[{"id":1534,"web_url":"https://patchwork.libcamera.org/comment/1534/","msgid":"","date":"2019-04-29T12:53:05","subject":"Re: [libcamera-devel] [PATCH v1.3 1/2] libcamera: Don't ignore the\n\treturn value of read() and write()","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Hi Laurent,\n\nOn 29/04/2019 13:38, Laurent Pinchart wrote:\n> The glibc read() and write() functions are defined with the\n> __warn_unused_result__ attribute when using FORTIFY_SOURCE. Don't ignore\n> their return value.\n> \n> Signed-off-by: Laurent Pinchart \n> Reviewed-by: Jacopo Mondi \n\nReviewed-by: Kieran Bingham \n\n> ---\n> src/libcamera/event_dispatcher_poll.cpp | 17 +++++++++++++++--\n> test/event.cpp | 13 +++++++++++--\n> 2 files changed, 26 insertions(+), 4 deletions(-)\n> ---\n> With real changes this time, sorry about the noise.\n> \n> diff --git a/src/libcamera/event_dispatcher_poll.cpp b/src/libcamera/event_dispatcher_poll.cpp\n> index 1f0f352a8e0a..0ff99fce47ab 100644\n> --- a/src/libcamera/event_dispatcher_poll.cpp\n> +++ b/src/libcamera/event_dispatcher_poll.cpp\n> @@ -162,7 +162,14 @@ void EventDispatcherPoll::processEvents()\n> void EventDispatcherPoll::interrupt()\n> {\n> \tuint64_t value = 1;\n> -\twrite(eventfd_, &value, sizeof(value));\n> +\tssize_t ret = write(eventfd_, &value, sizeof(value));\n> +\tif (ret != sizeof(value)) {\n> +\t\tif (ret < 0)\n\nThis might have been if (ret == -1), as that's when errno is valid, but\nI don't think that matters.\n\n> +\t\t\tret = -errno;\n> +\t\tLOG(Event, Error)\n> +\t\t\t<< \"Failed to interrupt event dispatcher (\"\n> +\t\t\t<< ret << \")\";\n> +\t}\n> }\n> \n> short EventDispatcherPoll::EventNotifierSetPoll::events() const\n> @@ -214,7 +221,13 @@ void EventDispatcherPoll::processInterrupt(const struct pollfd &pfd)\n> \t\treturn;\n> \n> \tuint64_t value;\n> -\tread(eventfd_, &value, sizeof(value));\n> +\tssize_t ret = read(eventfd_, &value, sizeof(value));\n> +\tif (ret != sizeof(value)) {\n> +\t\tif (ret < 0)\n> +\t\t\tret = -errno;\n> +\t\tLOG(Event, Error)\n> +\t\t\t<< \"Failed to process interrupt (\" << ret << \")\";\n> +\t}\n> }\n> \n> void EventDispatcherPoll::processNotifiers(const std::vector &pollfds)\n> diff --git a/test/event.cpp b/test/event.cpp\n> index 52bc0c7e77f5..9bd876153a18 100644\n> --- a/test/event.cpp\n> +++ b/test/event.cpp\n> @@ -38,6 +38,7 @@ protected:\n> \t\tEventDispatcher *dispatcher = CameraManager::instance()->eventDispatcher();\n> \t\tstd::string data(\"H2G2\");\n> \t\tTimer timeout;\n> +\t\tssize_t ret;\n> \n> \t\tEventNotifier readNotifier(pipefd_[0], EventNotifier::Read);\n> \t\treadNotifier.activated.connect(this, &EventTest::readReady);\n> @@ -46,7 +47,11 @@ protected:\n> \t\tmemset(data_, 0, sizeof(data_));\n> \t\tsize_ = 0;\n> \n> -\t\twrite(pipefd_[1], data.data(), data.size());\n> +\t\tret = write(pipefd_[1], data.data(), data.size());\n> +\t\tif (ret < 0) {\n> +\t\t\tcout << \"Pipe write failed\" << endl;\n> +\t\t\treturn TestFail;\n> +\t\t}\n> \n> \t\ttimeout.start(100);\n> \t\tdispatcher->processEvents();\n> @@ -73,7 +78,11 @@ protected:\n> \t\tnotified_ = false;\n> \t\treadNotifier.setEnabled(false);\n> \n> -\t\twrite(pipefd_[1], data.data(), data.size());\n> +\t\tret = write(pipefd_[1], data.data(), data.size());\n> +\t\tif (ret < 0) {\n> +\t\t\tcout << \"Pipe write failed\" << endl;\n> +\t\t\treturn TestFail;\n> +\t\t}\n> \n> \t\ttimeout.start(100);\n> \t\tdispatcher->processEvents();\n>","headers":{"Return-Path":"","Received":["from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id CCEF460C46\n\tfor ;\n\tMon, 29 Apr 2019 14:53:09 +0200 (CEST)","from [192.168.0.20]\n\t(cpc89242-aztw30-2-0-cust488.18-1.cable.virginm.net [86.31.129.233])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id E9CB82E7;\n\tMon, 29 Apr 2019 14:53:08 +0200 (CEST)"],"DKIM-Signature":"v=1; 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