webassembly: Add support for VFS and enable VFS_POSIX.

This gets filesystem support working.

Signed-off-by: Damien George <damien@micropython.org>

ports/webassembly/Makefile

@@ -37,7 +37,10 @@ OBJ += $(addprefix $(BUILD)/, $(SRC_SHARED:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
 
 JSFLAGS += -s ASYNCIFY
-JSFLAGS += -s EXPORTED_FUNCTIONS="['_mp_js_init', '_mp_js_init_repl', '_mp_js_do_str', '_mp_js_process_char', '_mp_hal_get_interrupt_char', '_mp_sched_keyboard_interrupt']" -s EXPORTED_RUNTIME_METHODS="['ccall', 'cwrap']" -s --memory-init-file 0 --js-library library.js
+JSFLAGS += -s EXPORTED_FUNCTIONS="['_mp_js_init', '_mp_js_init_repl', '_mp_js_do_str', '_mp_js_process_char', '_mp_hal_get_interrupt_char', '_mp_sched_keyboard_interrupt']"
+JSFLAGS += -s EXPORTED_RUNTIME_METHODS="['ccall', 'cwrap', 'FS']"
+JSFLAGS += -s --memory-init-file 0
+JSFLAGS += --js-library library.js
 
 all: $(BUILD)/micropython.js
 

ports/webassembly/main.c

@@ -35,6 +35,8 @@
 #include "py/repl.h"
 #include "py/gc.h"
 #include "py/mperrno.h"
+#include "extmod/vfs.h"
+#include "extmod/vfs_posix.h"
 #include "shared/runtime/pyexec.h"
 
 #include "emscripten.h"
@@ -92,6 +94,18 @@ void mp_js_init(int heap_size) {
     #endif
 
     mp_init();
+
+    #if MICROPY_VFS_POSIX
+    {
+        // Mount the host FS at the root of our internal VFS
+        mp_obj_t args[2] = {
+            MP_OBJ_TYPE_GET_SLOT(&mp_type_vfs_posix, make_new)(&mp_type_vfs_posix, 0, 0, NULL),
+            MP_OBJ_NEW_QSTR(qstr_from_str("/")),
+        };
+        mp_vfs_mount(2, args, (mp_map_t *)&mp_const_empty_map);
+        MP_STATE_VM(vfs_cur) = MP_STATE_VM(vfs_mount_table);
+    }
+    #endif
 }
 
 void mp_js_init_repl() {
@@ -109,6 +123,7 @@ void gc_collect(void) {
     gc_collect_end();
 }
 
+#if !MICROPY_VFS
 mp_lexer_t *mp_lexer_new_from_file(const char *filename) {
     mp_raise_OSError(MP_ENOENT);
 }
@@ -121,6 +136,7 @@ mp_obj_t mp_builtin_open(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs)
     return mp_const_none;
 }
 MP_DEFINE_CONST_FUN_OBJ_KW(mp_builtin_open_obj, 1, mp_builtin_open);
+#endif
 
 void nlr_jump_fail(void *val) {
     while (1) {

ports/webassembly/mpconfigport.h

@@ -37,6 +37,7 @@
 #define MICROPY_ENABLE_COMPILER     (1)
 
 #define MICROPY_ALLOC_PATH_MAX      (256)
+#define MICROPY_READER_VFS          (MICROPY_VFS)
 #define MICROPY_ENABLE_GC           (1)
 #define MICROPY_ENABLE_PYSTACK      (1)
 #define MICROPY_STACK_CHECK         (0)
@@ -48,6 +49,10 @@
 #define MICROPY_FLOAT_IMPL          (MICROPY_FLOAT_IMPL_DOUBLE)
 #define MICROPY_USE_INTERNAL_ERRNO  (1)
 #define MICROPY_USE_INTERNAL_PRINTF (0)
+#ifndef MICROPY_VFS
+#define MICROPY_VFS                 (1)
+#endif
+#define MICROPY_VFS_POSIX           (MICROPY_VFS)
 #define MICROPY_PY_UTIME_MP_HAL     (1)
 #define MICROPY_PY_SYS_PLATFORM     "webassembly"
 #define MICROPY_PY_SYS_STDFILES     (0)
@@ -86,3 +91,8 @@ typedef long mp_off_t;
 #define MICROPY_HW_MCU_NAME "Emscripten"
 
 #define MP_STATE_PORT MP_STATE_VM
+
+#if MICROPY_VFS
+// _GNU_SOURCE must be defined to get definitions of DT_xxx symbols from dirent.h.
+#define _GNU_SOURCE
+#endif

ports/webassembly/mphalport.h

@@ -37,3 +37,26 @@ mp_uint_t mp_hal_ticks_us(void);
 mp_uint_t mp_hal_ticks_cpu(void);
 
 int mp_hal_get_interrupt_char(void);
+
+#if MICROPY_VFS_POSIX
+
+#include <errno.h>
+
+// This macro is used to implement PEP 475 to retry specified syscalls on EINTR
+#define MP_HAL_RETRY_SYSCALL(ret, syscall, raise) \
+    { \
+        for (;;) { \
+            ret = syscall; \
+            if (ret == -1) { \
+                int err = errno; \
+                if (err == EINTR) { \
+                    mp_handle_pending(true); \
+                    continue; \
+                } \
+                raise; \
+            } \
+            break; \
+        } \
+    }
+
+#endif