info does not recognize file format of vpc with subformat=fixed

Bug #1819182 reported by Scott Moser on 2019-03-08
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
QEMU
Undecided
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Bug Description

After creating or converting an image to vpc with 'subformat=fixed'
'qemu-img info' incorrectly identifies the image as 'raw' format.

$ qemu-img --version
qemu-img version 2.11.1(Debian 1:2.11+dfsg-1ubuntu7.10)
Copyright (c) 2003-2017 Fabrice Bellard and the QEMU Project developers

$ qemu-img create -f vpc -o subformat=fixed my.vpc 2G
Formatting 'my.vpc', fmt=vpc size=2147483648 subformat=fixed

$ qemu-img info my.vpc
image: my.vpc
file format: raw
virtual size: 2.0G (2147992064 bytes)
disk size: 4.0K

$ qemu-img info -f vpc my.vpc
image: my.vpc
file format: vpc
virtual size: 2.0G (2147991552 bytes)
disk size: 4.0K

Revision history for this message
Scott Moser (smoser) wrote :

$ ./go-create
#version: 2.11.1
qcow: PASS fmt=qcow auto=qcow exp=qcow [name=my-img.qcow opts=]
qcow2: PASS fmt=qcow2 auto=qcow2 exp=qcow2 [name=my-img.qcow2 opts=]
qed: PASS fmt=qed auto=qed exp=qed [name=my-img.qed opts=]
raw: PASS fmt=raw auto=raw exp=raw [name=my-img.raw opts=]
vdi: PASS fmt=vdi auto=vdi exp=vdi [name=my-img.vdi opts=]
vhdx: PASS fmt=vhdx auto=vhdx exp=vhdx [name=my-img.vhdx opts=]
vmdk: PASS fmt=vmdk auto=vmdk exp=vmdk [name=my-img.vmdk opts=]
vpc: PASS fmt=vpc auto=vpc exp=vpc [name=my-img.vpc opts=]
vpc-fixed: FAIL fmt=vpc auto=raw exp=vpc [name=my-img.vpc-fixed opts=-o subformat=fixed]
vpc-fforce: FAIL fmt=vpc auto=raw exp=vpc [name=my-img.vpc-fforce opts=-o subformat=fixed,force_size]
FAIL [2]

Revision history for this message
John Snow (jnsnow) wrote :

Well, 2.11 is way too old, but it still does reproduce on the latest development head.

Revision history for this message
Thomas Huth (th-huth) wrote :
Changed in qemu:
status: New → Confirmed
Revision history for this message
Scott Moser (smoser) wrote :

@Thomas,

Is there really no way to detect the format other than relying on extension? :-(

Revision history for this message
Thomas Huth (th-huth) wrote :

@smoser : fixed-size VHD images don't have a header, and there is AFAIK currently no way for probing a footer in the QEMU code, so relying on the extension seems to be the only way right now, as far as I can tell.

Thomas Huth (th-huth) on 2021-05-11
Changed in qemu:
status: Confirmed → In Progress
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