libxl: log bootloader output

This involves adding a new log feature to libxl__datacopier, and then
using it.

If the bootloader exits nonzero we print the log filename in a log
message from libxl.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/tools/libxl/libxl_aoutils.c b/tools/libxl/libxl_aoutils.c
index 734a5dc29c..91e34dea95 100644
--- a/tools/libxl/libxl_aoutils.c
+++ b/tools/libxl/libxl_aoutils.c
@@ -118,6 +118,16 @@ static void datacopier_readable(libxl__egc *egc, libxl__ev_fd *ev,
             libxl__ev_fd_deregister(gc, &dc->toread);
             break;
         }
+        if (dc->log) {
+            int wrote = fwrite(buf->buf + buf->used, 1, r, dc->log);
+            if (wrote != r) {
+                assert(ferror(dc->log));
+                assert(errno);
+                LOGE(ERROR, "error logging %s", dc->copywhat);
+                datacopier_callback(egc, dc, 0, errno);
+                return;
+            }
+        }
         buf->used += r;
         dc->used += r;
         assert(buf->used <= sizeof(buf->buf));