builtin.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ctype.h>
#include <mach.h>
#include <regexp.h>
#define Extern extern
#include "acid.h"
#include "y.tab.h"

void	cvtatof(Node*, Node*);
void	cvtatoi(Node*, Node*);
void	cvtitoa(Node*, Node*);
void	bprint(Node*, Node*);
void	funcbound(Node*, Node*);
void	printto(Node*, Node*);
void	getfile(Node*, Node*);
void	fmt(Node*, Node*);
void	pcfile(Node*, Node*);
void	pcline(Node*, Node*);
void	setproc(Node*, Node*);
void	strace(Node*, Node*);
void	follow(Node*, Node*);
void	reason(Node*, Node*);
void	newproc(Node*, Node*);
void	startstop(Node*, Node*);
void	match(Node*, Node*);
void	status(Node*, Node*);
void	kill(Node*,Node*);
void	waitstop(Node*, Node*);
void	stop(Node*, Node*);
void	start(Node*, Node*);
void	filepc(Node*, Node*);
void	doerror(Node*, Node*);
void	rc(Node*, Node*);
void	doaccess(Node*, Node*);
void	map(Node*, Node*);
void	readfile(Node*, Node*);
void	interpret(Node*, Node*);
void	include(Node*, Node*);
void	regexp(Node*, Node*);
void	dosysr1(Node*, Node*);

typedef struct Btab Btab;
struct Btab
{
	char	*name;
	void	(*fn)(Node*, Node*);
} tab[] =
{
	"atof",		cvtatof,
	"atoi",		cvtatoi,
	"error",	doerror,
	"file",		getfile,
	"readfile",	readfile,
	"access",	doaccess,
	"filepc",	filepc,
	"fnbound",	funcbound,
	"fmt",		fmt,
	"follow",	follow,
	"itoa",		cvtitoa,
	"kill",		kill,
	"match",	match,
	"newproc",	newproc,
	"pcfile",	pcfile,
	"pcline",	pcline,
	"print",	bprint,
	"printto",	printto,
	"rc",		rc,
	"reason",	reason,
	"setproc",	setproc,
	"start",	start,
	"startstop",	startstop,
	"status",	status,
	"stop",		stop,
	"strace",	strace,
	"sysr1",	dosysr1,
	"waitstop",	waitstop,
	"map",		map,
	"interpret",	interpret,
	"include",	include,
	"regexp",	regexp,
	0
};

char vfmt[] = "aBbcCdDfFgGiIoOqQrRsSuUVWxXYZ";

void
mkprint(Lsym *s)
{
	prnt = malloc(sizeof(Node));
	memset(prnt, 0, sizeof(Node));
	prnt->op = OCALL;
	prnt->left = malloc(sizeof(Node));
	memset(prnt->left, 0, sizeof(Node));
	prnt->left->sym = s;
}

void
installbuiltin(void)
{
	Btab *b;
	Lsym *s;

	b = tab;
	while(b->name) {
		s = look(b->name);
		if(s == 0)
			s = enter(b->name, Tid);

		s->builtin = b->fn;
		if(b->fn == bprint)
			mkprint(s);
		b++;
	}
}

void
dosysr1(Node *r, Node*)
{
	extern int sysr1(void);
	
	r->op = OCONST;
	r->type = TINT;
	r->fmt = 'D';
	r->ival = sysr1();
}

void
match(Node *r, Node *args)
{
	int i;
	List *f;
	Node *av[Maxarg];
	Node resi, resl;

	na = 0;
	flatten(av, args);
	if(na != 2)
		error("match(obj, list): arg count");

	expr(av[1], &resl);
	if(resl.type != TLIST)
		error("match(obj, list): need list");
	expr(av[0], &resi);

	r->op = OCONST;
	r->type = TINT;
	r->fmt = 'D';
	r->ival = -1;

	i = 0;
	for(f = resl.l; f; f = f->next) {
		if(resi.type == f->type) {
			switch(resi.type) {
			case TINT:
				if(resi.ival == f->ival) {
					r->ival = i;
					return;
				}
				break;
			case TFLOAT:
				if(resi.fval == f->fval) {
					r->ival = i;
					return;
				}
				break;
			case TSTRING:
				if(scmp(resi.string, f->string)) {
					r->ival = i;
					return;
				}
				break;
			case TLIST:
				error("match(obj, list): not defined for list");
			}
		}
		i++;
	}
}

void
newproc(Node *r, Node *args)
{
	int i;
	Node res;
	char *p, *e;
	char *argv[Maxarg], buf[Strsize];

	i = 1;
	argv[0] = aout;

