[Bug 1692420] Re: [SRU] powerpc-utils commands exhibits "command substitution: ignored null byte in input" warning message

[Brian Murray]

** Summary changed:

- [SRU] powerpc-utils commans exhibits "command substitution: ignored null byte in input" warning message
+ [SRU] powerpc-utils commands exhibits "command substitution: ignored null byte in input" warning message

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Title:
  [SRU] powerpc-utils commands exhibits "command substitution: ignored
  null byte in input" warning message

Status in The Ubuntu-power-systems project:
  New
Status in powerpc-utils package in Ubuntu:
  Triaged

Bug description:
  [Impact]

  The current version of powerpc-utils in Ubuntu Zesty and Artful
  carries a bug exposed by bash 4.4+ which causes a warning to be logged
  to stderr in 4 different commands: ls-veth, ls-vscsi, lsdevinfo, and
  ofpathname. Bash is unable to store the NUL bytes in the result of a
  command substitution, prior to 4.4 it silently dropped the NUL bytes,
  but since 4.4 it drops the NUL bytes with a warning: "command
  substitution: ignored null byte in input".

  Additionally to that the ofpathname command also had a bug that caused
  a "cd: too many arguments" warning.

  Upstream has fixed both [1] and they now need to be backport to Zesty.

  [Test Case 1]

  Call any of the affected commands without arguments, they should
  output "command substitution: ignored null byte in input" to stderr.

  The same warning can easily be reproduced in bash 4.4+ by executing:
  $ x=$(cat < /proc/$$/cmdline)
  bash: warning: command substitution: ignored null byte in input

  And to fix it:
  $ x=$(tr -d '\0' < /proc/$$/cmdline)
  <no output, as expected>

  [Test Case 2]
  Call ofpathname with no arguments:
  $ ofpathname
  cd: too many arguments

  [Regression Potential]

  The replacement of 'cat' with 'tr -d "\0"' causes no regression. Also,
  both commands are part of coreutils.

  The 'cd' fix replaces it with a drop_dir call. In case the requested
  path is not found then the previous behavior would be kept (ie. no
  directory change).

  [Other Info]

  Upstream fix link:
  [1] https://github.com/ibm-power-utilities/powerpc-utils/commit/4fcc611a09caea70e6bca6a1275211c72ac4bb45

  [Old description]
  Please cherry pick...

  https://github.com/ibm-power-utilities/powerpc-
  utils/commit/4fcc611a09caea70e6bca6a1275211c72ac4bb45

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