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  1. MariaDB Connector/C
  2. CONC-591

C connector ignoring SIGPIPE

Details

    • Bug
    • Status: Open (View Workflow)
    • Minor
    • Resolution: Unresolved
    • None
    • None
    • None
    • None
    • Debian Unstable
      libmariadb from Debian package, version 10.6.7-3+b1

    Description

      Hi,

      I have encountered an issue where a perl script which uses the MariaDB C connector (via DBD::MariaDB or DBD::mysql) ends up ignoring SIGPIPE. This results in problems such as:

      • continuing to run even when the pipeline is broken
      • printing an error on exit

      I am pretty sure that I tracked this down to code in the C connector introduced in this commit:
      https://github.com/mariadb-corporation/mariadb-connector-c/commit/1cefbbecb929b4b4a67b0ac23058ab0167e1c6d6#diff-478b1bbb2170532b687be58bd28e9850ccc0b9a6aec137eb8fff7b8e6d1107bbR3460

      A backtrace seems to confirm this (note the ignore_sigpipe() at #4):

      (gdb) bt
      		 
      #0  0x00007ffff7cab9f2 in __GI___libc_sigaction (sig=sig@entry=13, act=act@entry=0x7fffffffd950, 
          oact=oact@entry=0x7fffffffd9f0) at ../sysdeps/unix/sysv/linux/sigaction.c:58
      		 
      #1  0x00007ffff7cabb25 in __GI___sigaction (sig=sig@entry=13, act=act@entry=0x7fffffffd950, oact=oact@entry=0x7fffffffd9f0)
      		 
          at ../nptl/sigaction.c:30
      		 
      #2  0x00007ffff7cab6e5 in __bsd_signal (sig=sig@entry=13, handler=handler@entry=0x1) at ../sysdeps/posix/signal.c:45
      		 
      #3  0x00007ffff7cab73b in __bsd_signal (sig=sig@entry=13, handler=handler@entry=0x1) at ../sysdeps/posix/signal.c:35
      		 
      #4  0x00007ffff78ca025 in ignore_sigpipe () at ./libmariadb/libmariadb/mariadb_lib.c:3842
      		 
      #5  mysql_once_init () at ./libmariadb/libmariadb/mariadb_lib.c:3898
      		 
      #6  mysql_once_init () at ./libmariadb/libmariadb/mariadb_lib.c:3851
      		 
      #7  0x00007ffff7e5b610 in __pthread_once_slow (once_control=0x7ffff78f7b6c <init_once>, 
          init_routine=0x7ffff78c9fb0 <mysql_once_init>) at pthread_once.c:116
      		 
      #8  0x00007ffff7904f1d in ?? () from /usr/lib/x86_64-linux-gnu/perl5/5.34/auto/DBD/MariaDB/MariaDB.so
      		 
      #9  0x00007ffff7907f2c in ?? () from /usr/lib/x86_64-linux-gnu/perl5/5.34/auto/DBD/MariaDB/MariaDB.so
      		 
      #10 0x00007ffff7901ef0 in ?? () from /usr/lib/x86_64-linux-gnu/perl5/5.34/auto/DBD/MariaDB/MariaDB.so
      		 
      #11 0x0000555555667877 in Perl_pp_entersub ()
      		 
      #12 0x000055555565df36 in Perl_runops_standard ()
      		 
      #13 0x00005555555c1f9d in Perl_call_sv ()
      		 
      #14 0x00007ffff79310b9 in XS_DBI_dispatch () from /usr/lib/x86_64-linux-gnu/perl5/5.34/auto/DBI/DBI.so
      		 
      #15 0x0000555555667877 in Perl_pp_entersub ()
      		 
      #16 0x000055555565df36 in Perl_runops_standard ()
      		 
      #17 0x00005555555ca36c in perl_run ()
      		 
      #18 0x000055555559d4c2 in main ()

      I filed a bug with DBD::MariaDB first, but word there is that the C connector should not be ignoring SIGPIPE.
      https://github.com/perl5-dbi/DBD-MariaDB/issues/170

      It seems like this behavior must exist for an intended purpose, but I don't know what that would be. Even if there is a good reason to ignore SIGPIPE, it does have some undesired consequences.

      Thanks,
      Corey

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          pali Pali added a comment - - edited

          georg any comments for this issue?

          pali Pali added a comment - - edited georg any comments for this issue?
          pali Pali added a comment -

          This issue really needs to be fixed in MariaDB C connector. It is really hard or maybe impossible to fix it in the application which uses MariaDB C connector library.

          I this comment I wrote all details about this issue and how to fix it:
          https://github.com/perl5-dbi/DBD-MariaDB/pull/196#issuecomment-1710697577

          pali Pali added a comment - This issue really needs to be fixed in MariaDB C connector. It is really hard or maybe impossible to fix it in the application which uses MariaDB C connector library. I this comment I wrote all details about this issue and how to fix it: https://github.com/perl5-dbi/DBD-MariaDB/pull/196#issuecomment-1710697577
          pali Pali added a comment -

          I think that the fix for MariaDB C connector could be simple. When MSG_NOSIGNAL is supported or SO_NOSIGPIPE is supported or Windows is used then do not call ignore_sigpipe(). This should be enough as MariaDB C connector is already using MSG_NOSIGNAL or SO_NOSIGPIPE when supported to prevent triggering SIGPIPE when writing to disconnected socket.

          pali Pali added a comment - I think that the fix for MariaDB C connector could be simple. When MSG_NOSIGNAL is supported or SO_NOSIGPIPE is supported or Windows is used then do not call ignore_sigpipe(). This should be enough as MariaDB C connector is already using MSG_NOSIGNAL or SO_NOSIGPIPE when supported to prevent triggering SIGPIPE when writing to disconnected socket.
          pali Pali added a comment -

          georg , otto any comments for this issue?

          pali Pali added a comment - georg , otto any comments for this issue?

          People

            georg Georg Richter
            bugfood Corey Hickey
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            Dates

              Created:
              Updated:

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