Most OS platforms have already provided solutions to
Y2038 32-bit signed time_t 5 - 10 years ago (or more!)
Notable exceptions are Linux i686 and FreeBSD i386.
Since 32-bit systems tend to be embedded systems,
and since many distros take years to pick up new software,
this commit aims to provide Y2038 mitigations for lighttpd
running on 32-bit systems with Y2038-unsafe 32-bit signed time_t
* Y2038: lighttpd 1.4.60 and later report Y2038 safety
$ lighttpd -V
+ Y2038 support # Y2038-SAFE
$ lighttpd -V
- Y2038 support (unsafe 32-bit signed time_t) # Y2038-UNSAFE
* Y2038: general platform info
* Y2038-SAFE: lighttpd 64-bit builds on platforms using 64-bit time_t
- all major 64-bit platforms (known to this author) use 64-bit time_t
* Y2038-SAFE: lighttpd 32-bit builds on platforms using 64-bit time_t
- Linux x32 ABI (different from i686)
- FreeBSD all 32-bit and 64-bit architectures *except* 32-bit i386
- NetBSD 6.0 (released Oct 2012) all 32-bit and 64-bit architectures
- OpenBSD 5.5 (released May 2014) all 32-bit and 64-bit architectures
- Microsoft Windows XP and Visual Studio 2005 (? unsure ?)
Another reference suggests Visual Studio 2015 defaults to 64-bit time_t
- MacOS 10.15 Catalina (released 2019) drops support for 32-bit apps
* Y2038-SAFE: lighttpd 32-bit builds on platforms using 32-bit unsigned time_t
- e.g. OpenVMS (unknown if lighttpd builds on this platform)
* Y2038-UNSAFE: lighttpd 32-bit builds on platforms using 32-bit signed time_t
- Linux 32-bit (including i686)
- glibc 32-bit library support not yet available for 64-bit time_t
- https://sourceware.org/glibc/wiki/Y2038ProofnessDesign
- Linux kernel 5.6 on 32-bit platforms does support 64-bit time_t
https://itsubuntu.com/linux-kernel-5-6-to-fix-the-year-2038-issue-unix-y2k/
- https://www.gnu.org/software/libc/manual/html_node/64_002dbit-time-symbol-handling.html
"Note: at this point, 64-bit time support in dual-time
configurations is work-in-progress, so for these
configurations, the public API only makes the 32-bit time
support available. In a later change, the public API will
allow user code to choose the time size for a given
compilation unit."
- compiling with -D_TIME_BITS=64 currently has no effect
- glibc recent (Jul 2021) mailing list discussion
- https://public-inbox.org/bug-gnulib/878s2ozq70.fsf@oldenburg.str.redhat.com/T/
- FreeBSD i386
- DragonFlyBSD 32-bit
* Y2038 mitigations attempted on Y2038-UNSAFE platforms (32-bit signed time_t)
* lighttpd prefers system monotonic clock instead of realtime clock
in places where realtime clock is not required
* lighttpd treats negative time_t values as after 19 Jan 2038 03:14:07 GMT
* (lighttpd presumes that lighttpd will not encounter dates before 1970
during normal operation.)
* lighttpd casts struct stat st.st_mtime (and st.st_*time) through uint64_t
to convert negative timestamps for comparisions with 64-bit timestamps
(treating negative timestamp values as after 19 Jan 2038 03:14:07 GMT)
* lighttpd provides unix_time64_t (int64_t) and
* lighttpd provides struct unix_timespec64 (unix_timespec64_t)
(struct timespec equivalent using unix_time64_t tv_sec member)
* lighttpd provides gmtime64_r() and localtime64_r() wrappers
for platforms 32-bit platforms using 32-bit time_t and
lighttpd temporarily shifts the year in order to use
gmtime_r() and localtime_r() (or gmtime() and localtime())
from standard libraries, before readjusting year and passing
struct tm to formatting functions such as strftime()
* lighttpd provides TIME64_CAST() macro to cast signed 32-bit time_t to
unsigned 32-bit and then to unix_time64_t
* Note: while lighttpd tries handle times past 19 Jan 2038 03:14:07 GMT
on 32-bit platforms using 32-bit signed time_t, underlying libraries and
underlying filesystems might not behave properly after 32-bit signed time_t
overflows (19 Jan 2038 03:14:08 GMT). If a given 32-bit OS does not work
properly using negative time_t values, then lighttpd likely will not work
properly on that system.
* Other references and blogs
- https://en.wikipedia.org/wiki/Year_2038_problem
- https://en.wikipedia.org/wiki/Time_formatting_and_storage_bugs
- http://www.lieberbiber.de/2017/03/14/a-look-at-the-year-20362038-problems-and-time-proofness-in-various-systems/
This commit is a large set of code changes and results in removal of
hundreds, perhaps thousands, of CPU instructions, a portion of which
are on hot code paths.
Most (buffer *) used by lighttpd are not NULL, especially since buffers
were inlined into numerous larger structs such as request_st and chunk.
In the small number of instances where that is not the case, a NULL
check is often performed earlier in a function where that buffer is
later used with a buffer_* func. In the handful of cases that remained,
a NULL check was added, e.g. with r->http_host and r->conf.server_tag.
