[Xen-changelog] [xen master] libxl: Reset toolstack_save file position in libxl

[patchbot@xxxxxxx]

commit b327a3f421bb57d262b7d1fb3c43b710852b103b
Author:     Jason Andryuk <andryuk@xxxxxxxx>
AuthorDate: Mon May 19 14:36:37 2014 -0400
Commit:     Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CommitDate: Thu May 22 16:35:22 2014 +0100

    libxl: Reset toolstack_save file position in libxl
    
    toolstack_save data is written to a temporary file in libxl and read
    back in libxl-save-helper.  The file position must be reset prior to
    reading the file, which is done in libxl-save-helper with lseek.
    
    lseek is unsupported for pipes and sockets, so a wrapper passing such an
    fd to libxl-save-helper fails the lseek.  Moving the lseek to libxl
    avoids the error, allowing the save to continue.
    
    Signed-off-by: Jason Andryuk <andryuk@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---
 tools/libxl/libxl_save_callout.c |    4 ++++
 tools/libxl/libxl_save_helper.c  |    5 ++---
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/libxl/libxl_save_callout.c b/tools/libxl/libxl_save_callout.c
index e3bda8f..c35da4d 100644
--- a/tools/libxl/libxl_save_callout.c
+++ b/tools/libxl/libxl_save_callout.c
@@ -105,6 +105,10 @@ void libxl__xc_domain_save(libxl__egc *egc, 
libxl__domain_suspend_state *dss,
                                 toolstack_data_buf, toolstack_data_len,
                                 "toolstack data tmpfile", 0);
         if (r) { rc = ERROR_FAIL; goto out; }
+
+        /* file position must be reset before passing to libxl-save-helper. */
+        r = lseek(toolstack_data_fd, 0, SEEK_SET);
+        if (r) { rc = ERROR_FAIL; goto out; }
     }
 
     const unsigned long argnums[] = {
diff --git a/tools/libxl/libxl_save_helper.c b/tools/libxl/libxl_save_helper.c
index c36314c..b259bd0 100644
--- a/tools/libxl/libxl_save_helper.c
+++ b/tools/libxl/libxl_save_helper.c
@@ -163,10 +163,9 @@ static uint32_t toolstack_save_len;
 static int toolstack_save_cb(uint32_t domid, uint8_t **buf,
                              uint32_t *len, void *data)
 {
-    assert(toolstack_save_fd > 0);
+    int r;
 
-    int r = lseek(toolstack_save_fd, 0, SEEK_SET);
-    if (r) fail(errno,"rewind toolstack data tmpfile");
+    assert(toolstack_save_fd > 0);
 
     *buf = xmalloc(toolstack_save_len);
     r = read_exactly(toolstack_save_fd, *buf, toolstack_save_len);
--
generated by git-patchbot for /home/xen/git/xen.git#master

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