Index: mojo/public/c/system/message_pipe.h |
diff --git a/mojo/public/c/system/message_pipe.h b/mojo/public/c/system/message_pipe.h |
new file mode 100644 |
index 0000000000000000000000000000000000000000..ffedd9e369d702d7e8c0ad1fcd37bbc077e37844 |
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+// Copyright 2014 The Chromium Authors. All rights reserved. |
+// Use of this source code is governed by a BSD-style license that can be |
+// found in the LICENSE file. |
+ |
+// This file contains types/constants and functions specific to message pipes. |
+ |
+// Note: This header should be compilable as C. |
+ |
+#ifndef MOJO_PUBLIC_C_SYSTEM_MESSAGE_PIPE_H_ |
+#define MOJO_PUBLIC_C_SYSTEM_MESSAGE_PIPE_H_ |
+ |
+#include "mojo/public/c/system/system_export.h" |
+#include "mojo/public/c/system/types.h" |
+ |
+// |MojoWriteMessageFlags|: Used to specify different modes to |
+// |MojoWriteMessage()|. |
+// |MOJO_WRITE_MESSAGE_FLAG_NONE| - No flags; default mode. |
+ |
+typedef uint32_t MojoWriteMessageFlags; |
+ |
+#ifdef __cplusplus |
+const MojoWriteMessageFlags MOJO_WRITE_MESSAGE_FLAG_NONE = 0; |
+#else |
+#define MOJO_WRITE_MESSAGE_FLAG_NONE ((MojoWriteMessageFlags) 0) |
+#endif |
+ |
+// |MojoReadMessageFlags|: Used to specify different modes to |
+// |MojoReadMessage()|. |
+// |MOJO_READ_MESSAGE_FLAG_NONE| - No flags; default mode. |
+// |MOJO_READ_MESSAGE_FLAG_MAY_DISCARD| - If the message is unable to be read |
+// for whatever reason (e.g., the caller-supplied buffer is too small), |
+// discard the message (i.e., simply dequeue it). |
+ |
+typedef uint32_t MojoReadMessageFlags; |
+ |
+#ifdef __cplusplus |
+const MojoReadMessageFlags MOJO_READ_MESSAGE_FLAG_NONE = 0; |
+const MojoReadMessageFlags MOJO_READ_MESSAGE_FLAG_MAY_DISCARD = 1 << 0; |
+#else |
+#define MOJO_READ_MESSAGE_FLAG_NONE ((MojoReadMessageFlags) 0) |
+#define MOJO_READ_MESSAGE_FLAG_MAY_DISCARD ((MojoReadMessageFlags) 1 << 0) |
+#endif |
+ |
+#ifdef __cplusplus |
+extern "C" { |
+#endif |
+ |
+// Note: See the comment in functions.h about the meaning of the "optional" |
+// label for pointer parameters. |
+ |
+// Creates a message pipe, which is a bidirectional communication channel for |
+// framed data (i.e., messages). Messages can contain plain data and/or Mojo |
+// handles. On success, |*message_pipe_handle0| and |*message_pipe_handle1| are |
+// set to handles for the two endpoints (ports) for the message pipe. |
+// |
+// Returns: |
+// |MOJO_RESULT_OK| on success. |
+// |MOJO_RESULT_INVALID_ARGUMENT| if |message_pipe_handle0| and/or |
+// |message_pipe_handle1| do not appear to be valid pointers. |
+// |MOJO_RESULT_RESOURCE_EXHAUSTED| if a process/system/quota/etc. limit has |
+// been reached. |
+// |
+// TODO(vtl): Add an options struct pointer argument. |
+MOJO_SYSTEM_EXPORT MojoResult MojoCreateMessagePipe( |
+ MojoHandle* message_pipe_handle0, // Out. |
+ MojoHandle* message_pipe_handle1); // Out. |
+ |
+// Writes a message to the message pipe endpoint given by |message_pipe_handle|, |
+// with message data specified by |bytes| of size |num_bytes| and attached |
+// handles specified by |handles| of count |num_handles|, and options specified |
+// by |flags|. If there is no message data, |bytes| may be null, in which case |
+// |num_bytes| must be zero. If there are no attached handles, |handles| may be |
+// null, in which case |num_handles| must be zero. |
+// |
+// If handles are attached, on success the handles will no longer be valid (the |
