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bh=XExzAlB9hioR6/71riasaaqxWc+GgRvUIex+5d/LKR4=; b=PdaZLum5c7bDLfVF7Zj33OQ9nlKkEkJdV8MWXrv2QxElN1lSXjKyfxknn4Mzv0310JChSf qKmNeQJRDYU3wGe4VxCluE74LfwP4KpNjWpOB/Bmfu6Ci1liN2lRDcaogQ9boi2MzhYnGt lZ8oQvhSI0vtIAF+BV8OmNHOCqVnlIw= X-MC-Unique: _5QyKeMgMNCNc26MZIurCw-1 From: marcandre.lureau@redhat.com To: qemu-devel@nongnu.org Cc: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Subject: [PATCH v3 1/5] osdep: make readv_writev() work with partial read/write Date: Thu, 6 Oct 2022 12:12:18 +0400 Message-Id: <20221006081222.2606746-2-marcandre.lureau@redhat.com> In-Reply-To: <20221006081222.2606746-1-marcandre.lureau@redhat.com> References: <20221006081222.2606746-1-marcandre.lureau@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=marcandre.lureau@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1665044408109100001 From: Marc-Andr=C3=A9 Lureau With a pipe or other reasons, read/write may return less than the requested bytes. This happens with the test-io-channel-command test on Windows. glib spawn code uses a binary pipe of 4096 bytes, and the first read returns that much (although more are requested), for some unclear reason... Signed-off-by: Marc-Andr=C3=A9 Lureau Reviewed-by: Daniel P. Berrang=C3=A9 --- util/osdep.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/util/osdep.c b/util/osdep.c index 60fcbbaebe..b85715a743 100644 --- a/util/osdep.c +++ b/util/osdep.c @@ -544,12 +544,17 @@ readv_writev(int fd, const struct iovec *iov, int iov= _cnt, bool do_write) { unsigned i =3D 0; ssize_t ret =3D 0; + ssize_t off =3D 0; while (i < iov_cnt) { ssize_t r =3D do_write - ? write(fd, iov[i].iov_base, iov[i].iov_len) - : read(fd, iov[i].iov_base, iov[i].iov_len); + ? write(fd, iov[i].iov_base + off, iov[i].iov_len - off) + : read(fd, iov[i].iov_base + off, iov[i].iov_len - off); if (r > 0) { ret +=3D r; + off +=3D r; + if (off < iov[i].iov_len) { + continue; + } } else if (!r) { break; } else if (errno =3D=3D EINTR) { @@ -562,6 +567,7 @@ readv_writev(int fd, const struct iovec *iov, int iov_c= nt, bool do_write) } break; } + off =3D 0; i++; } return ret; --=20 2.37.3