104 lines
2.7 KiB
Diff
104 lines
2.7 KiB
Diff
From: Olaf Hering <olaf@aepfle.de>
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Date: Wed, 28 Oct 2020 12:07:36 +0100
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Subject: libxc sr readv_exact
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tools: add readv_exact to libxenctrl
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Read a batch of iovec's.
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Short reads are the common case, finish the trailing iov with read_exact.
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Signed-off-by: Olaf Hering <olaf@aepfle.de>
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v2:
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- add comment to short-read handling
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---
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tools/libs/ctrl/xc_private.c | 57 +++++++++++++++++++++++++++++++++++-
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tools/libs/ctrl/xc_private.h | 1 +
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2 files changed, 57 insertions(+), 1 deletion(-)
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--- a/tools/libs/ctrl/xc_private.c
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+++ b/tools/libs/ctrl/xc_private.c
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@@ -699,8 +699,23 @@ int write_exact(int fd, const void *data
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#if defined(__MINIOS__)
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/*
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- * MiniOS's libc doesn't know about writev(). Implement it as multiple write()s.
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+ * MiniOS's libc doesn't know about readv/writev().
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+ * Implement it as multiple read/write()s.
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*/
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+int readv_exact(int fd, const struct iovec *iov, int iovcnt)
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+{
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+ int rc, i;
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+
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+ for ( i = 0; i < iovcnt; ++i )
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+ {
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+ rc = read_exact(fd, iov[i].iov_base, iov[i].iov_len);
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+ if ( rc )
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+ return rc;
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+ }
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+
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+ return 0;
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+}
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+
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int writev_exact(int fd, const struct iovec *iov, int iovcnt)
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{
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int rc, i;
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@@ -715,6 +730,46 @@ int writev_exact(int fd, const struct io
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return 0;
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}
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#else
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+int readv_exact(int fd, const struct iovec *iov, int iovcnt)
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+{
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+ int rc = 0, idx = 0;
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+ ssize_t len;
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+
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+ while ( idx < iovcnt )
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+ {
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+ len = readv(fd, &iov[idx], min(iovcnt - idx, IOV_MAX));
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+ if ( len == -1 && errno == EINTR )
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+ continue;
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+ if ( len <= 0 )
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+ {
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+ rc = -1;
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+ goto out;
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+ }
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+
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+ /* Finish a potential short read in the last iov */
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+ while ( len > 0 && idx < iovcnt )
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+ {
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+ if ( len >= iov[idx].iov_len )
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+ {
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+ len -= iov[idx].iov_len;
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+ }
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+ else
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+ {
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+ void *p = iov[idx].iov_base + len;
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+ size_t l = iov[idx].iov_len - len;
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+
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+ rc = read_exact(fd, p, l);
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+ if ( rc )
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+ goto out;
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+ len = 0;
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+ }
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+ idx++;
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+ }
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+ }
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+out:
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+ return rc;
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+}
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+
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int writev_exact(int fd, const struct iovec *iov, int iovcnt)
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{
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struct iovec *local_iov = NULL;
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--- a/tools/libs/ctrl/xc_private.h
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+++ b/tools/libs/ctrl/xc_private.h
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@@ -395,6 +395,7 @@ int xc_flush_mmu_updates(xc_interface *x
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/* Return 0 on success; -1 on error setting errno. */
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int read_exact(int fd, void *data, size_t size); /* EOF => -1, errno=0 */
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+int readv_exact(int fd, const struct iovec *iov, int iovcnt);
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int write_exact(int fd, const void *data, size_t size);
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int writev_exact(int fd, const struct iovec *iov, int iovcnt);
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