When exiting a process, rtdk buffers are not flushed. Fix that by
introducing a destructor for the library which flushes the buffers.

When forking, if the main thread has an rt_printf buffer, it is reused by
the child, which is a good thing, however, it is not emptied, so could cause
the same message to be printed twice. Fix that by emptying the main thread
buffer upon fork.

When spawning the rt_print thread, it uses a stack size of
PTHREAD_STACK_MIN, which may be too small for printf to work reliably on
some architectures, set the stack size to the
empirically-known-to-be-working size of... 32Kb.
---
 src/rtdk/init.c     |    5 +++++
 src/rtdk/internal.h |    1 +
 src/rtdk/rt_print.c |   21 ++++++++++++++++++++-
 3 files changed, 26 insertions(+), 1 deletions(-)

diff --git a/src/rtdk/init.c b/src/rtdk/init.c
index 2084c73..b864175 100644
--- a/src/rtdk/init.c
+++ b/src/rtdk/init.c
@@ -22,3 +22,8 @@ static __attribute__ ((constructor)) void __init_rtdk(void)
 {
        __rt_print_init();
 }
+
+static __attribute__ ((destructor)) void __exit_rtdk(void)
+{
+       __rt_print_exit();
+}
diff --git a/src/rtdk/internal.h b/src/rtdk/internal.h
index bd15b2d..345d4fa 100644
--- a/src/rtdk/internal.h
+++ b/src/rtdk/internal.h
@@ -23,6 +23,7 @@
 #include <sys/time.h>
 
 void __rt_print_init(void);
+void __rt_print_exit(void);
 
 void __real_free(void *ptr);
 void *__real_malloc(size_t size);
diff --git a/src/rtdk/rt_print.c b/src/rtdk/rt_print.c
index c6b5c55..dae7d7b 100644
--- a/src/rtdk/rt_print.c
+++ b/src/rtdk/rt_print.c
@@ -455,7 +455,7 @@ static void spawn_printer_thread(void)
        pthread_attr_t thattr;
 
        pthread_attr_init(&thattr);
-       pthread_attr_setstacksize(&thattr, PTHREAD_STACK_MIN);
+       pthread_attr_setstacksize(&thattr, 32768);
        pthread_create(&printer_thread, &thattr, printer_loop, NULL);
 }
 
@@ -464,6 +464,15 @@ static void forked_child_init(void)
        struct print_buffer *my_buffer = pthread_getspecific(buffer_key);
        struct print_buffer **pbuffer = &first_buffer;
 
+       if (my_buffer) {
+               /* Any content of my_buffer should be printed by our parent,
+                  not us. */
+               memset(my_buffer->ring, 0, my_buffer->size);
+
+               my_buffer->read_pos  = 0;
+               my_buffer->write_pos = 0;
+       }
+
        /* re-init to avoid finding it locked by some parent thread */
        pthread_mutex_init(&buffer_lock, NULL);
 
@@ -518,3 +527,13 @@ void __rt_print_init(void)
        spawn_printer_thread();
        pthread_atfork(NULL, NULL, forked_child_init);
 }
+
+void __rt_print_exit(void)
+{
+       if (buffers) {
+               /* Flush the buffers. Do not call print_buffers here
+                * since we do not know if our stack is big enough. */
+               nanosleep(&print_period, NULL);
+               nanosleep(&print_period, NULL);
+       }
+}
-- 
1.5.6.5


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