awk: tighten parsing - disallow extra semicolons

'; BEGIN {...}' and 'BEGIN {...} ;; {...}' are not accepted by gawk

function                                             old     new   delta
parse_program                                        332     353     +21

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

1 files changed, 24 insertions, 16 deletions

diff --git a/editors/awk.c b/editors/awk.c
index 7a282356d..2f8a18c8e 100644
--- a/editors/awk.c
+++ b/editors/awk.c
@@ -1634,7 +1634,7 @@ static void chain_group(void)
                 debug_printf_parse("%s: ST_FOR\n", __func__);
                 next_token(TC_LPAREN);
                 n2 = parse_expr(TC_SEMICOL | TC_RPAREN);
-                if (t_tclass & TC_RPAREN) {     /* for-in */
+                if (t_tclass & TC_RPAREN) {     /* for (I in ARRAY) */
                         if (!n2 || n2->info != TI_IN)
                                 syntax_error(EMSG_UNEXP_TOKEN);
                         n = chain_node(OC_WALKINIT | VV);
@@ -1700,20 +1700,15 @@ static void parse_program(char *p)
         for (;;) {
                 uint32_t tclass;
 
-                tclass = next_token(TC_EOF | TS_OPSEQ | TC_LBRACE |
-                        TC_SEMICOL | TC_NEWLINE | TC_BEGIN | TC_END | TC_FUNCDECL);
-
+                tclass = next_token(TS_OPSEQ | TC_LBRACE | TC_BEGIN | TC_END | TC_FUNCDECL
+                        | TC_EOF | TC_NEWLINE /* but not TC_SEMICOL */);
+ got_tok:
                 if (tclass == TC_EOF) {
                         debug_printf_parse("%s: TC_EOF\n", __func__);
                         break;
                 }
-                if (tclass & (TC_SEMICOL | TC_NEWLINE)) {
-                        debug_printf_parse("%s: TC_SEMICOL | TC_NEWLINE\n", __func__);
-//NB: gawk allows many newlines, but does not allow more than one semicolon:
-//  BEGIN {...}<newline>;<newline>;
-//would complain "each rule must have a pattern or an action part".
-//Same message for
-//  ; BEGIN {...}
+                if (tclass == TC_NEWLINE) {
+                        debug_printf_parse("%s: TC_NEWLINE\n", __func__);
                         continue;
                 }
                 if (tclass == TC_BEGIN) {
@@ -1722,7 +1717,7 @@ static void parse_program(char *p)
                         /* ensure there is no newline between BEGIN and { */
                         next_token(TC_LBRACE);
                         chain_until_rbrace();
-                        continue;
+                        goto next_tok;
                 }
                 if (tclass == TC_END) {
                         debug_printf_parse("%s: TC_END\n", __func__);
@@ -1730,7 +1725,7 @@ static void parse_program(char *p)
                         /* ensure there is no newline between END and { */
                         next_token(TC_LBRACE);
                         chain_until_rbrace();
-                        continue;
+                        goto next_tok;
                 }
                 if (tclass == TC_FUNCDECL) {
                         func *f;
@@ -1765,7 +1760,7 @@ static void parse_program(char *p)
                                 continue;
                         chain_until_rbrace();
                         hash_clear(ahash);
-                        continue;
+                        goto next_tok;
                 }
                 seq = &mainseq;
                 if (tclass & TS_OPSEQ) {
@@ -1784,12 +1779,25 @@ static void parse_program(char *p)
                                 chain_node(OC_PRINT);
                         }
                         cn->r.n = mainseq.last;
-                        continue;
+                        goto next_tok;
                 }
                 /* tclass == TC_LBRACE */
                 debug_printf_parse("%s: TC_LBRACE(?)\n", __func__);
                 chain_until_rbrace();
-        }
+ next_tok:
+                /* Same as next_token() at the top of the loop, + TC_SEMICOL */
+                tclass = next_token(TS_OPSEQ | TC_LBRACE | TC_BEGIN | TC_END | TC_FUNCDECL
+                        | TC_EOF | TC_NEWLINE | TC_SEMICOL);
+                /* gawk allows many newlines, but does not allow more than one semicolon:
+                 *  BEGIN {...}<newline>;<newline>;
+                 * would complain "each rule must have a pattern or an action part".
+                 * Same message for
+                 *  ; BEGIN {...}
+                 */
+                if (tclass != TC_SEMICOL)
+                        goto got_tok; /* use this token */
+                /* else: loop back - ate the semicolon, get and use _next_ token */
+        } /* for (;;) */
 }