var.c

来自「Android 一些工具」· C语言 代码 · 共 826 行 · 第 1/2 页

/*
 * Called when a shell procedure is invoked to clear out nonexported
 * variables.  It is also necessary to reallocate variables of with
 * VSTACK set since these are currently allocated on the stack.
 */

#ifdef mkinit
void shprocvar(void);

SHELLPROC {
	shprocvar();
}
#endif

void
shprocvar(void)
{
	struct var **vpp;
	struct var *vp, **prev;

	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
		for (prev = vpp ; (vp = *prev) != NULL ; ) {
			if ((vp->flags & VEXPORT) == 0) {
				*prev = vp->next;
				if ((vp->flags & VTEXTFIXED) == 0)
					ckfree(vp->text);
				if ((vp->flags & VSTRFIXED) == 0)
					ckfree(vp);
			} else {
				if (vp->flags & VSTACK) {
					vp->text = savestr(vp->text);
					vp->flags &=~ VSTACK;
				}
				prev = &vp->next;
			}
		}
	}
	initvar();
}



/*
 * Command to list all variables which are set.  Currently this command
 * is invoked from the set command when the set command is called without
 * any variables.
 */

void
print_quoted(const char *p)
{
	const char *q;

	if (strcspn(p, "|&;<>()$`\\\"' \t\n*?[]#~=%") == strlen(p)) {
		out1fmt("%s", p);
		return;
	}
	while (*p) {
		if (*p == '\'') {
			out1fmt("\\'");
			p++;
			continue;
		}
		q = index(p, '\'');
		if (!q) {
			out1fmt("'%s'", p );
			return;
		}
		out1fmt("'%.*s'", (int)(q - p), p );
		p = q;
	}
}

static int
sort_var(const void *v_v1, const void *v_v2)
{
	const struct var * const *v1 = v_v1;
	const struct var * const *v2 = v_v2;

	/* XXX Will anyone notice we include the '=' of the shorter name? */
	return strcmp((*v1)->text, (*v2)->text);
}

/*
 * POSIX requires that 'set' (but not export or readonly) output the
 * variables in lexicographic order - by the locale's collating order (sigh).
 * Maybe we could keep them in an ordered balanced binary tree
 * instead of hashed lists.
 * For now just roll 'em through qsort for printing...
 */

int
showvars(const char *name, int flag, int show_value)
{
	struct var **vpp;
	struct var *vp;
	const char *p;

	static struct var **list;	/* static in case we are interrupted */
	static int list_len;
	int count = 0;

	if (!list) {
		list_len = 32;
		list = ckmalloc(list_len * sizeof *list);
	}

	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
		for (vp = *vpp ; vp ; vp = vp->next) {
			if (flag && !(vp->flags & flag))
				continue;
			if (vp->flags & VUNSET && !(show_value & 2))
				continue;
			if (count >= list_len) {
				list = ckrealloc(list,
					(list_len << 1) * sizeof *list);
				list_len <<= 1;
			}
			list[count++] = vp;
		}
	}

	qsort(list, count, sizeof *list, sort_var);

	for (vpp = list; count--; vpp++) {
		vp = *vpp;
		if (name)
			out1fmt("%s ", name);
		for (p = vp->text ; *p != '=' ; p++)
			out1c(*p);
		if (!(vp->flags & VUNSET) && show_value) {
			out1fmt("=");
			print_quoted(++p);
		}
		out1c('\n');
	}
	return 0;
}



/*
 * The export and readonly commands.
 */

int
exportcmd(int argc, char **argv)
{
	struct var *vp;
	char *name;
	const char *p;
	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
	int pflag;

	pflag = nextopt("p") == 'p' ? 3 : 0;
	if (argc <= 1 || pflag) {
		showvars( pflag ? argv[0] : 0, flag, pflag );
		return 0;
	}

	while ((name = *argptr++) != NULL) {
		if ((p = strchr(name, '=')) != NULL) {
			p++;
		} else {
			vp = find_var(name, NULL, NULL);
			if (vp != NULL) {
				vp->flags |= flag;
				continue;
			}
		}
		setvar(name, p, flag);
	}
	return 0;
}


/*
 * The "local" command.
 */

int
localcmd(int argc, char **argv)
{
	char *name;

	if (! in_function())
		error("Not in a function");
	while ((name = *argptr++) != NULL) {
		mklocal(name, 0);
	}
	return 0;
}


/*
 * Make a variable a local variable.  When a variable is made local, it's
 * value and flags are saved in a localvar structure.  The saved values
 * will be restored when the shell function returns.  We handle the name
 * "-" as a special case.
 */

void
mklocal(const char *name, int flags)
{
	struct localvar *lvp;
	struct var **vpp;
	struct var *vp;

