This resulted in a disclosure of previously freed memory if upstream
server returned specially crafted response, potentially exposing
sensitive information.
Reported by Matthew Daley.
Embedded perl module assumes there is a space for terminating NUL character,
make sure to provide it in all situations by allocating one extra byte for
value buffer. Default ssi_value_length is reduced accordingly to
preserve 256 byte allocations.
While here, fixed another one byte value buffer overrun possible in
ssi_quoted_symbol_state.
Reported by Matthew Daley.
It wasn't enforced for a long time, and there are reports that people
use up to 100 simultaneous subrequests now. As this is a safety limit
to prevent loops, it's raised accordingly.
ZFS reports incorrect st_blocks until file settles on disk, and this
may take a while (i.e. just after creation of a file the st_blocks value
is incorrect). As a workaround we now use st_blocks only if
st_blocks * 512 > st_size, this should fix ZFS problems while still
preserving accuracy for other filesystems.
The problem had appeared in r3900 (1.0.1).
Previous code incorrectly assumed that nodes with identical keys are linked
together. This might not be true after tree rebalance.
Patch by Lanshun Zhou.
The cycle->new_log.file may not be set before config parsing finished if
there are no error_log directive defined at global level. Fix is to
copy it after config parsing.
Patch by Roman Arutyunyan.
With previous code raw buffer might be lost if p->input_filter() was called
on a buffer without any data and used ngx_event_pipe_add_free_buf() to
return it to the free list. This eventually might cause "all buffers busy"
problem, resulting in segmentation fault due to null pointer dereference in
ngx_event_pipe_write_chain_to_temp_file().
In ngx_event_pipe_add_free_buf() the buffer was added to the list start
due to pos == last, and then "p->free_raw_bufs = cl->next" in
ngx_event_pipe_read_upstream() dropped both chain links to the buffer
from the p->free_raw_bufs list.
Fix is to move "p->free_raw_bufs = cl->next" before calling the
p->input_filter().
the last path component if "if_not_owner" parameter is used.
To prevent race condition we have to open a file before checking its owner and
there's no way to change access flags for already opened file descriptor, so
we disable symlinks for the last path component at all if flags allow creating
or truncating the file.
Solaris has AT_FDCWD defined to unsigned value, and comparison of a file
descriptor with it causes warnings in modern versions of gcc. Explicitly
cast AT_FDCWD to ngx_fd_t to resolve these warnings.
To completely disable symlinks (disable_symlinks on)
we use openat(O_NOFOLLOW) for each path component
to avoid races.
To allow symlinks with the same owner (disable_symlinks if_not_owner),
use openat() (followed by fstat()) and fstatat(AT_SYMLINK_NOFOLLOW),
and then compare uids between fstat() and fstatat().
As there is a race between openat() and fstatat() we don't
know if openat() in fact opened symlink or not. Therefore,
we have to compare uids even if fstatat() reports the opened
component isn't a symlink (as we don't know whether it was
symlink during openat() or not).
Default value is off, i.e. symlinks are allowed.
Nuke NGX_PARSE_LARGE_TIME, it's not used since 0.6.30. The only error
ngx_parse_time() can currently return is NGX_ERROR, check it explicitly
and make sure to cast it to appropriate type (either time_t or ngx_msec_t)
to avoid signedness warnings on platforms with unsigned time_t (notably QNX).
Now redirects to named locations are counted against normal uri changes
limit, and post_action respects this limit as well. As a result at least
the following (bad) configurations no longer trigger infinite cycles:
1. Post action which recursively triggers post action:
location / {
post_action /index.html;
}
2. Post action pointing to nonexistent named location:
location / {
post_action @nonexistent;
}
3. Recursive error page for 500 (Internal Server Error) pointing to
a nonexistent named location:
location / {
recursive_error_pages on;
error_page 500 @nonexistent;
return 500;
}
Without the protection, subrequest loop results in r->count overflow and
SIGSEGV. Protection was broken in 0.7.25.
Note that this also limits number of parallel subrequests. This
wasn't exactly the case before 0.7.25 as local subrequests were
completed directly.
See here for details:
http://nginx.org/pipermail/nginx-ru/2010-February/032184.html
Variables with the "not_found" flag set follow the same rules as ones with
the "valid" flag set. Make sure ngx_http_get_flushed_variable() will flush
non-cacheable variables with the "not_found" flag set.
