Small layout adjustments to summary and blob view

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Add display of tree content w/ui-tree.c

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

cache_lock: do xstrdup/free on lockfile

Since fmt() uses 8 alternating static buffers, and cache_lock might call
cache_create_dirs() multiple times, which in turn might call fmt() twice,
after four iterations lockfile would be overwritten by a cachedirectory
path.

In worst case, this could cause the cachedirectory to be unlinked and replaced
by a cachefile.

Fix: use xstrdup() on the result from fmt() before assigning to lockfile, and
call free(lockfile) before exit.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Don't truncate valid cachefiles

An embarrassing thinko in cgit_check_cache() would truncate valid cachefiles
in the following situation:
  1) process A notices a missing/expired cachefile
  2) process B gets scheduled, locks, fills and unlocks the cachefile
  3) process A gets scheduled, locks the cachefile, notices that the cachefile
     now exist/is not expired anymore, and continues to overwrite it with an
     empty lockfile.

Thanks to Linus for noticing (again).

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Move global variables + callback functions into shared.c

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Move functions for generic object output into ui-view.c

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Move log-functions into ui-log.c

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Move repo summary functions into ui-summary.c

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Move functions for repolist output into ui-repolist.c

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Move common output-functions into ui-shared.c

While at it, replace the cgit_[lib_]error constants with a proper function

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Rename config.c to parsing.c + move cgit_parse_query from cgit.c to parsing.c

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Avoid infinite loops in caching layer

Add a global variable, cgit_max_lock_attemps, to avoid the possibility of
infinite loops when failing to acquire a lockfile. This could happen on
broken setups or under crazy server load.

Incidentally, this also fixes a lurking bug in cache_lock() where an
uninitialized returnvalue was used.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Let 'make install' clear all cachefiles

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Fix cache algorithm loophole

This closes the door for unneccessary calls to cgit_fill_cache().

Noticed by Linus.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Add version identifier in generated files

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Add license file and copyright notices

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Add caching infrastructure

This enables internal caching of page output.

Page requests are split into four groups:
  1) repo listing (front page)
  2) repo summary
  3) repo pages w/symbolic references in query string
  4) repo pages w/constant sha1's in query string

Each group has a TTL specified in minutes. When a page is requested, a cached
filename is stat(2)'ed and st_mtime is compared to time(2). If TTL has expired
(or the file didn't exist), the cached file is regenerated.

When generating a cached file, locking is used to avoid parallell processing
of the request. If multiple processes tries to aquire the same lock, the ones
who fail to get the lock serves the (expired) cached file. If the cached file
don't exist, the process instead calls sched_yield(2) before restarting the
request processing.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Add .gitignore

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Replace useless make rules with generic $(OBJECTS) dependency

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Import cgit prototype from git tree

This enables basic cgit functionality, using libgit.a and xdiff/lib.a from
git + a custom "git.h" + openssl for sha1 routines.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>