(Please copy dw...@janestreet.com on reply, as I am not subscribed to the list.)
I'd like to strace a multi-threaded program which calls fcntl
sometimes, but the combination of threads and fcntl causes strace to
segfault.
Here's a small reproduction:
cd /tmp
cat > foo.c <<'EOF'
#include <fcntl.h>
#include <unistd.h>
#include <pthread.h>
void * thread_start(void * unused) {
sleep(1);
}
int main (int argc, char **argv) {
pthread_t thread;
/* ordering of these two lines does not matter */
fcntl(1, F_GETFD, 0);
pthread_create(&thread, NULL, thread_start, NULL);
return 0;
}
EOF
gcc -l pthread foo.c
strace -f -c ./a.out
Looks like omitting any one of -f, or -c, or the pthread_create, or
the fcntl is enough to avoid the segfault, but unfortunately I need
all four of them.
What's going wrong? Is there any workaround? If not, is this
something you would fix? (No urgency on my end, but I think this is a
reasonable thing to support eventually.)
Thanks for writing strace.
Wang
Random system info, not sure what would be helpful to you:
$ strace -V
strace -- version 4.5.19
$ uname -a
Linux tot-qws-u12112a 2.6.32-431.1.2.0.1.el6.x86_64 #1 SMP Fri Dec 13
13:06:13 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
$ rpm -q --whatprovides /usr/lib64/libpthread.so
glibc-devel-2.12-1.132.el6.x86_64
$ rpm -q --whatprovides /usr/include/fcntl.h
glibc-headers-2.12-1.132.el6.x86_64
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