This fixes at least one known problem with $args not available in a subrequest
(with args) when there were no args in the main request and $args variable was
queried in the main request (reported by Laurence Rowe aka elro on irc).
Also this eliminates unneeded call to ngx_http_get_indexed_variable() in
cacheable case (as it will return cached value anyway).
Temporary files might not be removed if the "proxy_store" or "fastcgi_store"
directives were used for subrequests (e.g. ssi includes) and client closed
connection prematurely.
Non-active subrequests are finalized out of the control of the upstream
module when client closes a connection. As a result, the code to remove
unfinished temporary files in ngx_http_upstream_process_request() wasn't
executed.
Fix is to move relevant code into ngx_http_upstream_finalize_request() which
is called in all cases, either directly or via the cleanup handler.
Empty flush buffers are legitimate and may happen e.g. due to $r->flush()
calls in embedded perl. If there are no data buffered in zlib, deflate()
will return Z_BUF_ERROR (i.e. no progress possible) without adding anything
to output. Don't treat Z_BUF_ERROR as fatal and correctly send empty flush
buffer if we have no data in output at all.
See this thread for details:
http://mailman.nginx.org/pipermail/nginx/2010-November/023693.html
If header filter postponed processing of a header by returning NGX_AGAIN
and not moved u->buffer->pos, previous check incorrectly assumed there
is additional space and did another recv() with zero-size buffer. This
resulted in "upstream prematurely closed connection" error instead
of correct "upstream sent too big header" one.
Patch by Feibo Li.
the way.
It was unintentionally changed in r4272, so that it could only limit the first
location where the processing of the request has reached PREACCESS phase.
The PCRE JIT compiler uses mmap to allocate memory for its executable codes, so
we have to explicitly call the pcre_free_study() function to free this memory.
Example configuration to reproduce:
server {
proxy_redirect off;
location / {
proxy_pass http://localhost:8000;
proxy_redirect http://localhost:8000/ /;
location ~ \.php$ {
proxy_pass http://localhost:8000;
# proxy_redirect must be inherited from the level above,
# but instead it was switched off here
}
}
}
Previously if ngx_add_event() failed a connection was freed two times (once
in the ngx_event_connect_peer(), and again by a caller) as pc->connection was
left set. Fix is to always use ngx_close_connection() to close connection
properly and set pc->connection to NULL on errors.
Patch by Piotr Sikora.
Doing a cleanup before every lookup seems to be too aggressive. It can lead to
premature removal of the nodes still usable, which increases the amount of work
under a mutex lock and therefore decreases performance.
In order to improve cleanup behavior, cleanup function call has been moved right
before the allocation of a new node.
"limit_req_zone" directive; minimum size of zone is increased.
Previously an unsigned variable was used to keep the return value of
ngx_parse_size() function, which led to an incorrect zone size if NGX_ERROR
was returned.
The new code has been taken from the "limit_conn_zone" directive.
The aio_return() must be called regardless of the error returned by
aio_error(). Not calling it resulted in various problems up to segmentation
faults (as AIO events are level-triggered and were reported again and again).
Additionally, in "aio sendfile" case r->blocked was incremented in case of
error returned from ngx_file_aio_read(), thus causing request hangs.
It's already called by OPENSSL_config(). Calling it again causes some
openssl engines (notably GOST) to corrupt memory, as they don't expect
to be created more than once.
The ngx_hash_init() function did not expect call with zero elements count,
which caused FPE error on configs with an empty "types" block in http context
and "types_hash_max_size" > 10000.
Example configuration to reproduce:
events { }
http {
types_hash_max_size 10001;
types {}
server {}
}
Second argument (cpusetsize) is size in bytes, not in bits. Previously
used constant 32 resulted in reading of uninitialized memory and caused
EINVAL to be returned on some Linux kernels.
Support for TLSv1.1 and TLSv1.2 protocols was introduced in OpenSSL 1.0.1
(-beta1 was recently released). This change makes it possible to disable
these protocols and/or enable them without other protocols.
The problem was localized in ngx_http_proxy_rewrite_redirect_regex() handler
function which did not take into account prefix when overwriting header value.
New directives: proxy_cache_lock on/off, proxy_cache_lock_timeout. With
proxy_cache_lock set to on, only one request will be allowed to go to
upstream for a particular cache item. Others will wait for a response
to appear in cache (or cache lock released) up to proxy_cache_lock_timeout.
