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• How to port signal() to sigaction() ?

  28 septembre 2016, par Shark

  due to recent problems discovered with NDK12 and NDK13b2, i’m thinking of ’porting’ libx264’s use of signal() (and missing bsd_signal() in ndk12) to use sigaction() instead.

  The problem is, I’m not quite sure what’s the simple&fastest way to replace signal() calls with sigaction() ones.

  For all i see, it’s mainly used in x264-snapshot/common/cpu.c in the following manner :

  using the following signal handler :

  static void sigill_handler( int sig )
  
  {
  
      if( !canjump )
  
      {
  
          signal( sig, SIG_DFL );
  
          raise( sig );
  
      }
  
  
  
      canjump = 0;
  
      siglongjmp( jmpbuf, 1 );
  
  }

  This is the problematic x264_cpu_detect function... currently, i’m guessing i only need to tackle the ARM version, but i’ ; ; still have to replace all occurances of signal() with sigaction() so i might just cover both of them to get the thing building...

  FYI - the NDK13 beta2 still has "unstable" libc and the build doesn’t fail on this part, but rather the first invocation of the rand() function somewhere else... So i’m out of luck and replacing the signal() calls might be better than just waiting for the official NDK13 release. I’m doing this to get rid of text-relocations so i can run the library (and doubango) on API 24 (Android N)

  the problematic part of function that invokes signal() :

  #elif SYS_LINUX
  
  
  
  uint32_t x264_cpu_detect( void )
  
  {
  
      static void (*oldsig)( int );
  
  
  
      oldsig = signal( SIGILL, sigill_handler );
  
      if( sigsetjmp( jmpbuf, 1 ) )
  
      {
  
          signal( SIGILL, oldsig );
  
          return 0;
  
      }
  
  
  
      canjump = 1;
  
      asm volatile( "mtspr 256, %0\n\t"
  
                    "vand 0, 0, 0\n\t"
  
                    :
  
                    : "r"(-1) );
  
      canjump = 0;
  
  
  
      signal( SIGILL, oldsig );
  
  
  
      return X264_CPU_ALTIVEC;
  
  }
  
  #endif
  
  
  
  #elif ARCH_ARM
  
  
  
  void x264_cpu_neon_test( void );
  
  int x264_cpu_fast_neon_mrc_test( void );
  
  
  
  uint32_t x264_cpu_detect( void )
  
  {
  
      int flags = 0;
  
  #if HAVE_ARMV6
  
      flags |= X264_CPU_ARMV6;
  
  
  
      // don't do this hack if compiled with -mfpu=neon
  
  #if !HAVE_NEON
  
      static void (* oldsig)( int );
  
      oldsig = signal( SIGILL, sigill_handler );
  
      if( sigsetjmp( jmpbuf, 1 ) )
  
      {
  
          signal( SIGILL, oldsig );
  
          return flags;
  
      }
  
  
  
      canjump = 1;
  
      x264_cpu_neon_test();
  
      canjump = 0;
  
      signal( SIGILL, oldsig );
  
  #endif
  
  
  
      flags |= X264_CPU_NEON;
  
  
  
      // fast neon -> arm (Cortex-A9) detection relies on user access to the
  
      // cycle counter; this assumes ARMv7 performance counters.
  
      // NEON requires at least ARMv7, ARMv8 may require changes here, but
  
      // hopefully this hacky detection method will have been replaced by then.
  
      // Note that there is potential for a race condition if another program or
  
      // x264 instance disables or reinits the counters while x264 is using them,
  
      // which may result in incorrect detection and the counters stuck enabled.
  
