[Xen-devel] [PATCH v12 09/26] libxc/migration: export read_record for common use

[Changlong Xie <xiecl.fnst@xxxxxxxxxxxxxx>]

From: Wen Congyang <wency@xxxxxxxxxxxxxx>

read_record() could be used by primary to read dirty bitmap
record sent by secondary under COLO.
When used by xc save side, we need to pass the backchannel fd
instead of ctx->fd to read_record(), so we added a fd param to
it.
No functional changes.

CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Yang Hongyang <hongyang.yang@xxxxxxxxxxxx>
Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
Signed-off-by: Changlong Xie <xiecl.fnst@xxxxxxxxxxxxxx>
Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---
 tools/libxc/xc_sr_common.c  | 49 +++++++++++++++++++++++++++++++++++
 tools/libxc/xc_sr_common.h  | 14 ++++++++++
 tools/libxc/xc_sr_restore.c | 63 +--------------------------------------------
 3 files changed, 64 insertions(+), 62 deletions(-)

diff --git a/tools/libxc/xc_sr_common.c b/tools/libxc/xc_sr_common.c
index 3313a90..b228a15 100644
--- a/tools/libxc/xc_sr_common.c
+++ b/tools/libxc/xc_sr_common.c
@@ -89,6 +89,55 @@ int write_split_record(struct xc_sr_context *ctx, struct 
xc_sr_record *rec,
     return -1;
 }
 
+int read_record(struct xc_sr_context *ctx, int fd, struct xc_sr_record *rec)
+{
+    xc_interface *xch = ctx->xch;
+    struct xc_sr_rhdr rhdr;
+    size_t datasz;
+
+    if ( read_exact(fd, &rhdr, sizeof(rhdr)) )
+    {
+        PERROR("Failed to read Record Header from stream");
+        return -1;
+    }
+    else if ( rhdr.length > REC_LENGTH_MAX )
+    {
+        ERROR("Record (0x%08x, %s) length %#x exceeds max (%#x)", rhdr.type,
+              rec_type_to_str(rhdr.type), rhdr.length, REC_LENGTH_MAX);
+        return -1;
+    }
+
+    datasz = ROUNDUP(rhdr.length, REC_ALIGN_ORDER);
+
+    if ( datasz )
+    {
+        rec->data = malloc(datasz);
+
+        if ( !rec->data )
+        {
+            ERROR("Unable to allocate %zu bytes for record data (0x%08x, %s)",
+                  datasz, rhdr.type, rec_type_to_str(rhdr.type));
+            return -1;
+        }
+
+        if ( read_exact(fd, rec->data, datasz) )
+        {
+            free(rec->data);
+            rec->data = NULL;
+            PERROR("Failed to read %zu bytes of data for record (0x%08x, %s)",
+                   datasz, rhdr.type, rec_type_to_str(rhdr.type));
+            return -1;
+        }
+    }
+    else
+        rec->data = NULL;
+
+    rec->type   = rhdr.type;
+    rec->length = rhdr.length;
+
+    return 0;
+};
+
 static void __attribute__((unused)) build_assertions(void)
 {
     XC_BUILD_BUG_ON(sizeof(struct xc_sr_ihdr) != 24);
diff --git a/tools/libxc/xc_sr_common.h b/tools/libxc/xc_sr_common.h
index e7568b5..c990664 100644
--- a/tools/libxc/xc_sr_common.h
+++ b/tools/libxc/xc_sr_common.h
@@ -372,6 +372,20 @@ static inline int write_record(struct xc_sr_context *ctx,
 }
 
 /*
+ * Reads a record from the stream, and fills in the record structure.
+ *
+ * Returns 0 on success and non-0 on failure.
+ *
+ * On success, the records type and size shall be valid.
+ * - If size is 0, data shall be NULL.
+ * - If size is non-0, data shall be a buffer allocated by malloc() which must
+ *   be passed to free() by the caller.
+ *
+ * On failure, the contents of the record structure are undefined.
+ */
+int read_record(struct xc_sr_context *ctx, int fd, struct xc_sr_record *rec);
+
+/*
  * This would ideally be private in restore.c, but is needed by
  * x86_pv_localise_page() if we receive pagetables frames ahead of the
  * contents of the frames they point at.
diff --git a/tools/libxc/xc_sr_restore.c b/tools/libxc/xc_sr_restore.c
index 2b9a0ea..3e4ca7f 100644
--- a/tools/libxc/xc_sr_restore.c
+++ b/tools/libxc/xc_sr_restore.c
@@ -69,67 +69,6 @@ static int read_headers(struct xc_sr_context *ctx)
 }
 
 /*
- * Reads a record from the stream, and fills in the record structure.
- *
- * Returns 0 on success and non-0 on failure.
- *
- * On success, the records type and size shall be valid.
- * - If size is 0, data shall be NULL.
- * - If size is non-0, data shall be a buffer allocated by malloc() which must
- *   be passed to free() by the caller.
- *
- * On failure, the contents of the record structure are undefined.
- */
-static int read_record(struct xc_sr_context *ctx, struct xc_sr_record *rec)
-{
-    xc_interface *xch = ctx->xch;
-    struct xc_sr_rhdr rhdr;
-    size_t datasz;
-
-    if ( read_exact(ctx->fd, &rhdr, sizeof(rhdr)) )
-    {
-        PERROR("Failed to read Record Header from stream");
-        return -1;
-    }
-    else if ( rhdr.length > REC_LENGTH_MAX )
-    {
-        ERROR("Record (0x%08x, %s) length %#x exceeds max (%#x)", rhdr.type,
-              rec_type_to_str(rhdr.type), rhdr.length, REC_LENGTH_MAX);
-        return -1;
-    }
-
-    datasz = ROUNDUP(rhdr.length, REC_ALIGN_ORDER);
-
-    if ( datasz )
-    {
-        rec->data = malloc(datasz);
-
-        if ( !rec->data )
-        {
-            ERROR("Unable to allocate %zu bytes for record data (0x%08x, %s)",
-                  datasz, rhdr.type, rec_type_to_str(rhdr.type));
-            return -1;
-        }
-
-        if ( read_exact(ctx->fd, rec->data, datasz) )
-        {
-            free(rec->data);
-            rec->data = NULL;
-            PERROR("Failed to read %zu bytes of data for record (0x%08x, %s)",
-                   datasz, rhdr.type, rec_type_to_str(rhdr.type));
-            return -1;
-        }
-    }
-    else
-        rec->data = NULL;
-
-    rec->type   = rhdr.type;
-    rec->length = rhdr.length;
-
-    return 0;
-};
-
-/*
  * Is a pfn populated?
  */
 static bool pfn_is_populated(const struct xc_sr_context *ctx, xen_pfn_t pfn)
@@ -650,7 +589,7 @@ static int restore(struct xc_sr_context *ctx)
 
     do
     {
-        rc = read_record(ctx, &rec);
+        rc = read_record(ctx, ctx->fd, &rec);
         if ( rc )
         {
             if ( ctx->restore.buffer_all_records )
-- 
1.9.3




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