process.c

早期freebsd实现

 *
 * If we're single-stepping by source line we want to step to the
 * next source line.  Otherwise we're going to continue so there's
 * no reason to do all the work necessary to single-step to the next
 * source line.
 */

public stepover()
{
    Boolean b;

    if (traceexec) {
	printf("!! stepping over 0x%x\n", process->reg[PROGCTR]);
    }
    if (single_stepping) {
	dostep(false);
    } else {
	b = inst_tracing;
	inst_tracing = true;
	dostep(false);
	inst_tracing = b;
    }
    if (traceexec) {
	printf("!! stepped over to 0x%x\n", process->reg[PROGCTR]);
    }
}

/*
 * Resume execution up to the given address.  We can either ignore
 * breakpoints (stepto) or catch them (contto).
 */

public stepto(addr)
Address addr;
{
    xto(addr, false);
}

private contto (addr)
Address addr;
{
    xto(addr, true);
}

private xto (addr, catchbps)
Address addr;
boolean catchbps;
{
    Address curpc;

    if (catchbps) {
	stepover();
    }
    curpc = process->reg[PROGCTR];
    if (addr != curpc) {
	if (traceexec) {
	    printf("!! stepping from 0x%x to 0x%x\n", curpc, addr);
	}
	if (catchbps) {
	    setallbps();
	}
	setbp(addr);
	resume(DEFSIG);
	unsetbp(addr);
	if (catchbps) {
	    unsetallbps();
	}
	if (not isbperr()) {
	    printstatus();
	}
    }
}

/*
 * Print the status of the process.
 * This routine does not return.
 */

public printstatus ()
{
    int status;

    if (process->status == FINISHED) {
	exit(0);
    } else {
	if (runfirst) {
	    fprintf(stderr, "\nEntering debugger ...\n");
	    printheading();
	    init();
	}
	setcurfunc(whatblock(pc));
	getsrcpos();
	if (process->signo == SIGINT) {
	    isstopped = true;
	    printerror();
	} else if (isbperr() and isstopped) {
	    printf("stopped ");
	    printloc();
	    putchar('\n');
	    if (curline > 0) {
		printlines(curline, curline);
	    } else {
		printinst(pc, pc);
	    }
	    erecover();
	} else {
	    fixintr();
	    isstopped = true;
	    printerror();
	}
    }
}

/*
 * Print out the current location in the debuggee.
 */

public printloc()
{
    printf("in ");
    printname(stdout, curfunc);
    putchar(' ');
    if (curline > 0 and not useInstLoc) {
	printsrcpos();
    } else {
	useInstLoc = false;
	curline = 0;
	printf("at 0x%x", pc);
    }
}

/*
 * Some functions for testing the state of the process.
 */

public Boolean notstarted(p)
Process p;
{
    return (Boolean) (p->status == NOTSTARTED);
}

public Boolean isfinished(p)
Process p;
{
    return (Boolean) (p->status == FINISHED);
}

/*
 * Predicate to test if the reason the process stopped was because
 * of a breakpoint.  If so, as a side effect clear the local copy of
 * signal handler associated with process.  We must do this so as to
 * not confuse future stepping or continuing by possibly concluding
 * the process should continue with a SIGTRAP handler.
 */

public boolean isbperr()
{
    Process p;
    boolean b;

    p = process;
    if (p->status == STOPPED and p->signo == SIGTRAP) {
	b = true;
	p->sigstatus = 0;
    } else {
	b = false;
    }
    return b;
}

/*
 * Return the signal number that stopped the process.
 */

public integer errnum (p)
Process p;
{
    return p->signo;
}

/*
 * Return the signal code associated with the signal.
 */

public integer errcode (p)
Process p;
{
    return p->sigcode;
}

/*
 * Return the termination code of the process.
 */

public integer exitcode (p)
Process p;
{
    return p->exitval;
}

/*
 * These routines are used to access the debuggee process from
 * outside this module.
 *
 * They invoke "pio" which eventually leads to a call to "ptrace".
 * The system generates an I/O error when a ptrace fails.  During reads
 * these are ignored, during writes they are reported as an error, and
 * for anything else they cause a fatal error.
 */

extern Intfunc *onsyserr();

private badaddr;
private read_err(), write_err();

