STATIC mp_obj_t stream_read(uint n_args, const mp_obj_t *args) { struct _mp_obj_base_t *o = (struct _mp_obj_base_t *)args[0]; if (o->type->stream_p == NULL || o->type->stream_p->read == NULL) { // CPython: io.UnsupportedOperation, OSError subclass nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "Operation not supported")); } mp_int_t sz; if (n_args == 1 || ((sz = mp_obj_get_int(args[1])) == -1)) { return stream_readall(args[0]); } #if MICROPY_PY_BUILTINS_STR_UNICODE if (!o->type->stream_p->is_bytes) { mp_not_implemented("Reading from unicode text streams by character count"); } #endif byte *buf = m_new(byte, sz); int error; mp_int_t out_sz = o->type->stream_p->read(o, buf, sz, &error); if (out_sz == -1) { if (is_nonblocking_error(error)) { // https://docs.python.org/3.4/library/io.html#io.RawIOBase.read // "If the object is in non-blocking mode and no bytes are available, // None is returned." // This is actually very weird, as naive truth check will treat // this as EOF. return mp_const_none; } nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError, "[Errno %d]", error)); } else { mp_obj_t s = mp_obj_new_str_of_type(STREAM_CONTENT_TYPE(o->type->stream_p), buf, out_sz); // will reallocate to use exact size m_free(buf, sz); return s; } }
STATIC mp_obj_t stream_read_generic(size_t n_args, const mp_obj_t *args, byte flags) { // What to do if sz < -1? Python docs don't specify this case. // CPython does a readall, but here we silently let negatives through, // and they will cause a MemoryError. mp_int_t sz; if (n_args == 1 || ((sz = mp_obj_get_int(args[1])) == -1)) { return stream_readall(args[0]); } const mp_stream_p_t *stream_p = mp_get_stream(args[0]); #if MICROPY_PY_BUILTINS_STR_UNICODE if (stream_p->is_text) { // We need to read sz number of unicode characters. Because we don't have any // buffering, and because the stream API can only read bytes, we must read here // in units of bytes and must never over read. If we want sz chars, then reading // sz bytes will never over-read, so we follow this approach, in a loop to keep // reading until we have exactly enough chars. This will be 1 read for text // with ASCII-only chars, and about 2 reads for text with a couple of non-ASCII // chars. For text with lots of non-ASCII chars, it'll be pretty inefficient // in time and memory. vstr_t vstr; vstr_init(&vstr, sz); mp_uint_t more_bytes = sz; mp_uint_t last_buf_offset = 0; while (more_bytes > 0) { char *p = vstr_add_len(&vstr, more_bytes); int error; mp_uint_t out_sz = mp_stream_read_exactly(args[0], p, more_bytes, &error); if (error != 0) { vstr_cut_tail_bytes(&vstr, more_bytes); if (mp_is_nonblocking_error(error)) { // With non-blocking streams, we read as much as we can. // If we read nothing, return None, just like read(). // Otherwise, return data read so far. // TODO what if we have read only half a non-ASCII char? if (vstr.len == 0) { vstr_clear(&vstr); return mp_const_none; } break; } mp_raise_OSError(error); } if (out_sz < more_bytes) { // Finish reading. // TODO what if we have read only half a non-ASCII char? vstr_cut_tail_bytes(&vstr, more_bytes - out_sz); if (out_sz == 0) { break; } } // count chars from bytes just read for (mp_uint_t off = last_buf_offset;;) { byte b = vstr.buf[off]; int n; if (!UTF8_IS_NONASCII(b)) { // 1-byte ASCII char n = 1; } else if ((b & 0xe0) == 0xc0) { // 2-byte char n = 2; } else if ((b & 0xf0) == 0xe0) { // 3-byte char n = 3; } else if ((b & 0xf8) == 0xf0) { // 4-byte char n = 4; } else { // TODO n = 5; } if (off + n <= vstr.len) { // got a whole char in n bytes off += n; sz -= 1; last_buf_offset = off; if (off >= vstr.len) { more_bytes = sz; break; } } else { // didn't get a whole char, so work out how many extra bytes are needed for // this partial char, plus bytes for additional chars that we want more_bytes = (off + n - vstr.len) + (sz - 1); break; } } } return mp_obj_new_str_from_vstr(&mp_type_str, &vstr); } #endif vstr_t vstr; vstr_init_len(&vstr, sz); int error; mp_uint_t out_sz = mp_stream_rw(args[0], vstr.buf, sz, &error, flags); if (error != 0) { vstr_clear(&vstr); if (mp_is_nonblocking_error(error)) { // https://docs.python.org/3.4/library/io.html#io.RawIOBase.read // "If the object is in non-blocking mode and no bytes are available, // None is returned." // This is actually very weird, as naive truth check will treat // this as EOF. return mp_const_none; } mp_raise_OSError(error); } else { vstr.len = out_sz; return mp_obj_new_str_from_vstr(STREAM_CONTENT_TYPE(stream_p), &vstr); } }