Re: Problem with git-http-backend.exe as iis cgi

[Konstantin Khomoutov <kostix+git@007spb.ru>]

On Thu, 10 Mar 2016 07:28:50 +0000
Florian Manschwetus <manschwetus@cs-software-gmbh.de> wrote:

> I tried to setup git-http-backend with iis, as iis provides proper
> impersonation for cgi under windows, which leads to have the
> filesystem access performed with the logon user, therefore the
> webserver doesn't need generic access to the files. I stumbled across
> a problem, ending up with post requests hanging forever. After some
> investigation I managed to get it work by wrapping the http-backend
> into a bash script, giving a lot of control about the environmental
> things, I was unable to solve within IIS configuration. The
> workaround, I use currently, is to use "/bin/head -c
> ${CONTENT_LENGTH} | ./git-http-backend.exe", which directly shows the
> issue. Git http-backend should check if CONTENT_LENGTH is set to
> something reasonable (e.g. >0) and should in this case read only
> CONTENT_LENGTH bytes from stdin, instead of reading till EOF what I
> suspect it is doing currently.

The rfc [1] states in its section 4.2:

| A request-body is supplied with the request if the CONTENT_LENGTH is
| not NULL.  The server MUST make at least that many bytes available
| for the script to read.  The server MAY signal an end-of-file
| condition after CONTENT_LENGTH bytes have been read or it MAY supply
| extension data.  Therefore, the script MUST NOT attempt to read more
| than CONTENT_LENGTH bytes, even if more data is available.  However,
| it is not obliged to read any of the data.

So yes, if Git currently reads until EOF, it's an error.
The correct way would be:

1) Check to see if the CONTENT_LENGTH variable is available in the
   environment.  If no, read nothing.

2) Otherwise read as many bytes it specifies, and no more.

1. https://www.ietf.org/rfc/rfc3875