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John Keeping 2efb59ed0f ui-patch: Flush stdout after outputting data
It looks like cached patches are truncated to the nearest 1024-byte
boundary in the patch body. E.g.:

> mricon@nikko:[/tmp]$ wget -O no-cache
> "http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/patch/?id=6e1b4fdad5157bb9e88777d525704aba24389bee"
...
> 2014-06-11 15:34:51 (80.4 MB/s) - ‘no-cache’ saved [4767]

Patch is complete, without truncation. Next hit, with cache in place:

> mricon@nikko:[/tmp]$ wget -O yes-cache
> "http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/patch/?id=6e1b4
> fdad5157bb9e88777d525704aba24389bee"
...
> 2014-06-11 15:35:01 (17.0 MB/s) - ‘yes-cache’ saved [4096/4096]

Length truncated to 4096. The cache on disk looks truncated as well, so
the bug must me during the process of saving cache. The same is true for
larger patches:

> mricon@nikko:[/tmp]$ wget -O no-cache
> "http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/patch/?id=2840c566e95599cd60c7143762ca8b49d9395050"
...
> 2014-06-11 15:41:33 (1.07 MB/s) - ‘no-cache’ saved [979644]

979644 bytes with a cache-miss

> mricon@nikko:[/tmp]$ wget -O yes-cache
> "http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/patch/?id=2840c
> 566e95599cd60c7143762ca8b49d9395050"
...
> 2014-06-11 15:41:46 (1.05 MB/s) - ‘yes-cache’ saved [978944]

978944 (956KB exactly) with a cache-hit

Since the "html" functions use raw write(2) to STDIO_FILENO, we don't
notice problems with most pages, but raw patches write using printf(3).
This is fine if we're outputting straight to stdout since the buffers
are flushed on exit, but we close the cache output before this, so the
cached output ends up being truncated.

Make sure the buffers are flushed when we finish outputting a patch so
that we avoid this.

No other UIs use printf(3) so we do not need to worry about them.

Actually, it's slightly more interesting than this... since we don't set
GIT_FLUSH, Git decides whether or not it will flush stdout after writing
each commit based on whether or not stdout points to a regular file (in
maybe_flush_or_die()).

Which means that when writing directly to the webserver, Git flushes
stdout for us, but when we redirect stdout to the cache it points to a
regular file so Git no longer flushes the output for us.

The patch is still correct, but perhaps the full explanation is
interesting!

