codegen.c: no integer overflow error in `codegen`; close #5376

Add new pool value type `IREP_TT_BIGINT` and generate integer overflow
error in the VM. In the future, `mruby` will support `Bignum` for
integers bigger than `mrb_int` (probably using `mpz`).

5 files changed, 46 insertions, 3 deletions

diff --git a/src/codedump.c b/src/codedump.c
index f382bb7eb..3a5f0eadb 100644
--- a/src/codedump.c
+++ b/src/codedump.c
@@ -6,7 +6,7 @@
 #include <mruby/proc.h>
 #include <mruby/dump.h>
 
-#ifndef MRB_NO_STDIO
+#ifndef MRB_NOP_STDIO
 static void
 print_r(mrb_state *mrb, const mrb_irep *irep, size_t n)
 {
diff --git a/src/dump.c b/src/dump.c
index 51e8dca4e..0822b2fac 100644
--- a/src/dump.c
+++ b/src/dump.c
@@ -129,6 +129,15 @@ get_pool_block_size(mrb_state *mrb, const mrb_irep *irep)
       size += 4;                /* 32bits = 4bytes */
       break;
 
+    case IREP_TT_BIGINT:
+      {
+        mrb_int len = irep->pool[pool_no].u.str[0];
+        mrb_assert_int_fit(mrb_int, len, size_t, SIZE_MAX);
+        size += sizeof(uint8_t);
+        size += (size_t)len+2;
+      }
+      break;
+
     case IREP_TT_FLOAT:
 #ifndef MRB_NO_FLOAT
       {
@@ -187,6 +196,14 @@ write_pool_block(mrb_state *mrb, const mrb_irep *irep, uint8_t *buf)
       cur += uint32_to_bin(irep->pool[pool_no].u.i32, cur); /* i32 */
       break;
 
+    case IREP_TT_BIGINT:
+      cur += uint8_to_bin(IREP_TT_BIGINT, cur); /* data type */
+      len = irep->pool[pool_no].u.str[0];
+      memcpy(cur, irep->pool[pool_no].u.str, (size_t)len+2);
+      cur += len+2;
+      *cur++ = '\0';
+      break;
+
     case IREP_TT_FLOAT:
       cur += uint8_to_bin(IREP_TT_FLOAT, cur); /* data type */
 #ifndef MRB_NO_FLOAT
@@ -216,7 +233,6 @@ write_pool_block(mrb_state *mrb, const mrb_irep *irep, uint8_t *buf)
   return cur - buf;
 }
 
-
 static size_t
 get_syms_block_size(mrb_state *mrb, const mrb_irep *irep)
 {
@@ -941,6 +957,17 @@ dump_pool(mrb_state *mrb, const mrb_pool_value *p, FILE *fp)
       }
 #endif
       break;
+    case IREP_TT_BIGINT:
+      {
+        const char *s = p->u.str;
+        int len = s[0]+2;
+        fputs("{IREP_TT_BIGINT, {\"", fp);
+        for (int i=0; i<len; i++) {
+          fprintf(fp, "\\x%02x", (int)s[i]&0xff);
+        }
+        fputs("\"}},\n", fp);
+      }
+      break;
     }
   }
   else {                        /* string */
diff --git a/src/load.c b/src/load.c
index 68be23546..f370dc67e 100644
--- a/src/load.c
+++ b/src/load.c
@@ -161,6 +161,19 @@ read_irep_record_1(mrb_state *mrb, const uint8_t *bin, size_t *len, uint8_t flag
         return FALSE;           /* INT64 not supported on MRB_32BIT */
 #endif
 
+      case IREP_TT_BIGINT:
+        pool_data_len = bin_to_uint8(src); /* pool data length */
+        src += sizeof(uint8_t);
+        {
+          char *p;
+          pool[i].tt = IREP_TT_BIGINT;
+          p = (char*)mrb_malloc(mrb, pool_data_len+2);
+          memcpy(p, src, pool_data_len+2);
+          pool[i].u.str = (const char*)p;
+        }
+        src += pool_data_len + 2;
+        break;
+
       case IREP_TT_FLOAT:
 #ifndef MRB_NO_FLOAT
         pool[i].tt = tt;
diff --git a/src/state.c b/src/state.c
index 0ba6db6ce..1b50eec34 100644
--- a/src/state.c
+++ b/src/state.c
@@ -154,7 +154,8 @@ mrb_irep_free(mrb_state *mrb, mrb_irep *irep)
     mrb_free(mrb, (void*)irep->iseq);
   if (irep->pool) {
     for (i=0; i<irep->plen; i++) {
-      if ((irep->pool[i].tt & 3) == IREP_TT_STR) {
+      if ((irep->pool[i].tt & 3) == IREP_TT_STR ||
+          irep->pool[i].tt == IREP_TT_BIGINT) {
         mrb_free(mrb, (void*)irep->pool[i].u.str);
       }
     }
diff --git a/src/vm.c b/src/vm.c
index 2607ba308..1009fb638 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -1143,6 +1143,8 @@ RETRY_TRY_BLOCK:
 #endif
         goto L_INT_OVERFLOW;
 #endif
+      case IREP_TT_BIGINT:
+        goto L_INT_OVERFLOW;
 #ifndef MRB_NO_FLOAT
       case IREP_TT_FLOAT:
         regs[a] = mrb_float_value(mrb, pool[b].u.f);