ref: 6afce2e422614341756c2e4c19dc68135d440013
dir: /sys/src/cmd/unix/u9fs/utfrune.c/
#include <plan9.h> char* utfrune(char *s, long c) { long c1; Rune r; int n; if(c < Runesync) /* not part of utf sequence */ return strchr(s, c); for(;;) { c1 = *(uchar*)s; if(c1 < Runeself) { /* one byte rune */ if(c1 == 0) return 0; if(c1 == c) return s; s++; continue; } n = chartorune(&r, s); if(r == c) return s; s += n; } return 0; }