changed page number reading

this is far from complete since in fact, we read page references
which follow a more complex syntax. while specifying page numbers
is one option for them, they might also specify page names. we
currently do not yet have code for this case and we will return
"-1" for all page references we can not parse.

djvu.c

@@ -17,6 +17,7 @@
 */
 #include <math.h>
 #include <string.h>
+#include <errno.h>
 #include <libdjvu/miniexp.h>
 #include <libdjvu/ddjvuapi.h>
 
@@ -134,17 +135,28 @@ static int walkTableOfContent(lua_State *L, miniexp_t r, int *count, int depth)
 
 	int length = miniexp_length(r);
 	int counter = 0;
-	char page_number[6];
+	const char* page_name;
+	int page_number;
 
 	while(counter < length-1) {
 		lua_pushnumber(L, *count);
 		lua_newtable(L);
 
 		lua_pushstring(L, "page");
-		strcpy(page_number,miniexp_to_str(miniexp_car(miniexp_cdr(miniexp_nth(counter, lista)))));
-		/* page numbers appear as #11, set # to 0 so strtol works */
-		page_number[0]= '0';
-		lua_pushnumber(L, strtol(page_number, NULL, 10));
+		page_name = miniexp_to_str(miniexp_car(miniexp_cdr(miniexp_nth(counter, lista))));
+		if(page_name != NULL && page_name[0] == '#') {
+			errno = 0;
+			page_number = strtol(page_name + 1, NULL, 10);
+			if(!errno) {
+				lua_pushnumber(L, page_number);
+			} else {
+				/* we can not parse this as a number, TODO: parse page names */
+				lua_pushnumber(L, -1);
+			}
+		} else {
+			/* something we did not expect here */
+			lua_pushnumber(L, -1);
+		}
 		lua_settable(L, -3);
 
 		lua_pushstring(L, "depth");