extmod: Add VfsPosix filesystem component.

This VFS component allows to mount a host POSIX filesystem within the uPy
VFS sub-system.  All traditional POSIX file access then goes through the
VFS, allowing to sandbox a uPy process to a certain sub-dir of the host
system, as well as mount other filesystem types alongside the host
filesystem.

1 files changed, 261 insertions, 0 deletions

diff --git a/extmod/vfs_posix_file.c b/extmod/vfs_posix_file.c
new file mode 100644
index 000000000..435ac65cd
--- /dev/null
+++ b/extmod/vfs_posix_file.c
@@ -0,0 +1,261 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013-2018 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/runtime.h"
+#include "py/stream.h"
+#include "extmod/vfs_posix.h"
+
+#if MICROPY_VFS_POSIX
+
+#include <fcntl.h>
+
+#ifdef _WIN32
+#define fsync _commit
+#endif
+
+typedef struct _mp_obj_vfs_posix_file_t {
+    mp_obj_base_t base;
+    int fd;
+} mp_obj_vfs_posix_file_t;
+
+#ifdef MICROPY_CPYTHON_COMPAT
+STATIC void check_fd_is_open(const mp_obj_vfs_posix_file_t *o) {
+    if (o->fd < 0) {
+        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "I/O operation on closed file"));
+    }
+}
+#else
+#define check_fd_is_open(o)
+#endif
+
+STATIC void vfs_posix_file_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    (void)kind;
+    mp_obj_vfs_posix_file_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_printf(print, "<io.%s %d>", mp_obj_get_type_str(self_in), self->fd);
+}
+
+mp_obj_t mp_vfs_posix_file_open(const mp_obj_type_t *type, mp_obj_t file_in, mp_obj_t mode_in) {
+    mp_obj_vfs_posix_file_t *o = m_new_obj(mp_obj_vfs_posix_file_t);
+    const char *mode_s = mp_obj_str_get_str(mode_in);
+
+    int mode_rw = 0, mode_x = 0;
+    while (*mode_s) {
+        switch (*mode_s++) {
+            case 'r':
+                mode_rw = O_RDONLY;
+                break;
+            case 'w':
+                mode_rw = O_WRONLY;
+                mode_x = O_CREAT | O_TRUNC;
+                break;
+            case 'a':
+                mode_rw = O_WRONLY;
+                mode_x = O_CREAT | O_APPEND;
+                break;
+            case '+':
+                mode_rw = O_RDWR;
+                break;
+            #if MICROPY_PY_IO_FILEIO
+            // If we don't have io.FileIO, then files are in text mode implicitly
+            case 'b':
+                type = &mp_type_vfs_posix_fileio;
+                break;
+            case 't':
+                type = &mp_type_vfs_posix_textio;
+                break;
+            #endif
+        }
+    }
+
+    o->base.type = type;
+
+    mp_obj_t fid = file_in;
+
+    if (MP_OBJ_IS_SMALL_INT(fid)) {
+        o->fd = MP_OBJ_SMALL_INT_VALUE(fid);
+        return MP_OBJ_FROM_PTR(o);
+    }
+
+    const char *fname = mp_obj_str_get_str(fid);
+    int fd = open(fname, mode_x | mode_rw, 0644);
+    if (fd == -1) {
+        mp_raise_OSError(errno);
+    }
+    o->fd = fd;
+    return MP_OBJ_FROM_PTR(o);
+}
+
+STATIC mp_obj_t vfs_posix_file_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_file, MP_ARG_OBJ | MP_ARG_REQUIRED, {.u_rom_obj = MP_ROM_PTR(&mp_const_none_obj)} },
+        { MP_QSTR_mode, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_QSTR(MP_QSTR_r)} },
+    };
+
+    mp_arg_val_t arg_vals[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all_kw_array(n_args, n_kw, args, MP_ARRAY_SIZE(allowed_args), allowed_args, arg_vals);
+    return mp_vfs_posix_file_open(type, arg_vals[0].u_obj, arg_vals[1].u_obj);
+}
+
+STATIC mp_obj_t vfs_posix_file_fileno(mp_obj_t self_in) {
+    mp_obj_vfs_posix_file_t *self = MP_OBJ_TO_PTR(self_in);
+    check_fd_is_open(self);
+    return MP_OBJ_NEW_SMALL_INT(self->fd);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(vfs_posix_file_fileno_obj, vfs_posix_file_fileno);
+
+STATIC mp_obj_t vfs_posix_file___exit__(size_t n_args, const mp_obj_t *args) {
+    (void)n_args;
+    return mp_stream_close(args[0]);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(vfs_posix_file___exit___obj, 4, 4, vfs_posix_file___exit__);
+
+STATIC mp_uint_t vfs_posix_file_read(mp_obj_t o_in, void *buf, mp_uint_t size, int *errcode) {
+    mp_obj_vfs_posix_file_t *o = MP_OBJ_TO_PTR(o_in);
+    check_fd_is_open(o);
+    mp_int_t r = read(o->fd, buf, size);
+    if (r == -1) {
+        *errcode = errno;
