one note below
Sasha Levin wrote:
Added scatter-gather variants of [x,xp][read,write]() and [p]read_in_full().
Signed-off-by: Sasha Levin<levinsasha928@xxxxxxxxx>
---
tools/kvm/include/kvm/read-write.h | 13 +++
tools/kvm/read-write.c | 172 ++++++++++++++++++++++++++++++++++++
2 files changed, 185 insertions(+), 0 deletions(-)
diff --git a/tools/kvm/include/kvm/read-write.h b/tools/kvm/include/kvm/read-write.h
index 069326b..3351103 100644
--- a/tools/kvm/include/kvm/read-write.h
+++ b/tools/kvm/include/kvm/read-write.h
@@ -2,6 +2,7 @@
#define KVM_READ_WRITE_H
#include<sys/types.h>
+#include<sys/uio.h>
#include<unistd.h>
ssize_t xread(int fd, void *buf, size_t count);
@@ -16,4 +17,16 @@ ssize_t xpwrite(int fd, const void *buf, size_t count, off_t offset);
ssize_t pread_in_full(int fd, void *buf, size_t count, off_t offset);
ssize_t pwrite_in_full(int fd, const void *buf, size_t count, off_t offset);
+ssize_t xreadv(int fd, const struct iovec *iov, int iovcnt);
+ssize_t xwritev(int fd, const struct iovec *iov, int iovcnt);
+
+ssize_t readv_in_full(int fd, const struct iovec *iov, int iovcnt);
+ssize_t writev_in_full(int fd, const struct iovec *iov, int iovcnt);
+
+ssize_t xpreadv(int fd, const struct iovec *iov, int iovcnt, off_t offset);
+ssize_t xpwritev(int fd, const struct iovec *iov, int iovcnt, off_t offset);
+
+ssize_t preadv_in_full(int fd, const struct iovec *iov, int iovcnt, off_t offset);
+ssize_t pwritev_in_full(int fd, const struct iovec *iov, int iovcnt, off_t offset);
+
#endif /* KVM_READ_WRITE_H */
diff --git a/tools/kvm/read-write.c b/tools/kvm/read-write.c
index 398918b..449e8a2 100644
--- a/tools/kvm/read-write.c
+++ b/tools/kvm/read-write.c
@@ -152,3 +152,175 @@ ssize_t pwrite_in_full(int fd, const void *buf, size_t count, off_t offset)
return total;
}
+
+/* Same as readv(2) except that this function never returns EAGAIN or EINTR. */
+ssize_t xreadv(int fd, const struct iovec *iov, int iovcnt)
+{
+ ssize_t nr;
+
+restart:
+ nr = readv(fd, iov, iovcnt);
+ if ((nr< 0)&& ((errno == EAGAIN) || (errno == EINTR)))
+ goto restart;
+
+ return nr;
+}
+
+/* Same as writev(2) except that this function never returns EAGAIN or EINTR. */
+ssize_t xwritev(int fd, const struct iovec *iov, int iovcnt)
+{
+ ssize_t nr;
+
+restart:
+ nr = write(fd, iov, iovcnt);
+ if ((nr< 0)&& ((errno == EAGAIN) || (errno == EINTR)))
+ goto restart;
+
+ return nr;
+}
+
+static inline ssize_t get_iov_size(const struct iovec *iov, int iovcnt)
+{
+ size_t size = 0;
+ while (iovcnt--)
+ size += (iov++)->iov_len;
+
+ return size;
+}
+
+ssize_t readv_in_full(int fd, const struct iovec *iov, int iovcnt)
+{
+ ssize_t total = 0;
+ ssize_t count = get_iov_size(iov, iovcnt);
+
+ while (count> 0) {
+ ssize_t nr;
+
+ nr = xreadv(fd, iov, iovcnt);
+ if (nr<= 0) {
+ if (total> 0)
+ return total;
+
+ return -1;
+ }
+
+ while ((size_t)nr>= iov->iov_len) {
