hush: more rodust detection of unterminated strings etc;

 fix a case where we forget to copy `cmd` text;
 optimize nommu heredoc helper by not passing environment to it;
 add several tests

function                                             old     new   delta
add_till_closing_paren                               256     308     +52
parse_stream                                        2337    2378     +41
add_till_backquote                                    82     111     +29
re_execute_shell                                     269     284     +15
handle_dollar                                        802     812     +10
parse_stream_dquoted                                 316     320      +4
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 6/0 up/down: 151/0)             Total: 151 bytes

1 files changed, 65 insertions, 31 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 4641dca11..9920e98c6 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -2241,7 +2241,10 @@ static void re_execute_shell(const char *s, int is_heredoc)
 
 	debug_printf_exec("re_execute_shell pid:%d cmd:'%s'\n", getpid(), s);
 	sigprocmask(SIG_SETMASK, &G.inherited_set, NULL);
-	execv(bb_busybox_exec_path, G.argv_from_re_execing);
+	execve(bb_busybox_exec_path,
+		G.argv_from_re_execing,
+		(is_heredoc ? pp /* points to NULL ptr */ : environ)
+		);
 	/* Fallback. Useful for init=/bin/hush usage etc */
 	if (G.argv0_for_re_execing[0] == '/')
 		execv(G.argv0_for_re_execing, G.argv_from_re_execing);
@@ -4402,35 +4405,40 @@ static int parse_group(o_string *dest, struct parse_context *ctx,
 
 #if ENABLE_HUSH_TICK || ENABLE_SH_MATH_SUPPORT
 /* Subroutines for copying $(...) and `...` things */
-static void add_till_backquote(o_string *dest, struct in_str *input);
+static int add_till_backquote(o_string *dest, struct in_str *input);
 /* '...' */
-static void add_till_single_quote(o_string *dest, struct in_str *input)
+static int add_till_single_quote(o_string *dest, struct in_str *input)
 {
 	while (1) {
 		int ch = i_getch(input);
-		if (ch == EOF)
-			break;
+		if (ch == EOF) {
+			syntax("unterminated '");
+			return 1;
+		}
 		if (ch == '\'')
-			break;
+			return 0;
 		o_addchr(dest, ch);
 	}
 }
 /* "...\"...`..`...." - do we need to handle "...$(..)..." too? */
-static void add_till_double_quote(o_string *dest, struct in_str *input)
+static int add_till_double_quote(o_string *dest, struct in_str *input)
 {
 	while (1) {
 		int ch = i_getch(input);
+		if (ch == EOF) {
+			syntax("unterminated \"");
+			return 1;
+		}
 		if (ch == '"')
-			break;
+			return 0;
 		if (ch == '\\') {  /* \x. Copy both chars. */
 			o_addchr(dest, ch);
 			ch = i_getch(input);
 		}
-		if (ch == EOF)
-			break;
 		o_addchr(dest, ch);
 		if (ch == '`') {
-			add_till_backquote(dest, input);
+			if (add_till_backquote(dest, input))
+				return 1;
 			o_addchr(dest, ch);
 			continue;
 		}
@@ -4451,20 +4459,27 @@ static void add_till_double_quote(o_string *dest, struct in_str *input)
  * Example                               Output
  * echo `echo '\'TEST\`echo ZZ\`BEST`    \TESTZZBEST
  */
-static void add_till_backquote(o_string *dest, struct in_str *input)
+static int add_till_backquote(o_string *dest, struct in_str *input)
 {
 	while (1) {
 		int ch = i_getch(input);
+		if (ch == EOF) {
+			syntax("unterminated `");
+			return 1;
+		}
 		if (ch == '`')
-			break;
-		if (ch == '\\') {  /* \x. Copy both chars unless it is \` */
+			return 0;
+		if (ch == '\\') {
+			/* \x. Copy both chars unless it is \` */
 			int ch2 = i_getch(input);
+			if (ch2 == EOF) {
+				syntax("unterminated `");
+				return 1;
+			}
 			if (ch2 != '`' && ch2 != '$' && ch2 != '\\')
 				o_addchr(dest, ch);
 			ch = ch2;
 		}
-		if (ch == EOF)
-			break;
 		o_addchr(dest, ch);
 	}
 }
@@ -4480,13 +4495,15 @@ static void add_till_backquote(o_string *dest, struct in_str *input)
  * echo $(echo 'TEST)' BEST)            TEST) BEST
  * echo $(echo \(\(TEST\) BEST)         ((TEST) BEST
  */
-static void add_till_closing_paren(o_string *dest, struct in_str *input, bool dbl)
+static int add_till_closing_paren(o_string *dest, struct in_str *input, bool dbl)
 {
 	int count = 0;
 	while (1) {
 		int ch = i_getch(input);
-		if (ch == EOF)
-			break;
+		if (ch == EOF) {
+			syntax("unterminated )");
+			return 1;
+		}
 		if (ch == '(')
 			count++;
 		if (ch == ')') {
@@ -4501,23 +4518,29 @@ static void add_till_closing_paren(o_string *dest, struct in_str *input, bool db
 		}
 		o_addchr(dest, ch);
 		if (ch == '\'') {
-			add_till_single_quote(dest, input);
+			if (add_till_single_quote(dest, input))
+				return 1;
 			o_addchr(dest, ch);
 			continue;
 		}
 		if (ch == '"') {
-			add_till_double_quote(dest, input);
+			if (add_till_double_quote(dest, input))
+				return 1;
 			o_addchr(dest, ch);
 			continue;
 		}
-		if (ch == '\\') { /* \x. Copy verbatim. Important for  \(, \) */
+		if (ch == '\\') {
+			/* \x. Copy verbatim. Important for  \(, \) */
 			ch = i_getch(input);
-			if (ch == EOF)
-				break;
+			if (ch == EOF) {
+				syntax("unterminated )");
+				return 1;
+			}
 			o_addchr(dest, ch);
 			continue;
 		}
 	}
+	return 0;
 }
 #endif /* ENABLE_HUSH_TICK || ENABLE_SH_MATH_SUPPORT */
 
