process.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

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

static char sccsid[] = "@(#)process.c 1.12 8/19/83";

static char rcsid[] = "$Header: process.c,v 1.3 84/03/27 10:23:24 linton Exp $";

/*
 * Process management.
 *
 * This module contains the routines to manage the execution and
 * tracing of the debuggee process.
 */

#include "defs.h"
#include "process.h"
#include "machine.h"
#include "events.h"
#include "tree.h"
#include "eval.h"
#include "operators.h"
#include "source.h"
#include "object.h"
#include "mappings.h"
#include "main.h"
#include "coredump.h"
#include <signal.h>
#include <errno.h>
#include <sys/param.h>
#include <sys/dir.h>
#include <sys/user.h>
#include <machine/reg.h>
#include <sys/stat.h>

#ifndef public

typedef struct Process *Process;

Process process;

#define DEFSIG -1

#include "machine.h"

#endif

#define NOTSTARTED 1
#define STOPPED 0177
#define FINISHED 0

/*
 * A cache of the instruction segment is kept to reduce the number
 * of system calls.  Might be better just to read the entire
 * code space into memory.
 */

#define CSIZE 1003       /* size of instruction cache */

typedef struct {
    Word addr;
    Word val;
} CacheWord;

/*
 * This structure holds the information we need from the user structure.
 */

struct Process {
    int pid;			/* process being traced */
    int mask;			/* process status word */
    Word reg[NREG];		/* process' registers */
    Word oreg[NREG];		/* registers when process last stopped */
    short status;		/* either STOPPED or FINISHED */
    short signo;		/* signal that stopped process */
    int exitval;		/* return value from exit() */
    long sigset;		/* bit array of traced signals */
    CacheWord word[CSIZE];	/* text segment cache */
    Ttyinfo ttyinfo;		/* process' terminal characteristics */
    Address sigstatus;		/* process' handler for current signal */
};

/*
 * These definitions are for the arguments to "pio".
 */

typedef enum { PREAD, PWRITE } PioOp;
typedef enum { TEXTSEG, DATASEG } PioSeg;

private struct Process pbuf;

#define MAXNCMDARGS 100         /* maximum number of arguments to RUN */

extern int errno;

private Boolean just_started;
private int argc;
private String argv[MAXNCMDARGS];
private String infile, outfile;

/*
 * Initialize process information.
 */

public process_init()
{
    register Integer i;
    Char buf[10];

    process = &pbuf;
    process->status = (coredump) ? STOPPED : NOTSTARTED;
    setsigtrace();
    for (i = 0; i < NREG; i++) {
	sprintf(buf, "$r%d", i);
	defregname(identname(buf, false), i);
    }
    defregname(identname("$ap", true), ARGP);
    defregname(identname("$fp", true), FRP);
    defregname(identname("$sp", true), STKP);
    defregname(identname("$pc", true), PROGCTR);
    if (coredump) {
	coredump_readin(process->mask, process->reg, process->signo);
	pc = process->reg[PROGCTR];
	getsrcpos();
    }
    arginit();
}

/*
 * Routines to get at process information from outside this module.
 */

public Word reg(n)
Integer n;
{
    register Word w;

    if (n == NREG) {
	w = process->mask;
    } else {
	w = process->reg[n];
    }
    return w;
}

public setreg(n, w)
Integer n;
Word w;
{
    process->reg[n] = w;
}

/*
 * Begin execution.
 *
 * We set a breakpoint at the end of the code so that the
 * process data doesn't disappear after the program terminates.
 */

private Boolean remade();

public start(argv, infile, outfile)
String argv[];
String infile, outfile;
{
    String pargv[4];
    Node cond;

    if (coredump) {
	coredump = false;
	fclose(corefile);
	coredump_close();
    }
    if (argv == nil) {
	argv = pargv;
	pargv[0] = objname;
	pargv[1] = nil;
    } else {
	argv[argc] = nil;
    }
    if (remade(objname)) {
	reinit(argv, infile, outfile);
    }
    pstart(process, argv, infile, outfile);
    if (process->status == STOPPED) {
	pc = 0;
	setcurfunc(program);
	if (objsize != 0) {
	    cond = build(O_EQ, build(O_SYM, pcsym), build(O_LCON, lastaddr()));
	    event_once(cond, buildcmdlist(build(O_ENDX)));
	}
    }
}

/*
 * Check to see if the object file has changed since the symbolic
 * information last was read.
 */

private time_t modtime;

private Boolean remade(filename)
String filename;
{
    struct stat s;
    Boolean b;

    stat(filename, &s);
    b = (Boolean) (modtime != 0 and modtime < s.st_mtime);
    modtime = s.st_mtime;
    return b;
}

