set.c

早期freebsd实现

    Char   *var;
    struct varent *head;
{
    register struct varent *vp;

    vp = adrof1(var, head);
    return (vp == 0 || vp->vec[0] == 0 ? STRNULL : vp->vec[0]);
}

static struct varent *
madrof(pat, vp)
    Char   *pat;
    register struct varent *vp;
{
    register struct varent *vp1;

    for (; vp; vp = vp->v_right) {
	if (vp->v_left && (vp1 = madrof(pat, vp->v_left)))
	    return vp1;
	if (Gmatch(vp->v_name, pat))
	    return vp;
    }
    return vp;
}

struct varent *
adrof1(name, v)
    register Char *name;
    register struct varent *v;
{
    register cmp;

    v = v->v_left;
    while (v && ((cmp = *name - *v->v_name) ||
		 (cmp = Strcmp(name, v->v_name))))
	if (cmp < 0)
	    v = v->v_left;
	else
	    v = v->v_right;
    return v;
}

/*
 * The caller is responsible for putting value in a safe place
 */
void
set(var, val)
    Char   *var, *val;
{
    register Char **vec = (Char **) xmalloc((size_t) (2 * sizeof(Char **)));

    vec[0] = val;
    vec[1] = 0;
    set1(var, vec, &shvhed);
}

void
set1(var, vec, head)
    Char   *var, **vec;
    struct varent *head;
{
    register Char **oldv = vec;

    gflag = 0;
    tglob(oldv);
    if (gflag) {
	vec = globall(oldv);
	if (vec == 0) {
	    blkfree(oldv);
	    stderror(ERR_NAME | ERR_NOMATCH);
	    return;
	}
	blkfree(oldv);
	gargv = 0;
    }
    setq(var, vec, head);
}


void
setq(name, vec, p)
    Char   *name, **vec;
    register struct varent *p;
{
    register struct varent *c;
    register f;

    f = 0;			/* tree hangs off the header's left link */
    while ((c = p->v_link[f]) != NULL) {
	if ((f = *name - *c->v_name) == 0 &&
	    (f = Strcmp(name, c->v_name)) == 0) {
	    blkfree(c->vec);
	    goto found;
	}
	p = c;
	f = f > 0;
    }
    p->v_link[f] = c = (struct varent *) xmalloc((size_t) sizeof(struct varent));
    c->v_name = Strsave(name);
    c->v_bal = 0;
    c->v_left = c->v_right = 0;
    c->v_parent = p;
    balance(p, f, 0);
found:
    trim(c->vec = vec);
}

void
/*ARGSUSED*/
unset(v, t)
    Char **v;
    struct command *t;
{
    unset1(v, &shvhed);
#ifdef FILEC
    if (adrof(STRfilec) == 0)
	filec = 0;
#endif
    if (adrof(STRhistchars) == 0) {
	HIST = '!';
	HISTSUB = '^';
    }
    if (adrof(STRwordchars) == 0)
	word_chars = STR_WORD_CHARS;
}

void
unset1(v, head)
    register Char *v[];
    struct varent *head;
{
    register struct varent *vp;
    register int cnt;

    while (*++v) {
	cnt = 0;
	while ((vp = madrof(*v, head->v_left)) != NULL)
	    unsetv1(vp), cnt++;
	if (cnt == 0)
	    setname(vis_str(*v));
    }
}

void
unsetv(var)
    Char   *var;
{
    register struct varent *vp;

    if ((vp = adrof1(var, &shvhed)) == 0)
	udvar(var);
    unsetv1(vp);
}

static void
unsetv1(p)
    register struct varent *p;
{
    register struct varent *c, *pp;
    register f;

    /*
     * Free associated memory first to avoid complications.
     */
    blkfree(p->vec);
    xfree((ptr_t) p->v_name);
    /*
     * If p is missing one child, then we can move the other into where p is.
     * Otherwise, we find the predecessor of p, which is guaranteed to have no
     * right child, copy it into p, and move it's left child into it.
     */
    if (p->v_right == 0)
	c = p->v_left;
    else if (p->v_left == 0)
	c = p->v_right;
    else {
	for (c = p->v_left; c->v_right; c = c->v_right)
	    continue;
	p->v_name = c->v_name;
	p->vec = c->vec;
	p = c;
	c = p->v_left;
    }
    /*
     * Move c into where p is.
     */
    pp = p->v_parent;
    f = pp->v_right == p;
    if ((pp->v_link[f] = c) != NULL)
	c->v_parent = pp;
    /*
     * Free the deleted node, and rebalance.
     */
    xfree((ptr_t) p);
    balance(pp, f, 1);
}

void
setNS(cp)
    Char   *cp;
{
    set(cp, Strsave(STRNULL));
}

void
/*ARGSUSED*/
shift(v, t)
    Char **v;
    struct command *t;
{
    register struct varent *argv;
    register Char *name;

    v++;
    name = *v;
    if (name == 0)
	name = STRargv;
    else
	(void) strip(name);
    argv = adrof(name);
    if (argv == 0)
	udvar(name);
    if (argv->vec[0] == 0)
	stderror(ERR_NAME | ERR_NOMORE);
    lshift(argv->vec, 1);
}

static void
exportpath(val)
    Char  **val;
{
    Char    exppath[BUFSIZ];

    exppath[0] = 0;
    if (val)
	while (*val) {
	    if (Strlen(*val) + Strlen(exppath) + 2 > BUFSIZ) {
		(void) fprintf(csherr,
			       "Warning: ridiculously long PATH truncated\n");
		break;
	    }
	    if ((**val != '/' || **val == '\0') && (euid == 0 || uid == 0)) 
		    (void) fprintf(csherr,
		    "Warning: exported path contains relative components.\n");
	    (void) Strcat(exppath, *val++);
	    if (*val == 0 || eq(*val, STRRparen))
		break;
	    (void) Strcat(exppath, STRcolon);
	}
    Setenv(STRPATH, exppath);
}

