[Bug 1911188] [NEW] qemu-system-x86_64 prints obscure error message and exits when encountering an empty argument

[Bug 1911188] [NEW] qemu-system-x86_64 prints obscure error message and exits when encountering an empty argument

[Violet]

Public bug reported:

QEMU emulator version 4.2.1 (qemu-4.2.1-1.fc32) on Fedora 32.

When writing a script to start qemu automatically, I ran into a very
confusing error message due to a bug in my script and had trouble
understanding it. I isolated the problem to the following:

$ qemu-system-x86_64 ""
qemu-system-x86_64: Initialization of device ide-hd failed: Device needs media, but drive is empty

As you can see, running qemu with an empty argument prints a seemingly
random and unrelated error message about an ide-hd device, and the
program immediately exits with code 1. This happens when an empty
argument appears anywhere in the arguments list, always causing the
program to immediately die with this error.

This is a simply baffling message to be encountering when the problem is
really an empty argument.

Expected behaviour: Either flatly ignore the empty argument, or at most
trigger a warning (eg, "warning: saw empty argument"). It should not at
all prevent the program from running.

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1911188

Title:
  qemu-system-x86_64 prints obscure error message and exits when
  encountering an empty argument

Status in QEMU:
  New

Bug description:
  QEMU emulator version 4.2.1 (qemu-4.2.1-1.fc32) on Fedora 32.

  When writing a script to start qemu automatically, I ran into a very
  confusing error message due to a bug in my script and had trouble
  understanding it. I isolated the problem to the following:

  $ qemu-system-x86_64 ""
  qemu-system-x86_64: Initialization of device ide-hd failed: Device needs media, but drive is empty

  As you can see, running qemu with an empty argument prints a seemingly
  random and unrelated error message about an ide-hd device, and the
  program immediately exits with code 1. This happens when an empty
  argument appears anywhere in the arguments list, always causing the
  program to immediately die with this error.

  This is a simply baffling message to be encountering when the problem
  is really an empty argument.

  Expected behaviour: Either flatly ignore the empty argument, or at
  most trigger a warning (eg, "warning: saw empty argument"). It should
  not at all prevent the program from running.

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[Bug 1911188] Re: qemu-system-x86_64 prints obscure error message and exits when encountering an empty argument

[Daniel Berrange]

If QEMU receives an argument that isn't an option flag, then it
considers it to be the path to a disk. The block code treats the empty
string as indicating that no backing file should be opened for the
device. This only makes sense for devices that support removable media
(ie CDROM, floppy), hence getting an error message for the ide-hd disk.

So weird as this message might seem, I believe it does ultimately make
sense, and I don't think we can just ignore the empty string without
potentially breaking other things.

-- 
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https://bugs.launchpad.net/bugs/1911188

Title:
  qemu-system-x86_64 prints obscure error message and exits when
  encountering an empty argument

Status in QEMU:
  New

Bug description:
  QEMU emulator version 4.2.1 (qemu-4.2.1-1.fc32) on Fedora 32.

  When writing a script to start qemu automatically, I ran into a very
  confusing error message due to a bug in my script and had trouble
  understanding it. I isolated the problem to the following:

  $ qemu-system-x86_64 ""
  qemu-system-x86_64: Initialization of device ide-hd failed: Device needs media, but drive is empty

  As you can see, running qemu with an empty argument prints a seemingly
  random and unrelated error message about an ide-hd device, and the
  program immediately exits with code 1. This happens when an empty
  argument appears anywhere in the arguments list, always causing the
  program to immediately die with this error.

  This is a simply baffling message to be encountering when the problem
  is really an empty argument.

  Expected behaviour: Either flatly ignore the empty argument, or at
  most trigger a warning (eg, "warning: saw empty argument"). It should
  not at all prevent the program from running.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1911188/+subscriptions

[Bug 1911188] Re: qemu-system-x86_64 prints obscure error message and exits when encountering an empty argument

[Violet]

Thanks for the quick reply Daniel. I've looked at the qemu man page many
times but somehow never noticed that it can take one non-option argument
alongside any other options. That does explain what is going on here. In
that case I'm not going to push for a potentially breaking change.

Perhaps it would still be beneficial to emit a warning about the empty
string, at least when it has occurred in conjunction with a non-
removable drive (I suppose one is created automatically if no other
options are present?) which doesn't make sense to get such a path. I
feel like the scenario in which it is intended might be less common than
the scenario in which it has happened accidentally. Maybe I'm biased
though ;)

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1911188

Title:
  qemu-system-x86_64 prints obscure error message and exits when
  encountering an empty argument

Status in QEMU:
  New

Bug description:
  QEMU emulator version 4.2.1 (qemu-4.2.1-1.fc32) on Fedora 32.