	INTOFF;
	lvp = ckmalloc(sizeof (struct localvar));
	if (name[0] == '-' && name[1] == '\0') {
		char *p;
		p = ckmalloc(sizeof_optlist);
		lvp->text = memcpy(p, optlist, sizeof_optlist);
		vp = NULL;
	} else {
		vp = find_var(name, &vpp, NULL);
		if (vp == NULL) {
			if (strchr(name, '='))
				setvareq(savestr(name), VSTRFIXED|flags);
			else
				setvar(name, NULL, VSTRFIXED|flags);
			vp = *vpp;	/* the new variable */
			lvp->text = NULL;
			lvp->flags = VUNSET;
		} else {
			lvp->text = vp->text;
			lvp->flags = vp->flags;
			vp->flags |= VSTRFIXED|VTEXTFIXED;
			if (name[vp->name_len] == '=')
				setvareq(savestr(name), flags);
		}
	}
	lvp->vp = vp;
	lvp->next = localvars;
	localvars = lvp;
	INTON;
}


/*
 * Called after a function returns.
 */

void
poplocalvars(void)
{
	struct localvar *lvp;
	struct var *vp;

	while ((lvp = localvars) != NULL) {
		localvars = lvp->next;
		vp = lvp->vp;
		TRACE(("poplocalvar %s", vp ? vp->text : "-"));
		if (vp == NULL) {	/* $- saved */
			memcpy(optlist, lvp->text, sizeof_optlist);
			ckfree(lvp->text);
		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
			(void)unsetvar(vp->text, 0);
		} else {
			if (vp->func && (vp->flags & VNOFUNC) == 0)
				(*vp->func)(lvp->text + vp->name_len + 1);
			if ((vp->flags & VTEXTFIXED) == 0)
				ckfree(vp->text);
			vp->flags = lvp->flags;
			vp->text = lvp->text;
		}
		ckfree(lvp);
	}
}


int
setvarcmd(int argc, char **argv)
{
	if (argc <= 2)
		return unsetcmd(argc, argv);
	else if (argc == 3)
		setvar(argv[1], argv[2], 0);
	else
		error("List assignment not implemented");
	return 0;
}


/*
 * The unset builtin command.  We unset the function before we unset the
 * variable to allow a function to be unset when there is a readonly variable
 * with the same name.
 */

int
unsetcmd(int argc, char **argv)
{
	char **ap;
	int i;
	int flg_func = 0;
	int flg_var = 0;
	int ret = 0;

	while ((i = nextopt("evf")) != '\0') {
		if (i == 'f')
			flg_func = 1;
		else
			flg_var = i;
	}
	if (flg_func == 0 && flg_var == 0)
		flg_var = 1;

	for (ap = argptr; *ap ; ap++) {
		if (flg_func)
			ret |= unsetfunc(*ap);
		if (flg_var)
			ret |= unsetvar(*ap, flg_var == 'e');
	}
	return ret;
}


/*
 * Unset the specified variable.
 */

int
unsetvar(const char *s, int unexport)
{
	struct var **vpp;
	struct var *vp;

	vp = find_var(s, &vpp, NULL);
	if (vp == NULL)
		return 1;

	if (vp->flags & VREADONLY)
		return (1);

	INTOFF;
	if (unexport) {
		vp->flags &= ~VEXPORT;
	} else {
		if (vp->text[vp->name_len + 1] != '\0')
			setvar(s, nullstr, 0);
		vp->flags &= ~VEXPORT;
		vp->flags |= VUNSET;
		if ((vp->flags & VSTRFIXED) == 0) {
			if ((vp->flags & VTEXTFIXED) == 0)
				ckfree(vp->text);
			*vpp = vp->next;
			ckfree(vp);
		}
	}
	INTON;
	return 0;
}


/*
 * Returns true if the two strings specify the same varable.  The first
 * variable name is terminated by '='; the second may be terminated by
 * either '=' or '\0'.
 */

STATIC int
strequal(const char *p, const char *q)
{
	while (*p == *q++) {
		if (*p++ == '=')
			return 1;
	}
	if (*p == '=' && *(q - 1) == '\0')
		return 1;
	return 0;
}

/*
 * Search for a variable.
 * 'name' may be terminated by '=' or a NUL.
 * vppp is set to the pointer to vp, or the list head if vp isn't found
 * lenp is set to the number of charactets in 'name'
 */

STATIC struct var *
find_var(const char *name, struct var ***vppp, int *lenp)
{
	unsigned int hashval;
	int len;
	struct var *vp, **vpp;
	const char *p = name;

	hashval = 0;
	while (*p && *p != '=')
		hashval = 2 * hashval + (unsigned char)*p++;
	len = p - name;

	if (lenp)
		*lenp = len;
	vpp = &vartab[hashval % VTABSIZE];
	if (vppp)
		*vppp = vpp;

	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
		if (vp->name_len != len)
			continue;
		if (memcmp(vp->text, name, len) != 0)
			continue;
		if (vppp)
			*vppp = vpp;
		return vp;
	}
	return NULL;
}