From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 83989 invoked by alias); 21 Nov 2016 13:16:39 -0000 Mailing-List: contact newlib-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: newlib-owner@sourceware.org Received: (qmail 80758 invoked by uid 89); 21 Nov 2016 13:16:38 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-4.9 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_PASS autolearn=ham version=3.3.2 spammy=H*Ad:D*nl X-HELO: smtp1.rug.nl Received: from smtp1.rug.nl (HELO smtp1.rug.nl) (129.125.60.1) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 21 Nov 2016 13:16:35 +0000 Received: from mail-wm0-f70.google.com ([172.23.16.207]) by smtp1.rug.nl (8.14.9/8.14.9) with ESMTP id uALDGXCk018512 for ; Mon, 21 Nov 2016 14:16:33 +0100 Received: by mail-wm0-f70.google.com with SMTP id m203so39287677wma.2 for ; Mon, 21 Nov 2016 05:16:33 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:to:from:subject:message-id:date:user-agent :mime-version; bh=uumg2HNT/ZO/CTjkuvkwTzs3K6PdzhSVT3zyluqJ8XY=; b=SoRwa8JwdX8W3wDyG4H0uQAjC48MEMr4ca5Rj4sGgwo3hRttT1MNpXBhsXHxd1NyBS MbpBXCHP56m7M8W3m41M/fF6bXBvuAhsW7xAR+/Vc7ttTM+75gDQsJjDS4NckE+eiUwB IY83x10WFmD4BlpoATQkHUFbt3NxSyIUiQ/cl9BSk45pcU3UTeOUEsq0AKcwn12Su0Tj m904BIXL/ut65Zej7uR1usfru7wAbvA5nLTWydt+/O+LiKC284M19aIiziNRyn87gMRz LlDe6h8vIwjyTRa6ZYuN8Ub6d/a34ou4s8OcxqlBVvWlsKWiUnzxzye5wiGm6kVPb/Bo YSYA== X-Gm-Message-State: AKaTC024vxLT+SjqZfMvlj/jCrTMS+RoVFoC7gTEiZMXstSrUPXxq+OtjN5l9PtNANhB1EZkF4paBsA97qEipVc2ul30dy50LjeWZaOiCJBPrsgd3NIkr+Vt58u3H2LYYyNI8Y4Rvg== X-Received: by 10.28.45.142 with SMTP id t136mr16045171wmt.110.1479734192997; Mon, 21 Nov 2016 05:16:32 -0800 (PST) X-Received: by 10.28.45.142 with SMTP id t136mr16045132wmt.110.1479734192587; Mon, 21 Nov 2016 05:16:32 -0800 (PST) Received: from [129.125.16.202] (fwn-nb4-16-202.phys.rug.nl. [129.125.16.202]) by smtp.gmail.com with ESMTPSA id m9sm19471418wma.0.2016.11.21.05.16.31 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 21 Nov 2016 05:16:32 -0800 (PST) To: newlib@sourceware.org From: "s.achterop@rug.nl" Subject: Intended semantics for syscalls function _read? Message-ID: <71f9ff19-b7c6-2611-3bc0-745920655e72@rug.nl> Date: Mon, 21 Nov 2016 13:16:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-256; boundary="------------ms060204060103020407040105" X-IsSubscribed: yes X-SW-Source: 2016/txt/msg01107.txt.bz2 This is a cryptographically signed message in MIME format. --------------ms060204060103020407040105 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-length: 877 Hello list, The documentation of this function does not describe how this function is t= o behave. Is it blocking, or can it also be non-blocking. What is the meaning of the return value? Or is it intentionally left ambigu= ous? My guess would be: >=3D0 number of characters actually read zero meaning: zero characters read. < 0 error code (including eof?) I want to use this function to read from serial/usb ports, using (man 2) re= ad and scanf. But also to test for the availability of a character on a port: a character= _ready function. Can I use (man 2) read in a non-blocking way? Or is there an other way? Or should I directly use the _read function to make the character_ready fun= ction? Thanks in advance, Sietse Achterop PS. I am using newlib as part of the GNU Embedded toolchain for a number of= arm systems (stm32f4 based). --------------ms060204060103020407040105 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature Content-length: 4909 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG 9w0BBwEAAKCCCj4wggUAMIID6KADAgECAhADS+4XH7fhBjcv1HJCQL0qMA0G CSqGSIb3DQEBCwUAMGUxCzAJBgNVBAYTAlVTMRUwEwYDVQQKEwxEaWdpQ2Vy dCBJbmMxGTAXBgNVBAsTEHd3dy5kaWdpY2VydC5jb20xJDAiBgNVBAMTG0Rp Z2lDZXJ0IEFzc3VyZWQgSUQgUm9vdCBDQTAeFw0xNDExMTgxMjAwMDBaFw0y NDExMTgxMjAwMDBaMGkxCzAJBgNVBAYTAk5MMRYwFAYDVQQIEw1Ob29yZC1I b2xsYW5kMRIwEAYDVQQHEwlBbXN0ZXJkYW0xDzANBgNVBAoTBlRFUkVOQTEd MBsGA1UEAxMUVEVSRU5BIFBlcnNvbmFsIENBIDMwggEiMA0GCSqGSIb3DQEB AQUAA4IBDwAwggEKAoIBAQDGpbsfVYL0pTRyFHJlm1/V6qBo2JuCiU9TYpx7 jM4O2tQyDq8bjMum69vg6wM0lMGHflMgqB75GxeKfQFmEldoXi2cLishqFUv 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