bc: fixes for multi-line if/while/for

function                                             old     new   delta
zbc_vm_process                                       561     589     +28
zbc_lex_next_and_skip_NLINE                            -      22     +22
zbc_parse_stmt_possibly_auto                        2232    2253     +21
zbc_lex_skip_if_at_NLINE                               -      14     +14
zbc_lex_number                                       192     200      +8
zbc_num_divmod                                       150     156      +6
bc_vm_run                                            134     139      +5
bc_vm_init                                           757     760      +3
bc_num_printNewline                                   51      54      +3
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 7/0 up/down: 110/0)             Total: 110 bytes
   text	   data	    bss	    dec	    hex	filename
 982138	    485	   7296	 989919	  f1adf	busybox_old
 982275	    485	   7296	 990056	  f1b68	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 45 insertions, 8 deletions

diff --git a/miscutils/bc.c b/miscutils/bc.c
index 4dc382476..a5d7a01c0 100644
--- a/miscutils/bc.c
+++ b/miscutils/bc.c
@@ -3018,6 +3018,29 @@ static BC_STATUS zbc_lex_next(BcLex *l)
 # define zbc_lex_next(...) (zbc_lex_next(__VA_ARGS__), BC_STATUS_SUCCESS)
 #endif
 
+static BC_STATUS zbc_lex_skip_if_at_NLINE(BcLex *l)
+{
+	if (l->t.t == BC_LEX_NLINE)
+		RETURN_STATUS(zbc_lex_next(l));
+	RETURN_STATUS(BC_STATUS_SUCCESS);
+}
+#if ERRORS_ARE_FATAL
+# define zbc_lex_skip_if_at_NLINE(...) (zbc_lex_skip_if_at_NLINE(__VA_ARGS__), BC_STATUS_SUCCESS)
+#endif
+
+static BC_STATUS zbc_lex_next_and_skip_NLINE(BcLex *l)
+{
+	BcStatus s;
+	s = zbc_lex_next(l);
+	if (s) RETURN_STATUS(s);
+	// if(cond)<newline>stmt is accepted too (but not 2+ newlines)
+	s = zbc_lex_skip_if_at_NLINE(l);
+	RETURN_STATUS(s);
+}
+#if ERRORS_ARE_FATAL
+# define zbc_lex_next_and_skip_NLINE(...) (zbc_lex_next_and_skip_NLINE(__VA_ARGS__), BC_STATUS_SUCCESS)
+#endif
+
 static BC_STATUS zbc_lex_text_init(BcLex *l, const char *text)
 {
 	l->buf = text;
@@ -4152,7 +4175,8 @@ static BC_STATUS zbc_parse_if(BcParse *p)
 	if (s) RETURN_STATUS(s);
 
 	if (p->l.t.t != BC_LEX_RPAREN) RETURN_STATUS(bc_error_bad_token());
-	s = zbc_lex_next(&p->l);
+	// if(cond)<newline>stmt is accepted too (but not 2+ newlines)
+	s = zbc_lex_next_and_skip_NLINE(&p->l);
 	if (s) RETURN_STATUS(s);
 
 	bc_parse_push(p, BC_INST_JUMP_ZERO);
@@ -4216,12 +4240,15 @@ static BC_STATUS zbc_parse_while(BcParse *p)
 	s = zbc_parse_expr(p, BC_PARSE_REL, bc_parse_next_rel);
 	if (s) RETURN_STATUS(s);
 	if (p->l.t.t != BC_LEX_RPAREN) RETURN_STATUS(bc_error_bad_token());
-	s = zbc_lex_next(&p->l);
+
+	// while(cond)<newline>stmt is accepted too
+	s = zbc_lex_next_and_skip_NLINE(&p->l);
 	if (s) RETURN_STATUS(s);
 
 	bc_parse_push(p, BC_INST_JUMP_ZERO);
 	bc_parse_pushIndex(p, ip.idx);
 
+//TODO: diagnose "while(cond)<newline><newline>"? Now it is seen as "while() with empty body"
 	s = zbc_parse_stmt(p);
 	if (s) RETURN_STATUS(s);
 
@@ -4321,7 +4348,9 @@ static BC_STATUS zbc_parse_for(BcParse *p)
 
 	bc_vec_push(&p->exits, &ip);
 	bc_vec_push(&p->func->labels, &ip.idx);
-	s = zbc_lex_next(&p->l);
+
+	// for(...)<newline>stmt is accepted as well
+	s = zbc_lex_next_and_skip_NLINE(&p->l);
 	if (s) RETURN_STATUS(s);
 
 	s = zbc_parse_stmt(p);
@@ -4453,11 +4482,9 @@ static BC_STATUS zbc_parse_funcdef(BcParse *p)
 	if (p->l.t.t != BC_LEX_LBRACE)
 		s = bc_POSIX_requires("the left brace be on the same line as the function header");
 
-	// Prevent "define z()<newline>" to be interpreted as function with empty stmt as body
-	while (p->l.t.t == BC_LEX_NLINE) {
-		s = zbc_lex_next(&p->l);
-		if (s) RETURN_STATUS(s);
-	}
+	// Prevent "define z()<newline>" from being interpreted as function with empty stmt as body
+	s = zbc_lex_skip_if_at_NLINE(&p->l);
+	if (s) RETURN_STATUS(s);
 //TODO: GNU bc requires a {} block even if function body has single stmt, enforce this?
 
 	p->in_funcdef++; // to determine whether "return" stmt is allowed, and such
diff --git a/testsuite/bc.tests b/testsuite/bc.tests
index 093b3950e..95cc28dad 100755
--- a/testsuite/bc.tests
+++ b/testsuite/bc.tests
@@ -56,6 +56,16 @@ testing "bc define with body on next line" \
 	"8\n9\n" \
 	"" "define w()\n{ auto z; return 8; }\nw()\n9"
 
+testing "bc if(cond)<NL>" \
+	"bc" \
+	"9\n" \
+	"" "if(0)\n3\n9"
+
+testing "bc while(cond)<NL>" \
+	"bc" \
+	"8\n7\n6\n5\n4\n3\n2\n1\n9\n" \
+	"" "i=9;while(--i)\ni\n9"
+
 tar xJf bc_large.tar.xz
 
 for f in bc*.bc; do