This one time, at band camp, Aurelien Jarno said: > > cpio uses structures to map the file header, and the whole structure is > read at once. This does not work on all architectures (like ARM), as > they may use padding. The structures should be declared as packed to > avoid padding. > > You will find a patch below to fix the problem.
(disclaimer: not related to cpio in any way)
This patch certainly looks good enough to be a dpatch or whatever system
is in use, but I just wanted to mention that before pushing this
upstream, you might want to add tests for how to pack the structures
depending on compiler capabilities.
This is the first example I happened on (clamav, from configure.in)
dnl check for __attribute__((packed))
AC_MSG_CHECKING([for structure packing via __attribute__((packed))])
AC_CACHE_VAL(have_attrib_packed,[
AC_TRY_COMPILE(,
[struct { int i __attribute__((packed)); } s; ],
[have_attrib_packed=yes],
[have_attrib_packed=no])
])
AC_MSG_RESULT($have_attrib_packed)
if test "$have_attrib_packed" = no; then
AC_MSG_CHECKING(for structure packing via pragma)
AC_CACHE_VAL(have_pragma_pack,[
AC_TRY_RUN([int main(int argc, char **argv) {
#pragma pack(1) /* has to be in column 1 ! */
struct { char c; long l; } s;
return sizeof(s)==sizeof(s.c)+sizeof(s.l) ? 0:1; } ],
[have_pragma_pack=yes],
[have_pragma_pack=no])
])
AC_MSG_RESULT($have_pragma_pack)
if test "$have_pragma_pack" = yes; then
AC_DEFINE(HAVE_PRAGMA_PACK, 1, "pragma pack")
else
AC_MSG_CHECKING(for structure packing via hppa/hp-ux pragma)
AC_CACHE_VAL(have_pragma_pack_hpux,[
AC_TRY_RUN([
/* hppa/hp-ux wants pragma outside of function */
#pragma pack 1 /* has to be in column 1 ! */
struct { char c; long l; } s;
int main(int argc, char **argv) {
return sizeof(s)==sizeof(s.c)+sizeof(s.l) ? 0:1; } ],
[have_pragma_pack_hpux=yes],
[have_pragma_pack_hpux=no])
])
AC_MSG_RESULT($have_pragma_pack_hpux)
AC_DEFINE(HAVE_PRAGMA_PACK_HPPA, 1, "pragma pack hppa/hp-ux
style")
fi
fi
if test "$have_attrib_packed" = no -a "$have_pragma_pack" = no -a
"$have_pragma_pack_hpux" = no; then
AC_MSG_ERROR(Need to know how to pack structures with this compiler)
fi
if test "$have_attrib_packed" = yes; then
AC_DEFINE(HAVE_ATTRIB_PACKED, 1, [attrib packed])
fi
And then later test for HAVE_ATTRIB_PACKED, HAVE_PRAGMA_PACK or
HAVE_PRAGMA_PACK_HPPA.
Take care,
--
-----------------------------------------------------------------
| ,''`. Stephen Gran |
| : :' : [EMAIL PROTECTED] |
| `. `' Debian user, admin, and developer |
| `- http://www.debian.org |
-----------------------------------------------------------------
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