Merge wasip2/wasip3 reading/writing (WebAssembly#756)

* Generalize the `wasip2_{read,write}_t` types to `wasi_{read,write}_t`
with conditional internals depending on the WASI version.
* Fix error handling for stdin to use stdin error codes instead of
filesystem error codes.
* Call `subtask.drop` for writes to acknowledge the subtask being done.
* When stdin is done, drop the future for the error after it's read to
ensure the future isn't read twice.

Author: alexcrichton

expected/wasm32-wasip3/defined-symbols.txt

@@ -331,7 +331,7 @@ __wasilibc_parse_port
 __wasilibc_populate_preopens
 __wasilibc_pthread_self
 __wasilibc_random
-__wasilibc_read_stream3
+__wasilibc_read
 __wasilibc_rename_newat
 __wasilibc_rename_oldat
 __wasilibc_reset_preopens
@@ -345,7 +345,7 @@ __wasilibc_unspecified_addr
 __wasilibc_utimens
 __wasilibc_wasi_family_to_libc
 __wasilibc_wasi_to_sockaddr
-__wasilibc_write_stream3
+__wasilibc_write
 __wasm_call_dtors
 __wcscoll_l
 __wcsftime_l

libc-bottom-half/CMakeLists.txt

@@ -139,6 +139,7 @@ else()
     sources/descriptor_table.c
     sources/getsockpeername.c
     sources/listen.c
+    sources/file_utils.c
     sources/recv.c
     sources/send.c
     sources/shutdown.c
@@ -155,7 +156,6 @@ if(WASI STREQUAL "p2")
     sources/netdb.c
     sources/wasip2.c
     sources/wasip2_file.c
-    sources/wasip2_file_utils.c
     sources/wasip2_stdio.c
   )
 endif()
@@ -165,7 +165,6 @@ if (WASI STREQUAL "p3")
     sources/wasip3.c
     sources/wasip3_block_on.c
     sources/wasip3_file.c
-    sources/wasip3_file_utils.c
     sources/wasip3_stdio.c
   )
 endif()

libc-bottom-half/cloudlibc/src/libc/poll/poll.c

@@ -216,7 +216,7 @@ static int poll_impl(struct pollfd *fds, size_t nfds, int timeout) {
 
     if (pollfd->events & POLLRDNORM) {
       if (entry->vtable->get_read_stream) {
-        wasip2_read_t read;
+        wasi_read_t read;
         if (entry->vtable->get_read_stream(entry->data, &read) < 0)
           return -1;
         if (__wasilibc_poll_add_input_stream(&state, read.input, read.pollable) < 0)
@@ -229,7 +229,7 @@ static int poll_impl(struct pollfd *fds, size_t nfds, int timeout) {
 
     if (pollfd->events & POLLWRNORM) {
       if (entry->vtable->get_write_stream) {
-        wasip2_write_t write;
+        wasi_write_t write;
         if (entry->vtable->get_write_stream(entry->data, &write) < 0)
           return -1;
         if (__wasilibc_poll_add_output_stream(&state, write.output, write.pollable) < 0)

libc-bottom-half/cloudlibc/src/libc/unistd/read.c

@@ -27,12 +27,12 @@ ssize_t read(int fildes, void *buf, size_t nbyte) {
     return -1;
   }
   return bytes_read;
-#elif defined(__wasip2__)
+#else
   descriptor_table_entry_t *entry = descriptor_table_get_ref(fildes);
   if (!entry)
     return -1;
   if (entry->vtable->get_read_stream) {
-    wasip2_read_t read;
+    wasi_read_t read;
     if (entry->vtable->get_read_stream(entry->data, &read) < 0)
       return -1;
     return __wasilibc_read(&read, buf, nbyte);
@@ -41,30 +41,5 @@ ssize_t read(int fildes, void *buf, size_t nbyte) {
     return entry->vtable->recvfrom(entry->data, buf, nbyte, 0, NULL, NULL);
   errno = EOPNOTSUPP;
   return -1;
-#elif defined(__wasip3__)
-  filesystem_tuple2_stream_u8_future_result_void_error_code_t *stream;
-  off_t *off;
-  if (__wasilibc_read_stream3(fildes, &stream, &off)<0)
-    return -1;
-  wasip3_waitable_status_t status =
-      filesystem_stream_u8_read(stream->f0, buf, nbyte);
-  size_t amount = wasip3_waitable_block_on(status, stream->f0);
-  if (amount > 0 || nbyte == 0) {
-    if (off)
-      *off += amount;
-    return amount;
-  } else {
-    filesystem_result_void_error_code_t error;
-    status = filesystem_future_result_void_error_code_read(stream->f1, &error);
-    amount = wasip3_waitable_block_on(status, stream->f1);
-    if (amount > 0 && error.is_err) {
-      translate_error(error.val.err);
-      return -1;
-    }
-    // EOF
-    return 0;
-  }
-#else
-# error "Unsupported WASI version"
 #endif
 }