/*
 * Read from the process' instruction area.
 */

public iread(buff, addr, nbytes)
char *buff;
Address addr;
int nbytes;
{
    Intfunc *f;

    f = onsyserr(EIO, read_err);
    badaddr = addr;
    if (coredump) {
	coredump_readtext(buff, addr, nbytes);
    } else {
	pio(process, PREAD, TEXTSEG, buff, addr, nbytes);
    }
    onsyserr(EIO, f);
}

/* 
 * Write to the process' instruction area, usually in order to set
 * or unset a breakpoint.
 */

public iwrite(buff, addr, nbytes)
char *buff;
Address addr;
int nbytes;
{
    Intfunc *f;

    if (coredump) {
	error("no process to write to");
    }
    f = onsyserr(EIO, write_err);
    badaddr = addr;
    pio(process, PWRITE, TEXTSEG, buff, addr, nbytes);
    onsyserr(EIO, f);
}

/*
 * Read for the process' data area.
 */

public dread(buff, addr, nbytes)
char *buff;
Address addr;
int nbytes;
{
    Intfunc *f;

    badaddr = addr;
    if (coredump) {
	f = onsyserr(EFAULT, read_err);
	coredump_readdata(buff, addr, nbytes);
	onsyserr(EFAULT, f);
    } else {
	f = onsyserr(EIO, read_err);
	pio(process, PREAD, DATASEG, buff, addr, nbytes);
	onsyserr(EIO, f);
    }
}

/*
 * Write to the process' data area.
 */

public dwrite(buff, addr, nbytes)
char *buff;
Address addr;
int nbytes;
{
    Intfunc *f;

    if (coredump) {
	error("no process to write to");
    }
    f = onsyserr(EIO, write_err);
    badaddr = addr;
    pio(process, PWRITE, DATASEG, buff, addr, nbytes);
    onsyserr(EIO, f);
}

/*
 * Trap for errors in reading or writing to a process.
 * The current approach is to "ignore" read errors and complain
 * bitterly about write errors.
 */

private read_err()
{
    /*
     * Ignore.
     */
}

private write_err()
{
    error("can't write to process (address 0x%x)", badaddr);
}

/*
 * Ptrace interface.
 */

#define WMASK           (~(sizeof(Word) - 1))
#define cachehash(addr) ((unsigned) ((addr >> 2) % CACHESIZE))

#define FIRSTSIG        SIGINT
#define LASTSIG         SIGQUIT
#define ischild(pid)    ((pid) == 0)
#define traceme()       ptrace(0, 0, 0, 0)
#define setrep(n)       (1 << ((n)-1))
#define istraced(p)     (p->sigset&setrep(p->signo))

/*
 * Ptrace options (specified in first argument).
 */

#define UREAD   3       /* read from process's user structure */
#define UWRITE  6       /* write to process's user structure */
#define IREAD   1       /* read from process's instruction space */
#define IWRITE  4       /* write to process's instruction space */
#define DREAD   2       /* read from process's data space */
#define DWRITE  5       /* write to process's data space */
#define CONT    7       /* continue stopped process */
#define SSTEP   9       /* continue for approximately one instruction */
#define PKILL   8       /* terminate the process */

#ifdef IRIS
#   define readreg(p, r)	ptrace(10, p->pid, r, 0)
#   define writereg(p, r, v)	ptrace(11, p->pid, r, v)
#else
#   define readreg(p, r)	ptrace(UREAD, p->pid, regloc(r), 0);
#   define writereg(p, r, v)	ptrace(UWRITE, p->pid, regloc(r), v);
#endif

/*
 * Start up a new process by forking and exec-ing the
 * given argument list, returning when the process is loaded
 * and ready to execute.  The PROCESS information (pointed to
 * by the first argument) is appropriately filled.
 *
 * If the given PROCESS structure is associated with an already running
 * process, we terminate it.
 */

