git/Documentation/git-http-backend.txt, branch v2.48.2

documentation: wording improvements

2023-10-09T19:04:21Z

Diff best viewed with --color-diff. Signed-off-by: Elijah Newren Signed-off-by: Junio C Hamano

docs/http-backend: mention v2 protocol

2021-09-10T22:34:59Z

Historically there was a little bit of configuration needed at the webserver level in order to get the client's v2 protocol probes to Git. But when we introduced the v2 protocol, we never documented these. As of the previous commit, this should mostly work out of the box without any explicit configuration. But it's worth documenting this to make it clear how we expect it to work, especially in the face of webservers which don't provide all headers over the CGI interface. Or anybody who runs across this documentation but has an older version of Git (or _used_ to have an older version, and wonders why they still have a SetEnvIf line in their Apache config and whether it's still necessary). Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

Documentation: turn middle-of-line tabs into spaces

2019-03-07T00:25:32Z

These tabs happen to appear in columns where they don't stand out too much, so the diff here is non-obvious. Some of these are rendered differently by AsciiDoc and Asciidoctor (although the difference might be invisible!), which is how I found a few of them. The remainder were found using `git grep "[a-zA-Z.,)]$TAB[a-zA-Z]"`. Signed-off-by: Martin Ågren Signed-off-by: Junio C Hamano

doc: more consistency in environment variables format

2016-06-08T19:04:37Z

Wrap with backticks (monospaced font) unwrapped or single-quotes wrapped (italic type) environment variables which are followed by the word "environment". It was obtained with: perl -pi -e "s/\'?(\\\$?[0-9A-Z\_]+)\'?(?= environment ?)/\`\1\`/g" *.txt One of the main purposes is to stick to the CodingGuidelines as possible so that people writting new documentation by mimicking the existing are more likely to have it right (even if they didn't read the CodingGuidelines). Signed-off-by: Tom Russello Signed-off-by: Erwan Mathoniere Signed-off-by: Samuel Groot Signed-off-by: Matthieu Moy Reviewed-by: Matthieu Moy Signed-off-by: Junio C Hamano

Merge branch 'jk/http-backend-deadlock'

2015-06-01T19:45:09Z

Communication between the HTTP server and http_backend process can lead to a dead-lock when relaying a large ref negotiation request. Diagnose the situation better, and mitigate it by reading such a request first into core (to a reasonable limit). * jk/http-backend-deadlock: http-backend: spool ref negotiation requests to buffer t5551: factor out tag creation http-backend: fix die recursion with custom handler

http-backend: spool ref negotiation requests to buffer

2015-05-26T03:43:18Z

When http-backend spawns "upload-pack" to do ref negotiation, it streams the http request body to upload-pack, who then streams the http response back to the client as it reads. In theory, git can go full-duplex; the client can consume our response while it is still sending the request. In practice, however, HTTP is a half-duplex protocol. Even if our client is ready to read and write simultaneously, we may have other HTTP infrastructure in the way, including the webserver that spawns our CGI, or any intermediate proxies. In at least one documented case[1], this leads to deadlock when trying a fetch over http. What happens is basically: 1. Apache proxies the request to the CGI, http-backend. 2. http-backend gzip-inflates the data and sends the result to upload-pack. 3. upload-pack acts on the data and generates output over the pipe back to Apache. Apache isn't reading because it's busy writing (step 1). This works fine most of the time, because the upload-pack output ends up in a system pipe buffer, and Apache reads it as soon as it finishes writing. But if both the request and the response exceed the system pipe buffer size, then we deadlock (Apache blocks writing to http-backend, http-backend blocks writing to upload-pack, and upload-pack blocks writing to Apache). We need to break the deadlock by spooling either the input or the output. In this case, it's ideal to spool the input, because Apache does not start reading either stdout _or_ stderr until we have consumed all of the input. So until we do so, we cannot even get an error message out to the client. The solution is fairly straight-forward: we read the request body into an in-memory buffer in http-backend, freeing up Apache, and then feed the data ourselves to upload-pack. But there are a few important things to note: 1. We limit the in-memory buffer to prevent an obvious denial-of-service attack. This is a new hard limit on requests, but it's unlikely to come into play. The default value is 10MB, which covers even the ridiculous 100,000-ref negotation in the included test (that actually caps out just over 5MB). But it's configurable on the off chance that you don't mind spending some extra memory to make even ridiculous requests work. 2. We must take care only to buffer when we have to. For pushes, the incoming packfile may be of arbitrary size, and we should connect the input directly to receive-pack. There's no deadlock problem here, though, because we do not produce any output until the whole packfile has been read. For upload-pack's initial ref advertisement, we similarly do not need to buffer. Even though we may generate a lot of output, there is no request body at all (i.e., it is a GET, not a POST). [1] http://article.gmane.org/gmane.comp.version-control.git/269020 Test-adapted-from: Dennis Kaarsemaker Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

doc: put example URLs and emails inside literal backticks

2015-05-13T05:14:46Z

This makes sure that AsciiDoc does not turn them into links. Regular AsciiDoc does not catch these cases, but AsciiDoctor does treat them as links. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

Merge commit 'doc/http-backend: missing accent grave in literal mark-up'

2014-04-09T18:45:04Z

* commit '5df05146d5cb94628a3dfc53063c802ee1152cec': doc/http-backend: missing accent grave in literal mark-up

doc/http-backend: missing accent grave in literal mark-up

2014-04-09T18:43:56Z

Signed-off-by: Thomas Ackermann Signed-off-by: Junio C Hamano

doc: remote author/documentation sections from more pages

2014-01-27T16:34:34Z

We decided at 48bb914e (doc: drop author/documentation sections from most pages, 2011-03-11) to remove "author" and "documentation" sections from our documentation. Remove a few stragglers. Signed-off-by: Michael Haggerty Reviewed-by: Jonathan Nieder Signed-off-by: Junio C Hamano