HelenOS sources

strtoul           291 common/strtol.c unsigned long strtoul(const char *nptr, char **endptr, int base)
strtoul           291 kernel/generic/common/strtol.c unsigned long strtoul(const char *nptr, char **endptr, int base)
strtoul           291 uspace/lib/c/common/strtol.c unsigned long strtoul(const char *nptr, char **endptr, int base)