win: crashpad_handler should create its own pipe name in ephemeral mode

handler/crashpad_handler.ad

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
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 On OS X, this server is normally started by its initial client, and it performs
 a handshake with this client via a pipe established by the client that is
 inherited by the server, referenced by the *--handshake-fd* argument. During the
 handshake, the server furnishes the client with a send right that the client may
 use as an exception port. The server retains the corresponding receive right,
 which it monitors for exception messages. When the receive right loses all
 senders, the server exits after allowing any upload in progress to complete.
 
 On Windows, clients register with this server by communicating with it via the
-named pipe identified by the *--pipe-name* argument. During registration, a
-client provides the server with an OS event object that it will signal should it
-crash. The server obtains the client’s process handle and waits on the crash
-event object for a crash, as well as the client’s process handle for the client
-to exit cleanly without crashing. When the server loses all clients and
-*--persistent* is not specified, it exits after allowing any upload in progress
-to complete.
+named pipe identified by the *--pipe-name* argument. Alternatively, the server
+can create a new pipe with a random name and inform a client of this name via
+the *--handshake-handle* mechanism; clients may then register by communicating
+with it via that named pipe. During registration, a client provides the server
+with an OS event object that it will signal should it crash. The server obtains
+the client’s process handle and waits on the crash event object for a crash, as
+well as the client’s process handle for the client to exit cleanly without
+crashing. When a server started via the *--handshake-handle* mechanism loses all
+of its clients, it exits after allowing any upload in progress to complete.
 
 It is not normally appropriate to invoke this program directly. Usually, it will
 be invoked by a Crashpad client using the Crashpad client library. Arbitrary
 programs may be run with a Crashpad handler by using
 man_link:run_with_crashpad[1] to establish the Crashpad client environment
 before running a program.
 
 == Options
 *--annotation*='KEY=VALUE'::
 Sets a process-level annotation mapping 'KEY' to 'VALUE' in each crash report
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 Use 'PATH' as the path to the Crashpad crash report database. This option is
 required. Crash reports are written to this database, and if uploads are
 enabled, uploaded from this database to a crash report collection server. If the
 database does not exist, it will be created, provided that the parent directory
 of 'PATH' exists.
 
 *--handshake-fd*='FD'::
 Perform the handshake with the initial client on the file descriptor at 'FD'.
 This option is required. This option is only valid on Mac OS X.
 
-*--persistent*::
-Continue running after the last client exits. If this option is not specified,
-this server will exit as soon as it has no clients, although on startup, it
-always waits for at least one client to connect. This option is only valid on
-Windows.
+*--handshake-handle*='HANDLE'::
+Perform the handshake with the initial client on the HANDLE at 'HANDLE'. Either
+this option or *--pipe-name*, but not both, is required. This option is only
+valid on Windows.
++
+When this option is present, the server creates a new named pipe at a random
+name and informs its client of the name. The server waits for at least one
+client to register, and exits when all clients have exited, after waiting for
+any uploads in progress to complete.
 
 *--pipe-name*='PIPE'::
 Listen on the given pipe name for connections from clients. 'PIPE' must be of
-the form +\\.\pipe\<somename>+. This option is required. This option is only
-valid on Windows.
+the form +\\.\pipe\<somename>+. Either this option or *--handshake-handle*, but
+not both, is required. This option is only valid on Windows.
++
+When this option is present, the server creates a named pipe at 'PIPE', a name
+known to both the server and its clients. The server continues running even
+after all clients have exited.
 
 *--reset-own-crash-exception-port-to-system-default*::
 Causes the exception handler server to set its own crash handler to the system
 default before beginning operation. This is only expected to be useful in cases
 where the server inherits an inappropriate crash handler from its parent
 process. This option is only valid on OS X. Use of this option is discouraged.
 It should not be used absent extraordinary circumstances.
 
 *--url*='URL'::
 If uploads are enabled, sends crash reports to the Breakpad-type crash report
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 Failure, with a message printed to the standard error stream.
 
 == See Also
 
 man_link:catch_exception_tool[1],
 man_link:crashpad_database_util[1],
 man_link:generate_dump[1],
 man_link:run_with_crashpad[1]
 
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