bc: fix for() to not leave data on stack

function                                             old     new   delta
zbc_parse_stmt_possibly_auto                        1665    1697     +32
zbc_vm_process                                       672     701     +29
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 61/0)               Total: 61 bytes
   text	   data	    bss	    dec	    hex	filename
 981656	    485	   7296	 989437	  f18fd	busybox_old
 981748	    485	   7296	 989529	  f1959	busybox_unstripped

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

diff --git a/miscutils/bc.c b/miscutils/bc.c
index 50e5457b9a24ab5d88835c01a85d7d0e77937c36..441cb04676ed235e5f669836c70101d8fda1d6cf 100644 (file)
--- a/miscutils/bc.c
+++ b/miscutils/bc.c
@@ -170,6 +170,8 @@
 #define DEBUG_LEXER   0
 #define DEBUG_COMPILE 0
 #define DEBUG_EXEC    0
+// This can be left enabled for production as well:
+#define SANITY_CHECKS 1
 
 #if DEBUG_LEXER
 static uint8_t lex_indent;
@@ -1218,8 +1220,6 @@ static char** bc_program_const(size_t idx)
        IF_DC(return bc_vec_item(&G.prog.consts, idx);)
 }
 
-
-
 static int bc_id_cmp(const void *e1, const void *e2)
 {
        return strcmp(((const BcId *) e1)->name, ((const BcId *) e2)->name);
@@ -4227,12 +4227,15 @@ static BC_STATUS zbc_parse_for(BcParse *p)
        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
 
-       if (p->l.t.t != BC_LEX_SCOLON)
+       if (p->l.t.t != BC_LEX_SCOLON) {
                s = zbc_parse_expr(p, 0);
-       else
+               bc_parse_push(p, BC_INST_POP);
+               if (s) RETURN_STATUS(s);
+       } else {
                s = bc_POSIX_does_not_allow_empty_X_expression_in_for("init");
+               IF_ERROR_RETURN_POSSIBLE(if (s) RETURN_STATUS(s);)
+       }
 
-       if (s) RETURN_STATUS(s);
        if (p->l.t.t != BC_LEX_SCOLON) RETURN_STATUS(bc_error_bad_token());
        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
@@ -4254,8 +4257,8 @@ static BC_STATUS zbc_parse_for(BcParse *p)
                bc_parse_pushNUM(p);
                s = bc_POSIX_does_not_allow_empty_X_expression_in_for("condition");
        }
-
        if (s) RETURN_STATUS(s);
+
        if (p->l.t.t != BC_LEX_SCOLON) RETURN_STATUS(bc_error_bad_token());
 
        s = zbc_lex_next(&p->l);
@@ -4267,12 +4270,14 @@ static BC_STATUS zbc_parse_for(BcParse *p)
        bc_vec_push(&p->conds, &update_idx);
        bc_vec_push(&p->func->labels, &p->func->code.len);
 
-       if (p->l.t.t != BC_LEX_RPAREN)
+       if (p->l.t.t != BC_LEX_RPAREN) {
                s = zbc_parse_expr(p, 0);
-       else
+               bc_parse_push(p, BC_INST_POP);
+               if (s) RETURN_STATUS(s);
+       } else {
                s = bc_POSIX_does_not_allow_empty_X_expression_in_for("update");
-
-       if (s) RETURN_STATUS(s);
+               IF_ERROR_RETURN_POSSIBLE(if (s) RETURN_STATUS(s);)
+       }
 
        if (p->l.t.t != BC_LEX_RPAREN) RETURN_STATUS(bc_error_bad_token());
        bc_parse_pushJUMP(p, cond_idx);
@@ -6434,12 +6439,13 @@ static BC_STATUS zbc_program_exec(void)
        BcFunc *func = bc_program_func(ip->func);
        char *code = func->code.v;
 
-       dbg_exec("func:%zd bytes:%zd ip:%zd", ip->func, func->code.len, ip->idx);
+       dbg_exec("func:%zd bytes:%zd ip:%zd results.len:%d",
+                       ip->func, func->code.len, ip->idx, G.prog.results.len);
        while (ip->idx < func->code.len) {
                BcStatus s = BC_STATUS_SUCCESS;
                char inst = code[ip->idx++];
 
-               dbg_exec("inst at %zd:%d", ip->idx - 1, inst);
+               dbg_exec("inst at %zd:%d results.len:%d", ip->idx - 1, inst, G.prog.results.len);
                switch (inst) {
 #if ENABLE_BC
                        case BC_INST_JUMP_ZERO: {
@@ -6671,7 +6677,6 @@ static BC_STATUS zbc_program_exec(void)
                }
 
                fflush_and_check();
-
        }
 
        RETURN_STATUS(BC_STATUS_SUCCESS);
@@ -6723,23 +6728,16 @@ static BC_STATUS zbc_vm_process(const char *text)
                // storage.
                if (IS_BC) {
                        BcFunc *f;
-                       BcInstPtr *ip;
-
-                       //FIXME: this does not clear up the stack
-                       //for(i=1; i<3; i++) {
-                       //    i
-                       //    if(i==2) continue
-                       //    77
-                       //}
-//                     if (G.prog.results.len != 0)
-//                             bb_error_msg_and_die("data stack not empty: %d slots", G.prog.results.len);
+                       BcInstPtr *ip = (void*)G.prog.exestack.v;
 
+#if SANITY_CHECKS
+                       if (G.prog.results.len != 0)
+                               bb_error_msg_and_die("data stack not empty: %d slots", G.prog.results.len);
                        if (G.prog.exestack.len != 1) // should be empty
                                bb_error_msg_and_die("BUG:call stack");
-
-                       ip = (void*)G.prog.exestack.v;
                        if (ip->func != BC_PROG_MAIN)
                                bb_error_msg_and_die("BUG:not MAIN");
+#endif
 //bb_error_msg("ip->func:%d >idx:%d >len:%d", ip->func, ip->idx, ip->len);
                        f = bc_program_func_BC_PROG_MAIN();
 //bb_error_msg("MAIN->code.len:%d >strs.len:%d >consts.len:%d", f->code.len, f->strs.len, f->consts.len); // labels, autos, nparams

diff --git a/testsuite/bc.tests b/testsuite/bc.tests
index edff209bbdf3fb644e836b47a3f169a342239035..b3ce894ee46c8c2cd68070a7f367e2beb3872626 100755 (executable)
--- a/testsuite/bc.tests
+++ b/testsuite/bc.tests
@@ -56,6 +56,21 @@ testing "bc for(;;)" \
        "2\n3\n2\n9\n" \
        "" "i=2; for (;;) { 2; if(--i==0) break; 3; }; 9"
 
+testing "bc for (;cond;)" \
+       "bc" \
+       "1\n2\n3\n9\n" \
+       "" "i=0; for(;i<3;)++i; 9"
+
+testing "bc for (;cond;upd)" \
+       "bc" \
+       "1\n2\n3\n9\n" \
+       "" "i=1; for(;i<4;i++)i; 9"
+
+testing "bc for (init;cond;upd)" \
+       "bc" \
+       "1\n2\n3\n9\n" \
+       "" "for(i=1;i<4;i++)i; 9"
+
 testing "bc define auto" \
        "bc" \
        "8\n9\n" \