Waiting requests will recheck if they have cached response ready (or are
allowed to run) every 500ms.
Note: we intentionally don't intercept NGX_DECLINED possibly returned by
ngx_http_file_cache_read(). This needs more work (possibly safe, but needs
further investigation). Anyway, it's exceptional situation.
Note: probably there should be a way to disable caching of responses
if there is already one request fetching resource to cache (without waiting
at all). Two possible ways include another cache lock option ("no_cache")
or using proxy_no_cache with some supplied variable.
Note: probably there should be a way to lock updating requests as well. For
now "proxy_cache_use_stale updating" is available.
It's possible that configured limit_rate will permit more bytes per
single operation than sendfile_max_chunk. To protect disk from takeover
by a single client it is necessary to apply sendfile_max_chunk as a limit
regardless of configured limit_rate.
See here for report (in Russian):
http://mailman.nginx.org/pipermail/nginx-ru/2010-March/032806.html
If proxy_pass was used with variables and there was no URI component,
nginx always used unparsed URI. This isn't consistent with "no variables"
case, where e.g. rewrites are applied even if there is no URI component.
Fix is to use the same logic in both cases, i.e. only use unparsed URI if
it's valid and request is the main one.
This resolves issue with try_files (see ticket #70), configuration like
location / { try_files $uri /index.php; }
location /index.php { proxy_pass http://backend; }
caused nginx to use original request uri in a request to a backend.
Historically, not clearing of the r->valid_unparsed_uri on internal redirect
was a feature: it allowed to pass the same request to (another) upstream
server via error_page redirection. Since then named locations appeared
though, and it's time to start resetting r->valid_unparsed_uri on internal
redirects. Configurations still using this feature should be converted
to use named locations instead.
Patch by Lanshun Zhou.
The SCGI specification doesn't specify format of the response, and assuming
CGI specs should be used there is no reason to complain. RFC 3875
explicitly states that "A Status header field is optional, and status
200 'OK' is assumed if it is omitted".
The r->http_version is a version of client's request, and modules must
not set it unless they are really willing to downgrade protocol version
used for a response (i.e. to HTTP/0.9 if no response headers are available).
In neither case r->http_version may be upgraded.
The former code downgraded response from HTTP/1.1 to HTTP/1.0 for no reason,
causing various problems (see ticket #66). It was also possible that
HTTP/0.9 requests were upgraded to HTTP/1.0.
There have been multiple reports of cases where a real locked entry was
removed, resulting in a segmentation fault later in a worker which locked
the entry. It looks like default inactive timeout isn't enough in real
life.
For now just ignore such locked entries, and move them to the top of the
inactive queue to allow processing of other entries.
There are two possible situations which can lead to this: response was
cached with bigger proxy_buffer_size value (and nginx was restared since
then, i.e. shared memory zone content was lost), or due to the race in
the cache update code (see [1]) we've end up with fcn->body_start from
a different response stored in shared memory zone.
[1] http://mailman.nginx.org/pipermail/nginx-devel/2011-September/001287.html
The ngx_http_cache() and ngx_http_no_cache_set_slot() functions were replaced
by ngx_http_test_predicates() and ngx_http_set_predicate_slot() in 0.8.46 and
no longer used since then.
FreeBSD kernel checks headers/trailers pointer against NULL, not
corresponding count. Passing NULL if there are no headers/trailers
helps to avoid unneeded work in kernel, as well as unexpected 0 bytes
GIO in traces.
haven't been sent to a client.
The ngx_http_variable_headers() and ngx_http_variable_unknown_header() functions
did not ignore response header entries with zero "hash" field.
Thanks to Yichun Zhang (agentzh).
It was working for nginx's own 206 replies as they are seen as 200 in the
headers filter module (range filter goes later in the headers filter chain),
but not for proxied replies.
Additional parsing logic added to correctly handle RFC 3986 compliant IPv6 and
IPvFuture characters enclosed in square brackets.
The host validation was completely rewritten. The behavior for non IP literals
was changed in a more proper and safer way:
- Host part is now delimited either by the first colon or by the end of string
if there's no colon. Previously the last colon was used as delimiter which
allowed substitution of a port number in the $host variable.
