replace atoi with my own impl to make sure that no errors occour

XD.1

@@ -13,6 +13,10 @@
 .Nm
 Displays information using a smiley face like so: :)
 to interpret it refer to the following tables:
+Displays information using a smiley face.
+to interpret XD's output refer to the following tables (or
+.Nm
+\fB-e\fR):
 .Ss Eyes
 .TS
 tab(;) allbox;
@@ -42,6 +46,13 @@ c;l.
  /;command not found
  (;previous signal is failure
 .TE
+.Ss Exit Status:
+.Nm
+returns the number that was passed in to allow the user to re-run the program
+and get the same results. If there's an internal error
+.Nm
+returns 1. If you wish to find out more infomation about the error enable ERR
+in the config.mk.
 .Sh OPTIONS
 .Ss -v
 Print version information to stdout and exit.

XD.c

@@ -230,6 +230,34 @@ has_staged(git_repository *repo)
 }
 #endif
 
+inline unsigned
+numcat(unsigned x, unsigned y)
+{
+  unsigned pow = 10;
+  while(y >= pow) {
+    pow *= 10;
+  }
+
+  return (x * pow) + y;
+}
+
+int
+str_to_int(char *str)
+{
+  int res = -1;
+  char *c;
+
+  for (c = str; (*c != '\0') && isdigit(*c); c++) {
+    if (res == -1) {
+      res = *c - '0';
+    } else {
+      res = numcat(res, *c - '0');
+    }
+  }
+
+  return res;
+}
+
 int
 main(int argc, char *argv[])
 {
@@ -282,8 +310,12 @@ main(int argc, char *argv[])
   }
 
   /* get exit code from user args */
-  if (argv[1]) {
+  if (argc > 1 && argv[argc - 1]) {
-    code = atoi(argv[1]);
+    code = str_to_int(argv[argc - 1]);
+    if (code < 0) {
+      L("Return code, %d, not valid", code);
+      exit(1);
+    }
   }
 
   /* change mouth based on exit code */