Here is how to reproduce the problem:
$ dd if=/dev/zero of=file2G bs=1M count=2049
2049+0 records in
2049+0 records out
2148532224 bytes (2.1 GB) copied, 47.9032 s, 44.9 MB/s
$ ar q ar2G.ar file2G
$ od -a ar2G.ar
0000000 ! < a r c h > nl f i l e 2 G / sp
0000020 sp sp sp sp sp sp sp sp 1 3 2 4 4 6 6 2
0000040 8 0 sp sp 1 0 0 0 sp sp 1 0 0 0 sp sp
0000060 1 0 0 6 4 4 sp sp - 2 1 4 6 4 3 5
0000100 0 7 ` nl nul nul nul nul nul nul nul nul nul nul nul nul
Note that the archive claims that the 'file2G' size is negative:
-214643507. This results in an invalid archive that cannot be extracted:
$ ar xv ar2G.ar
x - file2G
ar: ar2G.ar is not a valid archive
As a consequence of this it is impossible to generate Debian packages
bigger than 2GB (for instance for applications that have a large
Obviously the file size was stored into a signed 32bit variable. Reading
the source code shows that it was actually a long which means there will
be further issues if such an archive is moved from a 32bit system to a
More precisely, the archive file format is a linked list of element
headers and relies on these having accurate size information to find the
position of the next element header. Since the archive format allocates
10 characters for the file size, it should be able to handle files up to
* Files between 2GiB and 4GiB
The file size is stored as being negative. The archive cannot be
extracted by either the 32bit ar or the 64bit one.
* Files between 4GiB and 10GB
Only the first 32bits are taken into account so ar will write a size
of 0.1GiB for a 4.1GiB file. As a result, during extraction ar will
think there is an archive element header in the middle of the file,
resulting in an error (if not worse).
There are also sign issues between 6GiB and 8GiB.
* Files bigger than 10GB
ar will silently truncated the file size to its first 10 decimal
digits. Decoding will fail for the same reason as above.
Even 64bit systems are not immune to these issues due to the file sizes
being stored in 'unsigned int' variables in various places.
Created attachment 6123 [details]
bfd: Fix writing the size of 2+GB elements in the archive.
Created attachment 6124 [details]
bfd: Refuse to create an invalid archive when an archive element is too big.
Created attachment 6125 [details]
bfd: Fix parsing the size of archive elements larger than 2GB.
Created attachment 6126 [details]
bfd: Always use bfd_size_type to manipulate the size of an archive element.
Created attachment 6127 [details]
ar: Fix handling of archive elements larger than 2GB.
I attached a set of 5 patches that fix this issue (at least for me). I hope they're ok. If not let me know.
Module name: src
Changes by: email@example.com 2012-01-20 14:42:57
bfd : ChangeLog archive.c archive64.c bfdio.c
* archive.c (_bfd_ar_sizepad): New function. Correctly install and
pad the size field in an archive header.
(_bfd_generic_read_ar_hdr_mag): Use the correct type and scan
function for the archive size field.
(_bfd_bsd44_write_ar_hdr): Use the new function.
* archive64.c (bfd_elf64_archive_write_armap): Likewise.
* bfdio.c (bfd_bread): Use correct type for archive element
* ar.c (open_inarch): Likewise.
* libbfd-in.h (struct areltdata): Use correct types for
parsed_size and extra_size fields.
Prototype _bfd_ar_sizepad function.
* libbfd.h: Regenerate.
Thanks for reporting this problem, and supplying a patch to fix it.
I have checked in your patch with minor change - I made _bfd_ar_sizepad a boolean function - and one slightly more important change - I created a changelog entry.