(e.g. Host: 127.0.0.1:9000:80)
- Fixed stripping of the ending dot in the Host header when the host was also
followed by a port number.
(e.g. Host: nginx.com.:80)
- Fixed upper case characters detection. Previously it was broken which led to
wasting memory and CPU.
If process exited abnormally while holding lock on some shared memory zone -
unlock it. It may be not safe thing to do (as crash with lock held may
result in corrupted shared memory structure, and other processes will
subsequently crash while trying to access shared data), therefore complain
loudly if unlock succeeds.
It is currently used from master process on abnormal worker termination to
unlock accept mutex (unlocking of accept mutex was broken in 1.0.2). It is
expected to be used in the future to unlock other mutexes as well.
Shared mutex code was rewritten to make this possible in a safe way, i.e.
with a check if lock was actually held by the exited process. We again use
pid to lock mutex, and use separate atomic variable for a count of processes
waiting in sem_wait().
Stale write event may happen if epoll_wait() reported both read and write
events, and processing of the read event closed descriptor.
Patch by Yichun Zhang (agentzh).
Check if received data length match Content-Length header (if present),
don't cache response if no match found. This prevents caching of corrupted
response in case of premature connection close by upstream.
Used "\x5" in 5th byte to claim presence of both audio and video. Used
previous tag size 0 in the beginning of the flv body (bytes 10 .. 13) as
required by specification (see http://www.adobe.com/devnet/f4v.html).
Patch by Piotr Sikora.
Previously it used a hardcoded value of 300 seconds. Also added the
"valid=" parameter to the "resolver" directive that can be used to
override the cache validity time.
Patch by Kirill A. Korinskiy with minor changes.
The following problems were fixed:
1. Directive fastcgi_cache affected headers sent to backends in unrelated
servers / locations (see ticket #45).
2. If-Unmodified-Since, If-Match and If-Range headers were sent to backends
if fastcgi_cache was used.
3. Cache-related headers were sent to backends if there were no fastcgi_param
directives and fastcgi_cache was used at server level.
Headers cleared with cache enabled (If-Modified-Since etc.) might be cleared
in unrelated servers/locations without proxy_cache enabled if proxy_cache was
used in some server/location.
Example config which triggered the problem:
proxy_set_header X-Test "test";
server { location /1 { proxy_cache name; proxy_pass ... } }
server { location /2 { proxy_pass ... } }
Another one:
server {
proxy_cache name;
location /1 { proxy_pass ... }
location /2 { proxy_cache off; proxy_pass ... }
}
In both cases If-Modified-Since header wasn't sent to backend in location /2.
Fix is to not modify conf->headers_source, but instead merge user-supplied
headers from conf->headers_source and default headers (either cache or not)
into separate headers_merged array.
The following config caused segmentation fault due to conf->file not
being properly set if "ssl on" was inherited from the http level:
http {
ssl on;
server {
}
}
If possible we now just extend already present file buffer in p->out chain
instead of keeping ngx_buf_t for each buffer we've flushed to disk. This
saves about 120 bytes of memory per buffer flushed to disk, and resolves
high CPU usage observed in edge cases (due to coalescing these buffers on
send).
1. In ngx_event_pipe_write_chain_to_temp_file() make sure to fully write
all shadow buffers up to last_shadow. With this change recycled buffers
cannot appear in p->out anymore. This also fixes segmentation faults
observed due to ngx_event_pipe_write_chain_to_temp() not freeing any
raw buffers while still returning NGX_OK.
2. In ngx_event_pipe_write_to_downstream() we now properly check for busy
size as a size of buffers, not a size of data in these buffers. This
fixes situations where all available buffers became busy (including
segmentation faults due to this).
3. The ngx_event_pipe_free_shadow_raw_buf() function is dropped. It's
incorrect and not needed.
Previously result of last iteration's writev() was returned. This was
unnoticed as return value was only used if chain contained only one or
two buffers.
Previously nginx used to mark backend again as live as soon as fail_timeout
passes (10s by default) since last failure. On the other hand, detecting
dead backend takes up to 60s (proxy_connect_timeout) in typical situation
"backend is down and doesn't respond to any packets". This resulted in
suboptimal behaviour in the above situation (up to 23% of requests were
directed to dead backend with default settings).
More detailed description of the problem may be found here (in Russian):
http://mailman.nginx.org/pipermail/nginx-ru/2011-August/042172.html
Fix is to only allow one request after fail_timeout passes, and
mark backend as "live" only if this request succeeds.
