Loading...
#include "stdio_impl.h" #include <limits.h> #include <string.h> #include <errno.h> #include <stdint.h> struct cookie { char *s; size_t n; }; #define MIN(a, b) ((a) < (b) ? (a) : (b)) static size_t sn_write(FILE *f, const unsigned char *s, size_t l) { struct cookie *c = f->cookie; size_t k = MIN(c->n, f->wpos - f->wbase); if (k) { memcpy(c->s, f->wbase, k); c->s += k; c->n -= k; } k = MIN(c->n, l); if (k) { memcpy(c->s, s, k); c->s += k; c->n -= k; } *c->s = 0; f->wpos = f->wbase = f->buf; /* pretend to succeed, even if we discarded extra data */ return l; } int vsnprintf(char *restrict s, size_t n, const char *restrict fmt, va_list ap) { unsigned char buf[1]; char dummy[1]; struct cookie c = { .s = n ? s : dummy, .n = n ? n-1 : 0 }; FILE f = { .lbf = EOF, .write = sn_write, .lock = -1, .buf = buf, .cookie = &c, }; *c.s = 0; return vfprintf(&f, fmt, ap); } |