Reported-by: Konstantin Ryabitsev <mricon@kernel.org>
2014-06-28 15:59:15 +02:00
filters remove trailing whitespaces from source files 2014-04-17 12:55:09 +02:00
git@e156455ea4 git: update for git 2.0 2014-06-28 15:14:56 +02:00
tests tests: only do lua tests if lua is compiled-in 2014-01-20 13:11:10 +01:00
.gitignore tests/.gitignore: update for using Git's test infrastructure 2013-04-08 22:27:53 +02:00
.gitmodules Delete submodules.sh and prepare for using git-submodule 2007-09-03 22:54:51 +02:00
.mailmap mailmap: source before lighttpd 2014-01-17 16:04:27 +01:00
AUTHORS authors: specify maintainers 2014-01-14 02:00:07 +01:00
cache.c Skip cache slot when time-to-live is zero 2014-02-21 01:19:45 +01:00
cache.h Switch to exclusively using global ctx 2014-01-17 00:44:54 +01:00
cgit-doc.css Add cgit-doc.css 2009-02-12 10:24:25 +01:00
cgit.c git: update for git 2.0 2014-06-28 15:14:56 +02:00
cgit.css Reduce line number bloat, fix hover effect 2014-01-08 14:59:38 +01:00
cgit.h Add a cache-snapshot-ttl configuration variable 2014-02-20 19:56:44 +01:00
cgit.mk Makefile: suppress pkg-config error 2014-02-20 20:06:29 +01:00
cgit.png Use transparent background for the cgit logo 2011-02-19 14:41:39 +01:00
cgitrc.5.txt remove trailing whitespaces from source files 2014-04-17 12:55:09 +02:00
cmd.c Remove unused parameter from cgit_print_snapshot() 2014-02-21 18:19:00 +01:00
cmd.h Switch to exclusively using global ctx 2014-01-17 00:44:54 +01:00
configfile.c Update copyright information 2014-01-08 15:10:49 +01:00
configfile.h Use strbuf for reading configuration files 2013-08-12 13:14:10 -06:00
COPYING Add license file and copyright notices 2006-12-10 22:41:14 +01:00
favicon.ico Add favicon 2013-05-31 02:52:24 +02:00
filter.c remove trailing whitespaces from source files 2014-04-17 12:55:09 +02:00
gen-version.sh gen-version.sh: check if git is available before trying to call it 2014-02-05 15:09:15 +01:00
html.c html: remove redundant htmlfd variable 2014-01-12 20:15:55 +01:00
html.h html.c: add various strbuf and varadic helpers 2013-04-08 16:10:11 +02:00
Makefile git: update for git 2.0 2014-06-28 15:14:56 +02:00
parsing.c git: update for git 2.0 2014-06-28 15:14:56 +02:00
README remove trailing whitespaces from source files 2014-04-17 12:55:09 +02:00
robots.txt robots.txt: disallow access to snapshots 2013-08-12 13:14:10 -06:00
scan-tree.c git: update for git 2.0 2014-06-28 15:14:56 +02:00
scan-tree.h Add support for 'project-list' option 2010-08-04 03:09:32 +02:00
shared.c diffstat: do not rely on uninitialized data 2014-02-20 19:48:24 +01:00
ui-atom.c Switch to exclusively using global ctx 2014-01-17 00:44:54 +01:00
ui-atom.h Add atom-support 2008-08-01 22:12:34 +02:00
ui-blob.c remove trailing whitespaces from source files 2014-04-17 12:55:09 +02:00
ui-blob.h readme: use string_list instead of space deliminations 2013-05-26 16:30:03 +02:00
ui-clone.c git: update for git 2.0 2014-06-28 15:14:56 +02:00
ui-clone.h Switch to exclusively using global ctx 2014-01-17 00:44:54 +01:00
ui-commit.c filter: add page source to email filter 2014-01-14 02:00:07 +01:00
ui-commit.h ui-commit: Limit diff based on path limit in qry.path 2010-06-19 10:40:23 +02:00
ui-diff.c Switch to exclusively using global ctx 2014-01-17 00:44:54 +01:00
ui-diff.h Allow for creating raw diffs with cgit_print_diff() 2013-08-16 13:15:37 -06:00
ui-log.c ui-log: ignore unhandled arguments 2014-06-28 15:57:02 +02:00
ui-log.h ui-log: Add "commit-sort" option for controlling commit ordering 2012-10-17 16:30:29 +02:00
ui-patch.c ui-patch: Flush stdout after outputting data 2014-06-28 15:59:15 +02:00
ui-patch.h ui-patch: Rename variables 2013-08-20 19:55:54 +02:00
ui-plain.c Switch to exclusively using global ctx 2014-01-17 00:44:54 +01:00
ui-plain.h Switch to exclusively using global ctx 2014-01-17 00:44:54 +01:00
ui-refs.c git: update for git 2.0 2014-06-28 15:14:56 +02:00
ui-refs.h Add separate header-files for each page/view 2008-03-24 16:38:47 +01:00
ui-repolist.c git: update for git 2.0 2014-06-28 15:14:56 +02:00
ui-repolist.h Prepare for 'about site' page / add 'root-readme' option to cgitrc 2008-04-29 01:06:30 +02:00
ui-shared.c git: update for git 2.0 2014-06-28 15:14:56 +02:00
ui-shared.h Switch to exclusively using global ctx 2014-01-17 00:44:54 +01:00
ui-snapshot.c git: update for git 2.0 2014-06-28 15:14:56 +02:00
ui-snapshot.h Remove unused parameter from cgit_print_snapshot() 2014-02-21 18:19:00 +01:00
ui-ssdiff.c Reduce line number bloat, fix hover effect 2014-01-08 14:59:38 +01:00
ui-ssdiff.h ui-ssdiff: move LCS table away from the stack 2012-01-03 15:16:01 +00:00
ui-stats.c Switch to exclusively using global ctx 2014-01-17 00:44:54 +01:00
ui-stats.h Switch to exclusively using global ctx 2014-01-17 00:44:54 +01:00
ui-summary.c git: update for git 2.0 2014-06-28 15:14:56 +02:00
ui-summary.h readme: use string_list instead of space deliminations 2013-05-26 16:30:03 +02:00
ui-tag.c filter: add page source to email filter 2014-01-14 02:00:07 +01:00
ui-tag.h Add separate header-files for each page/view 2008-03-24 16:38:47 +01:00
ui-tree.c filter: pass extra arguments via cgit_open_filter 2014-01-12 20:20:20 +01:00
ui-tree.h Add separate header-files for each page/view 2008-03-24 16:38:47 +01:00