+ nr -= iov->iov_len;
+ total += iov->iov_len;
+ count -= iov->iov_len;
+ iovcnt--;
+ iov++;
+ }
+ }
+
+ return total;
+}
+
+ssize_t writev_in_full(int fd, const struct iovec *iov, int iovcnt)
+{
+ ssize_t total = 0;
+ size_t count = get_iov_size(iov, iovcnt);
+
+ while (count> 0) {
+ ssize_t nr;
+
+ nr = xwritev(fd, iov, iovcnt);
+ if (nr< 0)
+ return -1;
+ if (nr == 0) {
+ errno = ENOSPC;
+ return -1;
+ }
+
+ while ((size_t)nr>= iov->iov_len) {
+ nr -= iov->iov_len;
+ total += iov->iov_len;
+ count -= iov->iov_len;
+ iovcnt--;
+ iov++;
+ }
+ }
+
+ return total;
+}
+
+/* Same as preadv(2) except that this function never returns EAGAIN or EINTR. */
+ssize_t xpreadv(int fd, const struct iovec *iov, int iovcnt, off_t offset)
+{
+ ssize_t nr;
+
+restart:
+ nr = preadv(fd, iov, iovcnt, offset);
+ if ((nr< 0)&& ((errno == EAGAIN) || (errno == EINTR)))
+ goto restart;
+
+ return nr;
+}
+
+/* Same as pwritev(2) except that this function never returns EAGAIN or EINTR. */
+ssize_t xpwritev(int fd, const struct iovec *iov, int iovcnt, off_t offset)
+{
+ ssize_t nr;
+
+restart:
+ nr = pwritev(fd, iov, iovcnt, offset);
+ if ((nr< 0)&& ((errno == EAGAIN) || (errno == EINTR)))
+ goto restart;
+
+ return nr;
+}
+
+ssize_t preadv_in_full(int fd, const struct iovec *iov, int iovcnt, off_t offset)
+{
+ ssize_t total = 0;
+ size_t count = get_iov_size(iov, iovcnt);
+
+ while (count> 0) {
+ ssize_t nr;
+
+ nr = xpreadv(fd, iov, iovcnt, offset);
+ if (nr<= 0) {
+ if (total> 0)
+ return total;
+
+ return -1;
+ }
+
+ while ((size_t)nr>= iov->iov_len) {
+ nr -= iov->iov_len;
+ total += iov->iov_len;
+ count -= iov->iov_len;
+ iovcnt--;
+ iov++;
+ }
+ }
+
+ return total;
+}
+
+ssize_t pwritev_in_full(int fd, const struct iovec *iov, int iovcnt, off_t offset)
+{
+ ssize_t total = 0;
+ size_t count = get_iov_size(iov, iovcnt);
+
+ while (count> 0) {
+ ssize_t nr;
+
+ nr = xpwritev(fd, iov, iovcnt, offset);
+ if (nr< 0)
+ return -1;
+ if (nr == 0) {
+ errno = ENOSPC;
+ return -1;
+ }
+ while ((size_t)nr>= iov->iov_len) {
+ nr -= iov->iov_len;
+ total += iov->iov_len;
+ count -= iov->iov_len;
+ iovcnt--;
+ iov++;
You forget here to change offset.
+ }
+ }
+
+ return total;
+}
It might be better to add an helper function, something like this:
static inline void shift_iovec(const struct iovec **iov, int *iovcnt,
size_t nr, ssize_t *total, off_t *offset)
{
while (nr >= (*iov)->iov_len) {
nr -= (*iov)->iov_len;
*total += (*iov)->iov_len;
*offset += (*iov)->iov_len;
*iovcnt--;
*iov++;
}
}
ssize_t pwritev_in_full(int fd, const struct iovec *iov, int iovcnt, off_t offset)
{
ssize_t nr, total = 0;
while (iovcnt) {
nr = xpwritev(fd, iov, iovcnt, offset);
if (nr < 0)
return -1;
if (nr == 0) {
errno = ENOSPC;
return -1;
}
shift_iovec(&iov, &iovcnt, nr, &total, &offset);
}
return total;
}
--
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