      // right now Apple does not seem to support performance counters for this test
  
  #ifndef __MACH__
  
      flags |= x264_cpu_fast_neon_mrc_test() ? X264_CPU_FAST_NEON_MRC : 0;
  
  #endif
  
      // TODO: write dual issue test? currently it's A8 (dual issue) vs. A9 (fast      mrc)
  
  #endif
  
      return flags;
  
  }
  
  
  
  #else
  
  
  
  uint32_t x264_cpu_detect( void )
  
  {
  
      return 0;
  
  }

  So the question is really this : what would be the quickest/easiest//fastest way to replace the signal() calls with sigaction() ones while preserving the current functionality ?

  EDIT :
  The reason i’m trying to get rid of signal() are these build errors :

  /home/devshark/SCRATCH/doubango/thirdparties/android/armv5te/lib/dist/libx264.a(cpu.o):cpu.c:function sigill_handler: error: undefined reference to 'bsd_signal'
  
  
  
  /home/devshark/SCRATCH/doubango/thirdparties/android/armv5te/lib/dist/libx264.a(cpu.o):cpu.c:function x264_cpu_detect: error: undefined reference to 'bsd_signal'
  
  /home/devshark/SCRATCH/doubango/thirdparties/android/armv5te/lib/dist/libx264.a(cpu.o):cpu.c:function x264_cpu_detect: error: undefined reference to 'bsd_signal'
  
  
  
  /home/devshark/SCRATCH/doubango/thirdparties/android/armv5te/lib/dist/libx264.a(cpu.o):cpu.c:function x264_cpu_detect: error: undefined reference to 'bsd_signal'

  I already know that this is a known NDK12 problem, that might be solved by bringing bsd_signal back to the libc in NDK13. However, in it’ beta state with it’s unstable libc - it’s currently missing the rand() function and simply waiting for it might not do the trick. But in the worst-case scenario, i guess i’ll just have to wait for it and retry after it’s release.

  But as it currently is, the prebuilt version of the library i want to use has text-relocations and is being rejected by phones running newer API / version of the android OS.

  EDIT2 :
  I also know that signal() usually works by using sigaction() under the hood, but maybe i won’t get bsd_signal related build-errors... since i’m suspecting that this one isn’t using it. It’s obviously using bsd_signal, which may or may not be the same underlying thing :/

• How to port signal() to sigaction() ?

  28 septembre 2016, par Shark

  due to recent problems discovered with NDK12 and NDK13b2, i’m thinking of ’porting’ libx264’s use of signal() (and missing bsd_signal() in ndk12) to use sigaction() instead.

  The problem is, I’m not quite sure what’s the simple&fastest way to replace signal() calls with sigaction() ones.

  For all i see, it’s mainly used in x264-snapshot/common/cpu.c in the following manner :

  using the following signal handler :

  static void sigill_handler( int sig )
  
  {
  
      if( !canjump )
  
      {
  
          signal( sig, SIG_DFL );
  
          raise( sig );
  
      }
  
  
  
      canjump = 0;
  
      siglongjmp( jmpbuf, 1 );
  
  }

  This is the problematic x264_cpu_detect function... currently, i’m guessing i only need to tackle the ARM version, but i’ ; ; still have to replace all occurances of signal() with sigaction() so i might just cover both of them to get the thing building...

  FYI - the NDK13 beta2 still has "unstable" libc and the build doesn’t fail on this part, but rather the first invocation of the rand() function somewhere else... So i’m out of luck and replacing the signal() calls might be better than just waiting for the official NDK13 release. I’m doing this to get rid of text-relocations so i can run the library (and doubango) on API 24 (Android N)

  the problematic part of function that invokes signal() :

  #elif SYS_LINUX
  
  
  
  uint32_t x264_cpu_detect( void )
  
  {
  
      static void (*oldsig)( int );
  
  
  
      oldsig = signal( SIGILL, sigill_handler );
  
      if( sigsetjmp( jmpbuf, 1 ) )
  
      {
  
          signal( SIGILL, oldsig );
  
          return 0;
  
      }
  
  
  
      canjump = 1;
  
      asm volatile( "mtspr 256, %0\n\t"
  
