events.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

/*#@(#)events.c	4.1	Ultrix	7/17/90*/
/* Copyright (c) 1982 Regents of the University of California */

static char sccsid[] = "@(#)events.c 1.3 4/8/83";

static char rcsid[] = "$Header: events.c,v 1.3 84/03/27 10:20:41 linton Exp $";

/*
 * Event/breakpoint managment.
 */

#include "defs.h"
#include "events.h"
#include "main.h"
#include "symbols.h"
#include "tree.h"
#include "eval.h"
#include "source.h"
#include "mappings.h"
#include "runtime.h"
#include "process.h"
#include "machine.h"
#include "lists.h"

#ifndef public
typedef struct Event *Event;
typedef struct Breakpoint *Breakpoint;

Boolean inst_tracing;
Boolean single_stepping;
Boolean isstopped;

#include "symbols.h"

Symbol linesym;
Symbol procsym;
Symbol pcsym;
Symbol retaddrsym;

#define addevent(cond, cmdlist) event_alloc(false, cond, cmdlist)
#define event_once(cond, cmdlist) event_alloc(true, cond, cmdlist)

#endif

struct Event {
    unsigned int id;
    Boolean temporary;
    Node condition;
    Cmdlist actions;
};

struct Breakpoint {
    Event event;
    Address bpaddr;	
    Lineno bpline;
    Cmdlist actions;
};

typedef List Eventlist;
typedef List Bplist;

#define eventlist_append(event, el) list_append(list_item(event), nil, el)
#define bplist_append(bp, bl) list_append(list_item(bp), nil, bl)

private Eventlist eventlist;		/* list of active events */
private Bplist bplist;			/* list of active breakpoints */
private Integer eventid;		/* id number of next allocated event */
private Integer trid;			/* id number of next allocated trace */

typedef struct Trcmd {
    Integer trid;
    Event event;
    Cmdlist cmdlist;
} *Trcmd;

private List eachline;		/* commands to execute after each line */
private List eachinst;		/* commands to execute after each instruction */

private Breakpoint bp_alloc();

/*
 * Initialize breakpoint information.
 */

private Symbol builtinsym(str, class, type)
String str;
Symclass class;
Symbol type;
{
    Symbol s;

    s = insert(identname(str, true));
    s->language = findlanguage(".s");
    s->class = class;
    s->type = type;
    return s;
}

public bpinit()
{
    linesym = builtinsym("$line", VAR, t_int);
    procsym = builtinsym("$proc", PROC, nil);
    pcsym = lookup(identname("$pc", true));
    if (pcsym == nil) {
	panic("can't find $pc");
    }
    retaddrsym = builtinsym("$retaddr", VAR, t_int);
    eventlist = list_alloc();
    bplist = list_alloc();
    eachline = list_alloc();
    eachinst = list_alloc();
}

/*
 * Trap an event and do the associated commands when it occurs.
 */

public Event event_alloc(istmp, econd, cmdlist)
Boolean istmp;
Node econd;
Cmdlist cmdlist;
{
    register Event e;

    e = new(Event);
    ++eventid;
    e->id = eventid;
    e->temporary = istmp;
    e->condition = econd;
    e->actions = cmdlist;
    eventlist_append(e, eventlist);
    translate(e);
    return e;
}

/*
 * Delete the event with the given id.
 * Returns whether it's successful or not.
 */

public boolean delevent (id)
unsigned int id;
{
    Event e;
    Breakpoint bp;
    Trcmd t;
    boolean found;

    found = false;
    foreach (Event, e, eventlist)
	if (e->id == id) {
	    found = true;
	    foreach (Breakpoint, bp, bplist)
		if (bp->event == e) {
		    if (tracebpts) {
			printf("deleting breakpoint at 0x%x\n", bp->bpaddr);
			fflush(stdout);
		    }
		    list_delete(list_curitem(bplist), bplist);
		}
	    endfor
	    list_delete(list_curitem(eventlist), eventlist);
	    break;
	}
    endfor
    foreach (Trcmd, t, eachline)
	if (t->event->id == id) {
	    found = true;
	    printrmtr(t);
	    list_delete(list_curitem(eachline), eachline);
	}
    endfor
    foreach (Trcmd, t, eachinst)
	if (t->event->id == id) {
	    found = true;
	    printrmtr(t);
	    list_delete(list_curitem(eachinst), eachinst);
	}
    endfor
    if (list_size(eachinst) == 0) {
	inst_tracing = false;
	if (list_size(eachline) == 0) {
	    single_stepping = false;
	}
    }
    return found;
}

