[RFC PATCH 04/20] Make QEMUFile buf expandable, and introduce qemu_realloc_buffer() and qemu_clear_buffer().

[Yoshiaki Tamura <tamura.yoshiaki@xxxxxxxxxxxxx>]

Currently buf size is fixed at 32KB.  It would be useful if it could
be flexible.

Signed-off-by: Yoshiaki Tamura <tamura.yoshiaki@xxxxxxxxxxxxx>
---
 hw/hw.h  |    2 ++
 savevm.c |   26 +++++++++++++++++++++++++-
 2 files changed, 27 insertions(+), 1 deletions(-)

diff --git a/hw/hw.h b/hw/hw.h
index 05131a0..fc9ed29 100644
--- a/hw/hw.h
+++ b/hw/hw.h
@@ -61,6 +61,8 @@ void qemu_fflush(QEMUFile *f);
 int qemu_fclose(QEMUFile *f);
 void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size);
 void qemu_put_byte(QEMUFile *f, int v);
+void *qemu_realloc_buffer(QEMUFile *f, int size);
+void qemu_clear_buffer(QEMUFile *f);
 
 static inline void qemu_put_ubyte(QEMUFile *f, unsigned int v)
 {
diff --git a/savevm.c b/savevm.c
index 2fd3de6..490ab70 100644
--- a/savevm.c
+++ b/savevm.c
@@ -174,7 +174,8 @@ struct QEMUFile {
                            when reading */
     int buf_index;
     int buf_size; /* 0 when writing */
-    uint8_t buf[IO_BUF_SIZE];
+    int buf_max_size;
+    uint8_t *buf;
 
     int has_error;
 };
@@ -424,6 +425,9 @@ QEMUFile *qemu_fopen_ops(void *opaque, QEMUFilePutBufferFunc *put_buffer,
     f->get_rate_limit = get_rate_limit;
     f->is_write = 0;
 
+    f->buf_max_size = IO_BUF_SIZE;
+    f->buf = qemu_mallocz(sizeof(uint8_t) * f->buf_max_size);
+
     return f;
 }
 
@@ -454,6 +458,25 @@ void qemu_fflush(QEMUFile *f)
     }
 }
 
+void *qemu_realloc_buffer(QEMUFile *f, int size)
+{
+    f->buf_max_size = size;
+
+    f->buf = qemu_realloc(f->buf, f->buf_max_size);
+    if (f->buf == NULL) {
+        fprintf(stderr, "qemu file buffer realloc failed\n");
+        exit(1);
+    }
+
+    return f->buf;
+}
+
+void qemu_clear_buffer(QEMUFile *f)
+{
+    f->buf_size = f->buf_index = f->buf_offset = 0;
+    memset(f->buf, 0, f->buf_max_size);
+}
+
 static void qemu_fill_buffer(QEMUFile *f)
 {
     int len;
@@ -479,6 +502,7 @@ int qemu_fclose(QEMUFile *f)
     qemu_fflush(f);
     if (f->close)
         ret = f->close(f->opaque);
+    qemu_free(f->buf);
     qemu_free(f);
     return ret;
 }
-- 
1.7.0.31.g1df487

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