[Bug 1187722] Re: dpkg-shlibdeps fails on armhf ELF binaries that do not define architecture specific information

[Adam Conrad]

Is this actually needed for any sane reason for quantal and raring, or
is this just a wishlist from people who like to pointlessly build
everything on every release in PPAs?

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https://bugs.launchpad.net/bugs/1187722

Title:
  dpkg-shlibdeps fails on armhf ELF binaries that do not define
  architecture specific information

Status in “dpkg” package in Ubuntu:
  Fix Released
Status in “golang” package in Ubuntu:
  Fix Released
Status in “dpkg” source package in Precise:
  Fix Released
Status in “dpkg” source package in Quantal:
  New
Status in “golang” source package in Quantal:
  Invalid
Status in “dpkg” source package in Raring:
  New
Status in “golang” source package in Raring:
  Invalid

Bug description:
  [Impact]

  This causes a build failure on armhf for any package that uses a
  toolchain that does not provide the optional ELF architecture specific
  tags like the gcc toolchain does. Example: golang. This stops us
  building armhf golang packages on Precise, such as the juju-core
  precise backport.

  [Stable Fix]

  Before reading any architecture specific tags, consider the ELF header
  flags field first for a match against the new "hard-float ABI" flag,
  and use this information over architecture specific tags if available.

  [Development Fix]

  Exactly the same patch as the stable fix.

  [Test Case]

  Attempt to build the unmodified golang source package from Saucy on
  Precise armhf.

  Expected results: successful build.

  Failure results:

  Errors of the form: dpkg-shlibdeps: error: couldn't find library
  libpthread.so.0 needed by debian/golang-go/usr/bin/go (ELF format:
  'elf32-littlearm-sfabi'; RPATH: '').

  [Regression Potential]

  The change is limited to dpkg-shlibdeps on ARM ELF binaries only, so
  should only affect rebuilds or backports.

  [Original Description]

  This causes an FTBFS in golang. See:
  https://launchpad.net/ubuntu/+source/golang/2:1.1-1/+build/4578681

  Affected: dpkg 1.16.10ubuntu1
  Not affected: dpkg 1.16.10

  I believe the difference is caused by Steve McIntyre's armhf detection patch
  applied in the Ubuntu dpkg delta.

  For convenience, I attach a golang armhf binary which dpkg-shlibdeps
  doesn't work with. The error is:

  dpkg-shlibdeps: error: couldn't find library libpthread.so.0 needed by /tmp/go (ELF format: 'elf32-littlearm-sfabi'; RPATH: '')
  dpkg-shlibdeps: error: couldn't find library libc.so.6 needed by /tmp/go (ELF format: 'elf32-littlearm-sfabi'; RPATH: '')
  dpkg-shlibdeps: error: couldn't find library ld-linux-armhf.so.3 needed by /tmp/go (ELF format: 'elf32-littlearm-sfabi'; RPATH: '')
  dpkg-shlibdeps: warning: binaries to analyze should already be installed in their package's directory
  dpkg-shlibdeps: error: cannot continue due to the errors listed above
  Note: libraries are not searched in other binary packages that do not have any shlibs or symbols file.
  To help dpkg-shlibdeps find private libraries, you might need to set LD_LIBRARY_PATH.

  The cause is that "readelf -A -- /tmp/go" doesn't produce any output. The
  arm-specific handling in Dpkg::Shlibs::Objdump then errnoneously decides that
  this means that the binary is "elf32-littlearm-sfabi", which mismatches its
  dependencies.  This causes it to fail, when in fact there is no problem with
  the binary's linkage or execution.

  Is it a requirement for armhf binaries to have Tag_ABI_VFP_args? I'm not sure
  whether the ABI spec actually requires this in order for a binary to be
  expected to dynamically link against a libc that does declare the tag. Even if
  so, does it make sense for dpkg to handle this condition more gracefully?

  Is there a spec which defines a requirement to have Tag_ABI_VFP_args set, so
  that we may refer golang upstream to it for a fix? Or is golang producing valid
  binaries and dpkg-shlibdeps is buggy?

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