Plan 9 from Bell Labs’s /usr/web/sources/plan9/sys/src/libstdio/vsprintf.c
/* * pANS stdio -- vsprintf */ #include "iolib.h" int vsprintf(char *buf, const char *fmt, va_list args){ int n; FILE *f=sopenw(); if(f==NULL) return 0; setvbuf(f, buf, _IOFBF, 100000); n=vfprintf(f, fmt, args); sclose(f); return n; }