The rewrite of BIND 9 build system is a large work and cannot be reasonable
split into separate merge requests. Addition of the automake has a positive
effect on the readability and maintainability of the build system as it is more
declarative, it allows conditional and we are able to drop all of the custom
make code that BIND 9 developed over the years to overcome the deficiencies of
autoconf + custom Makefile.in files.
This squashed commit contains following changes:
- conversion (or rather fresh rewrite) of all Makefile.in files to Makefile.am
by using automake
- the libtool is now properly integrated with automake (the way we used it
was rather hackish as the only official way how to use libtool is via
automake
- the dynamic module loading was rewritten from a custom patchwork to libtool's
libltdl (which includes the patchwork to support module loading on different
systems internally)
- conversion of the unit test executor from kyua to automake parallel driver
- conversion of the system test executor from custom make/shell to automake
parallel driver
- The GSSAPI has been refactored, the custom SPNEGO on the basis that
all major KRB5/GSSAPI (mit-krb5, heimdal and Windows) implementations
support SPNEGO mechanism.
- The various defunct tests from bin/tests have been removed:
bin/tests/optional and bin/tests/pkcs11
- The text files generated from the MD files have been removed, the
MarkDown has been designed to be readable by both humans and computers
- The xsl header is now generated by a simple sed command instead of
perl helper
- The <irs/platform.h> header has been removed
- cleanups of configure.ac script to make it more simpler, addition of multiple
macros (there's still work to be done though)
- the tarball can now be prepared with `make dist`
- the system tests are partially able to run in oot build
Here's a list of unfinished work that needs to be completed in subsequent merge
requests:
- `make distcheck` doesn't yet work (because of system tests oot run is not yet
finished)
- documentation is not yet built, there's a different merge request with docbook
to sphinx-build rst conversion that needs to be rebased and adapted on top of
the automake
- msvc build is non functional yet and we need to decide whether we will just
cross-compile bind9 using mingw-w64 or fix the msvc build
- contributed dlz modules are not included neither in the autoconf nor automake
These are mostly false positives, the clang-analyzer FAQ[1] specifies
why and how to fix it:
> The reason the analyzer often thinks that a pointer can be null is
> because the preceding code checked compared it against null. So if you
> are absolutely sure that it cannot be null, remove the preceding check
> and, preferably, add an assertion as well.
The 4 warnings reported are:
dnssec-cds.c:781:4: warning: Access to field 'base' results in a dereference of a null pointer (loaded from variable 'buf')
isc_buffer_availableregion(buf, &r);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/builds/isc-projects/bind9/lib/isc/include/isc/buffer.h:996:36: note: expanded from macro 'isc_buffer_availableregion'
^
/builds/isc-projects/bind9/lib/isc/include/isc/buffer.h:821:16: note: expanded from macro 'ISC__BUFFER_AVAILABLEREGION'
(_r)->base = isc_buffer_used(_b); \
^~~~~~~~~~~~~~~~~~~
/builds/isc-projects/bind9/lib/isc/include/isc/buffer.h:152:29: note: expanded from macro 'isc_buffer_used'
((void *)((unsigned char *)(b)->base + (b)->used)) /*d*/
^~~~~~~~~
1 warning generated.
--
byname_test.c:308:34: warning: Access to field 'fwdtable' results in a dereference of a null pointer (loaded from variable 'view')
RUNTIME_CHECK(dns_fwdtable_add(view->fwdtable, dns_rootname,
^~~~~~~~~~~~~~
/builds/isc-projects/bind9/lib/isc/include/isc/util.h:318:52: note: expanded from macro 'RUNTIME_CHECK'
^~~~
/builds/isc-projects/bind9/lib/isc/include/isc/error.h:50:21: note: expanded from macro 'ISC_ERROR_RUNTIMECHECK'
((void)(ISC_LIKELY(cond) || \
^~~~
/builds/isc-projects/bind9/lib/isc/include/isc/likely.h:23:43: note: expanded from macro 'ISC_LIKELY'
^
1 warning generated.
--
./rndc.c:255:6: warning: Dereference of null pointer (loaded from variable 'host')
if (*host == '/') {
^~~~~
1 warning generated.
--
./main.c:1254:9: warning: Access to field 'sctx' results in a dereference of a null pointer (loaded from variable 'named_g_server')
sctx = named_g_server->sctx;
^~~~~~~~~~~~~~~~~~~~
1 warning generated.
References:
1. https://clang-analyzer.llvm.org/faq.html#null_pointer
The previous commit removed the code related to the internal symbol
table. On platforms where available, we can now use backtrace_symbols()
to print more verbose symbols table to the output.
As there's now general availability of backtrace() and
backtrace_symbols() functions (see below), the commit also removes the
usage of glibc internals and the custom stack tracing.
* backtrace(), backtrace_symbols(), and backtrace_symbols_fd() are
provided in glibc since version 2.1.