libc-bottom-half/cloudlibc/src/libc/unistd/write.c

@@ -28,12 +28,12 @@ ssize_t write(int fildes, const void *buf, size_t nbyte) {
     return -1;
   }
   return bytes_written;
-#elif defined(__wasip2__)
+#else
   descriptor_table_entry_t *entry = descriptor_table_get_ref(fildes);
   if (!entry)
     return -1;
   if (entry->vtable->get_write_stream) {
-    wasip2_write_t write;
+    wasi_write_t write;
     if (entry->vtable->get_write_stream(entry->data, &write) < 0)
       return -1;
     return __wasilibc_write(&write, buf, nbyte);
@@ -42,33 +42,5 @@ ssize_t write(int fildes, const void *buf, size_t nbyte) {
     return entry->vtable->sendto(entry->data, buf, nbyte, 0, NULL, 0);
   errno = EOPNOTSUPP;
   return -1;
-#elif defined(__wasip3__)
-  wasip3_write_t *write_end;
-  off_t *off;
-  if (__wasilibc_write_stream3(fildes, &write_end, &off) < 0)
-    return -1;
-  if (WASIP3_SUBTASK_STATE(write_end->subtask) == WASIP3_SUBTASK_STARTING ||
-      WASIP3_SUBTASK_STATE(write_end->subtask) == WASIP3_SUBTASK_STARTED) {
-    // the stream is still active
-    wasip3_waitable_status_t status =
-        filesystem_stream_u8_write(write_end->output, buf, nbyte);
-    size_t amount = wasip3_waitable_block_on(status, write_end->output);
-    if (amount > 0 || nbyte == 0) {
-      if (off)
-        *off += amount;
-      return amount;
-    }
-    // error or eof
-    wasip3_subtask_block_on(write_end->subtask);
-    write_end->subtask = WASIP3_SUBTASK_RETURNED;
-  }
-  if (write_end->pending_result.is_err) {
-    translate_error(write_end->pending_result.val.err);
-    return -1;
-  }
-  // EOF
-  return 0;
-#else
-# error "Unknown WASI version"
 #endif
 }

libc-bottom-half/headers/private/wasi/descriptor_table.h

@@ -8,48 +8,54 @@
 #include <sys/stat.h>
 #include <netinet/in.h>
 
-#ifdef __wasip2__
 // Metadata for WASI reads which is used to delegate to `__wasilibc_read(...)`
 // to perform the actual read of a stream.
-typedef struct wasip2_read_t {
-  // The `wasi:io/streams.input-stream` that this is reading from.
-  streams_borrow_input_stream_t input;
+typedef struct wasi_read_t {
   // An optional pointer to the internal offset of this stream, updated on
   // successful reads.
   off_t *offset;
-  // A required pointer to an owned pollable for `input`. This is lazily
-  // initialized as-necessary.
-  poll_own_pollable_t *pollable;
   // Whether or not this read will use blocking I/O.
   bool blocking;
   // The timeout, in nanoseconds, for this operation.
   monotonic_clock_duration_t timeout;
-} wasip2_read_t;
+#ifdef __wasip2__
+  // The `wasi:io/streams.input-stream` that this is reading from.
+  streams_borrow_input_stream_t input;
+  // A required pointer to an owned pollable for `input`. This is lazily
+  // initialized as-necessary.
+  poll_own_pollable_t *pollable;
+#else
+  // The `stream<u8>` that's being read.
+  filesystem_stream_u8_t stream;
+
+  // A callback/ptr pair to invoke when EOF is reached to set errno and return
+  // an error code.
+  int (*eof)(void*);
+  void *eof_data;
+#endif
+} wasi_read_t;
 
