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/
NB: r->tmp_buf == srv->tmp_buf (pointer is copied for quicker access)
NB: request read and write chunkqueues currently point to connection
chunkqueues; per-request and per-connection chunkqueues are
not distinct from one another
con->read_queue == r->read_queue
con->write_queue == r->write_queue
NB: in the future, a separate connection config may be needed for
connection-level module hooks. Similarly, might need to have
per-request chunkqueues separate from per-connection chunkqueues.
Should probably also have a request_reset() which is distinct from
connection_reset().
array_get_element_klen() is now intended for read-only access
array_get_data_unset() is used by config processing for r/w access
array_get_buf_ptr() is used for r/w access to ds->value (string buffer)
provide standard types in first.h instead of base.h
provide lighttpd types in base_decls.h instead of settings.h
reduce headers exposed by headers for core data structures
do not expose <pcre.h> or <stdlib.h> in headers
move stat_cache_entry to stat_cache.h
reduce use of "server.h" and "base.h" in headers
centralize most waitpid() handling in core server, with hooks for
modules to be informed of pid and status when a process exits.
This enables faster discovery (and restart) of exited processes,
and also allows for lighttpd to manage backend processes in the
parent (master) process when server.max-worker > 0.
connection attempts in progress count towards proc load so that bursts
of new connections do not all queue for current least busy proc
(makes a difference only for local backends with more than one proc)
common codebase for socket backends, based off mod_fastcgi with
some features added for mod_proxy
(mostly intended to reduce code duplication and enhance code isolation)
mod_fastcgi and mod_scgi can now use fastcgi.balance and scgi.balance
for similar behavior as proxy.balance, but the balancing is per-host
and not per-proc. proxy.balance is also per-host and not per-proc.
mod_proxy and mod_scgi can now use proxy.map-extensions and
scgi.map-extensions, similar to fastcgi.map-extensions.
mod_fastcgi behavior change (affects only mod_status):
- statistics tags have been renamed from "fastcgi.*" to "gw.*"
"fastcgi.backend.*" -> "gw.backend.*"
"fastcgi.active-requests" -> "gw.active-requests"
("fastcgi.requests" remains "fastcgi.requests")
("proxy.requests" is new)
("scgi.requests" is new)
mod_scgi behavior change (likely minor):
- removed scgi_proclist_sort_down() and scgi_proclist_sort_up().
procs now chosen based on load as measured by num socket connnections
Note:
modules using gw_backend.[ch] are currently still independent modules.
If it had been written as a single module with fastcgi, scgi, proxy
implementations, then there would have been a chance of breaking some
existing user configurations where module ordering made a difference
for which module handled a given request, though for most people, this
would have made no difference.
Details about mod_fastcgi code transformations:
unsigned int debug -> int debug
fastcgi_env member removed from plugin_config
renamed "fcgi" and "fastcgi" to "gw", and "FCGI" to "GW"
reorganize routines for high-level and lower-level interfaces
some lower-level internal interfaces changed to use host,proc,debug
args rather than knowing about higher-level (app) hctx and plugin_data
tabs->spaces and reformatting
Glenn Strauss