cgit - CGI for Git
==================

This is an attempt to create a fast web interface for the Git SCM, using a
built-in cache to decrease server I/O pressure.

Installation
------------

Building cgit involves building a proper version of Git. How to do this
depends on how you obtained the cgit sources:

a) If you're working in a cloned cgit repository, you first need to
initialize and update the Git submodule:

    $ git submodule init     # register the Git submodule in .git/config
    $ $EDITOR .git/config    # if you want to specify a different url for git
    $ git submodule update   # clone/fetch and checkout correct git version

b) If you're building from a cgit tarball, you can download a proper git
version like this:

    $ make get-git

When either a) or b) has been performed, you can build and install cgit like
this:

    $ make
    $ sudo make install

This will install `cgit.cgi` and `cgit.css` into `/var/www/htdocs/cgit`. You
can configure this location (and a few other things) by providing a `cgit.conf`
file (see the Makefile for details).

If you'd like to compile without Lua support, you may use:

    $ make NO_LUA=1

And if you'd like to specify a Lua implementation, you may use:

    $ make LUA_PKGCONFIG=lua5.1

If this is not specified, the Lua implementation will be auto-detected,
preferring LuaJIT if many are present. Acceptable values are generally "lua",
"luajit", "lua5.1", and "lua5.2".


Dependencies
------------

* libzip
* libcrypto (OpenSSL)
* libssl (OpenSSL)
* optional: luajit or lua, most reliably used when pkg-config is available

Apache configuration
--------------------

A new `Directory` section must probably be added for cgit, possibly something
like this:

    <Directory "/var/www/htdocs/cgit/">
        AllowOverride None
        Options +ExecCGI
        Order allow,deny
        Allow from all
    </Directory>


Runtime configuration
---------------------

The file `/etc/cgitrc` is read by cgit before handling a request. In addition
to runtime parameters, this file may also contain a list of repositories
displayed by cgit (see `cgitrc.5.txt` for further details).

The cache
---------

When cgit is invoked it looks for a cache file matching the request and
returns it to the client. If no such cache file exists (or if it has expired),
the content for the request is written into the proper cache file before the
file is returned.

If the cache file has expired but cgit is unable to obtain a lock for it, the
stale cache file is returned to the client. This is done to favour page
throughput over page freshness.

The generated content contains the complete response to the client, including
the HTTP headers `Modified` and `Expires`.

Online presence
---------------

* The cgit homepage is hosted by cgit at <http://git.zx2c4.com/cgit/about/>

* Patches, bug reports, discussions and support should go to the cgit
  mailing list: <cgit@lists.zx2c4.com>. To sign up, visit
  <http://lists.zx2c4.com/mailman/listinfo/cgit>