/*
 * Set up what signals we want to trace.
 */

private setsigtrace()
{
    register Integer i;
    register Process p;

    p = process;
    for (i = 1; i <= NSIG; i++) {
	psigtrace(p, i, true);
    }
    psigtrace(p, SIGHUP, false);
    psigtrace(p, SIGKILL, false);
    psigtrace(p, SIGALRM, false);
    psigtrace(p, SIGTSTP, false);
    psigtrace(p, SIGCONT, false);
    psigtrace(p, SIGCHLD, false);
}

/*
 * Initialize the argument list.
 */

public arginit()
{
    infile = nil;
    outfile = nil;
    argv[0] = objname;
    argc = 1;
}

/*
 * Add an argument to the list for the debuggee.
 */

public newarg(arg)
String arg;
{
    if (argc >= MAXNCMDARGS) {
	error("too many arguments");
    }
    argv[argc++] = arg;
}

/*
 * Set the standard input for the debuggee.
 */

public inarg(filename)
String filename;
{
    if (infile != nil) {
	error("multiple input redirects");
    }
    infile = filename;
}

/*
 * Set the standard output for the debuggee.
 * Probably should check to avoid overwriting an existing file.
 */

public outarg(filename)
String filename;
{
    if (outfile != nil) {
	error("multiple output redirect");
    }
    outfile = filename;
}

/*
 * Start debuggee executing.
 */

public run()
{
    process->status = STOPPED;
    fixbps();
    curline = 0;
    start(argv, infile, outfile);
    just_started = true;
    isstopped = false;
    cont(0);
}

/*
 * Continue execution wherever we left off.
 *
 * Note that this routine never returns.  Eventually bpact() will fail
 * and we'll call printstatus or step will call it.
 */

typedef int Intfunc();

private Intfunc *dbintr;
private intr();

#define succeeds    == true
#define fails       == false

public cont(signo)
integer signo;
{
    integer s;

    dbintr = signal(SIGINT, intr);
    if (just_started) {
	just_started = false;
    } else {
	if (not isstopped) {
	    error("can't continue execution");
	}
	isstopped = false;
	stepover();
    }
    s = signo;
    for (;;) {
	if (single_stepping) {
	    printnews();
	} else {
	    setallbps();
	    resume(s);
	    unsetallbps();
	    s = DEFSIG;
	    if (bpact() fails) {
		printstatus();
	    }
	}
	stepover();
    }
    /* NOTREACHED */
}

/*
 * This routine is called if we get an interrupt while "running" px
 * but actually in the debugger.  Could happen, for example, while
 * processing breakpoints.
 *
 * We basically just want to keep going; the assumption is
 * that when the process resumes it will get the interrupt
 * which will then be handled.
 */

private intr()
{
    signal(SIGINT, intr);
}

public fixintr()
{
    signal(SIGINT, dbintr);
}

/*
 * Resume execution.
 */

public resume(signo)
int signo;
{
    register Process p;

    p = process;
    pcont(p, signo);
    pc = process->reg[PROGCTR];
    if (p->status != STOPPED) {
	if (p->signo != 0) {
	    error("program terminated by signal %d", p->signo);
	} else if (not runfirst) {
	    error("program unexpectedly exited with %d", p->exitval);
	}
    }
}

/*
 * Continue execution up to the next source line.
 *
 * There are two ways to define the next source line depending on what
 * is desired when a procedure or function call is encountered.  Step
 * stops at the beginning of the procedure or call; next skips over it.
 */

/*
 * Stepc is what is called when the step command is given.
 * It has to play with the "isstopped" information.
 */

public stepc()
{
    if (not isstopped) {
	error("can't continue execution");
    }
    isstopped = false;
    dostep(false);
    isstopped = true;
}

public next()
{
    Address oldfrp, newfrp;

    if (not isstopped) {
	error("can't continue execution");
    }
    isstopped = false;
    oldfrp = reg(FRP);
    do {
	dostep(true);
	pc = reg(PROGCTR);
	newfrp = reg(FRP);
    } while (newfrp < oldfrp and newfrp != 0);
    isstopped = true;
}

/*
 * Continue execution until the current function returns, or,
 * if the given argument is non-nil, until execution returns to
 * somewhere within the given function.
 */

public rtnfunc (f)
Symbol f;
{
    Address addr;
    Symbol t;

    if (not isstopped) {
	error("can't continue execution");
    } else if (f != nil and not isactive(f)) {
	error("%s is not active", symname(f));
    } else {
	addr = return_addr();
	if (addr == nil) {
	    error("no place to return to");
	} else {
	    isstopped = false;
	    contto(addr);
	    if (f != nil) {
		for (;;) {
		    t = whatblock(pc);
		    addr = return_addr();
		if (t == f or addr == nil) break;
		    contto(addr);
		}
	    }
	    if (bpact() fails) {
		isstopped = true;
		printstatus();
	    }
	}
    }
}

/*
 * Single-step over the current machine instruction.
 *
 * 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.  It is assumed that
 * no breakpoints exist between the current address and the one
 * we're stepping to.  This saves us from setting all the breakpoints.
 */

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 {
	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);
}

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

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

/*
 * 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.
 */