Widen the YY_INPUT() interface to four args, since that seems to be
how it is actually used in the only real application that uses greg
I've tried so far (MMD-4).  Also convert two instances of sprintf(3)
to snprintf(3).

--- compile.c.orig	Tue Oct  8 22:39:24 2013
+++ compile.c	Fri Jan  2 14:31:43 2015
@@ -136,8 +136,12 @@ static char *yyqq(char* s) {
     } else if (*s == 92) { // '\'
       *d++ = '\\'; *d++ = *s++;
     } else if (*(signed char *)s<32) {
-      sprintf(d,"\\%03o", *s); // octal \000
-      d += 4; s++;
+      char octbuf[8];
+      size_t noct = snprintf(octbuf,sizeof(octbuf),"\\%03o",*s);
+      assert(noct < sizeof(octbuf));
+      memcpy(d,octbuf,noct+1);
+      d += noct;
+      s++;
     } else {
       *d++ = *s++;
     }
@@ -152,7 +156,7 @@ static char *makeCharClass(unsigned char *cclass)
   setter	 set;
   int		 c, prev= -1;
   static char	 string[256];
-  char		*ptr;
+  size_t	 left, off;
 
   if ('^' == *cclass)
     {
@@ -179,9 +183,14 @@ static char *makeCharClass(unsigned char *cclass)
   }
     }
 
-  ptr= string;
-  for (c= 0;  c < 32;  ++c)
-    ptr += sprintf(ptr, "\\%03o", bits[c]);
+  left = sizeof(string);
+  off = 0;
+  for (c= 0;  c < 32;  ++c) {
+    size_t n = snprintf(&string[off],left,"\\%03o",bits[c]);
+    assert(n < left);
+    left -= n;
+    off += n;
+  }
 
   return string;
 }
@@ -502,7 +511,7 @@ static char *preamble= "\
 #define YY_NAME(N) yy##N\n\
 #endif\n\
 #ifndef YY_INPUT\n\
-#define YY_INPUT(buf, result, max_size)			\\\n\
+#define YY_INPUT(buf, result, max_size, D)		\\\n\
   {							\\\n\
     int yyc= fgetc(G->input);				\\\n\
     if ('\\n' == yyc) ++G->lineno;      		\\\n\
@@ -624,7 +633,7 @@ YY_LOCAL(int) yyrefill(GREG *G)\n\
       G->buflen *= 2;\n\
       G->buf= (char*)YY_REALLOC(G->buf, G->buflen, G->data);\n\
     }\n\
-  YY_INPUT((G->buf + G->pos), yyn, (G->buflen - G->pos));\n\
+  YY_INPUT((G->buf + G->pos), yyn, (G->buflen - G->pos), G->data);\n\
   if (!yyn) return 0;\n\
   G->limit += yyn;\n\
   return 1;\n\