From: Olaf Hering <olaf@aepfle.de>
To: xen-devel@lists.xenproject.org
Cc: Olaf Hering <olaf@aepfle.de>, Ian Jackson <iwj@xenproject.org>,
Wei Liu <wl@xen.org>, Juergen Gross <jgross@suse.com>
Subject: [PATCH v20210713 05/31] tools: add readv_exact to libxenctrl
Date: Tue, 13 Jul 2021 20:05:39 +0200 [thread overview]
Message-ID: <20210713180605.12096-6-olaf@aepfle.de> (raw)
In-Reply-To: <20210713180605.12096-1-olaf@aepfle.de>
Read a batch of iovec's.
Short reads are the common case, finish the trailing iov with read_exact.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
---
v2:
- add comment to short-read handling
---
tools/libs/ctrl/xc_private.c | 57 +++++++++++++++++++++++++++++++++++-
tools/libs/ctrl/xc_private.h | 1 +
2 files changed, 57 insertions(+), 1 deletion(-)
diff --git a/tools/libs/ctrl/xc_private.c b/tools/libs/ctrl/xc_private.c
index c0422662f0..bab9a31a70 100644
--- a/tools/libs/ctrl/xc_private.c
+++ b/tools/libs/ctrl/xc_private.c
@@ -698,8 +698,23 @@ int write_exact(int fd, const void *data, size_t size)
#if defined(__MINIOS__)
/*
- * MiniOS's libc doesn't know about writev(). Implement it as multiple write()s.
+ * MiniOS's libc doesn't know about readv/writev().
+ * Implement it as multiple read/write()s.
*/
+int readv_exact(int fd, const struct iovec *iov, int iovcnt)
+{
+ int rc, i;
+
+ for ( i = 0; i < iovcnt; ++i )
+ {
+ rc = read_exact(fd, iov[i].iov_base, iov[i].iov_len);
+ if ( rc )
+ return rc;
+ }
+
+ return 0;
+}
+
int writev_exact(int fd, const struct iovec *iov, int iovcnt)
{
int rc, i;
@@ -714,6 +729,46 @@ int writev_exact(int fd, const struct iovec *iov, int iovcnt)
return 0;
}
#else
+int readv_exact(int fd, const struct iovec *iov, int iovcnt)
+{
+ int rc = 0, idx = 0;
+ ssize_t len;
+
+ while ( idx < iovcnt )
+ {
+ len = readv(fd, &iov[idx], min(iovcnt - idx, IOV_MAX));
+ if ( len == -1 && errno == EINTR )
+ continue;
+ if ( len <= 0 )
+ {
+ rc = -1;
+ goto out;
+ }
+
+ /* Finish a potential short read in the last iov */
+ while ( len > 0 && idx < iovcnt )
+ {
+ if ( len >= iov[idx].iov_len )
+ {
+ len -= iov[idx].iov_len;
+ }
+ else
+ {
+ void *p = iov[idx].iov_base + len;
+ size_t l = iov[idx].iov_len - len;
+
+ rc = read_exact(fd, p, l);
+ if ( rc )
+ goto out;
+ len = 0;
+ }
+ idx++;
+ }
+ }
+out:
+ return rc;
+}
+
int writev_exact(int fd, const struct iovec *iov, int iovcnt)
{
struct iovec *local_iov = NULL;
diff --git a/tools/libs/ctrl/xc_private.h b/tools/libs/ctrl/xc_private.h
index 3e299b943f..66086ef19f 100644
--- a/tools/libs/ctrl/xc_private.h
+++ b/tools/libs/ctrl/xc_private.h
@@ -410,6 +410,7 @@ int xc_flush_mmu_updates(xc_interface *xch, struct xc_mmu *mmu);
/* Return 0 on success; -1 on error setting errno. */
int read_exact(int fd, void *data, size_t size); /* EOF => -1, errno=0 */
+int readv_exact(int fd, const struct iovec *iov, int iovcnt);
int write_exact(int fd, const void *data, size_t size);
int writev_exact(int fd, const struct iovec *iov, int iovcnt);
next prev parent reply other threads:[~2021-07-13 18:06 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-13 18:05 [PATCH v20210713 00/31] leftover from 2020 Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 01/31] tools: fix make rpmball Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 02/31] hotplug/Linux: fix starting of xenstored with restarting systemd Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 03/31] tools: add API to work with sevaral bits at once Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 04/31] xl: fix description of migrate --debug Olaf Hering
2021-07-13 18:05 ` Olaf Hering [this message]
2021-07-13 18:05 ` [PATCH v20210713 06/31] tools: show migration transfer rate in send_dirty_pages Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 07/31] tools: save: preallocate mfns array Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 08/31] tools: save: preallocate types array Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 09/31] tools: save: preallocate errors array Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 10/31] tools: save: preallocate iov array Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 11/31] tools: save: preallocate rec_pfns array Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 12/31] tools: save: preallocate guest_data array Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 13/31] tools: save: preallocate local_pages array Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 14/31] tools: restore: preallocate pfns array Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 15/31] tools: restore: preallocate types array Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 16/31] tools: restore: preallocate mfns array Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 17/31] tools: restore: preallocate map_errs array Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 18/31] tools: restore: preallocate populate_pfns pfns array Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 19/31] tools: restore: preallocate populate_pfns mfns array Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 20/31] tools: restore: split record processing Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 21/31] tools: restore: split handle_page_data Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 22/31] tools: restore: write data directly into guest Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 23/31] tools: recognize LIBXL_API_VERSION for 4.16 Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 24/31] tools: adjust libxl_domain_suspend to receive a struct props Olaf Hering
2021-07-13 18:05 ` [PATCH v20210713 25/31] tools: add callback to libxl for precopy_policy and precopy_stats Olaf Hering
2021-07-13 18:06 ` [PATCH v20210713 26/31] tools: add --max_iters to libxl_domain_suspend Olaf Hering
2021-07-13 18:06 ` [PATCH v20210713 27/31] tools: add --min_remaining " Olaf Hering
2021-07-13 18:06 ` [PATCH v20210713 28/31] tools: add --abort_if_busy " Olaf Hering
2021-07-13 18:06 ` [PATCH v20210713 29/31] tools: add API for expandable bitmaps Olaf Hering
2021-07-13 18:06 ` [PATCH v20210713 30/31] tools: use xg_sr_bitmap for populated_pfns Olaf Hering
2021-07-13 18:06 ` [PATCH v20210713 31/31] tools: use superpages during restore of HVM guest Olaf Hering
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210713180605.12096-6-olaf@aepfle.de \
--to=olaf@aepfle.de \
--cc=iwj@xenproject.org \
--cc=jgross@suse.com \
--cc=wl@xen.org \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).