Ah, POSIX error codes. When systems programming, do you ever find yourself with an unfamiliar error code, and then you're off Googling what the heck it actually means? Where's the command line utility to just do this for you, right where you're at, in a terminal? It's actually pretty easy, with a glorified grep...
if echo "$code" | grep -qs "[0-9]"; then
grep -hw "\W$code\W" $headers | sed 's/^#define\s*//'
grep -hi "$code" $headers | sed 's/^#define\s*//'
ENAMETOOLONG 36 /* File name too long */
EEXIST 17 /* File exists */