These somehow got missed in my previous constification patches...

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

User @bes-internal reported a Perl module crasher on GitHub.

This was due to a Perl application sending back two responses, for each
response we would call down into XS_NGINX__Unit__Sandbox_cb(), the first
time pctx->req would point to a valid nxt_unit_request_info_t, the
second time pctx->req would be NULL.

Add an invalid responses check which covers this case.

Closes: <https://github.com/nginx/unit/issues/841>
Reviewed-by: Alejandro Colomar <alx@nginx.com>
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

The casts are unnecessary, since memchr(3)'s argument is 'const void *'.
It might have been necessary in the times of K&R, where 'void *' didn't
exist.  Nowadays, it's unnecessary, and _very_ unsafe, since casts can
hide all classes of bugs by silencing most compiler warnings.

The changes from nxt_memchr() to memchr(3) were scripted:

$ find src/ -type f \
  | grep '\.[ch]$' \
  | xargs sed -i 's/nxt_memchr/memchr/'

Reviewed-by: Andrew Clayton <a.clayton@nginx.com>
Signed-off-by: Alejandro Colomar <alx@nginx.com>

This is a preparatory patch that renames the 'local' and 'local_length'
members of the nxt_unit_request_t structure to 'local_addr' and
'local_addr_length' in preparation for the adding of 'local_port' and
'local_port_length' members.

Suggested-by: Zhidao HONG <z.hong@f5.com>
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

Some lines (incorrectly) had an indentation of 3 or 5, or 7 or 9,
or 11 or 13, or 15 or 17 spaces instead of 4, 8, 12, or 16.  Fix them.

Found with:

$ find src -type f | xargs grep -n '^   [^ ]';
$ find src -type f | xargs grep -n '^     [^ *]';
$ find src -type f | xargs grep -n '^       [^ ]';
$ find src -type f | xargs grep -n '^         [^ *]';
$ find src -type f | xargs grep -n '^           [^ +]';
$ find src -type f | xargs grep -n '^             [^ *+]';
$ find src -type f | xargs grep -n '^               [^ +]';
$ find src -type f | xargs grep -n '^                 [^ *+]';

Application handler can do anything with a stream object (including close it).
Once the stream is closed, Unit creates a new stream.

This closes #616 issue on GitHub.

Introducting application graceful stop.  For now only used when application
process reach request limit value.

This closes #585 issue on GitHub.

This closes #486 issue on GitHub.