Note that with new code backend will not be marked "live" unless "check"
request is completed, and this may take a while in some specific workloads
(e.g. streaming). This is believed to be acceptable.
Second aio post happened when timer set by limit_rate expired while we have
aio request in flight, resulting in "second aio post" alert and socket leak.
The patch adds actual protection from aio calls with r->aio already set to
aio sendfile code in ngx_http_copy_filter(). This should fix other cases
as well, e.g. when sending buffered to disk upstream replies while still
talking to upstream.
The ngx_http_writer() is also fixed to handle the above case (though it's
mostly optimization now).
Reported by Oleksandr V. Typlyns'kyi.
For files with '?' in their names autoindex generated links with '?' not
escaped. This resulted in effectively truncated links as '?' indicates
query string start.
This is an updated version of the patch originally posted at [1]. It
introduces generic NGX_ESCAPE_URI_COMPONENT which escapes everything but
unreserved characters as per RFC 3986. This approach also renders unneeded
special colon processing (as colon is percent-encoded now), it's dropped
accordingly.
[1] http://nginx.org/pipermail/nginx-devel/2010-February/000112.html
Reported by Konstantin Leonov.
If cache was bypassed with proxy_cache_bypass, cache-controlling headers
(Cache-Control, Expires) wasn't considered and response was cached even
if it was actually non-cacheable.
Patch by John Ferlito.
Configuration with duplicate upstream blocks defined after first use, i.e.
like
server {
...
location / {
proxy_pass http://backend;
}
}
upstream backend { ... }
upstream backend { ... }
now correctly results in "duplicate upstream" error.
Additionally, upstream blocks defined after first use now handle various
server directive parameters ("weight", "max_fails", etc.). Previously
configuration like
server {
...
location / {
proxy_pass http://backend;
}
}
upstream backend {
server 127.0.0.1 max_fails=5;
}
incorrectly resulted in "invalid parameter "max_fails=5"" error.
For normal cached responses ngx_http_cache_send() sends last buffer and then
request finalized via ngx_http_finalize_request() call, i.e. everything is
ok.
But for stale responses (i.e. when upstream died, but we have something in
cache) the same ngx_http_cache_send() sends last buffer, but then in
ngx_http_upstream_finalize_request() another last buffer is send. This
causes duplicate final chunk to appear if chunked encoding is used (and
resulting problems with keepalive connections and so on).
Fix this by not sending in ngx_http_upstream_finalize_request()
another last buffer if we know response was from cache.
The special case in question leads to replies without body in
configuration like
location / { error_page 404 /zero; return 404; }
location /zero { return 204; }
while replies with empty body are expected per protocol specs.
Correct one will look like
if (status == NGX_HTTP_NO_CONTENT) {
rc = ngx_http_send_header(r);
if (rc == NGX_ERROR || r->header_only) {
return rc;
}
return ngx_http_send_special(r, NGX_HTTP_LAST);
}
though it looks like it's better to drop this special case at all.
Big POST (not fully preread) to a
location / {
return 202;
}
resulted in incorrect behaviour due to "return" code path not calling
ngx_http_discard_request_body(). The same applies to all "return" used
with 2xx/3xx codes except 201 and 204, and to all "return ... text" uses.
Fix is to add ngx_http_discard_request_body() call to ngx_http_send_response()
function where it looks appropriate. Discard body call from emtpy gif module
removed as it's now redundant.
Reported by Pyry Hakulinen, see
http://mailman.nginx.org/pipermail/nginx/2011-August/028503.html
Test case:
location / {
error_page 405 /nope;
return 405;
}
location /nope {
return 200;
}
This is expected to return 405 with empty body, but in 0.8.42+ will return
builtin 405 error page as well (though not counted in Content-Length, thus
breaking protocol).
Fix is to use status provided by rewrite script execution in case
it's less than NGX_HTTP_BAD_REQUEST even if r->error_status set. This
check is in line with one in ngx_http_script_return_code().
Note that this patch also changes behaviour for "return 302 ..." and
"rewrite ... redirect" used as error handler. E.g.
location / {
error_page 405 /redirect;
return 405;
}
location /redirect {
rewrite ^ http://example.com/;
}
will actually return redirect to "http://example.com/" instead of builtin 405
error page with meaningless Location header. This looks like correct change
and it's in line with what happens on e.g. directory redirects in error
handlers.