/*
 * Translate an event into the appropriate breakpoints and actions.
 * While we're at it, turn on the breakpoints if the condition is true.
 */

private translate(e)
Event e;
{
    Breakpoint bp;
    Symbol s;
    Node place;
    Lineno line;
    Address addr;

    checkref(e->condition);
    switch (e->condition->op) {
	case O_EQ:
	    if (e->condition->value.arg[0]->op == O_SYM) {
		s = e->condition->value.arg[0]->value.sym;
		place = e->condition->value.arg[1];
		if (s == linesym) {
		    if (place->op == O_QLINE) {
			line = place->value.arg[1]->value.lcon;
			addr = objaddr(line, place->value.arg[0]->value.scon);
		    } else {
			eval(place);
			line = pop(long);
			addr = objaddr(line, cursource);
		    }
		    if (addr == NOADDR) {
			if (not delevent(e->id)) {
			    printf("!! dbx.translate: can't undo event %d?\n",
				e->id);
			}
			beginerrmsg();
			fprintf(stderr, "no executable code at line ");
			prtree(stderr, place);
			enderrmsg();
		    }
		    bp = bp_alloc(e, addr, line, e->actions);
		} else if (s == procsym) {
		    eval(place);
		    s = pop(Symbol);
		    bp = bp_alloc(e, codeloc(s), 0, e->actions);
		    if (isactive(s) and pc != codeloc(program)) {
			evalcmdlist(e->actions);
		    }
		} else if (s == pcsym) {
		    eval(place);
		    bp = bp_alloc(e, pop(Address), 0, e->actions);
		} else {
		    condbp(e);
		}
	    } else {
		condbp(e);
	    }
	    break;

	/*
	 * These should be handled specially.
	 * But for now I'm ignoring the problem.
	 */
	case O_AND:
	case O_OR:
	default:
	    condbp(e);
	    break;
    }
}

/*
 * Create a breakpoint for a condition that cannot be pinpointed
 * to happening at a particular address, but one for which we
 * must single step and check the condition after each statement.
 */

private condbp(e)
Event e;
{
    Symbol p;
    Breakpoint bp;
    Cmdlist actions;

    p = tcontainer(e->condition);
    if (p == nil) {
	p = program;
    }
    actions = buildcmdlist(build(O_IF, e->condition, e->actions));
    actions = buildcmdlist(build(O_TRACEON, false, actions));
    bp = bp_alloc(e, codeloc(p), 0, actions);
}

/*
 * Determine the deepest nested subprogram that still contains
 * all elements in the given expression.
 */

public Symbol tcontainer(exp)
Node exp;
{
    Integer i;
    Symbol s, t, u, v;

    checkref(exp);
    s = nil;
    if (exp->op == O_SYM) {
	s = container(exp->value.sym);
    } else if (not isleaf(exp->op)) {
	for (i = 0; i < nargs(exp->op); i++) {
	    t = tcontainer(exp->value.arg[i]);
	    if (t != nil) {
		if (s == nil) {
		    s = t;
		} else {
		    u = s;
		    v = t;
		    while (u != v and u != nil) {
			u = container(u);
			v = container(v);
		    }
		    if (u == nil) {
			panic("bad ancestry for \"%s\"", symname(s));
		    } else {
			s = u;
		    }
		}
	    }
	}
    }
    return s;
}

/*
 * Determine if the given function can be executed at full speed.
 * This can only be done if there are no breakpoints within the function.
 */

public Boolean canskip(f)
Symbol f;
{
    Breakpoint p;
    Boolean ok;

    ok = true;
    foreach (Breakpoint, p, bplist)
	if (whatblock(p->bpaddr) == f) {
	    ok = false;
	    break;
	}
    endfor
    return ok;
}

/*
 * Print out what's currently being traced by looking at
 * the currently active events.
 *
 * Some convolution here to translate internal representation
 * of events back into something more palatable.
 */

public status()
{
    Event e;

    foreach (Event, e, eventlist)
	if (not e->temporary) {
	    printevent(e);
	}
    endfor
}

public printevent(e)
Event e;
{
    Command cmd;

    if (not isredirected()) {
	printeventid(e->id);
    }
    cmd = list_element(Command, list_head(e->actions));
    if (cmd->op == O_PRINTCALL) {
	printf("trace ");
	printname(stdout, cmd->value.sym);
    } else {
	if (list_size(e->actions) > 1) {
	    printf("{ ");
	}
	foreach (Command, cmd, e->actions)
	    printcmd(stdout, cmd);
	    if (not list_islast()) {
		printf("; ");
	    }
	endfor
	if (list_size(e->actions) > 1) {
	    printf(" }");
	}
	printcond(e->condition);
    }
    printf("\n");
}

private printeventid (id)
integer id;
{
    printf("[%d] ", id);
}

/*
 * Print out a condition.
 */

private printcond(cond)
Node cond;
{
    Symbol s;
    Node place;

    if (cond->op == O_EQ and cond->value.arg[0]->op == O_SYM) {
	s = cond->value.arg[0]->value.sym;
	place = cond->value.arg[1];
	if (s == procsym) {
	    if (place->value.sym != program) {
		printf(" in ");
		printname(stdout, place->value.sym);
	    }
	} else if (s == linesym) {
	    printf(" at ");
	    prtree(stdout, place);
	} else if (s == pcsym or s == retaddrsym) {
	    printf("i at ");
	    prtree(stdout, place);
	} else {
	    printf(" when ");
	    prtree(stdout, cond);
	}
    } else {
	printf(" when ");
	prtree(stdout, cond);
    }
}

/*
 * Add a breakpoint to the list and return it.
 */

private Breakpoint bp_alloc(e, addr, line, actions)
Event e;
Address addr;
Lineno line;