It turns out that, while on most distributions "docdir" would be
/usr/share/doc, it's /usr/share/doc/packages/ on OpenSUSE Tumbleweed.
Use an explicit docdir as shown in:
  https://en.opensuse.org/openSUSE:Build_Service_cross_distribution_howto

and don't unnecessarily hardcode directory variables in the Makefile.
Otherwise, RPM builds for OpenSUSE will fail now that we have a README
there.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Suggested-by: Benson Muite <benson_muite@emailplus.org>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Distribution packages reasonably expect to have a human-readable
Markdown version of the README under /usr/share/doc/, but all we have
right now is a heavily web-oriented version.

Introduce a ugly hack to strip web-oriented parts from the current
README and install it.

It should probably work the other way around: a human-readable README
could be used as a source for the web page. But cgit needs a file
that's in the tree, not something that can be built, and
https://passt.top/ is based on cgit. It should eventually be doable
to work around this in cgit, instead.

Reported-by: Benson Muite <benson_muite@emailplus.org>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Some versions of valgrind (such as the version on my Fedora laptop -
valgrind-3.19.0-3.fc36.x86_64) use futexes.  But futex is currently not
allowed in the seccomp filter, even with the extra calls added for
valgrind builds.  Add it, to avoid spurious valgrind failures.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

We handle SIGQUIT and SIGTERM calling exit(), which is usually
implemented with the exit_group() system call.

If we don't allow exit_group(), we'll get a SIGSYS while handling
SIGQUIT and SIGTERM, which means a misleading non-zero exit code.

Reported-by: Wenli Quan <wquan@redhat.com>
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2101990
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

If the tests are interrupted at the right point a passt.pid file can be
left over.  Clean it up with "make clean" and add it to .gitignore so it
doesn't get accidentally committed.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

Two places in passt need to read files line by line (one parsing
resolv.conf, the other parsing /proc/net/*.  They can't use fgets()
because in glibc that can allocate memory.  Instead they use an
implementation line_read() in util.c.  This has some problems:

 * It has two completely separate modes of operation, one buffering
   and one not, the relation between these and how they're activated
   is subtle and confusing
 * At least in non-buffered mode, it will mishandle an empty line,
   folding them onto the start of the next non-empty line
 * In non-buffered mode it will use lseek() which prevents using this
   on non-regular files (we don't need that at present, but it's a
   surprising limitation)
 * It has a lot of difficult to read pointer mangling

Add a new cleaner implementation of allocation-free line-by-line
reading in lineread.c.  This one always buffers, using a state
structure to keep track of what we need.  This is larger than I'd
like, but it turns out handling all the edge cases of line-by-line
reading in C is surprisingly hard.

This just adds the code, subsequent patches will change the existing
users of line_read() to the new implementation.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

In order to probe availability of certain features the Makefile test
compiles a handful of tiny snippets, feeding those in from stdin.  However
in one case - the one for -fstack-protector - it forgets to redirect the
output to stdout, meaning it creates a stray '-.s' file when make is
invoked (even make clean).

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

The use of rm commands in the clean and uninstall targets adds an explicit
leading - to ignore errors.  However the built-in RM variable in make is
actually "rm -f" which already ignores errors, so the - isn't neccessary.

Also replace ${RM} with $(RM) which is the more conventional form in
Makefiles.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

pasta, pasta.avx2 and pasta.1 are all generated as a link to the
corresponding passt file.  We can consolidate the 3 rules for these targets
into a single pattern rule.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>