diff options
Diffstat (limited to 'src/stdio/setvbuf.c')
| -rw-r--r-- | src/stdio/setvbuf.c | 25 |
1 files changed, 14 insertions, 11 deletions
diff --git a/src/stdio/setvbuf.c b/src/stdio/setvbuf.c index 541a125f..0a0c139f 100644 --- a/src/stdio/setvbuf.c +++ b/src/stdio/setvbuf.c @@ -1,22 +1,25 @@ #include "stdio_impl.h" -/* This function makes no attempt to protect the user from his/her own - * stupidity. If called any time but when then ISO C standard specifically - * allows it, all hell can and will break loose, especially with threads! - * - * This implementation ignores all arguments except the buffering type, - * and uses the existing buffer allocated alongside the FILE object. - * In the case of stderr where the preexisting buffer is length 1, it - * is not possible to set line buffering or full buffering. */ +/* The behavior of this function is undefined except when it is the first + * operation on the stream, so the presence or absence of lockign is not + * observable in a program whose behavior is defined. Thus no locking is + * performed here. No allocation of buffers is performed, but a buffer + * provided by the caller is used as long as it is suitably sized. */ int setvbuf(FILE *restrict f, char *restrict buf, int type, size_t size) { f->lbf = EOF; - if (type == _IONBF) + if (type == _IONBF) { f->buf_size = 0; - else if (type == _IOLBF) - f->lbf = '\n'; + } else { + if (buf && size >= UNGET) { + f->buf = (void *)buf; + f->buf_size = size - UNGET; + } + if (type == _IOLBF && f->buf_size) + f->lbf = '\n'; + } f->flags |= F_SVB; |