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6c4f87e41

Denys Vlasenko

2020-02-17

SUCCESS Duration: 152s

Subject

ash: exec: Stricter pathopt parsing

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Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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Commit Diff GitHub →

shell/ash.c +104 -64

shell/ash.c+104 -64

@@ -2557,8 +2557,31 @@ listvars(int on, int off, struct strlist lp, char **end)
	}


-	/* ============ Path search helper
-	*
+	/* ============ Path search helper */
+	static const char *
+	legal_pathopt(const char opt, const char term, int magic)
+	{
+	switch (magic) {
+	case 0:
+	opt = NULL;
+	break;
+
+	case 1:
+	opt = prefix(opt, "builtin") ?: prefix(opt, "func");
+	break;
+
+	default:
+	opt += strcspn(opt, term);
+	break;
+	}
+
+	if (opt && *opt == '%')
+	opt++;
+
+	return opt;
+	}
+
+	/*
	* The variable path (passed by reference) should be set to the start
	* of the path before the first call; padvance will update
	* this value as it proceeds. Successive calls to padvance will return
@@ -2566,40 +2589,70 @@ listvars(int on, int off, struct strlist lp, char **end)
	* a percent sign) appears in the path entry then the global variable
	* pathopt will be set to point to it; otherwise pathopt will be set to
	* NULL.
+	*
+	* If magic is 0 then pathopt recognition will be disabled. If magic is
+	* 1 we shall recognise %builtin/%func. Otherwise we shall accept any
+	* pathopt.
	*/
	static const char pathopt; / set by padvance */

	static int
-	padvance(const char *path, const char name)
+	padvance_magic(const char *path, const char name, int magic)
	{
+	const char *term = "%:";
+	const char *lpathopt;
	const char *p;
	char *q;
	const char *start;
+	size_t qlen;
	size_t len;

	if (*path == NULL)
	return -1;
+
+	lpathopt = NULL;
	start = *path;
-	for (p = start; p && p != ':' && *p != '%'; p++)
-	continue;
-	len = p - start + strlen(name) + 2; /* "2" is for '/' and '\0' */
-	q = growstackto(len);
-	if (p != start) {
-	q = mempcpy(q, start, p - start);
-	*q++ = '/';
+
+	if (*start == '%' && (p = legal_pathopt(start + 1, term, magic))) {
+	lpathopt = start + 1;
+	start = p;
+	term = ":";
	}
-	strcpy(q, name);
-	pathopt = NULL;
+
+	len = strcspn(start, term);
+	p = start + len;
+
	if (*p == '%') {
-	pathopt = ++p;
-	while (p && p != ':')
-	p++;
+	size_t extra = strchrnul(p, ':') - p;
+
+	if (legal_pathopt(p + 1, term, magic))
+	lpathopt = p + 1;
+	else
+	len += extra;
+
+	p += extra;
	}
-	if (*p == ':')
-	*path = p + 1;
-	else
-	*path = NULL;
-	return len;
+
+	pathopt = lpathopt;
+	path = p == ':' ? p + 1 : NULL;
+
+	/* "2" is for '/' and '\0' */
+	qlen = len + strlen(name) + 2;
+	q = growstackto(qlen);
+
+	if (len) {
+	q = mempcpy(q, start, len);
+	*q++ = '/';
+	}
+	strcpy(q, name);
+
+	return qlen;
+	}
+
+	static int
+	padvance(const char *path, const char name)
+	{
+	return padvance_magic(path, name, 1);
	}


@@ -8217,11 +8270,10 @@ printentry(struct tblentry *cmdp)
	}

	/*
-	* Clear out command entries. The argument specifies the first entry in
-	* PATH which has changed.
+	* Clear out command entries.
	*/
	static void
-	clearcmdentry(int firstchange)
+	clearcmdentry(void)
	{
	struct tblentry **tblp;
	struct tblentry **pp;
@@ -8231,10 +8283,8 @@ clearcmdentry(int firstchange)
	for (tblp = cmdtable; tblp < &cmdtable[CMDTABLESIZE]; tblp++) {
	pp = tblp;
	while ((cmdp = *pp) != NULL) {
-	if ((cmdp->cmdtype == CMDNORMAL &&
-	cmdp->param.index >= firstchange)
-	\|\| (cmdp->cmdtype == CMDBUILTIN &&
-	builtinloc >= firstchange)
+	if (cmdp->cmdtype == CMDNORMAL
+	\|\| (cmdp->cmdtype == CMDBUILTIN && builtinloc > 0)
	) {
	*pp = cmdp->next;
	free(cmdp);
@@ -8334,7 +8384,7 @@ hashcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
	char *name;

