[Patch][RFC] ARM glibc-2.5 sigwait() with linuxthreads has a problem.

[ryosei at sm dot sony dot co dot jp]

Hi all,

I am using the following ARM toolchain and found a problem with
respect to sigwait().

binutils: binutils-2.17
     gcc: gcc-4.1.1
   glibc: glibc-2.5/glibc-linuxthreads-2.5

The problem is that sigwait() doesn't store the number of the
signal received in some cases.

Sample codes, build procedures and an execution result are as follows.

[sample codes]

--- main.c ---
extern int func(void);

int
main(void)
{
  func();
  return 0;
}

--- func.c ---
#include <stdio.h>
#include <pthread.h>
#include <signal.h>

sigset_t signal_set;

void *
thread_routine(void *arg)
{
  int signum;

  sigwait(&signal_set, &signum);

  if(signum == SIGUSR1)
    printf("OK: SIGUSR1\n");
  else
    printf("NG:  %d\n", signum);

  return 0;
}


int
func(void)
{
  pthread_t th;
  int ret;

  sigemptyset(&signal_set);
  sigaddset(&signal_set, SIGUSR1);
  pthread_sigmask(SIG_BLOCK, &signal_set, NULL);

  pthread_create(&th, NULL, thread_routine, NULL);

  /* wait for a while and send a signal*/
  sleep(1);
  pthread_kill(th, SIGUSR1);

  pthread_join(th, NULL);
  return 0;
}



[build procedures]
$ arm-unknown-linux-gnueabi-gcc -shared -o func.so func.c -fPIC -lpthread
$ arm-unknown-linux-gnueabi-gcc -o main main.c func.so

[execution result]
# LD_LIBRARY_PATH=./ ./main
NG:  0


As the execution result, sigwait() doesn't store the signal 
number[SIGUSR1]!


I suppose the cause of this problem is as follows.
* In the case of above sample codes, pthread_sigwait() in libpthread.so
  call sigaction() in libc.so
* And sigaction() in libc.so doesn't call pthread_sigaction() 
  in libpthread.so.
* This is because the following file exists but is not compiled.

       linuxthreads/sysdeps/pthread/sigaction.c

Are there any reasons why the above file, 
sigaction.c in linuxthreads directory, is not compiled??
# I have confirmed that in the case of glibc-2.3.6/glibc-linuxthreads-2.3.6
# the above sigaction.c is compiled.

With the below patch which I created, the above sigaction.c is compiled 
and the problem is fixed. Is this patch fine??

Best Regards,
Ryosei Takagi


diff -Naur glibc-ports-2.5.orig/sysdeps/unix/sysv/linux/arm/linuxthreads/sigaction.c glibc-ports-2.5/sysdeps/unix/sysv/linux/arm/linuxthreads/sigaction.c
--- glibc-ports-2.5.orig/sysdeps/unix/sysv/linux/arm/linuxthreads/sigaction.c   1970-01-01 00:00:00.000000000 +0000
+++ glibc-ports-2.5/sysdeps/unix/sysv/linux/arm/linuxthreads/sigaction.c        2007-11-13 03:59:06.000000000 +0000
@@ -0,0 +1,5 @@
+#ifndef LIBC_SIGACTION
+# include <linuxthreads/sysdeps/pthread/sigaction.c>
+#else
+# include_next <sigaction.c>
+#endif