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py/modio: Add uio.IOBase class to allow to define user streams.
A user class derived from IOBase and implementing readinto/write/ioctl can now be used anywhere a native stream object is accepted. The mapping from C to Python is: stream_p->read --> readinto(buf) stream_p->write --> write(buf) stream_p->ioctl --> ioctl(request, arg) Among other things it allows the user to: - create an object which can be passed as the file argument to print: print(..., file=myobj), and then print will pass all the data to the object via the objects write method (same as CPython) - pass a user object to uio.BufferedWriter to buffer the writes (same as CPython) - use select.select on a user object - register user objects with select.poll, in particular so user objects can be used with uasyncio - create user files that can be returned from user filesystems, and import can import scripts from these user files For example: class MyOut(io.IOBase): def write(self, buf): print('write', repr(buf)) return len(buf) print('hello', file=MyOut()) The feature is enabled via MICROPY_PY_IO_IOBASE which is disabled by default.
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‎py/modio.c‎

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@@ -30,6 +30,8 @@
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#include "py/runtime.h"
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#include "py/builtin.h"
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#include "py/stream.h"
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#include "py/binary.h"
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#include "py/objarray.h"
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#include "py/objstringio.h"
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#include "py/frozenmod.h"
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@@ -38,6 +40,70 @@
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extern const mp_obj_type_t mp_type_fileio;
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extern const mp_obj_type_t mp_type_textio;
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#if MICROPY_PY_IO_IOBASE
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STATIC const mp_obj_type_t mp_type_iobase;
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STATIC mp_obj_base_t iobase_singleton = {&mp_type_iobase};
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STATIC mp_obj_t iobase_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
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(void)type;
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(void)n_args;
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(void)n_kw;
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(void)args;
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return MP_OBJ_FROM_PTR(&iobase_singleton);
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}
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STATIC mp_uint_t iobase_read_write(mp_obj_t obj, void *buf, mp_uint_t size, int *errcode, qstr qst) {
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mp_obj_t dest[3];
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mp_load_method(obj, qst, dest);
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mp_obj_array_t ar = {{&mp_type_bytearray}, BYTEARRAY_TYPECODE, 0, size, buf};
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dest[2] = MP_OBJ_FROM_PTR(&ar);
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mp_obj_t ret = mp_call_method_n_kw(1, 0, dest);
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if (ret == mp_const_none) {
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*errcode = MP_EAGAIN;
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return MP_STREAM_ERROR;
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} else {
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return mp_obj_get_int(ret);
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}
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}
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STATIC mp_uint_t iobase_read(mp_obj_t obj, void *buf, mp_uint_t size, int *errcode) {
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return iobase_read_write(obj, buf, size, errcode, MP_QSTR_readinto);
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}
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STATIC mp_uint_t iobase_write(mp_obj_t obj, const void *buf, mp_uint_t size, int *errcode) {
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return iobase_read_write(obj, (void*)buf, size, errcode, MP_QSTR_write);
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}
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STATIC mp_uint_t iobase_ioctl(mp_obj_t obj, mp_uint_t request, uintptr_t arg, int *errcode) {
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mp_obj_t dest[4];
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mp_load_method(obj, MP_QSTR_ioctl, dest);
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dest[2] = mp_obj_new_int_from_uint(request);
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dest[3] = mp_obj_new_int_from_uint(arg);
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mp_int_t ret = mp_obj_get_int(mp_call_method_n_kw(2, 0, dest));
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if (ret >= 0) {
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return ret;
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} else {
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*errcode = -ret;
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return MP_STREAM_ERROR;
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}
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}
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STATIC const mp_stream_p_t iobase_p = {
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.read = iobase_read,
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.write = iobase_write,
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.ioctl = iobase_ioctl,
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};
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STATIC const mp_obj_type_t mp_type_iobase = {
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{ &mp_type_type },
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.name = MP_QSTR_IOBase,
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.make_new = iobase_make_new,
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.protocol = &iobase_p,
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};
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#endif // MICROPY_PY_IO_IOBASE
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#if MICROPY_PY_IO_BUFFEREDWRITER
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typedef struct _mp_obj_bufwriter_t {
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mp_obj_base_t base;
@@ -187,6 +253,9 @@ STATIC const mp_rom_map_elem_t mp_module_io_globals_table[] = {
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// Note: mp_builtin_open_obj should be defined by port, it's not
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// part of the core.
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{ MP_ROM_QSTR(MP_QSTR_open), MP_ROM_PTR(&mp_builtin_open_obj) },
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#if MICROPY_PY_IO_IOBASE
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{ MP_ROM_QSTR(MP_QSTR_IOBase), MP_ROM_PTR(&mp_type_iobase) },
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#endif
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#if MICROPY_PY_IO_RESOURCE_STREAM
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{ MP_ROM_QSTR(MP_QSTR_resource_stream), MP_ROM_PTR(&resource_stream_obj) },
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#endif

‎py/mpconfig.h‎

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@@ -998,6 +998,11 @@ typedef double mp_float_t;
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#define MICROPY_PY_IO (1)
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#endif
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// Whether to provide "io.IOBase" class to support user streams
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#ifndef MICROPY_PY_IO_IOBASE
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#define MICROPY_PY_IO_IOBASE (0)
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#endif
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// Whether to provide "uio.resource_stream()" function with
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// the semantics of CPython's pkg_resources.resource_stream()
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// (allows to access binary resources in frozen source packages).

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