From e3383e9352ca7704e650b07038207719c60b56fb Mon Sep 17 00:00:00 2001 From: Paul Sokolovsky Date: Sun, 20 Aug 2017 21:57:36 +0300 Subject: [PATCH] py/stream: seek: Consistently handle negative offset for SEEK_SET. Per POSIX, this is EINVAL, so raises OSError(EINVAL). --- py/stream.c | 7 ++++++- tests/io/bytesio_ext2.py | 13 +++++++++++++ tests/io/bytesio_ext2.py.exp | 1 + 3 files changed, 20 insertions(+), 1 deletion(-) create mode 100644 tests/io/bytesio_ext2.py create mode 100644 tests/io/bytesio_ext2.py.exp diff --git a/py/stream.c b/py/stream.c index 5d18681538..0029a59a75 100644 --- a/py/stream.c +++ b/py/stream.c @@ -448,11 +448,16 @@ STATIC mp_obj_t stream_seek(size_t n_args, const mp_obj_t *args) { struct mp_stream_seek_t seek_s; // TODO: Could be uint64 seek_s.offset = mp_obj_get_int(args[1]); - seek_s.whence = 0; + seek_s.whence = SEEK_SET; if (n_args == 3) { seek_s.whence = mp_obj_get_int(args[2]); } + // In POSIX, it's error to seek before end of stream, we enforce it here. + if (seek_s.whence == SEEK_SET && seek_s.offset < 0) { + mp_raise_OSError(MP_EINVAL); + } + int error; mp_uint_t res = stream_p->ioctl(args[0], MP_STREAM_SEEK, (mp_uint_t)(uintptr_t)&seek_s, &error); if (res == MP_STREAM_ERROR) { diff --git a/tests/io/bytesio_ext2.py b/tests/io/bytesio_ext2.py new file mode 100644 index 0000000000..c07ad900c9 --- /dev/null +++ b/tests/io/bytesio_ext2.py @@ -0,0 +1,13 @@ +try: + import uio as io +except ImportError: + import io + +a = io.BytesIO(b"foobar") +try: + a.seek(-10) +except Exception as e: + # CPython throws ValueError, but MicroPython has consistent stream + # interface, so BytesIO raises the same error as a real file, which + # is OSError(EINVAL). + print(repr(e)) diff --git a/tests/io/bytesio_ext2.py.exp b/tests/io/bytesio_ext2.py.exp new file mode 100644 index 0000000000..b52e4978aa --- /dev/null +++ b/tests/io/bytesio_ext2.py.exp @@ -0,0 +1 @@ +OSError(22,)