- check for empty strings at config time and set value to NULL if blank
string will be ignored at runtime; at runtime, simple pointer check
for NULL can be used to check for a value that has been set and is not
blank ("")
- use buffer_is_blank() instead of buffer_string_is_empty(),
and use buffer_is_unset() instead of buffer_is_empty(),
where buffer is known not to be NULL so that NULL check can be skipped
- use buffer_clen() instead of buffer_string_length() when buffer is
known not to be NULL (to avoid NULL check at runtime)
- use buffer_truncate() instead of buffer_string_set_length() to
truncate string, and use buffer_extend() to extend
Examples where buffer known not to be NULL:
- cpv->v.b from config_plugin_values_init is not NULL if T_CONFIG_BOOL
(though we might set it to NULL if buffer_is_blank(cpv->v.b))
- address of buffer is arg (&foo)
(compiler optimizer detects this in most, but not all, cases)
- buffer is checked for NULL earlier in func
- buffer is accessed in same scope without a NULL check (e.g. b->ptr)
internal behavior change:
callers must not pass a NULL buffer to some funcs.
- buffer_init_buffer() requires non-null args
- buffer_copy_buffer() requires non-null args
- buffer_append_string_buffer() requires non-null args
- buffer_string_space() requires non-null arg
optimize buffer_* primitives
Other than buffer_string_set_length(), reallocate with one power-2 step
in size (or use the requested size, if larger). This replaces the fixed
BUFFER_PIECE_SIZE round-up of only 64 bytes extension each reallocation,
which could lead to excessive reallocations in some scenarios.
buffer_extend() convenience routine to prep for batch append
(combines buffer_string_prepare_append() and buffer_commit())
mod_fastcgi, mod_scgi, mod_proxy and others now leverage buffer_extend()
mod_scgi directly performs little-endian encoding of short ints
http_response_write_header() optimizes writing response header,
leveraging buffer_extend()
modify mod_proxy to append line ends
similar to how it is done in http_response_write_header()
(removes one call to buffer_append_string_len())
Note: monotonic time does not change while VM is suspended
Continue to use real time where required by HTTP protocol, for logging
and for other user-visible instances, such as mod_status, as well as for
external databases and caches.
convert all log_error_write() to log_error() and pass (log_error_st *)
use con->errh in preference to srv->errh (even though currently same)
avoid passing (server *) when previously used only for logging (errh)
quickly clear buffer instead of buffer_string_set_length(b, 0) or
buffer_reset(b). Avoids free() of large buffers about to be reused,
or buffers that are module-scoped, persistent, and reused.
(buffer_reset() should still be used with buffers in connection *con
when the data in the buffers is supplied by external, untrusted source)
skip redundant calls to buffer_string_prepare_copy() when simply
clearing buffer is sufficient, e.g. when a blanked buffer is desired
before calling buffer_append_strftime(), which internally prepares
buffer for the resultant formatted string
fix potential NULL pointer dereference in mod_deflate.c
remove logically dead code in connection-glue.c
add coverity annotations to see if some issues will be reclassified
* takes uintmax_t now
* use in http_chunk_append_len
From: Stefan Bühler <stbuehler@web.de>
git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2980 152afb58-edef-0310-8abb-c4023f1b3aa9
- a lot of code tried to handle manually adding terminating zeroes and
keeping track of the correct "used" count.
Replaced all "external" usages with simple wrapper functions:
* buffer_string_is_empty (used <= 1), buffer_is_empty (used == 0);
prefer buffer_string_is_empty
* buffer_string_set_length
* buffer_string_length
* CONST_BUF_LEN() macro
- removed "static" buffer hacks (buffers pointing to constant/stack
memory instead of malloc()ed data)
- buffer_append_strftime(): refactor buffer+strftime uses
- li_tohex(): no need for a buffer for binary-to-hex conversion:
the output data length is easy to predict
- remove "-Winline" from extra warnings: the "inline" keyword just
supresses the warning about unused but defined (static) functions;
don't care whether it actually gets inlined or not.
From: Stefan Bühler <stbuehler@web.de>
git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2979 152afb58-edef-0310-8abb-c4023f1b3aa9
* removed almost all usages of buffer as "memory" (without terminating
zero)
* refactored cgi variable name encoding
From: Stefan Bühler <stbuehler@web.de>
git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2977 152afb58-edef-0310-8abb-c4023f1b3aa9
* remove unused structs and functions
(buffer_array, read_buffer)
* 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
buffer.
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
needed)
* refactor: create chunkqueue_steal: moving (partial) chunks into another
queue
* 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
chunked body.
From: Stefan Bühler <stbuehler@web.de>
git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2975 152afb58-edef-0310-8abb-c4023f1b3aa9
* The breakage-log simply replaces stderr (the old stderr is moved away if needed for errorlog),
and stderr isn't closed after forking.
It defaults to stderr if started with -n (no daemonize), otherwise it defaults to /dev/null.
It is _not_ reopened in log_error_cycle, as there may be many long running childs which have it
still open anyway. Use a pipe-logger with cycle-support if you need it.
git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2550 152afb58-edef-0310-8abb-c4023f1b3aa9
upper case stands for "don't append space"; o/O is for off_t, x/X for int as hex
git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2286 152afb58-edef-0310-8abb-c4023f1b3aa9
