Merge bugfix from https://github.com/hasherezade/udis86

fixes vmt#94 in the original udis86 project (also refer to PR vmt#96).

Merge remote-tracking branch 'hasherezade/fix-94'

libudis86/syn.c

@@ -121,11 +121,14 @@ ud_asmprintf(struct ud *u, const char *fmt, ...)
   int ret;
   int avail;
   va_list ap;
+  char* curr_buf = (u->asm_buf == NULL) ? u->asm_buf_int : u->asm_buf;
+  size_t curr_buf_size = (curr_buf == u->asm_buf_int) ? sizeof(u->asm_buf_int) : u->asm_buf_size;
+
   va_start(ap, fmt);
-  avail = (int) (u->asm_buf_size - u->asm_buf_fill - 1) /* nullchar */;
-  ret = vsnprintf((char*) u->asm_buf + u->asm_buf_fill, avail, fmt, ap);
+  avail = (int) (curr_buf_size - u->asm_buf_fill - 1) /* nullchar */;
+  ret = vsnprintf((char*) curr_buf + u->asm_buf_fill, avail, fmt, ap);
   if (ret < 0 || ret > avail) {
-      u->asm_buf_fill = u->asm_buf_size - 1;
+      u->asm_buf_fill = curr_buf_size - 1;
   } else {
       u->asm_buf_fill += ret;
   }

libudis86/udis86.c

@@ -52,11 +52,10 @@ ud_init(struct ud* u)
 #ifndef __UD_STANDALONE__
   ud_set_input_file(u, stdin);
 #endif /* __UD_STANDALONE__ */
-
-  ud_set_asm_buffer(u, u->asm_buf_int, sizeof(u->asm_buf_int));
+  u->asm_buf = NULL;
+  u->asm_buf_size = 0;
 }
 
-
 /* =============================================================================
  * ud_disassemble
  *    Disassembles one instruction and returns the number of
@@ -72,7 +71,10 @@ ud_disassemble(struct ud* u)
   }
   if ((len = ud_decode(u)) > 0) {
     if (u->translator != NULL) {
-      u->asm_buf[0] = '\0';
+      u->asm_buf_int[0] = '\0';
+      if (u->asm_buf && u->asm_buf_size > 0) {
+          u->asm_buf[0] = '\0';
+      }
       u->translator(u);
     }
   }
@@ -141,7 +143,10 @@ ud_set_syntax(struct ud* u, void (*t)(struct ud*))
 const char*
 ud_insn_asm(const struct ud* u)
 {
-  return u->asm_buf;
+  if (u->asm_buf != NULL) {
+    return u->asm_buf;
+  }
+  return u->asm_buf_int;
 }
 
 /* =============================================================================