QEMUSizedBuffer based QEMUFile

This is based on Stefan and Joel's patch that creates a QEMUFile that goes
to a memory buffer; from:

http://lists.gnu.org/archive/html/qemu-devel/2013-03/msg05036.html

Using the QEMUFile interface, this patch adds support functions for
operating on in-memory sized buffers that can be written to or read from.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Signed-off-by: Joel Schopp <jschopp@linux.vnet.ibm.com>

For fixes/tweeks I've done:
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

2 files changed, 27 insertions, 0 deletions

diff --git a/include/migration/qemu-file.h b/include/migration/qemu-file.h
index c90f5298ab..70ff347f2e 100644
--- a/include/migration/qemu-file.h
+++ b/include/migration/qemu-file.h
@@ -25,6 +25,8 @@
 #define QEMU_FILE_H 1
 #include "exec/cpu-common.h"
 
+#include <stdint.h>
+
 /* This function writes a chunk of data to a file at the given position.
  * The pos argument can be ignored if the file is only being used for
  * streaming.  The handler should try to write all of the data it can.
@@ -94,11 +96,19 @@ typedef struct QEMUFileOps {
     QEMURamSaveFunc *save_page;
 } QEMUFileOps;
 
+struct QEMUSizedBuffer {
+    struct iovec *iov;
+    size_t n_iov;
+    size_t size; /* total allocated size in all iov's */
+    size_t used; /* number of used bytes */
+};
+
 QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops);
 QEMUFile *qemu_fopen(const char *filename, const char *mode);
 QEMUFile *qemu_fdopen(int fd, const char *mode);
 QEMUFile *qemu_fopen_socket(int fd, const char *mode);
 QEMUFile *qemu_popen_cmd(const char *command, const char *mode);
+QEMUFile *qemu_bufopen(const char *mode, QEMUSizedBuffer *input);
 int qemu_get_fd(QEMUFile *f);
 int qemu_fclose(QEMUFile *f);
 int64_t qemu_ftell(QEMUFile *f);
@@ -111,6 +121,22 @@ void qemu_put_byte(QEMUFile *f, int v);
 void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size);
 bool qemu_file_mode_is_not_valid(const char *mode);
 
+QEMUSizedBuffer *qsb_create(const uint8_t *buffer, size_t len);
+QEMUSizedBuffer *qsb_clone(const QEMUSizedBuffer *);
+void qsb_free(QEMUSizedBuffer *);
+size_t qsb_set_length(QEMUSizedBuffer *qsb, size_t length);
+size_t qsb_get_length(const QEMUSizedBuffer *qsb);
+ssize_t qsb_get_buffer(const QEMUSizedBuffer *, off_t start, size_t count,
+                       uint8_t *buf);
+ssize_t qsb_write_at(QEMUSizedBuffer *qsb, const uint8_t *buf,
+                     off_t pos, size_t count);
+
+
+/*
+ * For use on files opened with qemu_bufopen
+ */
+const QEMUSizedBuffer *qemu_buf_get(QEMUFile *f);
+
 static inline void qemu_put_ubyte(QEMUFile *f, unsigned int v)
 {
     qemu_put_byte(f, (int)v);
diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h
index 04df51b6fc..168a4086d8 100644
--- a/include/qemu/typedefs.h
+++ b/include/qemu/typedefs.h
@@ -71,6 +71,7 @@ typedef struct SSIBus SSIBus;
 typedef struct EventNotifier EventNotifier;
 typedef struct VirtIODevice VirtIODevice;
 typedef struct QEMUSGList QEMUSGList;
+typedef struct QEMUSizedBuffer QEMUSizedBuffer;
 typedef struct SHPCDevice SHPCDevice;
 typedef struct FWCfgState FWCfgState;
 typedef struct PcGuestInfo PcGuestInfo;