From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: ludo@gnu.org (Ludovic =?UTF-8?Q?Court=C3=A8s?=) Newsgroups: gmane.lisp.guile.bugs Subject: bug#30066: 'get-bytevector-some' returns only 1 byte from unbuffered ports Date: Thu, 11 Jan 2018 22:02:29 +0100 Message-ID: <87po6gnm6y.fsf@gnu.org> References: <87zi5lrc3x.fsf@gnu.org> <87tvvtr9ge.fsf@gnu.org> <87fu7dptdn.fsf@igalia.com> <87o9m08nx2.fsf@gnu.org> <87fu7cf9wk.fsf@netris.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Trace: blaine.gmane.org 1515705331 9452 195.159.176.226 (11 Jan 2018 21:15:31 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 11 Jan 2018 21:15:31 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.3 (gnu/linux) Cc: Andy Wingo , 30066@debbugs.gnu.org To: Mark H Weaver Original-X-From: bug-guile-bounces+guile-bugs=m.gmane.org@gnu.org Thu Jan 11 22:15:26 2018 Return-path: Envelope-to: guile-bugs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1eZkC1-0001o3-7b for guile-bugs@m.gmane.org; Thu, 11 Jan 2018 22:15:21 +0100 Original-Received: from localhost ([::1]:42860 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eZkE0-00074l-Pr for guile-bugs@m.gmane.org; Thu, 11 Jan 2018 16:17:24 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:33636) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eZk0A-0002qH-GM for bug-guile@gnu.org; Thu, 11 Jan 2018 16:03:07 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eZk06-0006sp-0B for bug-guile@gnu.org; Thu, 11 Jan 2018 16:03:06 -0500 Original-Received: from debbugs.gnu.org ([208.118.235.43]:44636) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1eZk05-0006si-TI for bug-guile@gnu.org; Thu, 11 Jan 2018 16:03:01 -0500 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1eZk05-0008SX-M5 for bug-guile@gnu.org; Thu, 11 Jan 2018 16:03:01 -0500 X-Loop: help-debbugs@gnu.org Resent-From: ludo@gnu.org (Ludovic =?UTF-8?Q?Court=C3=A8s?=) Original-Sender: "Debbugs-submit" Resent-CC: bug-guile@gnu.org Resent-Date: Thu, 11 Jan 2018 21:03:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 30066 X-GNU-PR-Package: guile X-GNU-PR-Keywords: Original-Received: via spool by 30066-submit@debbugs.gnu.org id=B30066.151570455532483 (code B ref 30066); Thu, 11 Jan 2018 21:03:01 +0000 Original-Received: (at 30066) by debbugs.gnu.org; 11 Jan 2018 21:02:35 +0000 Original-Received: from localhost ([127.0.0.1]:52533 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1eZjzf-0008Rr-2r for submit@debbugs.gnu.org; Thu, 11 Jan 2018 16:02:35 -0500 Original-Received: from hera.aquilenet.fr ([185.233.100.1]:35224) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1eZjzc-0008Rj-LS for 30066@debbugs.gnu.org; Thu, 11 Jan 2018 16:02:33 -0500 Original-Received: from localhost (localhost [127.0.0.1]) by hera.aquilenet.fr (Postfix) with ESMTP id 0D8F7106B0; Thu, 11 Jan 2018 22:02:32 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at aquilenet.fr Original-Received: from hera.aquilenet.fr ([127.0.0.1]) by localhost (hera.aquilenet.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 2TKaHFTprSfH; Thu, 11 Jan 2018 22:02:31 +0100 (CET) Original-Received: from ribbon (unknown [IPv6:2a01:e0a:1d:7270:af76:b9b:ca24:c465]) by hera.aquilenet.fr (Postfix) with ESMTPSA id B7343F53A; Thu, 11 Jan 2018 22:02:30 +0100 (CET) X-URL: http://www.fdn.fr/~lcourtes/ X-Revolutionary-Date: 22 =?UTF-8?Q?Niv=C3=B4se?= an 226 de la =?UTF-8?Q?R=C3=A9volution?= X-PGP-Key-ID: 0x090B11993D9AEBB5 X-PGP-Key: http://www.fdn.fr/~lcourtes/ludovic.asc X-PGP-Fingerprint: 3CE4 6455 8A84 FDC6 9DB4 0CFB 090B 1199 3D9A EBB5 X-OS: x86_64-pc-linux-gnu In-Reply-To: <87fu7cf9wk.fsf@netris.org> (Mark H. Weaver's message of "Thu, 11 Jan 2018 14:55:07 -0500") X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 208.118.235.43 X-BeenThere: bug-guile@gnu.org List-Id: "Bug reports for GUILE, GNU's Ubiquitous Extension Language" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-guile-bounces+guile-bugs=m.gmane.org@gnu.org Original-Sender: "bug-guile" Xref: news.gmane.org gmane.lisp.guile.bugs:8960 Archived-At: Hello, Mark H Weaver skribis: > ludo@gnu.org (Ludovic Court=C3=A8s) writes: [...] >> + if (SCM_UNBUFFEREDP (port) && (avail < max_buffer_size)) >> + { >> + /* PORT is unbuffered. Read as much as possible from PORT. */ >> + size_t read; >> + >> + bv =3D scm_c_make_bytevector (max_buffer_size); >> + scm_port_buffer_take (buf, (scm_t_uint8 *) SCM_BYTEVECTOR_CONTENT= S (bv), >> + avail, cur, avail); >> + >> + read =3D scm_i_read_bytes (port, bv, avail, >> + SCM_BYTEVECTOR_LENGTH (bv) - avail); > > Here's the R6RS specification for 'get-bytevector-some': > > "Reads from BINARY-INPUT-PORT, blocking as necessary, until bytes are > available from BINARY-INPUT-PORT or until an end of file is reached. > If bytes become available, 'get-bytevector-some' returns a freshly > allocated bytevector containing the initial available bytes (at least > one), and it updates BINARY-INPUT-PORT to point just past these > bytes. If no input bytes are seen before an end of file is reached, > the end-of-file object is returned." > > By my reading of this, we should block only if necessary to ensure that > we return at least one byte (or EOF). In other words, if we can return > at least one byte (or EOF), then we must not block, which means that we > must not initiate another 'read'. Indeed. So perhaps the condition above should be changed to: if (SCM_UNBUFFEREDP (port) && (avail =3D=3D 0)) ? > Out of curiosity, is there a reason why you're using an unbuffered port > in your use case? It=E2=80=99s to implement redirect =C3=A0 la socat: https://git.savannah.gnu.org/cgit/guix.git/commit/?id=3D17af5d51de7c40756= a4a39d336f81681de2ba447 Thanks, Ludo=E2=80=99.