Currently if qemu is connected to a curl source (eg. web server), and the web server fails / times out / dies, you always see a bogus EIO "Input/output error".
For example, choose a large file located on any local webserver which you control: $ qemu-img convert -p http://example.com/large.iso /tmp/test Once it starts copying the file, stop the webserver and you will see qemu-img fail with: qemu-img: error while reading sector 61440: Input/output error This patch does two things: Firstly print the actual error from curl so it doesn't get lost. Secondly, change EIO to EPROTO. EPROTO is a POSIX.1 compatible errno which more accurately reflects that there was a protocol error, rather than some kind of hardware failure. After this patch is applied, the error changes to: $ qemu-img convert -p http://example.com/large.iso /tmp/test qemu-img: curl: transfer closed with 469989 bytes remaining to read qemu-img: error while reading sector 16384: Protocol error Signed-off-by: Richard W.M. Jones <rjo...@redhat.com> --- block/curl.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/block/curl.c b/block/curl.c index 3a2b63e..2fd7c06 100644 --- a/block/curl.c +++ b/block/curl.c @@ -22,6 +22,7 @@ * THE SOFTWARE. */ #include "qemu-common.h" +#include "qemu/error-report.h" #include "block/block_int.h" #include "qapi/qmp/qbool.h" #include "qapi/qmp/qstring.h" @@ -298,6 +299,12 @@ static void curl_multi_check_completion(BDRVCURLState *s) /* ACBs for successful messages get completed in curl_read_cb */ if (msg->data.result != CURLE_OK) { int i; + + /* Don't lose the original error message from curl, since + * it contains extra data. + */ + error_report("curl: %s", state->errmsg); + for (i = 0; i < CURL_NUM_ACB; i++) { CURLAIOCB *acb = state->acb[i]; @@ -305,7 +312,7 @@ static void curl_multi_check_completion(BDRVCURLState *s) continue; } - acb->common.cb(acb->common.opaque, -EIO); + acb->common.cb(acb->common.opaque, -EPROTO); qemu_aio_unref(acb); state->acb[i] = NULL; } -- 2.3.1