+// receiver will receive equivalent, but logically different, handles). Handles |
+// to be sent should not be in simultaneous use (e.g., on another thread). |
+// |
+// Returns: |
+// |MOJO_RESULT_OK| on success (i.e., the message was enqueued). |
+// |MOJO_RESULT_INVALID_ARGUMENT| if some argument was invalid (e.g., if |
+// |message_pipe_handle| is not a valid handle, or some of the |
+// requirements above are not satisfied). |
+// |MOJO_RESULT_RESOURCE_EXHAUSTED| if some system limit has been reached, or |
+// the number of handles to send is too large (TODO(vtl): reconsider the |
+// latter case). |
+// |MOJO_RESULT_FAILED_PRECONDITION| if the other endpoint has been closed. |
+// Note that closing an endpoint is not necessarily synchronous (e.g., |
+// across processes), so this function may be succeed even if the other |
+// endpoint has been closed (in which case the message would be dropped). |
+// |MOJO_RESULT_BUSY| if some handle to be sent is currently in use. |
+// |
+// TODO(vtl): Add a notion of capacity for message pipes, and return |
+// |MOJO_RESULT_SHOULD_WAIT| if the message pipe is full. |
+MOJO_SYSTEM_EXPORT MojoResult MojoWriteMessage( |
+ MojoHandle message_pipe_handle, |
+ const void* bytes, // Optional. |
+ uint32_t num_bytes, |
+ const MojoHandle* handles, // Optional. |
+ uint32_t num_handles, |
+ MojoWriteMessageFlags flags); |
+ |
+// Reads a message from the message pipe endpoint given by |
+// |message_pipe_handle|; also usable to query the size of the next message or |
+// discard the next message. |bytes|/|*num_bytes| indicate the buffer/buffer |
+// size to receive the message data (if any) and |handles|/|*num_handles| |
+// indicate the buffer/maximum handle count to receive the attached handles (if |
+// any). |
+// |
+// |num_bytes| and |num_handles| are optional "in-out" parameters. If non-null, |
+// on return |*num_bytes| and |*num_handles| will usually indicate the number |
+// of bytes and number of attached handles in the "next" message, respectively, |
+// whether that message was read or not. (If null, the number of bytes/handles |
+// is treated as zero.) |
+// |
+// If |bytes| is null, then |*num_bytes| must be zero, and similarly for |
+// |handles| and |*num_handles|. |
+// |
+// Partial reads are NEVER done. Either a full read is done and |MOJO_RESULT_OK| |
+// returned, or the read is NOT done and |MOJO_RESULT_RESOURCE_EXHAUSTED| is |
+// returned (if |MOJO_READ_MESSAGE_FLAG_MAY_DISCARD| was set, the message is |
+// also discarded in this case). |
+// |
+// Returns: |
+// |MOJO_RESULT_OK| on success (i.e., a message was actually read). |
+// |MOJO_RESULT_INVALID_ARGUMENT| if some argument was invalid. |
+// |MOJO_RESULT_FAILED_PRECONDITION| if the other endpoint has been closed. |
+// |MOJO_RESULT_RESOURCE_EXHAUSTED| if one of the buffers to receive the |
+// message/attached handles (|bytes|/|*num_bytes| or |
+// |handles|/|*num_handles|) was too small. (TODO(vtl): Reconsider this |
+// error code; should distinguish this from the hitting-system-limits |
+// case.) |
+// |MOJO_RESULT_SHOULD_WAIT| if no message was available to be read. |
+MOJO_SYSTEM_EXPORT MojoResult MojoReadMessage( |
+ MojoHandle message_pipe_handle, |
+ void* bytes, // Optional out. |
+ uint32_t* num_bytes, // Optional in/out. |
+ MojoHandle* handles, // Optional out. |
+ uint32_t* num_handles, // Optional in/out. |
+ MojoReadMessageFlags flags); |
+ |
+#ifdef __cplusplus |
+} // extern "C" |
+#endif |
+ |
+#endif // MOJO_PUBLIC_C_SYSTEM_MESSAGE_PIPE_H_ |