[Qemu-devel] [Bug 1524546] [NEW] qemu-img rebase error message mentions wrong file name

[Surojit Pathak]

Public bug reported:

While doing 'qemu-img rebase' for linking to a different backing file, if the 
old backing file does not exist, the command fails. During this failure, the 
error message shown is misleading.
e.g. qemu-img rebase -b <backing_file> <filename> throws error saying "Could 
not open <filename>"
Ideally it should "Could not open <old_backing_file>"

snippet -
address@hidden ~]# qemu-img info 
/opt/stack/data/nova/instances/94864a64-ebf8-45e6-a777-615921216a0a/disk
image: /opt/stack/data/nova/instances/94864a64-ebf8-45e6-a777-615921216a0a/disk
file format: qcow2
virtual size: 20G (21474836480 bytes)
disk size: 174M
cluster_size: 65536
backing file: /tmp/3559241a79b79ae663ec6e3d9b75d469967b383b
Format specific information:
    compat: 1.1
    lazy refcounts: false
address@hidden ~]# mv /tmp/3559241a79b79ae663ec6e3d9b75d469967b383b 
/tmp/3559241a79b79ae663ec6e3d9b75d469967b383a
address@hidden ~]# file !$
file /tmp/3559241a79b79ae663ec6e3d9b75d469967b383a
/tmp/3559241a79b79ae663ec6e3d9b75d469967b383a: x86 boot sector; partition 1: 
ID=0x83, active, starthead 32, startsector 2048, 409600 sectors; partition 2: 
ID=0x8e, starthead 159, startsector 411648, 16365568 sectors, code offset 0xc0
address@hidden ~]# file /tmp/3559241a79b79ae663ec6e3d9b75d469967b383b
/tmp/3559241a79b79ae663ec6e3d9b75d469967b383b: cannot open (No such file or 
directory)
address@hidden ~]# qemu-img rebase -b 
/tmp/3559241a79b79ae663ec6e3d9b75d469967b383a 
/opt/stack/data/nova/instances/94864a64-ebf8-45e6-a777-615921216a0a/disk
qemu-img: Could not open 
'/opt/stack/data/nova/instances/94864a64-ebf8-45e6-a777-615921216a0a/disk': 
Could not open file: No such file or directory
address@hidden ~]# 
qemu-img version 1.5.3
OS: RHEL7 - 3.10.0-229
libvirtd (libvirt) 1.2.8

** Affects: qemu
     Importance: Undecided
         Status: New

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1524546

Title:
  qemu-img rebase error message mentions wrong file name

Status in QEMU:
  New

Bug description:
  While doing 'qemu-img rebase' for linking to a different backing file, if the 
old backing file does not exist, the command fails. During this failure, the 
error message shown is misleading.
  e.g. qemu-img rebase -b <backing_file> <filename> throws error saying "Could 
not open <filename>"
  Ideally it should "Could not open <old_backing_file>"

  snippet -
  address@hidden ~]# qemu-img info 
/opt/stack/data/nova/instances/94864a64-ebf8-45e6-a777-615921216a0a/disk
  image: 
/opt/stack/data/nova/instances/94864a64-ebf8-45e6-a777-615921216a0a/disk
  file format: qcow2
  virtual size: 20G (21474836480 bytes)
  disk size: 174M
  cluster_size: 65536
  backing file: /tmp/3559241a79b79ae663ec6e3d9b75d469967b383b
  Format specific information:
      compat: 1.1
      lazy refcounts: false
  address@hidden ~]# mv /tmp/3559241a79b79ae663ec6e3d9b75d469967b383b 
/tmp/3559241a79b79ae663ec6e3d9b75d469967b383a
  address@hidden ~]# file !$
  file /tmp/3559241a79b79ae663ec6e3d9b75d469967b383a
  /tmp/3559241a79b79ae663ec6e3d9b75d469967b383a: x86 boot sector; partition 1: 
ID=0x83, active, starthead 32, startsector 2048, 409600 sectors; partition 2: 
ID=0x8e, starthead 159, startsector 411648, 16365568 sectors, code offset 0xc0
  address@hidden ~]# file /tmp/3559241a79b79ae663ec6e3d9b75d469967b383b
  /tmp/3559241a79b79ae663ec6e3d9b75d469967b383b: cannot open (No such file or 
directory)
  address@hidden ~]# qemu-img rebase -b 
/tmp/3559241a79b79ae663ec6e3d9b75d469967b383a 
/opt/stack/data/nova/instances/94864a64-ebf8-45e6-a777-615921216a0a/disk
  qemu-img: Could not open 
'/opt/stack/data/nova/instances/94864a64-ebf8-45e6-a777-615921216a0a/disk': 
Could not open file: No such file or directory
  address@hidden ~]# 
  qemu-img version 1.5.3
  OS: RHEL7 - 3.10.0-229
  libvirtd (libvirt) 1.2.8

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1524546/+subscriptions