From c1f798091319c74cd9a90f36af604c782e7ee7bd Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Date: Thu, 6 Oct 2022 15:36:52 +0400 Subject: [PATCH] osdep: make readv_writev() work with partial read/write MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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-André Lureau Reviewed-by: Daniel P. Berrangé Message-Id: <20221006113657.2656108-2-marcandre.lureau@redhat.com> --- util/osdep.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/util/osdep.c b/util/osdep.c index 60fcbbaebe..746d5f7d71 100644 --- a/util/osdep.c +++ b/util/osdep.c @@ -538,18 +538,22 @@ int socket_init(void) #ifndef CONFIG_IOVEC -/* helper function for iov_send_recv() */ static ssize_t readv_writev(int fd, const struct iovec *iov, int iov_cnt, bool do_write) { unsigned i = 0; ssize_t ret = 0; + ssize_t off = 0; while (i < iov_cnt) { ssize_t r = 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 += r; + off += r; + if (off < iov[i].iov_len) { + continue; + } } else if (!r) { break; } else if (errno == EINTR) { @@ -562,6 +566,7 @@ readv_writev(int fd, const struct iovec *iov, int iov_cnt, bool do_write) } break; } + off = 0; i++; } return ret;