makefile: use LUA_PKGCONFIG to set Lua implementation

This breaks compat with the previous LUA_IMPLEMENTATION but gives more
flexibility in that user can specify the pkg-config package name
directly.

Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
simple-authentication: style

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
gen-version.sh: check if git is available before trying to call it

Some people may clone the cgit repository and compile within a sandbox
or on another machine where git is not necessarily installed. When it
happens, cgit is getting compiled with an empty version number.

This commit fixes this.
diffstat: do not rely on uninitialized data

Right now if you visit:
<http://git.zx2c4.com/systemd/diff/src/udev/udev-builtin-input_id.c?id=bcfce235>
you'll see that if you reload the page a few times, a bunch of times the
diffstat comes out with no lines being shown or changed. I'm not
currently sure what the cause of this is, but I suspect it might have to
do with this uninitialized data.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Add a cache-snapshot-ttl configuration variable

This can be used to specify the TTL for snapshots. Snapshots are usually
static and do not ever change. On the other hand, tarball generation is
CPU intensive.

One use case of this setting (apart from increasing the lifetime of
snapshot cache slots) is caching of snapshots while disabling the cache
for static/dynamic HTML pages (by setting TTL to zero for everything
except for snapshot requests).

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>
Makefile: suppress pkg-config error

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
git: Update to 1.9.0

No code changes required, just bump the submodule and Makefile versions.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>
Skip cache slot when time-to-live is zero

If time-to-live is set to zero, we don't need to regenerate the cache
slots on every request. Instead, just skip the caching process and
immediately provide the dynamically generated version of the page.
Setting time-to-live to zero is useful when you want to disable caching
for certain pages.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>
Clean up cache documentation.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
print download link for reference string length == 1

I have a number of repositories that start tagging with just '1' and
count up. Actually references with sting length of one are skipped, this
patch changes that.
Remove unused parameter from cgit_print_snapshot()
ui-refs: simplify cmp_age logic

The check in parse_user that eventually makes it into committer_date and
tagger_date is:

else if (mode == 3 && isdigit(*p)) {
    *date = atol(p);
    mode++;
}

Since isdigit('-') is always false, date will never be negative. Thus
the sign of this function:

static int cmp_age(int age1, int age2)
{
    if (age1 != 0 && age2 != 0)
        return age2 - age1;

    if (age1 == 0 && age2 == 0)
        return 0;

    if (age1 == 0)
        return +1;

    return -1;
}

Will always be the same as the sign of this function:

static inline int cmp_age(int age1, int age2)
{
    return age2 - age1;
}

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Idea-by: Lukas Fleischer <cgit@cryptocrack.de>
Bump version.