diff mbox

[PULL,18/27] curl: Operate on zero-length file

Message ID 73e37a96a0485d8f5f2edb4ff86ebae6bd7b8135.1473839869.git.mjt@msgid.tls.msk.ru
State New
Headers show

Commit Message

Michael Tokarev Sept. 14, 2016, 7:58 a.m. UTC 
From: Tomáš Golembiovský <tgolembi@redhat.com>

Another attempt to fix the bug 1596870.

When creating new disk backed by remote file accessed via HTTPS and the
backing file has zero length, qemu-img terminates with uniformative
error message:

    qemu-img: disk.qcow2: CURL: Error opening file:

While it may not make much sense to operate on empty file, other block
backends (e.g. raw backend for regular files) seem to allow it. This
patch fixes it for the curl backend and improves the reported error.

Signed-off-by: Tomáš Golembiovský <tgolembi@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
---
 block/curl.c | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)
diff mbox

Patch

diff --git a/block/curl.c b/block/curl.c
index 426fb4d..571f24c 100644
--- a/block/curl.c
+++ b/block/curl.c
@@ -675,11 +675,28 @@  static int curl_open(BlockDriverState *bs, QDict *options, int flags,
     curl_easy_setopt(state->curl, CURLOPT_HEADERDATA, s);
     if (curl_easy_perform(state->curl))
         goto out;
-    curl_easy_getinfo(state->curl, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &d);
-    if (d)
-        s->len = (size_t)d;
-    else if(!s->len)
+    if (curl_easy_getinfo(state->curl, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &d)) {
         goto out;
+    }
+    /* Prior CURL 7.19.4 return value of 0 could mean that the file size is not
+     * know or the size is zero. From 7.19.4 CURL returns -1 if size is not
+     * known and zero if it is realy zero-length file. */
+#if LIBCURL_VERSION_NUM >= 0x071304
+    if (d < 0) {
+        pstrcpy(state->errmsg, CURL_ERROR_SIZE,
+                "Server didn't report file size.");
+        goto out;
+    }
+#else
+    if (d <= 0) {
+        pstrcpy(state->errmsg, CURL_ERROR_SIZE,
+                "Unknown file size or zero-length file.");
+        goto out;
+    }
+#endif
+
+    s->len = (size_t)d;
+
     if ((!strncasecmp(s->url, "http://", strlen("http://"))
         || !strncasecmp(s->url, "https://", strlen("https://")))
         && !s->accept_range) {