	if(args) {
		expr(args, &res);
		if(res.type != TSTRING)
			error("newproc(): arg not string");
		if(res.string->len >= sizeof(buf))
			error("newproc(): too many arguments");
		memmove(buf, res.string->string, res.string->len);
		buf[res.string->len] = '\0';
		p = buf;
		e = buf+res.string->len;
		for(;;) {
			while(p < e && (*p == '\t' || *p == ' '))
				*p++ = '\0';
			if(p >= e)
				break;
			argv[i++] = p;
			if(i >= Maxarg)
				error("newproc: too many arguments");
			while(p < e && *p != '\t' && *p != ' ')
				p++;
		}
	}
	argv[i] = 0;
	r->op = OCONST;
	r->type = TINT;
	r->fmt = 'D';
	r->ival = nproc(argv);
}

void
startstop(Node *r, Node *args)
{
	Node res;

	USED(r);
	if(args == 0)
		error("startstop(pid): no pid");
	expr(args, &res);
	if(res.type != TINT)
		error("startstop(pid): arg type");

	msg(res.ival, "startstop");
	notes(res.ival);
	dostop(res.ival);
}

void
waitstop(Node *r, Node *args)
{
	Node res;

	USED(r);
	if(args == 0)
		error("waitstop(pid): no pid");
	expr(args, &res);
	if(res.type != TINT)
		error("waitstop(pid): arg type");

	Bflush(bout);
	msg(res.ival, "waitstop");
	notes(res.ival);
	dostop(res.ival);
}

void
start(Node *r, Node *args)
{
	Node res;

	USED(r);
	if(args == 0)
		error("start(pid): no pid");
	expr(args, &res);
	if(res.type != TINT)
		error("start(pid): arg type");

	msg(res.ival, "start");
}

void
stop(Node *r, Node *args)
{
	Node res;

	USED(r);
	if(args == 0)
		error("stop(pid): no pid");
	expr(args, &res);
	if(res.type != TINT)
		error("stop(pid): arg type");

	Bflush(bout);
	msg(res.ival, "stop");
	notes(res.ival);
	dostop(res.ival);
}

void
kill(Node *r, Node *args)
{
	Node res;

	USED(r);
	if(args == 0)
		error("kill(pid): no pid");
	expr(args, &res);
	if(res.type != TINT)
		error("kill(pid): arg type");

	msg(res.ival, "kill");
	deinstall(res.ival);
}

void
status(Node *r, Node *args)
{
	Node res;
	char *p;

	USED(r);
	if(args == 0)
		error("status(pid): no pid");
	expr(args, &res);
	if(res.type != TINT)
		error("status(pid): arg type");

	p = getstatus(res.ival);
	r->string = strnode(p);
	r->op = OCONST;
	r->fmt = 's';
	r->type = TSTRING;
}

void
reason(Node *r, Node *args)
{
	Node res;

	if(args == 0)
		error("reason(cause): no cause");
	expr(args, &res);
	if(res.type != TINT)
		error("reason(cause): arg type");

	r->op = OCONST;
	r->type = TSTRING;
	r->fmt = 's';
	r->string = strnode((*machdata->excep)(cormap, rget));
}

void
follow(Node *r, Node *args)
{
	int n, i;
	Node res;
	uvlong f[10];
	List **tail, *l;

	if(args == 0)
		error("follow(addr): no addr");
	expr(args, &res);
	if(res.type != TINT)
		error("follow(addr): arg type");

	n = (*machdata->foll)(cormap, res.ival, rget, f);
	if (n < 0)
		error("follow(addr): %r");
	tail = &r->l;
	for(i = 0; i < n; i++) {
		l = al(TINT);
		l->ival = f[i];
		l->fmt = 'X';
		*tail = l;
		tail = &l->next;
	}
}

void
funcbound(Node *r, Node *args)
{
	int n;
	Node res;
	uvlong bounds[2];
	List *l;

	if(args == 0)
		error("fnbound(addr): no addr");
	expr(args, &res);
	if(res.type != TINT)
		error("fnbound(addr): arg type");

	n = fnbound(res.ival, bounds);
	if (n != 0) {
		r->l = al(TINT);
		l = r->l;
		l->ival = bounds[0];
		l->fmt = 'X';
		l->next = al(TINT);
		l = l->next;
		l->ival = bounds[1];
		l->fmt = 'X';
	}
}

void
setproc(Node *r, Node *args)
{
	Node res;

