sd.c: Handle NULL block backend in sd_get_inserted()

[qemu.git] / migration / qemu-file.c

diff --git a/migration/qemu-file.c b/migration/qemu-file.c
index df49023ed8c884749538dbca2df5fba0908d2fb6..6f4a1299b3100600bd22c992629538b40464bbb1 100644 (file)
--- a/migration/qemu-file.c
+++ b/migration/qemu-file.c
@@ -21,6 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+#include "qemu/osdep.h"
 #include <zlib.h>
 #include "qemu-common.h"
 #include "qemu/error-report.h"
@@ -44,6 +45,18 @@ int qemu_file_shutdown(QEMUFile *f)
     return f->ops->shut_down(f->opaque, true, true);
 }
 
+/*
+ * Result: QEMUFile* for a 'return path' for comms in the opposite direction
+ *         NULL if not available
+ */
+QEMUFile *qemu_file_get_return_path(QEMUFile *f)
+{
+    if (!f->ops->get_return_path) {
+        return NULL;
+    }
+    return f->ops->get_return_path(f->opaque);
+}
+
 bool qemu_file_mode_is_not_valid(const char *mode)
 {
     if (mode == NULL ||
@@ -433,6 +446,43 @@ size_t qemu_get_buffer(QEMUFile *f, uint8_t *buf, size_t size)
     return done;
 }
 
+/*
+ * Read 'size' bytes of data from the file.
+ * 'size' can be larger than the internal buffer.
+ *
+ * The data:
+ *   may be held on an internal buffer (in which case *buf is updated
+ *     to point to it) that is valid until the next qemu_file operation.
+ * OR
+ *   will be copied to the *buf that was passed in.
+ *
+ * The code tries to avoid the copy if possible.
+ *
+ * It will return size bytes unless there was an error, in which case it will
+ * return as many as it managed to read (assuming blocking fd's which
+ * all current QEMUFile are)
+ *
+ * Note: Since **buf may get changed, the caller should take care to
+ *       keep a pointer to the original buffer if it needs to deallocate it.
+ */
+size_t qemu_get_buffer_in_place(QEMUFile *f, uint8_t **buf, size_t size)
+{
+    if (size < IO_BUF_SIZE) {
+        size_t res;
+        uint8_t *src;
+
+        res = qemu_peek_buffer(f, &src, size, 0);
+
+        if (res == size) {
+            qemu_file_skip(f, res);
+            *buf = src;
+            return res;
+        }
+    }
+
+    return qemu_get_buffer(f, *buf, size);
+}
+
 /*
  * Peeks a single byte from the buffer; this isn't guaranteed to work if
  * offset leaves a gap after the previous read/peeked data.
@@ -611,3 +661,18 @@ size_t qemu_get_counted_string(QEMUFile *f, char buf[256])
 
     return res == len ? res : 0;
 }
+
+/*
+ * Set the blocking state of the QEMUFile.
+ * Note: On some transports the OS only keeps a single blocking state for
+ *       both directions, and thus changing the blocking on the main
+ *       QEMUFile can also affect the return path.
+ */
+void qemu_file_set_blocking(QEMUFile *f, bool block)
+{
+    if (block) {
+        qemu_set_block(qemu_get_fd(f));
+    } else {
+        qemu_set_nonblock(qemu_get_fd(f));
+    }
+}