Matt Turner <mattst88@xxxxxxxxx> writes: > tar2sqfs (part of https://github.com/topics/tar2sqfs) rejects tarballs > made with git archive with the message > > invalid tar header checksum! > > tar2sqfs recomputes the tarball's checksum to verify it. Its checksum > implementation agrees with GNU tar, which contains a comment that states > > Fill in the checksum field. It's formatted differently from the > other fields: it has [6] digits, a null, then a space ... > > Correcting this allows tar2sqfs to correctly process the tarballs made > by git archive. > > Signed-off-by: Matt Turner <mattst88@xxxxxxxxx> > --- > archive-tar.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/archive-tar.c b/archive-tar.c > index 3e53aac1e6..f9a157bfd1 100644 > --- a/archive-tar.c > +++ b/archive-tar.c > @@ -215,7 +215,9 @@ static void prepare_header(struct archiver_args *args, > memcpy(header->magic, "ustar", 6); > memcpy(header->version, "00", 2); > > - xsnprintf(header->chksum, sizeof(header->chksum), "%07o", ustar_header_chksum(header)); > + xsnprintf(header->chksum, sizeof(header->chksum), "%06o", ustar_header_chksum(header)); > + header->chksum[6] = '\0'; > + header->chksum[7] = ' '; Wow. The choice of %07o is as old as the very original of tar-tree implementation in our codebase, starting at ae64bbc1 ("tar-tree: Introduce write_entry()", 2006-03-25). I think the updated behaviour matches Wikipedia [*1*] where it spells out that 6 octal is followed by a NUL and a SP; it also says various implementations do not adhere to this format---perhaps they meant us ;-) Frustratingly, I couldn't find this spelled out in POSIX [*2*] X-<. The closest I found there was All other fields are leading zero-filled octal numbers using digits from the ISO/IEC 646:1991 standard IRV. Each numeric field is terminated by one or more <space> or NUL characters. which sounds as if the standard wanted to be deliberately more inclusive than what tar2sqfs is insisting on. I think a change like this would impact kernel.org folks' tarball uploading tool, but that is not a reason not to apply this patch. [References]. *1* https://en.wikipedia.org/wiki/Tar_(computing) *2* http://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html