#ifndef lint
 /*
  * Lint thinks these have null effect
  */
 /* macros to do single rotations on node p */
#define rright(p) (\
	t = (p)->v_left,\
	(t)->v_parent = (p)->v_parent,\
	((p)->v_left = t->v_right) ? (t->v_right->v_parent = (p)) : 0,\
	(t->v_right = (p))->v_parent = t,\
	(p) = t)
#define rleft(p) (\
	t = (p)->v_right,\
	(t)->v_parent = (p)->v_parent,\
	((p)->v_right = t->v_left) ? (t->v_left->v_parent = (p)) : 0,\
	(t->v_left = (p))->v_parent = t,\
	(p) = t)
#else
struct varent *
rleft(p)
    struct varent *p;
{
    return (p);
}
struct varent *
rright(p)
    struct varent *p;
{
    return (p);
}

#endif				/* ! lint */


/*
 * Rebalance a tree, starting at p and up.
 * F == 0 means we've come from p's left child.
 * D == 1 means we've just done a delete, otherwise an insert.
 */
static void
balance(p, f, d)
    register struct varent *p;
    register int f, d;
{
    register struct varent *pp;

#ifndef lint
    register struct varent *t;	/* used by the rotate macros */

#endif
    register ff;

    /*
     * Ok, from here on, p is the node we're operating on; pp is it's parent; f
     * is the branch of p from which we have come; ff is the branch of pp which
     * is p.
     */
    for (; (pp = p->v_parent) != NULL; p = pp, f = ff) {
	ff = pp->v_right == p;
	if (f ^ d) {		/* right heavy */
	    switch (p->v_bal) {
	    case -1:		/* was left heavy */
		p->v_bal = 0;
		break;
	    case 0:		/* was balanced */
		p->v_bal = 1;
		break;
	    case 1:		/* was already right heavy */
		switch (p->v_right->v_bal) {
		case 1:	/* sigle rotate */
		    pp->v_link[ff] = rleft(p);
		    p->v_left->v_bal = 0;
		    p->v_bal = 0;
		    break;
		case 0:	/* single rotate */
		    pp->v_link[ff] = rleft(p);
		    p->v_left->v_bal = 1;
		    p->v_bal = -1;
		    break;
		case -1:	/* double rotate */
		    (void) rright(p->v_right);
		    pp->v_link[ff] = rleft(p);
		    p->v_left->v_bal =
			p->v_bal < 1 ? 0 : -1;
		    p->v_right->v_bal =
			p->v_bal > -1 ? 0 : 1;
		    p->v_bal = 0;
		    break;
		}
		break;
	    }
	}
	else {			/* left heavy */
	    switch (p->v_bal) {
	    case 1:		/* was right heavy */
		p->v_bal = 0;
		break;
	    case 0:		/* was balanced */
		p->v_bal = -1;
		break;
	    case -1:		/* was already left heavy */
		switch (p->v_left->v_bal) {
		case -1:	/* single rotate */
		    pp->v_link[ff] = rright(p);
		    p->v_right->v_bal = 0;
		    p->v_bal = 0;
		    break;
		case 0:	/* signle rotate */
		    pp->v_link[ff] = rright(p);
		    p->v_right->v_bal = -1;
		    p->v_bal = 1;
		    break;
		case 1:	/* double rotate */
		    (void) rleft(p->v_left);
		    pp->v_link[ff] = rright(p);
		    p->v_left->v_bal =
			p->v_bal < 1 ? 0 : -1;
		    p->v_right->v_bal =
			p->v_bal > -1 ? 0 : 1;
		    p->v_bal = 0;
		    break;
		}
		break;
	    }
	}
	/*
	 * If from insert, then we terminate when p is balanced. If from
	 * delete, then we terminate when p is unbalanced.
	 */
	if ((p->v_bal == 0) ^ d)
	    break;
    }
}

void
plist(p)
    register struct varent *p;
{
    register struct varent *c;
    register len;

    if (setintr)
	(void) sigsetmask(sigblock((sigset_t) 0) & ~sigmask(SIGINT));

    for (;;) {
	while (p->v_left)
	    p = p->v_left;
x:
	if (p->v_parent == 0)	/* is it the header? */
	    return;
	len = blklen(p->vec);
	(void) fprintf(cshout, "%s\t", short2str(p->v_name));
	if (len != 1)
	    (void) fputc('(', cshout);
	blkpr(cshout, p->vec);
	if (len != 1)
	    (void) fputc(')', cshout);
	(void) fputc('\n', cshout);
	if (p->v_right) {
	    p = p->v_right;
	    continue;
	}
	do {
	    c = p;
	    p = p->v_parent;
	} while (p->v_right == c);
	goto x;
    }
}