	USED(r);
	if(args == 0)
		error("setproc(pid): no pid");
	expr(args, &res);
	if(res.type != TINT)
		error("setproc(pid): arg type");

	sproc(res.ival);
}

void
filepc(Node *r, Node *args)
{
	Node res;
	char *p, c;

	if(args == 0)
		error("filepc(filename:line): arg count");
	expr(args, &res);
	if(res.type != TSTRING)
		error("filepc(filename:line): arg type");

	p = strchr(res.string->string, ':');
	if(p == 0)
		error("filepc(filename:line): bad arg format");

	c = *p;
	*p++ = '\0';
	r->ival = file2pc(res.string->string, strtol(p, 0, 0));
	p[-1] = c;
	if(r->ival == ~0)
		error("filepc(filename:line): can't find address");

	r->op = OCONST;
	r->type = TINT;
	r->fmt = 'V';
}

void
interpret(Node *r, Node *args)
{
	Node res;
	int isave;

	if(args == 0)
		error("interpret(string): arg count");
	expr(args, &res);
	if(res.type != TSTRING)
		error("interpret(string): arg type");

	pushstr(&res);

	isave = interactive;
	interactive = 0;
	r->ival = yyparse();
	interactive = isave;
	popio();
	r->op = OCONST;
	r->type = TINT;
	r->fmt = 'D';
}

void
include(Node *r, Node *args)
{
	Node res;
	int isave;

	if(args == 0)
		error("include(string): arg count");
	expr(args, &res);
	if(res.type != TSTRING)
		error("include(string): arg type");

	pushfile(res.string->string);

	isave = interactive;
	interactive = 0;
	r->ival = yyparse();
	interactive = isave;
	popio();
	r->op = OCONST;
	r->type = TINT;
	r->fmt = 'D';
}

void
rc(Node *r, Node *args)
{
	Node res;
	int pid;
	char *p, *q, *argv[4];
	Waitmsg *w;

	USED(r);
	if(args == 0)
		error("error(string): arg count");
	expr(args, &res);
	if(res.type != TSTRING)
		error("error(string): arg type");

	argv[0] = "/bin/rc";
	argv[1] = "-c";
	argv[2] = res.string->string;
	argv[3] = 0;

	pid = fork();
	switch(pid) {
	case -1:
		error("fork %r");
	case 0:
		exec("/bin/rc", argv);
		exits(0);
	default:
		w = waitfor(pid);
		break;
	}
	p = w->msg;
	q = strrchr(p, ':');
	if (q)
		p = q+1;

	r->op = OCONST;
	r->type = TSTRING;
	r->string = strnode(p);
	free(w);
	r->fmt = 's';
}

void
doerror(Node *r, Node *args)
{
	Node res;

	USED(r);
	if(args == 0)
		error("error(string): arg count");
	expr(args, &res);
	if(res.type != TSTRING)
		error("error(string): arg type");

	error(res.string->string);
}

void
doaccess(Node *r, Node *args)
{
	Node res;

	if(args == 0)
		error("access(filename): arg count");
	expr(args, &res);
	if(res.type != TSTRING)
		error("access(filename): arg type");

	r->op = OCONST;
	r->type = TINT;
	r->ival = 0;		
	if(access(res.string->string, 4) == 0)
		r->ival = 1;
}

void
readfile(Node *r, Node *args)
{
	Node res;
	int n, fd;
	char *buf;
	Dir *db;

	if(args == 0)
		error("readfile(filename): arg count");
	expr(args, &res);
	if(res.type != TSTRING)
		error("readfile(filename): arg type");

	fd = open(res.string->string, OREAD);
	if(fd < 0)
		return;

	db = dirfstat(fd);
	if(db == nil || db->length == 0)
		n = 8192;
	else
		n = db->length;
	free(db);

	buf = malloc(n);
	n = read(fd, buf, n);

	if(n > 0) {
		r->op = OCONST;
		r->type = TSTRING;
		r->string = strnodlen(buf, n);
		r->fmt = 's';
	}
	free(buf);
	close(fd);
}

void
getfile(Node *r, Node *args)
{
	int n;
	char *p;
	Node res;
	String *s;
	Biobuf *bp;
	List **l, *new;

	if(args == 0)
		error("file(filename): arg count");
	expr(args, &res);
	if(res.type != TSTRING)
		error("file(filename): arg type");

	r->op = OCONST;
	r->type = TLIST;
	r->l = 0;

	p = res.string->string;
	bp = Bopen(p, OREAD);
	if(bp == 0)
		return;

	l = &r->l;
	for(;;) {
		p = Brdline(bp, '\n');
		n = Blinelen(bp);
		if(p == 0) {
			if(n == 0)
				break;