * things just right, it's worth it to get as close to MAXLINE
	     * as possible, because launching the commands we're executing 
	     * is likely to be much more compute intensive!
	     *
	     * Note we loop through at least once, for sourceless actions.
	     */

	    start = 0;
	    chunk = length = list_length( ns );

	    do
	    {
		/* Build cmd: cmd_new consumes its lists. */

		CMD *cmd = cmd_new( rule, 
			list_copy( L0, nt ), 
			list_sublist( ns, start, chunk ),
			list_copy( L0, shell ) );

		if( cmd )
		{
		    /* It fit: chain it up. */

		    if( !cmds ) cmds = cmd;
		    else cmds->tail->next = cmd;
		    cmds->tail = cmd;
		    start += chunk;
		}
		else if( ( actions->flags & RULE_PIECEMEAL ) && chunk > 1 )
		{
		    /* Reduce chunk size slowly. */

		    chunk = chunk * 9 / 10;
		}
		else
		{
		    /* Too long and not splittable. */

		    printf( "%s actions too long (max %d):\n", 
			rule->name, MAXLINE );

                    /* Tell the user what didn't fit */
                    cmd = cmd_new(
                        rule, list_copy( L0, nt ), 
			list_sublist( ns, start, chunk ),
			list_new( L0, newstr( "%" ) ) );

                    printf( cmd->buf );
                
		    exit( EXITBAD );
		}
	    }
	    while( start < length );

	    /* These were always copied when used. */

	    list_free( nt );
	    list_free( ns );

	    /* Free the variables whose values were bound by */
	    /* 'actions xxx bind vars' */

	    popsettings( boundvars );
	    freesettings( boundvars );
	}

        swap_settings( &settings_module, &settings_target, 0, 0 );
	return cmds;
}

/*
 * make1list() - turn a list of targets into a LIST, for $(<) and $(>)
 */

static LIST *
make1list( 
	LIST	*l,
	TARGETS	*targets,
	int	flags )
{
    for( ; targets; targets = targets->next )
    {
	TARGET *t = targets->target;

	if( t->binding == T_BIND_UNBOUND )
	    make1bind( t );

    if ( ( flags & RULE_EXISTING ) && ( flags & RULE_NEWSRCS ) )
    {
        if ( t->binding != T_BIND_EXISTS && t->fate <= T_FATE_STABLE)
            continue;
    }
    else
    { 
        if( ( flags & RULE_EXISTING ) && t->binding != T_BIND_EXISTS )
            continue;

        if( ( flags & RULE_NEWSRCS ) && t->fate <= T_FATE_STABLE )
            continue;
    }

	/* Prohibit duplicates for RULE_TOGETHER */

	if( flags & RULE_TOGETHER )
	{
	    LIST *m;

	    for( m = l; m; m = m->next )
		if( !strcmp( m->string, t->boundname ) )
		    break;

	    if( m )
		continue;
	}

	/* Build new list */

	l = list_new( l, copystr( t->boundname ) );
    }

    return l;
}

/*
 * make1settings() - for vars that get bound values, build up replacement lists
 */

static SETTINGS *
make1settings( LIST *vars )
{
	SETTINGS *settings = 0;

	for( ; vars; vars = list_next( vars ) )
	{
	    LIST *l = var_get( vars->string );
	    LIST *nl = 0;

	    for( ; l; l = list_next( l ) ) 
	    {
		TARGET *t = bindtarget( l->string );

		/* Make sure the target is bound */

		if( t->binding == T_BIND_UNBOUND )
		    make1bind( t );

		/* Build new list */

		nl = list_new( nl, copystr( t->boundname ) );
	    }

	    /* Add to settings chain */

	    settings = addsettings( settings, VAR_SET, vars->string, nl );
	}

	return settings;
}

/*
 * make1bind() - bind targets that weren't bound in dependency analysis
 *
 * Spot the kludge!  If a target is not in the dependency tree, it didn't 
 * get bound by make0(), so we have to do it here.  Ugly.
 */

static void
make1bind( 
	TARGET	*t )
{
	if( t->flags & T_FLAG_NOTFILE )
	    return;

	pushsettings( t->settings );
	t->boundname = search( t->name, &t->time, 0 );
	t->binding = t->time ? T_BIND_EXISTS : T_BIND_MISSING;
	popsettings( t->settings );
}