bc: disallow invalid syntax like "{ print 1 print 2 }"

statement parsing must NOT eat the terminator: caller needs to know
what it was, to correctly decide whether it is a valid one.

function                                             old     new   delta
zxc_program_read                                       -     234    +234
zdc_program_printStream                                -     144    +144
zbc_parse_stmt_possibly_auto                        1413    1460     +47
zxc_vm_process                                       869     859     -10
zxc_program_exec                                    4116    4101     -15
zdc_program_asciify                                  368       -    -368
------------------------------------------------------------------------------
(add/remove: 2/1 grow/shrink: 1/2 up/down: 425/-393)           Total: 32 bytes

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

1 files changed, 21 insertions, 15 deletions

diff --git a/miscutils/bc.c b/miscutils/bc.c
index bf174dafb..faf6226e1 100644
--- a/miscutils/bc.c
+++ b/miscutils/bc.c
@@ -4554,11 +4554,11 @@ static BC_STATUS zbc_parse_stmt_possibly_auto(bool auto_allowed)
 
         if (p->lex == XC_LEX_NLINE) {
                 dbg_lex_done("%s:%d done (seen XC_LEX_NLINE)", __func__, __LINE__);
-                RETURN_STATUS(zxc_lex_next());
+                RETURN_STATUS(s);
         }
         if (p->lex == BC_LEX_SCOLON) {
                 dbg_lex_done("%s:%d done (seen BC_LEX_SCOLON)", __func__, __LINE__);
-                RETURN_STATUS(zxc_lex_next());
+                RETURN_STATUS(s);
         }
 
         if (p->lex == BC_LEX_LBRACE) {
@@ -4574,9 +4574,19 @@ static BC_STATUS zbc_parse_stmt_possibly_auto(bool auto_allowed)
                 }
                 while (p->lex != BC_LEX_RBRACE) {
                         dbg_lex("%s:%d block parsing loop", __func__, __LINE__);
-//FIXME: prevent wrong syntax such as "{ print 1 print 2 }"
                         s = zbc_parse_stmt();
                         if (s) RETURN_STATUS(s);
+                        // Check that next token is a correct stmt delimiter -
+                        // disallows "print 1 print 2" and such.
+                        if (p->lex == BC_LEX_RBRACE)
+                                break;
+                        if (p->lex != BC_LEX_SCOLON
+                         && p->lex != XC_LEX_NLINE
+                        ) {
+                                RETURN_STATUS(bc_error_at("bad statement terminator"));
+                        }
+                        s = zxc_lex_next();
+                        if (s) RETURN_STATUS(s);
                 }
                 s = zxc_lex_next();
                 dbg_lex_done("%s:%d done (seen BC_LEX_RBRACE)", __func__, __LINE__);
@@ -4665,9 +4675,11 @@ static BC_STATUS zbc_parse_stmt_or_funcdef(void)
         BcStatus s;
 
         dbg_lex_enter("%s:%d entered", __func__, __LINE__);
-        if (p->lex == XC_LEX_EOF)
-                s = bc_error("end of file");
-        else if (p->lex == BC_LEX_KEY_DEFINE) {
+//why?
+//      if (p->lex == XC_LEX_EOF)
+//              s = bc_error("end of file");
+//      else
+        if (p->lex == BC_LEX_KEY_DEFINE) {
                 dbg_lex("%s:%d p->lex:BC_LEX_KEY_DEFINE", __func__, __LINE__);
                 s = zbc_parse_funcdef();
         } else {
@@ -6781,7 +6793,6 @@ static BC_STATUS zxc_vm_process(const char *text)
         s = zxc_parse_text_init(text); // does the first zxc_lex_next()
         if (s) RETURN_STATUS(s);
 
- IF_BC(check_eof:)
         while (G.prs.lex != XC_LEX_EOF) {
                 BcInstPtr *ip;
                 BcFunc *f;
@@ -6789,14 +6800,6 @@ static BC_STATUS zxc_vm_process(const char *text)
                 dbg_lex("%s:%d G.prs.lex:%d, parsing...", __func__, __LINE__, G.prs.lex);
                 if (IS_BC) {
 #if ENABLE_BC
-                        if (G.prs.lex == BC_LEX_SCOLON
-                         || G.prs.lex == XC_LEX_NLINE
-                        ) {
-                                s = zxc_lex_next();
-                                if (s) goto err;
-                                goto check_eof;
-                        }
-
                         s = zbc_parse_stmt_or_funcdef();
                         if (s) goto err;
 
@@ -6855,6 +6858,9 @@ static BC_STATUS zxc_vm_process(const char *text)
 #endif
                         IF_BC(bc_vec_pop_all(&f->strs);)
                         IF_BC(bc_vec_pop_all(&f->consts);)
+                        // We are at SCOLON/NLINE, skip it:
+                        s = zxc_lex_next();
+                        if (s) goto err;
                 } else {
                         if (G.prog.results.len == 0
                          && G.prog.vars.len == 0