                    "vand 0, 0, 0\n\t"
  
                    :
  
                    : "r"(-1) );
  
      canjump = 0;
  
  
  
      signal( SIGILL, oldsig );
  
  
  
      return X264_CPU_ALTIVEC;
  
  }
  
  #endif
  
  
  
  #elif ARCH_ARM
  
  
  
  void x264_cpu_neon_test( void );
  
  int x264_cpu_fast_neon_mrc_test( void );
  
  
  
  uint32_t x264_cpu_detect( void )
  
  {
  
      int flags = 0;
  
  #if HAVE_ARMV6
  
      flags |= X264_CPU_ARMV6;
  
  
  
      // don't do this hack if compiled with -mfpu=neon
  
  #if !HAVE_NEON
  
      static void (* oldsig)( int );
  
      oldsig = signal( SIGILL, sigill_handler );
  
      if( sigsetjmp( jmpbuf, 1 ) )
  
      {
  
          signal( SIGILL, oldsig );
  
          return flags;
  
      }
  
  
  
      canjump = 1;
  
      x264_cpu_neon_test();
  
      canjump = 0;
  
      signal( SIGILL, oldsig );
  
  #endif
  
  
  
      flags |= X264_CPU_NEON;
  
  
  
      // fast neon -> arm (Cortex-A9) detection relies on user access to the
  
      // cycle counter; this assumes ARMv7 performance counters.
  
      // NEON requires at least ARMv7, ARMv8 may require changes here, but
  
      // hopefully this hacky detection method will have been replaced by then.
  
      // Note that there is potential for a race condition if another program or
  
      // x264 instance disables or reinits the counters while x264 is using them,
  
      // which may result in incorrect detection and the counters stuck enabled.
  
      // right now Apple does not seem to support performance counters for this test
  
  #ifndef __MACH__
  
      flags |= x264_cpu_fast_neon_mrc_test() ? X264_CPU_FAST_NEON_MRC : 0;
  
  #endif
  
      // TODO: write dual issue test? currently it's A8 (dual issue) vs. A9 (fast      mrc)
  
  #endif
  
      return flags;
  
  }
  
  
  
  #else
  
  
  
  uint32_t x264_cpu_detect( void )
  
  {
  
      return 0;
  
  }

  So the question is really this : what would be the quickest/easiest//fastest way to replace the signal() calls with sigaction() ones while preserving the current functionality ?

  EDIT :
  The reason i’m trying to get rid of signal() are these build errors :

  /home/devshark/SCRATCH/doubango/thirdparties/android/armv5te/lib/dist/libx264.a(cpu.o):cpu.c:function sigill_handler: error: undefined reference to 'bsd_signal'
  
  
  
  /home/devshark/SCRATCH/doubango/thirdparties/android/armv5te/lib/dist/libx264.a(cpu.o):cpu.c:function x264_cpu_detect: error: undefined reference to 'bsd_signal'
  
  /home/devshark/SCRATCH/doubango/thirdparties/android/armv5te/lib/dist/libx264.a(cpu.o):cpu.c:function x264_cpu_detect: error: undefined reference to 'bsd_signal'
  
  
  
  /home/devshark/SCRATCH/doubango/thirdparties/android/armv5te/lib/dist/libx264.a(cpu.o):cpu.c:function x264_cpu_detect: error: undefined reference to 'bsd_signal'

  I already know that this is a known NDK12 problem, that might be solved by bringing bsd_signal back to the libc in NDK13. However, in it’ beta state with it’s unstable libc - it’s currently missing the rand() function and simply waiting for it might not do the trick. But in the worst-case scenario, i guess i’ll just have to wait for it and retry after it’s release.

  But as it currently is, the prebuilt version of the library i want to use has text-relocations and is being rejected by phones running newer API / version of the android OS.

