From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Ross Lagerwall <ross.lagerwall@citrix.com>,
Wei Liu <wei.liu2@citrix.com>,
Ian Campbell <Ian.Campbell@citrix.com>,
Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH v3 17/28] tools/libxl: Infrastructure for reading a libxl migration v2 stream
Date: Mon, 13 Jul 2015 16:13:40 +0100 [thread overview]
Message-ID: <55A3D5A4.2010204@citrix.com> (raw)
In-Reply-To: <21923.54363.294360.591599@mariner.uk.xensource.com>
On 13/07/15 16:08, Ian Jackson wrote:
> Andrew Cooper writes ("[PATCH v3 17/28] tools/libxl: Infrastructure for reading a libxl migration v2 stream"):
> ...
>> +static void write_emulator_blob(libxl__egc *egc,
>> + libxl__stream_read_state *stream,
>> + libxl__sr_record_buf *rec)
> ...
>> + libxl__carefd_begin();
>> + writefd = open(path, O_WRONLY | O_CREAT | O_TRUNC, 0600);
>> + if (writefd == -1) {
>> + rc = ERROR_FAIL;
>> + LOGE(ERROR, "unable to open %s", path);
>> + libxl__carefd_unlock();
>> + goto err;
>> + }
> I have just spotted something else which I think both of us missed
> from my review of v2:
>
> I wrote:
>
> If [you keep using carefd for this], then please use
> libxl__carefd_opened. (Best would be to libxl__carefd_opened to
> save and restore errno and then you can call it unconditionally
> after the open.)
>
> I meant `best would be to _change_ libxl__carefd_opened save and
> restore errno'.
>
>> + assert(stream->emu_carefd == NULL);
>> + stream->emu_carefd = libxl__carefd_opened(CTX, writefd);
> And then call it _unconditionally_, _immediately after_ the open.
>
> This means that the carefd functions bracketing open are easy to see
> and there is no entanglement with error-handling flow control.
libxl__carefd_opened() doesn't tolerate being handed -1. It cannot be
used ahead of the error check.
I could see about introducing something like libxl__carefd_open() as a
carefd wrapper to open(2)
~Andrew
next prev parent reply other threads:[~2015-07-13 15:13 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-13 12:01 [PATCH v3 00/27] Libxl migration v2 Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 01/28] bsd-sys-queue-h-seddery: Massage `offsetof' Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 02/28] tools/libxc: Always compile the compat qemu variables into xc_sr_context Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 03/28] tools/libxl: Introduce ROUNDUP() Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 04/28] tools/libxl: Introduce libxl__kill() Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 05/28] tools/libxl: Stash all restore parameters in domain_create_state Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 06/28] tools/libxl: Split libxl__domain_create_state.restore_fd in two Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 07/28] tools/libxl: Extra management APIs for the save helper Andrew Cooper
2015-07-13 13:21 ` Ian Campbell
2015-07-13 15:01 ` Ian Jackson
2015-07-13 12:01 ` [PATCH v3 08/28] tools/libxl: Add save_helper_state pointers to libxl__xc_domain_{save, restore}() Andrew Cooper
2015-07-13 13:24 ` Ian Campbell
2015-07-13 12:01 ` [PATCH v3 09/28] tools/xl: Mandatory flag indicating the format of the migration stream Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 10/28] docs: Libxl migration v2 stream specification Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 11/28] tools/python: Libxc migration v2 infrastructure Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 12/28] tools/python: Libxl " Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 13/28] tools/python: Other migration infrastructure Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 14/28] tools/python: Verification utility for v2 stream spec compliance Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 15/28] tools/python: Conversion utility for legacy migration streams Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 16/28] tools/libxl: Migration v2 stream format Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 17/28] tools/libxl: Infrastructure for reading a libxl migration v2 stream Andrew Cooper
2015-07-13 13:42 ` Ian Campbell
2015-07-13 13:53 ` Andrew Cooper
2015-07-13 14:11 ` Ian Jackson
2015-07-13 14:03 ` Ian Jackson
2015-07-13 14:31 ` Ian Jackson
2015-07-13 14:53 ` Andrew Cooper
2015-07-13 15:33 ` Ian Jackson
2015-07-13 15:08 ` Ian Jackson
2015-07-13 15:13 ` Andrew Cooper [this message]
2015-07-13 15:35 ` Ian Jackson
2015-07-13 12:01 ` [PATCH v3 18/28] tools/libxl: Infrastructure to convert a legacy stream Andrew Cooper
2015-07-13 14:45 ` Ian Jackson
2015-07-13 15:08 ` Andrew Cooper
2015-07-13 15:44 ` Ian Jackson
2015-07-13 15:53 ` Andrew Cooper
2015-07-13 15:56 ` Ian Jackson
2015-07-13 16:04 ` Ian Campbell
2015-07-13 12:01 ` [PATCH v3 19/28] tools/libxl: Convert a legacy stream if needed Andrew Cooper
2015-07-13 14:51 ` Ian Jackson
2015-07-13 15:20 ` Andrew Cooper
2015-07-13 15:44 ` Ian Jackson
2015-07-13 12:01 ` [PATCH v3 20/28] tools/libxc+libxl+xl: Restore v2 streams Andrew Cooper
2015-07-13 15:02 ` Ian Jackson
2015-07-13 12:01 ` [PATCH v3 21/28] tools/libxl: Infrastructure for writing a v2 stream Andrew Cooper
2015-07-13 15:09 ` Ian Jackson
2015-07-13 15:21 ` Ian Jackson
2015-07-13 15:33 ` Andrew Cooper
2015-07-13 15:47 ` Ian Jackson
2015-07-13 15:56 ` Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 22/28] tools/libxc+libxl+xl: Save v2 streams Andrew Cooper
2015-07-13 15:25 ` Ian Jackson
2015-07-13 12:01 ` [PATCH v3 23/28] docs/libxl: Introduce CHECKPOINT_END to support migration v2 remus streams Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 24/28] tools/libxl: Write checkpoint records into the stream Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 25/28] tools/libx{c, l}: Introduce restore_callbacks.checkpoint() Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 26/28] tools/libxl: Handle checkpoint records in a libxl migration v2 stream Andrew Cooper
2015-07-13 13:53 ` Ian Campbell
2015-07-14 10:33 ` Yang Hongyang
2015-07-14 10:35 ` Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 27/28] tools/libxc: Drop all XG_LIBXL_HVM_COMPAT code from libxc Andrew Cooper
2015-07-13 12:01 ` [PATCH v3 28/28] tools/libxl: Drop all knowledge of toolstack callbacks Andrew Cooper
2015-07-13 15:55 ` Ian Jackson
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