qcow2: Add qcow2_signal_corruption()

Add a helper function for easily marking an image corrupt (on fatal
corruptions) while outputting an informative message to stderr and via
QAPI.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NBenoît Canet <benoit.canet@nodalink.com>
Message-id: 1409926039-29044-3-git-send-email-mreitz@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

block/qcow2.c

@@ -31,6 +31,8 @@
 #include "qapi/qmp/qerror.h"
 #include "qapi/qmp/qbool.h"
 #include "qapi/util.h"
+#include "qapi/qmp/types.h"
+#include "qapi-event.h"
 #include "trace.h"
 #include "qemu/option_int.h"
 
@@ -2529,6 +2531,52 @@ static int qcow2_amend_options(BlockDriverState *bs, QemuOpts *opts)
     return 0;
 }
 
+/*
+ * If offset or size are negative, respectively, they will not be included in
+ * the BLOCK_IMAGE_CORRUPTED event emitted.
+ * fatal will be ignored for read-only BDS; corruptions found there will always
+ * be considered non-fatal.
+ */
+void qcow2_signal_corruption(BlockDriverState *bs, bool fatal, int64_t offset,
+                             int64_t size, const char *message_format, ...)
+{
+    BDRVQcowState *s = bs->opaque;
+    char *message;
+    va_list ap;
+
+    fatal = fatal && !bs->read_only;
+
+    if (s->signaled_corruption &&
+        (!fatal || (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT)))
+    {
+        return;
+    }
+
+    va_start(ap, message_format);
+    message = g_strdup_vprintf(message_format, ap);
+    va_end(ap);
+
+    if (fatal) {
+        fprintf(stderr, "qcow2: Marking image as corrupt: %s; further "
+                "corruption events will be suppressed\n", message);
+    } else {
+        fprintf(stderr, "qcow2: Image is corrupt: %s; further non-fatal "
+                "corruption events will be suppressed\n", message);
+    }
+
+    qapi_event_send_block_image_corrupted(bdrv_get_device_name(bs), message,
+                                          offset >= 0, offset, size >= 0, size,
+                                          fatal, &error_abort);
+    g_free(message);
+
+    if (fatal) {
+        qcow2_mark_corrupt(bs);
+        bs->drv = NULL; /* make BDS unusable */
+    }
+
+    s->signaled_corruption = true;
+}
+
 static QemuOptsList qcow2_create_opts = {
     .name = "qcow2-create-opts",
     .head = QTAILQ_HEAD_INITIALIZER(qcow2_create_opts.head),

block/qcow2.h

@@ -261,6 +261,7 @@ typedef struct BDRVQcowState {
     bool discard_passthrough[QCOW2_DISCARD_MAX];
 
     int overlap_check; /* bitmask of Qcow2MetadataOverlap values */
+    bool signaled_corruption;
 
     uint64_t incompatible_features;
     uint64_t compatible_features;
@@ -477,6 +478,10 @@ int qcow2_mark_corrupt(BlockDriverState *bs);
 int qcow2_mark_consistent(BlockDriverState *bs);
 int qcow2_update_header(BlockDriverState *bs);
 
+void qcow2_signal_corruption(BlockDriverState *bs, bool fatal, int64_t offset,
+                             int64_t size, const char *message_format, ...)
+                             GCC_FMT_ATTR(5, 6);
+
 /* qcow2-refcount.c functions */
 int qcow2_refcount_init(BlockDriverState *bs);
 void qcow2_refcount_close(BlockDriverState *bs);