* backtrace(), backtrace_symbols(), and backtrace_symbols_fd() first
appeared in Mac OS X 10.5.
* The backtrace() library of functions first appeared in NetBSD 7.0 and
FreeBSD 10.0.
this corrects some style glitches such as:
```
long_function_call(arg, arg2, arg3, arg4, arg5, "str"
"ing");
```
...by adjusting the penalties for breaking strings and call
parameter lists.
hp implementation requires an object for each thread accessing
a hazard pointer. previous implementation had a hardcoded
HP_MAX_THREAD value of 128, which failed on machines with lots of
CPU cores (named uses 3n threads). We make isc__hp_max_threads
configurable at startup, with the value set to 4*named_g_cpus.
It's also important for this value not to be too big as we do
linear searches on a list.
Previously, the dns_name API used isc_thread_key API for TLS, which is
fairly complicated and requires initialization of memory contexts, etc.
This part of code was refactored to use a ISC_THREAD_LOCAL pointer which
greatly simplifies the whole code related to storing TLS variables.
xmlInitThreads() and xmlCleanupThreads() are called from within
named_statschannels_configure() and named_statschannels_shutdown(),
respectively. Both of these functions are executed by worker threads,
not the main named thread. This causes ASAN to report memory leaks like
the following one upon shutdown (as long as named is asked to produce
any XML output over its configured statistics channels during its
lifetime):
Direct leak of 968 byte(s) in 1 object(s) allocated from:
#0 0x7f677c249cd8 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:153
#1 0x7f677bc1838f in xmlGetGlobalState (/usr/lib/libxml2.so.2+0xa838f)
The data mentioned in the above report is a libxml2 state structure
stored as thread-specific data. Such chunks of memory are automatically
released (by a destructor passed to pthread_key_create() by libxml2)
whenever a thread that allocated a given chunk exits. However, if
xmlCleanupThreads() is called by a given thread before it exits, the
destructor will not be invoked (due to xmlCleanupThreads() calling
pthread_key_delete()) and ASAN will report a memory leak. Thus,
xmlInitThreads() and xmlCleanupThreads() must not be called from worker
threads. Since xmlInitThreads() must be called on Windows in order for
libxml2 to work at all, move xmlInitThreads() and xmlCleanupThreads()
calls to the main named thread (which does not produce any XML output
itself) in order to prevent the memory leak from being reported by ASAN.
The saved_command_line buffer in bin/named/main.c is 8192 bytes long.
The size of libisc's internal logging buffer (defined by the value of
the LOG_BUFFER_SIZE constant in lib/isc/log.c) is also 8192 bytes.
Since the buffer containing the ellipsis is passed as the last argument
to isc_log_write() and the buffer containing the potentially trimmed
named command line (saved_command_line) is passed as the second argument
in the same isc_log_write() call, it may happen that saved_command_line
will exhaust all available space in libisc's internal logging buffer, in
which case the ellipsis will be elided from the output.
Make saved_command_line 4096 bytes long as that value is arguably also
large enough for any reasonable use case and at the same time it ensures
ellipsis will always be printed for excessively long named command
lines.
- ns__client_request() is now called by netmgr with an isc_nmhandle_t
parameter. The handle can then be permanently associated with an
ns_client object.
- The task manager is paused so that isc_task events that may be
triggred during client processing will not fire until after the netmgr is
finished with it. Before any asynchronous event, the client MUST
call isc_nmhandle_ref(client->handle), to prevent the client from
being reset and reused while waiting for an event to process. When
the asynchronous event is complete, isc_nmhandle_unref(client->handle)
must be called to ensure the handle can be reused later.
- reference counting of client objects is now handled in the nmhandle
object. when the handle references drop to zero, the client's "reset"
callback is used to free temporary resources and reiniialize it,
whereupon the handle (and associated client) is placed in the
"inactive handles" queue. when the sysstem is shutdown and the
handles are cleaned up, the client's "put" callback is called to free
all remaining resources.
- because client allocation is no longer handled in the same way,
the '-T clienttest' option has now been removed and is no longer
used by any system tests.
- the unit tests require wrapping the isc_nmhandle_unref() function;
when LD_WRAP is supported, that is used. otherwise we link a
libwrap.so interposer library and use that.
When a task manager is created, we can now specify an `isc_nm`
object to associate with it; thereafter when the task manager is
placed into exclusive mode, the network manager will be paused.
Make stderr fully buffered on Windows to improve named performance when
it is logging to stderr, which happens e.g. in system tests. Note that:
- line buffering (_IOLBF) is unavailable on Windows,
- fflush() is called anyway after each log message gets written to the
default stderr logging channels created by libisc.
The json-c have previously leaked into the global namespace leading
to forced -I<include_path> for every compilation unit using isc/xml.h
header. This MR fixes the usage making the caller object opaque.
The libxml2 have previously leaked into the global namespace leading
to forced -I<include_path> for every compilation unit using isc/xml.h
header. This MR fixes the usage making the caller object opaque.