-// Same as `wasip2_read_t`, but for writes.
-typedef struct wasip2_write_t {
-  streams_borrow_output_stream_t output;
+// Same as `wasip_read_t`, but for writes.
+typedef struct wasi_write_t {
   off_t *offset;
-  poll_own_pollable_t *pollable;
   bool blocking;
   monotonic_clock_duration_t timeout;
-} wasip2_write_t;
-#endif
-
-#ifdef __wasip3__
-// create an alias to distinguish the handle type in the API
-typedef uint32_t waitable_t;
 
-/**
- * This data structure represents the write end of a file
- */
-typedef struct wasip3_write_t {
+#ifdef __wasip2__
+  streams_borrow_output_stream_t output;
+  poll_own_pollable_t *pollable;
+#else
   filesystem_stream_u8_writer_t output;
   // contents will be filled by host (once write has an error)
   filesystem_result_void_error_code_t pending_result;
   // this task gets ready on error or eof
-  wasip3_subtask_t subtask;
-} wasip3_write_t;
+  wasip3_subtask_t *subtask;
+#endif
+} wasi_write_t;
+
+#ifdef __wasip3__
+// create an alias to distinguish the handle type in the API
+typedef uint32_t waitable_t;
 #endif
 
 /**
@@ -71,18 +77,12 @@ typedef struct descriptor_vtable_t {
   // =====================================================================
   // Generic I/O
 
-#ifdef __wasip2__
   /// Looks up metadata to perform a read operation for this stream. This is used
   /// to implement the `read` syscall, for example, and is also used with `poll`
   /// when waiting for readability.
-  int (*get_read_stream)(void*, wasip2_read_t*);
+  int (*get_read_stream)(void*, wasi_read_t*);
   /// Same as `get_read_stream`, but for output streams.
-  int (*get_write_stream)(void*, wasip2_write_t*);
-#endif
-#ifdef __wasip3__
-  int (*get_read_stream3)(void*, filesystem_tuple2_stream_u8_future_result_void_error_code_t **out, off_t** off);
-  int (*get_write_stream3)(void*, wasip3_write_t **write_end, off_t**);
-#endif
+  int (*get_write_stream)(void*, wasi_write_t*);
 
   /// Sets the nonblocking flag for this object to the specified value.
   int (*set_blocking)(void*, bool);

libc-bottom-half/headers/private/wasi/file_utils.h

@@ -2,15 +2,14 @@
 #define __wasi_file_utils_h
 
 #include <wasi/version.h>
-
 #if defined(__wasip2__) || defined(__wasip3__)
+
 #include <assert.h>
 #include <wasi/wasip2.h>
 #include <wasi/descriptor_table.h>
 #include <dirent.h>
 #include <fcntl.h>
 #include <errno.h>
-#endif
 
 #ifdef __wasip2__
 /// Handles a `wasi:io/streams.stream-error` for a `read`-style operation.
@@ -50,7 +49,6 @@ static inline int wasip2_handle_write_error(streams_stream_error_t error) {
 int wasip2_string_from_c(const char *s, wasip2_string_t* out);
 #endif
 
-#if defined(__wasip2__) || defined(__wasip3__)
 // Succeed only if fd is bound to a file handle in the descriptor table
 static inline int fd_to_file_handle(int fd, filesystem_borrow_descriptor_t* result) {
   descriptor_table_entry_t* entry = descriptor_table_get_ref(fd);
@@ -62,25 +60,16 @@ static inline int fd_to_file_handle(int fd, filesystem_borrow_descriptor_t* resu
   }
   return entry->vtable->get_file(entry->data, result);
 }
-#endif
 
-#ifdef __wasip2__
 // Reads from `read` into `buf`/`len`
 //
 // This perform the read configured by `read`, e.g. whether it's blocking or
 // not, and places the result in the specified buffer. Used to implement
 // `read` and `recvfrom`, for example.
-ssize_t __wasilibc_read(wasip2_read_t *read, void *buf, size_t len);
+ssize_t __wasilibc_read(wasi_read_t *read, void *buf, size_t len);
 // Same as `__wasilibc_read`, but for writes.
-ssize_t __wasilibc_write(wasip2_write_t *write, const void *buf, size_t len);
-#endif
-
-#ifdef __wasip3__
-int __wasilibc_write_stream3(int fildes, wasip3_write_t **write_end, off_t **off);
-int __wasilibc_read_stream3(int fildes, filesystem_tuple2_stream_u8_future_result_void_error_code_t **stream, off_t **off);
-#endif
+ssize_t __wasilibc_write(wasi_write_t *write, const void *buf, size_t len);
 
