From: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
Implement a read-only mode for libxl__datacopier. The mode is invoked
when readbuf is set and writefd is < 0. On success, the callback passes
the number of bytes read.
Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
---
tools/libxl/libxl_aoutils.c | 59 +++++++++++++++++++++++++-----------------
tools/libxl/libxl_internal.h | 4 ++-
2 files changed, 38 insertions(+), 25 deletions(-)
diff --git a/tools/libxl/libxl_aoutils.c b/tools/libxl/libxl_aoutils.c
index 6502325..9183716 100644
--- a/tools/libxl/libxl_aoutils.c
+++ b/tools/libxl/libxl_aoutils.c
@@ -134,7 +134,7 @@ static void datacopier_check_state(libxl__egc *egc,
libxl__datacopier_state *dc)
STATE_AO_GC(dc->ao);
int rc;
- if (dc->used) {
+ if (dc->used && !dc->readbuf) {
if (!libxl__ev_fd_isregistered(&dc->towrite)) {
rc = libxl__ev_fd_register(gc, &dc->towrite, datacopier_writable,
dc->writefd, POLLOUT);
@@ -147,7 +147,7 @@ static void datacopier_check_state(libxl__egc *egc,
libxl__datacopier_state *dc)
}
} else if (!libxl__ev_fd_isregistered(&dc->toread) || dc->maxread == 0) {
/* we have had eof */
- datacopier_callback(egc, dc, 0, 0);
+ datacopier_callback(egc, dc, 0, dc->readbuf ? dc->used : 0);
return;
} else {
/* nothing buffered, but still reading */
@@ -215,26 +215,31 @@ static void datacopier_readable(libxl__egc *egc,
libxl__ev_fd *ev,
}
assert(revents & POLLIN);
for (;;) {
- while (dc->used >= dc->maxsz) {
- libxl__datacopier_buf *rm = LIBXL_TAILQ_FIRST(&dc->bufs);
- dc->used -= rm->used;
- assert(dc->used >= 0);
- LIBXL_TAILQ_REMOVE(&dc->bufs, rm, entry);
- free(rm);
- }
+ libxl__datacopier_buf *buf = NULL;
+ int r;
+
+ if (dc->readbuf) {
+ r = read(ev->fd, dc->readbuf + dc->used, dc->maxread);
+ } else {
+ while (dc->used >= dc->maxsz) {
+ libxl__datacopier_buf *rm = LIBXL_TAILQ_FIRST(&dc->bufs);
+ dc->used -= rm->used;
+ assert(dc->used >= 0);
+ LIBXL_TAILQ_REMOVE(&dc->bufs, rm, entry);
+ free(rm);
+ }
- libxl__datacopier_buf *buf =
- LIBXL_TAILQ_LAST(&dc->bufs, libxl__datacopier_bufs);
- if (!buf || buf->used >= sizeof(buf->buf)) {
- buf = malloc(sizeof(*buf));
- if (!buf) libxl__alloc_failed(CTX, __func__, 1, sizeof(*buf));
- buf->used = 0;
- LIBXL_TAILQ_INSERT_TAIL(&dc->bufs, buf, entry);
- }
- int r = read(ev->fd,
- buf->buf + buf->used,
+ buf = LIBXL_TAILQ_LAST(&dc->bufs, libxl__datacopier_bufs);
+ if (!buf || buf->used >= sizeof(buf->buf)) {
+ buf = malloc(sizeof(*buf));
+ if (!buf) libxl__alloc_failed(CTX, __func__, 1, sizeof(*buf));
+ buf->used = 0;
+ LIBXL_TAILQ_INSERT_TAIL(&dc->bufs, buf, entry);
+ }
+ r = read(ev->fd, buf->buf + buf->used,
(sizeof(buf->buf) - buf->used) < dc->maxread ?
(sizeof(buf->buf) - buf->used) : dc->maxread);
+ }
if (r < 0) {
if (errno == EINTR) continue;
if (errno == EWOULDBLOCK) break;
@@ -257,10 +262,12 @@ static void datacopier_readable(libxl__egc *egc,
libxl__ev_fd *ev,
return;
}
}
- buf->used += r;
+ if (!dc->readbuf) {
+ buf->used += r;
+ assert(buf->used <= sizeof(buf->buf));
+ }
dc->used += r;
dc->maxread -= r;
- assert(buf->used <= sizeof(buf->buf));
assert(dc->maxread >= 0);
if (dc->maxread == 0)
break;
@@ -324,9 +331,13 @@ int libxl__datacopier_start(libxl__datacopier_state *dc)
if (rc) goto out;
}
- rc = libxl__ev_fd_register(gc, &dc->towrite, datacopier_writable,
- dc->writefd, POLLOUT);
- if (rc) goto out;
+ if (dc->writefd >= 0) {
+ rc = libxl__ev_fd_register(gc, &dc->towrite, datacopier_writable,
+ dc->writefd, POLLOUT);
+ if (rc) goto out;
+ }
+
+ assert(dc->readfd >= 0 || dc->writefd >= 0);
