libcxc / Blog: Recent posts

• Fixed: (BUG::RACE): SIG_CRITICAL_SECTION_LEAVE() signal could be delivered right after sig_code is checked and before before SIG_CS reset, i.e. the signal could be ignored. SIG_CS must be reset before sig_code is checked and armed again in cxc_throw()
• Fixed: cxc_propagate() does not need to enter SIG_CS - in all cases it is invoked within SIG_CS armed by cxc_connect()
• Fixed: TEST: silenced warnings on 'unused variables' in release build.
• Change: for internal SIG_CS the sig_cs_t.cs_enter is set to -1, what allows to recognise public / internal sections and allows builtin_sig_hdl() to detect internal libcxc errors.
• Update: configure.ac: updated test for exception stack size

• Fixed: (BUG) builtin_sig_hdl(): all signals must be passed to hook function and user signal handler (if provided),
• Change: Public signal critical sections allow 'unlimited' nesting,
• Added: cxc_entry.state.flags: CXF_SIG_CS: deferred exception thrown from signal critical section.

• Change: builtin_sig_hdl(): hook function can now return CXF_TOP_HDL to force execution of top-level CATCH section.

• Fixed: (BUG): AS-safety must be assured while switching exception stack nesting levels,
• Fixed: cxc_clear_restart() now clears the CXF_CATCH flag, so multiple errors can be handled on the same nesting level,
• Fixed: builtin_sig_hdl(): for all queued signals cxc_entry.uval == siginfo->si_value.sival_ptr, for consistency with CXC_THROW(),
• Added: Support for signal critical sections in client code,
• Added: Support for single-core systems: spinlocks are dynamically replaced with calls to sched_yield().... read more

• Update: rcode v4.0
• Change: using new rcode msg handler: cxc_msg_hdl()

• Fixed: (BUG::old::harmless): cxc_snprintf() invalid result for signed 64bit integers if the value is above 32bit range, harmless for libcxc.
• Change: cxc_snprintf(): removed support for %X, %P, %b - this is an internal function, so only used conversion specifiers needs to be implemented.

• Change: CXC_INIT() detects PID change and automatically initializes necessary structures/vars.
• Change: Removed cxc_init_forked().
• Change: Removed __cxc_snprintf() from public header.
• Change: cxc_free_sec_buf(): arg changed to **pptr: buffer pointer is zeroed after the operation.
• Change: __cxc_sighdl_hook() renamed to CXC_REG_SIG_HOOK()
• Adedd: TEST: test_init_forked_throw(): test CXC_INIT() PID change detection in a forked process.
• Update: rcode v3.0: ABI changed!

• Fixed: autotools build: missing symbol cxc_init_forked in linker script, compiled correctly from C::B project.

• Added: fall-back mode which uses full-barrier synchronization methods: sync_bool_compare_and_swap() and sync_synchronize(). This allows to use the library in older systems.

• Fixed: (BUG::regression::old) cxc_connect(): cxc_entry.ecd_rcd_scp and cxc_entry.xmk_rcd_scp were not initalized, unless CXC_THROW and CXC_MARK were invoked. This could cause a crash in cxc_backtrace().
• Change: cxc_secured_buf(), cxc_free_sec_buf() are not setting internal cxc_status rcode: cxc_try_switch() should not be affected by external calls to those functions.
• Change: CXC_THIS_SCOPE_PTR is now used also by CXC_TRY, CXC_THROW, CXC_MARK macros.
• Added: cxc_clear_status(): clear internal status rcode... read more

• Fixed: cxc_stack.s_offs should be of type int32_t,
• Fixed: TEST: test_td_stack_ovf(): gcc v12.2.0: silenced warning "-Winfinite-recursion",
• Change: cxc_stack.rzb now holds the address of the cxc_stack for stronger validation.
• Change: removed "[E!]" and "[w]" prefixes from rcode messages -> client app decides whether to use message prefixes.

• Fixed: cxc_rcdGetMsg_s(): in case when the scope ptr is NULL, use cxc_scope pointer. The behaviour is now consistent with code generated by rcd_autogen.
• Added: CXC_INIT(): checking if the cxc_stack is already initialized -> error.
• Added: cxc_initialized(): returns non-zero if cxc_stack is initialized.

• Update: rcd_autogen v2.9: Fixed: misuse of VMSG TLS pointer, race possible.