  When writing a script to start qemu automatically, I ran into a very
  confusing error message due to a bug in my script and had trouble
  understanding it. I isolated the problem to the following:

  $ qemu-system-x86_64 ""
  qemu-system-x86_64: Initialization of device ide-hd failed: Device needs media, but drive is empty

  As you can see, running qemu with an empty argument prints a seemingly
  random and unrelated error message about an ide-hd device, and the
  program immediately exits with code 1. This happens when an empty
  argument appears anywhere in the arguments list, always causing the
  program to immediately die with this error.

  This is a simply baffling message to be encountering when the problem
  is really an empty argument.

  Expected behaviour: Either flatly ignore the empty argument, or at
  most trigger a warning (eg, "warning: saw empty argument"). It should
  not at all prevent the program from running.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1911188/+subscriptions

[Bug 1911188] Re: qemu-system-x86_64 prints obscure error message and exits when encountering an empty argument

[Thomas Huth]

The QEMU project is currently moving its bug tracking to another system.
For this we need to know which bugs are still valid and which could be
closed already. Thus we are setting the bug state to "Incomplete" now.

If the bug has already been fixed in the latest upstream version of QEMU,
then please close this ticket as "Fix released".

If it is not fixed yet and you think that this bug report here is still
valid, then you have two options:

1) If you already have an account on gitlab.com, please open a new ticket
for this problem in our new tracker here:

    https://gitlab.com/qemu-project/qemu/-/issues

and then close this ticket here on Launchpad (or let it expire auto-
matically after 60 days). Please mention the URL of this bug ticket on
Launchpad in the new ticket on GitLab.

2) If you don't have an account on gitlab.com and don't intend to get
one, but still would like to keep this ticket opened, then please switch
the state back to "New" or "Confirmed" within the next 60 days (other-
wise it will get closed as "Expired"). We will then eventually migrate
the ticket automatically to the new system (but you won't be the reporter
of the bug in the new system and thus you won't get notified on changes
anymore).

Thank you and sorry for the inconvenience.


** Tags added: storage

** Changed in: qemu
       Status: New => Incomplete

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devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1911188

Title:
  qemu-system-x86_64 prints obscure error message and exits when
  encountering an empty argument

Status in QEMU:
  Incomplete

Bug description:
  QEMU emulator version 4.2.1 (qemu-4.2.1-1.fc32) on Fedora 32.

  When writing a script to start qemu automatically, I ran into a very
  confusing error message due to a bug in my script and had trouble
  understanding it. I isolated the problem to the following:

  $ qemu-system-x86_64 ""
  qemu-system-x86_64: Initialization of device ide-hd failed: Device needs media, but drive is empty

  As you can see, running qemu with an empty argument prints a seemingly
  random and unrelated error message about an ide-hd device, and the
  program immediately exits with code 1. This happens when an empty
  argument appears anywhere in the arguments list, always causing the
  program to immediately die with this error.

  This is a simply baffling message to be encountering when the problem
  is really an empty argument.

  Expected behaviour: Either flatly ignore the empty argument, or at
  most trigger a warning (eg, "warning: saw empty argument"). It should
  not at all prevent the program from running.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1911188/+subscriptions

[Bug 1911188] Re: qemu-system-x86_64 prints obscure error message and exits when encountering an empty argument

[Launchpad Bug Tracker]

[Expired for QEMU because there has been no activity for 60 days.]

** Changed in: qemu
       Status: Incomplete => Expired

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1911188

Title:
  qemu-system-x86_64 prints obscure error message and exits when
  encountering an empty argument

Status in QEMU:
  Expired

Bug description:
  QEMU emulator version 4.2.1 (qemu-4.2.1-1.fc32) on Fedora 32.

  When writing a script to start qemu automatically, I ran into a very
  confusing error message due to a bug in my script and had trouble
  understanding it. I isolated the problem to the following:

  $ qemu-system-x86_64 ""
  qemu-system-x86_64: Initialization of device ide-hd failed: Device needs media, but drive is empty

  As you can see, running qemu with an empty argument prints a seemingly
  random and unrelated error message about an ide-hd device, and the
  program immediately exits with code 1. This happens when an empty
  argument appears anywhere in the arguments list, always causing the
  program to immediately die with this error.

  This is a simply baffling message to be encountering when the problem
  is really an empty argument.

  Expected behaviour: Either flatly ignore the empty argument, or at
  most trigger a warning (eg, "warning: saw empty argument"). It should
  not at all prevent the program from running.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1911188/+subscriptions