BUG/MINOR: mworker: define _GNU_SOURCE for strsignal()

glibc < 2.10 requires _GNU_SOURCE in order to make use of strsignal(),
otherwise leading to SEGV at runtime.

  $ make V=1 TARGET=linux-glibc-legacy USE_THREAD= USE_ACCEPT4=
  ..
  src/mworker.c: In function 'mworker_catch_sigchld':
  src/mworker.c:285: warning: implicit declaration of function 'strsignal'
  src/mworker.c:285: warning: pointer/integer type mismatch in conditional expression
  ..

  $ make V=1 reg-tests REGTESTS_TYPES=slow,default
  ..
  ###### Test case: reg-tests/mcli/mcli_start_progs.vtc ######
  ## test results in: "/tmp/haregtests-2021-01-19_15-18-07.n24989/vtc.29077.28f6153d"
  ---- h1    Bad exit status: 0x008b exit 0x0 signal 11 core 128
  ---- h1    Assert error in haproxy_wait(), src/vtc_haproxy.c line 792:  Condition(*(&h->fds[1]) >= 0) not true.  Errno=0 Success
  ..

  $ gdb ./haproxy /tmp/core.0.haproxy.30270
  ..
  Core was generated by `/root/haproxy/haproxy -d -W -S fd@8 -dM -f /tmp/haregtests-2021-01-19_15-18-07.'.
  Program terminated with signal 11, Segmentation fault.
  #0  0x00002aaaab387a10 in strlen () from /lib64/libc.so.6
  (gdb) bt
  #0  0x00002aaaab387a10 in strlen () from /lib64/libc.so.6
  #1  0x00002aaaab354b69 in vfprintf () from /lib64/libc.so.6
  #2  0x00002aaaab37788a in vsnprintf () from /lib64/libc.so.6
  #3  0x00000000004a76a3 in memvprintf (out=0x7fffedc680a0, format=0x5a5d58 "Current worker #%d (%d) exited with code %d (%s)\n", orig_args=0x7fffedc680d0)
      at src/tools.c:3868
  #4  0x00000000004bbd40 in print_message (label=0x58abed "ALERT", fmt=0x5a5d58 "Current worker #%d (%d) exited with code %d (%s)\n", argp=0x7fffedc680d0)
      at src/log.c:1066
  #5  0x00000000004bc07f in ha_alert (fmt=0x5a5d58 "Current worker #%d (%d) exited with code %d (%s)\n") at src/log.c:1109
  #6  0x0000000000534b7b in mworker_catch_sigchld (sh=<value optimized out>) at src/mworker.c:293
  #7  0x0000000000556af3 in __signal_process_queue () at src/signal.c:88
  #8  0x00000000004f6216 in signal_process_queue () at include/haproxy/signal.h:39
  #9  run_poll_loop () at src/haproxy.c:2859
  #10 0x00000000004f63b7 in run_thread_poll_loop (data=<value optimized out>) at src/haproxy.c:3028
  #11 0x00000000004faaac in main (argc=<value optimized out>, argv=0x7fffedc68498) at src/haproxy.c:904

See: https://man7.org/linux/man-pages/man3/strsignal.3.html

Must be backported as far as 2.0.

(cherry picked from commit 25439de1811aeda7bf472f70f40c3fac9725907e)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
1 file changed