ref: 61870c24fae357b78029ce54be0c004e1ffdb3c7
dir: /libkern/cistrstr.c/
#include "lib9.h" char* cistrstr(char *s, char *sub) { int c, csub, n; csub = *sub; if(csub == '\0') return s; if(csub >= 'A' && csub <= 'Z') csub -= 'A' - 'a'; sub++; n = strlen(sub); for(; c = *s; s++){ if(c >= 'A' && c <= 'Z') c -= 'A' - 'a'; if(c == csub && cistrncmp(s+1, sub, n) == 0) return s; } return nil; }