/* VARARGS2 */
private pstart(p, argv, infile, outfile)
Process p;
String argv[];
String infile;
String outfile;
{
    int status;

    if (p->pid != 0) {
	pterm(p);
	cacheflush(p);
    }
    fflush(stdout);
    psigtrace(p, SIGTRAP, true);
#   ifdef IRIS
	p->pid = fork();
#   else
	p->pid = vfork();
#   endif
    if (p->pid == -1) {
	panic("can't fork");
    }
    if (ischild(p->pid)) {
	nocatcherrs();
	traceme();
	if (infile != nil) {
	    infrom(infile);
	}
	if (outfile != nil) {
	    outto(outfile);
	}
	execv(argv[0], argv);
	_exit(1);
    }
    pwait(p->pid, &status);
    getinfo(p, status);
    if (p->status != STOPPED) {
	beginerrmsg();
	fprintf(stderr, "warning: cannot execute %s\n", argv[0]);
    } else {
	ptraced(p->pid);
    }
}

/*
 * Terminate a ptrace'd process.
 */

public pterm (p)
Process p;
{
    integer status;

    if (p != nil and p->pid != 0) {
	ptrace(PKILL, p->pid, 0, 0);
	pwait(p->pid, &status);
	unptraced(p->pid);
    }
}

/*
 * Continue a stopped process.  The first argument points to a Process
 * structure.  Before the process is restarted it's user area is modified
 * according to the values in the structure.  When this routine finishes,
 * the structure has the new values from the process's user area.
 *
 * Pcont terminates when the process stops with a signal pending that
 * is being traced (via psigtrace), or when the process terminates.
 */

private pcont(p, signo)
Process p;
int signo;
{
    int s, status;

    if (p->pid == 0) {
	error("program is not active");
    }
    s = signo;
    do {
	setinfo(p, s);
	if (traceexec) {
	    printf("!! pcont from 0x%x with signal %d (%d)\n",
		p->reg[PROGCTR], s, p->signo);
	    fflush(stdout);
	}
	sigs_off();
	if (ptrace(CONT, p->pid, p->reg[PROGCTR], p->signo) < 0) {
	    panic("error %d trying to continue process", errno);
	}
	pwait(p->pid, &status);
	sigs_on();
	getinfo(p, status);
	if (p->status == STOPPED and traceexec and not istraced(p)) {
	    printf("!! ignored signal %d at 0x%x\n",
		p->signo, p->reg[PROGCTR]);
	    fflush(stdout);
	}
	s = p->signo;
    } while (p->status == STOPPED and not istraced(p));
    if (traceexec) {
	printf("!! pcont to 0x%x on signal %d\n", p->reg[PROGCTR], p->signo);
	fflush(stdout);
    }
}

/*
 * Single step as best ptrace can.
 */

public pstep(p, signo)
Process p;
integer signo;
{
    int s, status;

    s = signo;
    do {
	setinfo(p, s);
	if (traceexec) {
	    printf("!! pstep from 0x%x with signal %d (%d)\n",
		p->reg[PROGCTR], s, p->signo);
	    fflush(stdout);
	}
	sigs_off();
	if (ptrace(SSTEP, p->pid, p->reg[PROGCTR], p->signo) < 0) {
	    panic("error %d trying to step process", errno);
	}
	pwait(p->pid, &status);
	sigs_on();
	getinfo(p, status);
#	if mc68000 || m68000
	    if (p->status == STOPPED and p->signo == SIGTRAP) {
		p->reg[PROGCTR] += 2;
	    }
#	endif
	if (p->status == STOPPED and traceexec and not istraced(p)) {
	    printf("!! pstep ignored signal %d at 0x%x\n",
		p->signo, p->reg[PROGCTR]);
	    fflush(stdout);
	}
	s = p->signo;
    } while (p->status == STOPPED and not istraced(p));
    if (traceexec) {
	printf("!! pstep to 0x%x on signal %d\n",
	    p->reg[PROGCTR], p->signo);
	fflush(stdout);