	if (nextopt("r") != '\0') {
-	clearcmdentry(0);
+	clearcmdentry();
	return 0;
	}

@@ -8395,42 +8445,28 @@ hashcd(void)
	* Called with interrupts off.
	*/
	static void FAST_FUNC
-	changepath(const char *new)
+	changepath(const char *newval)
	{
-	const char *old;
-	int firstchange;
+	const char *new;
	int idx;
-	int idx_bltin;
+	int bltin;

-	old = pathval();
-	firstchange = 9999; /* assume no change */
+	new = newval;
	idx = 0;
-	idx_bltin = -1;
+	bltin = -1;
	for (;;) {
-	if (old != new) {
-	firstchange = idx;
-	if ((old == '\0' && new == ':')
-	\|\| (old == ':' && new == '\0')
-	) {
-	firstchange++;
-	}
-	old = new; /* ignore subsequent differences */
+	if (*new == '%' && prefix(new + 1, "builtin")) {
+	bltin = idx;
+	break;
	}
-	if (*new == '\0')
+	new = strchr(new, ':');
+	if (!new)
	break;
-	if (*new == '%' && idx_bltin < 0 && prefix(new + 1, "builtin"))
-	idx_bltin = idx;
-	if (*new == ':')
-	idx++;
+	idx++;
	new++;
-	old++;
	}
-	if (builtinloc < 0 && idx_bltin >= 0)
-	builtinloc = idx_bltin; /* zap builtins */
-	if (builtinloc >= 0 && idx_bltin < 0)
-	firstchange = 0;
-	clearcmdentry(firstchange);
-	builtinloc = idx_bltin;
+	builtinloc = bltin;
+	clearcmdentry();
	}
	enum {
	TEOF,
@@ -11024,7 +11060,7 @@ chkmail(void)
	for (;;) {
	int len;

-	len = padvance(&mpath, nullstr);
+	len = padvance_magic(&mpath, nullstr, 2);
	if (!len)
	break;
	p = stackblock();
@@ -13360,7 +13396,9 @@ find_dot_file(char *basename)

	while ((len = padvance(&path, basename)) >= 0) {
	fullname = stackblock();
-	if ((stat(fullname, &statb) == 0) && S_ISREG(statb.st_mode)) {
+	if ((!pathopt \|\| *pathopt == 'f')
+	&& !stat(fullname, &statb) && S_ISREG(statb.st_mode)
+	) {
	/* This will be freed by the caller. */
	return stalloc(len);
	}
@@ -13566,17 +13604,19 @@ find_command(char name, struct cmdentry entry, int act, const char *path)
	idx = -1;
	loop:
	while ((len = padvance(&path, name)) >= 0) {
+	const char *lpathopt = pathopt;
+
	fullname = stackblock();
	idx++;
-	if (pathopt) {
-	if (prefix(pathopt, "builtin")) {
+	if (lpathopt) {
+	if (*lpathopt == 'b') {
	if (bcmd)
	goto builtin_success;
	continue;
-	}
-	if ((act & DO_NOFUNC)
-	\|\| !prefix(pathopt, "func")
-	) { /* ignore unimplemented options */
+	} else if (!(act & DO_NOFUNC)) {
+	/* handled below */
+	} else {
+	/* ignore unimplemented options */
	continue;
	}
	}
@@ -13599,7 +13639,7 @@ find_command(char name, struct cmdentry entry, int act, const char *path)
	e = EACCES; /* if we fail, this will be the error */
	if (!S_ISREG(statb.st_mode))
	continue;
-	if (pathopt) { /* this is a %func directory */
+	if (lpathopt) { /* this is a %func directory */
	stalloc(len);
	/* NB: stalloc will return space pointed by fullname
	* (because we don't have any intervening allocations