setvbuf: return failure if mode is invalid

POSIX requires setvbuf to return non-zero if `mode` is not one of _IONBF,
_IOLBF, or _IOFBF.

diff --git a/src/stdio/setvbuf.c b/src/stdio/setvbuf.c
index 06ea296c6a64202ed4f95e23c6af884f5305e1e7..523dddc8ba28f53a7b3fcc4e3e5323de092acc22 100644 (file)
--- a/src/stdio/setvbuf.c
+++ b/src/stdio/setvbuf.c
@@ -12,13 +12,15 @@ int setvbuf(FILE *restrict f, char *restrict buf, int type, size_t size)
 
        if (type == _IONBF) {
                f->buf_size = 0;
-       } else {
+       } else if (type == _IOLBF || type == _IOFBF) {
                if (buf && size >= UNGET) {
                        f->buf = (void *)(buf + UNGET);
                        f->buf_size = size - UNGET;
                }
                if (type == _IOLBF && f->buf_size)
                        f->lbf = '\n';
+       } else {
+               return -1;
        }
 
        f->flags |= F_SVB;