http_chunk_append_file() opens fd when appending file to chunkqueue.
Defers calculation of content length until response is finished.
This reduces race conditions pertaining to stat() and then (later)
open(), when the result of the stat() was used for Content-Length
or to generate chunked headers.
Note: this does not change how lighttpd handles files that are modified
in-place by another process after having been opened by lighttpd --
don't do that. This *does* improve handling of files that are
frequently modified via a temporary file and then atomically renamed
mod_fastcgi has been modified to use http_chunk_append_file_range() with
X-Sendfile2 and will open the target file multiple times if there are
Note: (future todo) not implemented for chunk.[ch] interfaces used by
range requests in mod_staticfile or by mod_ssi. Those uses could lead
to too many open fds. For mod_staticfile, limits should be put in place
for max number of ranges accepted by mod_staticfile. For mod_ssi,
limits would need to be placed on the maximum number of includes, and
the primary SSI file split across lots of SSI directives should either
copy the pieces or perhaps chunk.h could be extended to allow for an
open fd to be shared across multiple chunks. Doing either of these
would improve the performance of SSI since they would replace many file
opens on the pieces of the SSI file around the SSI directives.
"Serving a file that is getting updated can cause an empty response or incorrect content-length error"
* remove unused structs and functions
* change return type from int to void for many functions,
as the return value (indicating error/success) was never checked,
and the function would only fail on programming errors and not on
invalid input; changed functions to use force_assert instead of
returning an error.
* all "len" parameters now are the real size of the memory to be read.
the length of strings is given always without the terminating 0.
* the "buffer" struct still counts the terminating 0 in ->used,
provide buffer_string_length() to get the length of a string in a
unset config "strings" have used == 0, which is used in some places
to distinguish unset values from "" (empty string) values.
* most buffer usages should now use it as string container.
* optimise some buffer copying by "moving" data to other buffers
* use (u)intmax_t for generic int-to-string functions
* remove unused enum values: UNUSED_CHUNK, ENCODING_UNSET
* converted BUFFER_APPEND_SLASH to inline function (no macro feature
* refactor: create chunkqueue_steal: moving (partial) chunks into another
* http_chunk: added separate function to terminate chunked body instead of
magic handling in http_chunk_append_mem().
http_chunk_append_* now handle empty chunks, and never terminate the
From: Stefan Bühler <firstname.lastname@example.org>
git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2975 152afb58-edef-0310-8abb-c4023f1b3aa9