Replies with 201 code contain body, and we should clearly indicate it's
empty if it's empty. Before 0.8.32 chunked was explicitly disabled for
201 replies and as a result empty body was indicated by connection close
(not perfect, but worked). Since 0.8.32 chunked is enabled, and this
causes incorrect responses from dav module when HTTP/1.1 is used: with
"Transfer-Encoding: chunked" but no chunks at all.
Fix is to actually return empty body in special response handler instead
of abusing r->header_only flag.
See here for initial report:
http://mailman.nginx.org/pipermail/nginx-ru/2010-October/037535.html
This fixes crashes observed with some 3rd party balancer modules. Standard
balancer modules (round-robin and ip hash) explicitly set pc->connection
(aka u->peer.connection) to NULL and aren't affected.
If client closed connection in ngx_event_pipe_write_to_downstream(), buffers
in the "out" chain were lost. This caused cpu hog if all available buffers
were in the "out" chain. Fix is to call ngx_chain_update_chains() before
checking return code of output filter to avoid loosing buffers in the "out"
chain.
Note that this situation (all available buffers in the "out" chain) isn't
normal, it should be prevented by busy buffers limit. Though right now it
may happen with complex protocols like fastcgi. This should be addressed
separately.
The default value is 32 AIO simultaneous requests per worker. Previously
they were hardcoded to 1024, and it was too large, since Linux allocated
them early on io_setup(), but not on request itself. So with default value
of /proc/sys/fs/aio-max-nr equal to 65536 only 64 worker processes could
be run simultaneously. 32 AIO requests are enough for modern disks even if
server runs only 1 worker.
and "chunked_transfer_encoding" directives, to be in line with all
directives taking a boolean argument. Both flags will ensure that
a directive takes one argument.
syscall(2) uses usual libc convention, it returns -1 on error and
sets errno. Obsolete _syscall(2) returns negative value of error.
Thanks to Hagai Avrahami.
By default follow the old behaviour, i.e. FASTCGI_KEEP_CONN flag isn't set
in request and application is responsible for closing connection once request
is done. To keep connections alive fastcgi_keep_conn must be activated.
As long as ngx_event_pipe() has more data read from upstream than specified
in p->length it's passed to input filter even if buffer isn't yet full. This
allows to process data with known length without relying on connection close
to signal data end.
By default p->length is set to -1 in upstream module, i.e. end of data is
indicated by connection close. To set it from per-protocol handlers upstream
input_filter_init() now called in buffered mode (as well as in
unbuffered mode).
Previous use of size_t may cause wierd effects on 32bit platforms with certain
big responses transferred in unbuffered mode.
Nuke "if (size > u->length)" check as it's not usefull anyway (preread
body data isn't subject to this check) and now requires additional check
for u->length being positive.
We no longer use r->headers_out.content_length_n as a primary source of
backend's response length. Instead we parse response length to
u->headers_in.content_length_n and copy to r->headers_out.content_length_n
when needed.
Just doing another connect isn't safe as peer.get() may expect peer.tries
to be strictly positive (this is the case e.g. with round robin with multiple
upstream servers). Increment peer.tries to at least avoid cpu hog in
round robin balancer (with the patch alert will be seen instead).
This is not enough to fully address the problem though, hence TODO. We
should be able to inform balancer that the error wasn't considered fatal
and it may make sense to retry the same peer.
The ngx_chain_update_chains() needs pool to free chain links used for buffers
with non-matching tags. Providing one helps to reduce memory consumption
for long-lived requests.
There were 2 buffers allocated on each buffer chain sent through chunked
filter (one buffer for chunk size, another one for trailing CRLF, about
120 bytes in total on 32-bit platforms). This resulted in large memory
consumption with long-lived requests sending many buffer chains. Usual
example of problematic scenario is streaming though proxy with
proxy_buffering set to off.
Introduced buffers reuse reduces memory consumption in the above problematic
scenario.
See here for initial report:
http://mailman.nginx.org/pipermail/nginx/2010-April/019814.html
If file inode was not changed, cached file information was not updated
on retest. As a result stale information might be cached forever if file
attributes was changed and/or file was extended.
This fix also makes obsolete r4077 change of is_directio flag handling,
since this flag is updated together with other file information.