@@ -4658,7 +4681,8 @@ static int handle_dollar(o_string *as_string,
 #  if !BB_MMU
 			pos = dest->length;
 #  endif
-			add_till_closing_paren(dest, input, true);
+			if (add_till_closing_paren(dest, input, true))
+				return 1;
 #  if !BB_MMU
 			if (as_string) {
 				o_addstr(as_string, dest->data + pos);
@@ -4671,20 +4695,19 @@ static int handle_dollar(o_string *as_string,
 		}
 # endif
 # if ENABLE_HUSH_TICK
-		//int pos = dest->length;
 		o_addchr(dest, SPECIAL_VAR_SYMBOL);
 		o_addchr(dest, quote_mask | '`');
 #  if !BB_MMU
 		pos = dest->length;
 #  endif
-		add_till_closing_paren(dest, input, false);
+		if (add_till_closing_paren(dest, input, false))
+			return 1;
 #  if !BB_MMU
 		if (as_string) {
 			o_addstr(as_string, dest->data + pos);
 			o_addchr(as_string, '`');
 		}
 #  endif
-		//debug_printf_subst("SUBST RES2 '%s'\n", dest->data + pos);
 		o_addchr(dest, SPECIAL_VAR_SYMBOL);
 # endif
 		break;
@@ -4778,7 +4801,8 @@ static int parse_stream_dquoted(o_string *as_string,
 		//int pos = dest->length;
 		o_addchr(dest, SPECIAL_VAR_SYMBOL);
 		o_addchr(dest, 0x80 | '`');
-		add_till_backquote(dest, input);
+		if (add_till_backquote(dest, input))
+			return 1;
 		o_addchr(dest, SPECIAL_VAR_SYMBOL);
 		//debug_printf_subst("SUBST RES3 '%s'\n", dest->data + pos);
 		goto again;
@@ -5043,10 +5067,20 @@ static struct pipe *parse_stream(char **pstring,
 			break;
 #if ENABLE_HUSH_TICK
 		case '`': {
-			//int pos = dest.length;
+#if !BB_MMU
+			int pos;
+#endif
 			o_addchr(&dest, SPECIAL_VAR_SYMBOL);
 			o_addchr(&dest, '`');
-			add_till_backquote(&dest, input);
+#if !BB_MMU
+			pos = dest.length;
+#endif
+			if (add_till_backquote(&dest, input))
+				goto parse_error;
+#if !BB_MMU
+			o_addstr(&ctx.as_string, dest.data + pos);
+			o_addchr(&ctx.as_string, '`');
+#endif
 			o_addchr(&dest, SPECIAL_VAR_SYMBOL);
 			//debug_printf_subst("SUBST RES3 '%s'\n", dest.data + pos);
 			break;