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#include "stdio_impl.h" static size_t sn_write(FILE *f, const unsigned char *s, size_t l) { size_t k = f->wend - f->wpos; if (k > l) k = l; memcpy(f->wpos, s, k); f->wpos += k; /* pretend to succeed, but discard extra data */ return l; } int vsnprintf(char *s, size_t n, const char *fmt, va_list ap) { int r; char b; FILE f = { .lbf = EOF, .write = sn_write, .lock = -1 }; if (n-1 > INT_MAX-1) { if (n) { errno = EOVERFLOW; return -1; } s = &b; n = 1; } /* Ensure pointers don't wrap if "infinite" n is passed in */ if (n > (char *)0+SIZE_MAX-s-1) n = (char *)0+SIZE_MAX-s-1; f.buf_size = n; f.buf = f.wpos = (void *)s; f.wbase = f.wend = (void *)(s+n); r = vfprintf(&f, fmt, ap); /* Null-terminate, overwriting last char if dest buffer is full */ if (n) f.wpos[-(f.wpos == f.wend)] = 0; return r; } |