• Fixed: (BUG::old) cnv_str() internal buffer too small to print 64bit value in base 2.
• Fixed: (BUG) ld script: missing symbol cxc_rcdGetMinMsgBufSz.
• Fixed: cxc_secured_buf(): added error messages, setting global __cxc_status.
• Change: cxc.h: missing CXC_THIS_SCOPE_PTR definition is now #error, not a warning.
• Added: new constant CXF_TRY_PARENT_HDL for use with CXC_TRY(): use handler set for parent entry.
  Full list in change log.

• Fixed: (BUG::old) cxc_try_switch(): don't propagate the exception in case when invoked from CXC_RESTART(),
• Fixed: (BUG) CXC_SIGQUEUE(): siginfo_t located on stack was not fully initialized,
• Fixed: (BUG::regression::old) rcd_autoconf.m4: changing rcd_autogen run mode at configure time didn't work,
• Change: Renamed cxc_entry accessors from cxc_get_xxx() to cxc_entry_get_xxx(),
• Added: cxc_rcdGetMsg() needed to get messages from CXC_INIT(), CXC_REG_SIGNAL() and CXC_REG_SIG_MASK(), before CXC_TRY() section,
• Update: rcd_autogen v2.7
  Full list in the change log.

No functional changes.
Update: rcd_autogen v2.6 : fixed-size array of units, variable declaration.

• Fixed: makefile.am: don't install debug.h
• Update: rcd_autogen v2.3

• Fixed: (BUG) cxc.h: undefined symbol CXC_THIS_SCOPE_PTR causes failure in autoconf tests in client apps.
• Fixed: (BUG) makefile.am: conflicting 'rcodedir' and 'install-data-hook' -> 'make install' fails.
• Fixed: cxc.h: removed redundant #defines
  Archive with v3.2.0 removed.

Some other projects are now released with rcd_autogen v2.1 - that version contains just few minor changes which are not affecting the resulting builds. The rcd_autogen released along with this project will be updated in next release.

• Update: new rcd_autogen v2.0 - got rid of rcd_autogen headers in lib interface.
• Added: full integration with rcd_autogen message bindings
• New public macro : CXC_CATCH_MSG(msg): the msg is attached to the cxc_backtrace() output.
  Full list in the changelog.

• Fixed: (BUG) cxc.h: incorrect include path to rcode.h
• Fixed: (BUG) makefile.am: rcd_autogen in basic mode: src/cxc_rcd_func.c is required to
  include stub funcions in the final DSO.
• Fixed: cxc_propagate() should propagate also the rcd_scope_t scope pointer.
• Update: rcd_autogen v1.3 and rcode v1.0.3
  Archive with v3.0.0 has been removed.

• Fixed: (BUG): packed cxc_stack members were not correctly aligned for WORDSIZE==64
• Fixed: new version of m4/build_switch.m4 - the previous version was incomplete and buggy.
• Change: cxc_backtrace(), cxc_backtrace_buf(): in case of error the error message is printed to defined fd/buffer (if possible)
• Added: new public function: cxc_get_sig_desc(): fully safe replacement for strsignal(), used in cxc_backtrce().
  The most important change hoowever, is upgrade to returncode v1.0.2. This version significantly increases functionality of the rcode, but requires special pre-build steps, which are performed using bash script: 'rcd_autogen'.
  Additionally, the m4/rcd_autoconf.m4 script is provided, to ease integration of 'rcd_autogen' with autoconf.
  The new rcode allowed to implement 3 new public macros:
  CXC_TRY_MSG(), CXC_MARK_MSG() and CXC_THROW_MSG().
  Now it's possible to connect rcode values with corresponding textual messages or comments, which are visible in the backtrace.
  Manpage and test program are updated.
  Besides that, lots of small changes and fixes have been introduced, see change log for details.

Most important changes:

• Added support for POSIX real-time signals - the library itself is now using SIGRTMIN for thread crash detection and for CXC_THROW_MAIN()
• Change: removed support for FINALLY section: it was useless in practice.
• Lots of other small changes and fixes.
• Manpage updated.

Full list of changes in the change logs.

Tests performed on x86, amd64 and armhf (BCM2835) - all passed.

• Fixed: Incorrect license in the COPYING file.
• Few small fixes in the code.
• Updated returncode.h and debug.h

Two bugs has been fixed, both non critical:

• returncode.h: old mislooked bug: RCD_RETURN_FALSE() returned RCD_TRUE! The only reason that this Bug have survived for a so long time is that true/false values of rcode was never used be me until now. Anyway, this has ZERO influence on the libcxc behaviour.
• locally aliased funcions: missing "hidden" attribute - discovered during investigating the asm code: now all the locally aliased functions are called without the use of PLT table -> faster.