  EDIT2 :
  I also know that signal() usually works by using sigaction() under the hood, but maybe i won’t get bsd_signal related build-errors... since i’m suspecting that this one isn’t using it. It’s obviously using bsd_signal, which may or may not be the same underlying thing :/

• Piwik 3 Development Update #4 – Important notes and breaking changes

  2 octobre 2016, par Piwik Core Team — Community, Development

  As mentioned in the previous development updates #1 New UI design, API changes & release date, #2 Git master branch will become Piwik 3 and #3 Marketplace we are actively working on the Piwik 3 update and we will release a first beta of it soon. While the update brings many new features and bugfixes, it also comes with some important changes that may require your attention which we detail in this blog post.

  Database updates

  To keep Piwik upgrades as easy as possible, we have usually avoided database schema changes that affect large tables during the Piwik 2.X release cycle. The Piwik 3 update will however require several database updates in order to fix some limitations and bugs in the Piwik database schema. If you have a fair amount of traffic and/or large Piwik database, we recommend to execute the database updates for Piwik 3 on the command line.

  If you struggle updating Piwik you can also get in touch with the Piwik Support and ask for a quote so we can help you with upgrading.

  New server & browser Requirements

  Piwik 3 updates the server requirements. Piwik 3 now requires :

  • PHP 5.5.9 or newer (we used to require PHP 5.3+),
  • MySQL 5.5 or newer or MariaDB (we used to require MySQL 4.1+).

  If you are still on an old PHP and MySQL version we highly recommend to update directly to PHP 7 and a recent MySQL version (MySQL 5.7+).

  Piwik 3 also drops support for the older browsers IE8 and IE9.

  Default filter_limit now applies to all HTTP API methods (#8458)

  In the past the default filter_limit of 100 rows was applied to HTTP API methods that return a report. This means that by default :

  • when you requested a method like SitesManager.getAllSites, UsersManager.getUsers or Goals.getGoals (which are not reports), we returned all rows.
  • when you fetched a report like Actions.getPageUrls (which is a report), the result was limited to 100 rows.

  This behaviour was inconsistent and it was hard to understand which methods apply the default limit and which did not. We now apply the default limit to all HTTP API methods by default.

  If your API consumer or app needs to fetch all results for an API method, you can append the following parameter to the URL : &filter_limit=-1. Alternatively, if you wish to change the default filter_limit automatically for all APIs, you can override the API_datatable_default_limit config setting in your config/config.ini.php file.

  For more information about the various APIs parameters you can use, see Piwik Analytics HTTP API Reference.

  Proxy client IP detection (#10342)

  This is only important if you are using the proxy_client_headers[] config in the config/config.ini.php file, ie. your Piwik server is behind a proxy.

  When Piwik is set up to fetch the client IP address from the proxy headers, and the header contained more than one IP address, we used to use the last IP address. From Piwik 3 we will be using the first IP address which is in line with the protocol definition. For example if HTTP_X_FORWARDED_FOR contains multiple IP addresses, we now use the first IP instead of the last one.

  Writable Piwik JavaScript Tracker file piwik.js

  From Piwik 3 we recommend to have the file /piwik.js writable in your Piwik directory, so that the PHP and webserver processes can edit this file. It is not required to have the file writable for Piwik to function well, but we are working on some enhanced features that will only work when the file is writable. If you don’t know whether this file is writable, go to “Administration => System Check” as a Super User and Piwik will display a warning if the file is not writable. If needed, you might be able to make the file writable by executing a command like chmod 0755 piwik.js or chown $webuser piwik.js (on Linux).

  Changes for plugin developers

  In the previous development updates we have already introduced some of the changes that affect Piwik plugin developers. We have made several improvements to the Marketplace that allow developers to promote their plugin better and to maintain their plugin page easier. We have also created a migration guide for plugin developers to make it easier to migrate a plugin to Piwik 3.

  For a list of all changes have a look at the developer changelog.

  Until our next Piwik 3 update, be well, and Happy Analytics !