+        return MP_STREAM_ERROR;
+    }
+    return r;
+}
+
+STATIC mp_uint_t vfs_posix_file_write(mp_obj_t o_in, const void *buf, mp_uint_t size, int *errcode) {
+    mp_obj_vfs_posix_file_t *o = MP_OBJ_TO_PTR(o_in);
+    check_fd_is_open(o);
+    #if MICROPY_PY_OS_DUPTERM
+    if (o->fd <= STDERR_FILENO) {
+        mp_hal_stdout_tx_strn(buf, size);
+        return size;
+    }
+    #endif
+    mp_int_t r = write(o->fd, buf, size);
+    while (r == -1 && errno == EINTR) {
+        if (MP_STATE_VM(mp_pending_exception) != MP_OBJ_NULL) {
+            mp_obj_t obj = MP_STATE_VM(mp_pending_exception);
+            MP_STATE_VM(mp_pending_exception) = MP_OBJ_NULL;
+            nlr_raise(obj);
+        }
+        r = write(o->fd, buf, size);
+    }
+    if (r == -1) {
+        *errcode = errno;
+        return MP_STREAM_ERROR;
+    }
+    return r;
+}
+
+STATIC mp_uint_t vfs_posix_file_ioctl(mp_obj_t o_in, mp_uint_t request, uintptr_t arg, int *errcode) {
+    mp_obj_vfs_posix_file_t *o = MP_OBJ_TO_PTR(o_in);
+    check_fd_is_open(o);
+    switch (request) {
+        case MP_STREAM_FLUSH:
+            if (fsync(o->fd) < 0) {
+                *errcode = errno;
+                return MP_STREAM_ERROR;
+            }
+            return 0;
+        case MP_STREAM_SEEK: {
+            struct mp_stream_seek_t *s = (struct mp_stream_seek_t*)arg;
+            off_t off = lseek(o->fd, s->offset, s->whence);
+            if (off == (off_t)-1) {
+                *errcode = errno;
+                return MP_STREAM_ERROR;
+            }
+            s->offset = off;
+            return 0;
+        }
+        case MP_STREAM_CLOSE:
+            close(o->fd);
+            #ifdef MICROPY_CPYTHON_COMPAT
+            o->fd = -1;
+            #endif
+            return 0;
+        default:
+            *errcode = EINVAL;
+            return MP_STREAM_ERROR;
+    }
+}
+
+STATIC const mp_rom_map_elem_t rawfile_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_fileno), MP_ROM_PTR(&vfs_posix_file_fileno_obj) },
+    { MP_ROM_QSTR(MP_QSTR_read), MP_ROM_PTR(&mp_stream_read_obj) },
+    { MP_ROM_QSTR(MP_QSTR_readinto), MP_ROM_PTR(&mp_stream_readinto_obj) },
+    { MP_ROM_QSTR(MP_QSTR_readline), MP_ROM_PTR(&mp_stream_unbuffered_readline_obj) },
+    { MP_ROM_QSTR(MP_QSTR_readlines), MP_ROM_PTR(&mp_stream_unbuffered_readlines_obj) },
+    { MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&mp_stream_write_obj) },
+    { MP_ROM_QSTR(MP_QSTR_seek), MP_ROM_PTR(&mp_stream_seek_obj) },
+    { MP_ROM_QSTR(MP_QSTR_tell), MP_ROM_PTR(&mp_stream_tell_obj) },
+    { MP_ROM_QSTR(MP_QSTR_flush), MP_ROM_PTR(&mp_stream_flush_obj) },
+    { MP_ROM_QSTR(MP_QSTR_close), MP_ROM_PTR(&mp_stream_close_obj) },
+    { MP_ROM_QSTR(MP_QSTR___enter__), MP_ROM_PTR(&mp_identity_obj) },
+    { MP_ROM_QSTR(MP_QSTR___exit__), MP_ROM_PTR(&vfs_posix_file___exit___obj) },
+};
+
+STATIC MP_DEFINE_CONST_DICT(rawfile_locals_dict, rawfile_locals_dict_table);
+
+#if MICROPY_PY_IO_FILEIO
+STATIC const mp_stream_p_t fileio_stream_p = {
+    .read = vfs_posix_file_read,
+    .write = vfs_posix_file_write,
+    .ioctl = vfs_posix_file_ioctl,
+};
+
+const mp_obj_type_t mp_type_vfs_posix_fileio = {
+    { &mp_type_type },
+    .name = MP_QSTR_FileIO,
+    .print = vfs_posix_file_print,
+    .make_new = vfs_posix_file_make_new,
+    .getiter = mp_identity_getiter,
+    .iternext = mp_stream_unbuffered_iter,
+    .protocol = &fileio_stream_p,
+    .locals_dict = (mp_obj_dict_t*)&rawfile_locals_dict,
+};
+#endif
+
+STATIC const mp_stream_p_t textio_stream_p = {
+    .read = vfs_posix_file_read,
+    .write = vfs_posix_file_write,
+    .ioctl = vfs_posix_file_ioctl,
+    .is_text = true,
+};
+
+const mp_obj_type_t mp_type_vfs_posix_textio = {
+    { &mp_type_type },
+    .name = MP_QSTR_TextIOWrapper,
+    .print = vfs_posix_file_print,
+    .make_new = vfs_posix_file_make_new,
+    .getiter = mp_identity_getiter,
+    .iternext = mp_stream_unbuffered_iter,
+    .protocol = &textio_stream_p,
+    .locals_dict = (mp_obj_dict_t*)&rawfile_locals_dict,
+};
+
+const mp_obj_vfs_posix_file_t mp_sys_stdin_obj  = {{&mp_type_textio}, STDIN_FILENO};
+const mp_obj_vfs_posix_file_t mp_sys_stdout_obj = {{&mp_type_textio}, STDOUT_FILENO};
+const mp_obj_vfs_posix_file_t mp_sys_stderr_obj = {{&mp_type_textio}, STDERR_FILENO};
+
+#endif // MICROPY_VFS_POSIX