-#if defined(__wasip2__) || defined(__wasip3__)
 static inline unsigned dir_entry_type_to_d_type(filesystem_descriptor_type_t ty) {
   switch(ty) {
   case FILESYSTEM_DESCRIPTOR_TYPE_UNKNOWN:
@@ -104,6 +93,6 @@ static inline unsigned dir_entry_type_to_d_type(filesystem_descriptor_type_t ty)
   }
 }
 
-#endif
+#endif // __wasip2__ || __wasip3__
 
-#endif
+#endif // __wasi_file_utils_h

…-bottom-half/sources/wasip2_file_utils.c libc-bottom-half/sources/file_utils.clibc-bottom-half/sources/wasip2_file_utils.c renamed to libc-bottom-half/sources/file_utils.c libc-bottom-half/sources/wasip2_file_utils.c renamed to libc-bottom-half/sources/file_utils.c

@@ -4,9 +4,9 @@
 #include <stddef.h>
 #include <string.h>
 #include <wasi/file_utils.h>
+#include <wasi/wasip3_block.h>
 
 #ifdef __wasip2__
-
 /**
  * Validates that `ptr_signed` is a valid utf-8 string.
  *
@@ -82,9 +82,11 @@ int wasip2_string_from_c(const char *s, wasip2_string_t *out) {
   out->len = len;
   return 0;
 }
+#endif
 
-ssize_t __wasilibc_write(wasip2_write_t *write, const void *buffer,
+ssize_t __wasilibc_write(wasi_write_t *write, const void *buffer,
                          size_t length) {
+#if defined(__wasip2__)
   assert(write->output.__handle != 0);
   while (true) {
     streams_stream_error_t error;
@@ -158,9 +160,36 @@ ssize_t __wasilibc_write(wasip2_write_t *write, const void *buffer,
       poll_method_pollable_block(pollable_borrow);
     }
   }
+#elif defined(__wasip3__)
+  if (WASIP3_SUBTASK_STATE(*write->subtask) == WASIP3_SUBTASK_STARTING ||
+      WASIP3_SUBTASK_STATE(*write->subtask) == WASIP3_SUBTASK_STARTED) {
+    // the stream is still active
+    wasip3_waitable_status_t status =
+        filesystem_stream_u8_write(write->output, buffer, length);
+    size_t amount = wasip3_waitable_block_on(status, write->output);
+    if (amount > 0 || length == 0) {
+      if (write->offset)
+        *write->offset += amount;
+      return amount;
+    }
+    // error or eof
+    wasip3_subtask_block_on(*write->subtask);
+    wasip3_subtask_drop(*write->subtask);
+    *write->subtask = WASIP3_SUBTASK_RETURNED;
+  }
+  if (write->pending_result.is_err) {
+    translate_error(write->pending_result.val.err);
+    return -1;
+  }
+  // EOF
+  return 0;
+#else
+#error "Unknown WASI version"
+#endif
 }
 
-ssize_t __wasilibc_read(wasip2_read_t *read, void *buffer, size_t length) {
+ssize_t __wasilibc_read(wasi_read_t *read, void *buffer, size_t length) {
+#if defined(__wasip2__)
   while (true) {
     wasip2_list_u8_t result;
     streams_stream_error_t error;
@@ -223,6 +252,17 @@ ssize_t __wasilibc_read(wasip2_read_t *read, void *buffer, size_t length) {
       poll_method_pollable_block(pollable_borrow);
     }
   }
+#elif defined(__wasip3__)
+  wasip3_waitable_status_t status =
+      filesystem_stream_u8_read(read->stream, buffer, length);
+  size_t amount = wasip3_waitable_block_on(status, read->stream);
+  if (amount > 0 || length == 0) {
+    if (read->offset)
+      *read->offset += amount;
+    return amount;
+  }
+  return read->eof(read->eof_data);
+#else
+#error "Unknown WASI version"
+#endif
 }
-
-#endif // __wasip2__