Add TLS (thread-local storage) tests

Add tls/ folder. __thread.c highlights the use of implicit TLS, i.e. via
the `__thread` storage class keyword. tsd.c uses explicit TLS, i.e. via
`pthread_setspecific()` / `pthread_getspecific` function calls.

Author: razvand

tls/.gitignore

@@ -0,0 +1,4 @@
+/__thread
+/__thread-static
+/tsd
+/tsd-static

tls/Makefile

@@ -0,0 +1,25 @@
+CFLAGS = -Wall
+LDLIBS = -lpthread
+
+.PHONY: all clean
+
+all: __thread __thread-static tsd tsd-static
+
+__thread-static: __thread.o
+	$(CC) $(LDLFAGS) -static -o $@ $^ $(LDLIBS)
+
+__thread: __thread.o
+
+__thread.o: __thread.c
+
+tsd-static: tsd.o
+	$(CC) $(LDLFAGS) -static -o $@ $^ $(LDLIBS)
+
+tsd: tsd.o
+
+tsd.o: tsd.c
+
+clean:
+	-rm -f __thread.o __thread __thread-static
+	-rm -f tsd.o tsd tsd-static
+	-rm -f *~

tls/__thread.c

@@ -0,0 +1,63 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/types.h>
+
+static __thread size_t me;
+static __thread size_t you;
+static __thread size_t them = 543;
+
+static void *tf(void *arg)
+{
+	unsigned long id = (unsigned long) arg;
+	static __thread size_t us = 13;
+
+	me = 200 + id;
+	us += id*id;
+	printf("me in thread (%p): %zu\n", &me, me);
+	printf("you in thread (%p): %zu\n", &you, you);
+	printf("you in thread (%p): %zu\n", &them, them);
+	printf("us in thread (%p): %zu\n", &us, us);
+	printf("errno in thread (%p): %d\n", &errno, errno);
+
+	return NULL;
+}
+
+int main(void)
+{
+	pthread_t new;
+	int err;
+
+	me = 100;
+	you = 999;
+	them = 3;
+	printf("me before create (%p): %zu\n", &me, me);
+	printf("you before create (%p): %zu\n", &you, you);
+	printf("them before create (%p): %zu\n", &them, them);
+	printf("errno before create (%p): %d\n", &errno, errno);
+
+	err = pthread_create(&new, NULL, tf, (void *) 1);
+	if (err < 0) {
+		perror("pthread_create");
+		exit(EXIT_FAILURE);
+	}
+	err = pthread_create(&new, NULL, tf, (void *) 2);
+	if (err < 0) {
+		perror("pthread_create");
+		exit(EXIT_FAILURE);
+	}
+
+	printf("me after create before join (%p): %zu\n", &me, me);
+	printf("you after create before join (%p): %zu\n", &you, you);
+	printf("them after create before join (%p): %zu\n", &them, them);
+	printf("errno after create before join (%p): %d\n", &errno, errno);
+	pthread_join(new, NULL);
+	printf("me after join (%p): %zu\n", &me, me);
+	printf("you after join (%p): %zu\n", &you, you);
+	printf("them after join (%p): %zu\n", &them, them);
+	printf("errno after join (%p): %d\n", &errno, errno);
+
+	return 0;
+}

tls/tsd.c

@@ -0,0 +1,57 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+static pthread_key_t me_key;
+static pthread_key_t you_key;
+static pthread_key_t them_key;
+
+static void *tf(void *arg)
+{
+	pthread_setspecific(me_key, (const void *) 200);
+	printf("me_key in thread (%p): %u, me value in thread: %zu\n", &me_key, me_key, (size_t) pthread_getspecific(me_key));
+	printf("you_key in thread (%p): %u, you value in thread: %zu\n", &you_key, you_key, (size_t) pthread_getspecific(you_key));
+	printf("them_key in thread (%p): %u, them value in thread: %zu\n", &them_key, them_key, (size_t) pthread_getspecific(them_key));
+
+	return NULL;
+}
+
+int main(void)
+{
+	pthread_t new;
+	int err;
+
+	pthread_key_create(&me_key, NULL);
+	pthread_key_create(&you_key, NULL);
+	pthread_key_create(&them_key, NULL);
+
+	pthread_setspecific(me_key, (const void *) 100);
+	pthread_setspecific(you_key, (const void *) 999);
+	pthread_setspecific(them_key, (const void *) 3);
+	printf("me_key before create (%p): %u, me value before create: %zu\n", &me_key, me_key, (size_t) pthread_getspecific(me_key));
+	printf("you_key before create (%p): %u, me value before create: %zu\n", &you_key, you_key, (size_t) pthread_getspecific(you_key));
+	printf("them_key before create (%p): %u, me value before create: %zu\n", &them_key, them_key, (size_t) pthread_getspecific(them_key));
+
+	err = pthread_create(&new, NULL, tf, NULL);
+	if (err < 0) {
+		perror("pthread_create");
+		exit(EXIT_FAILURE);
+	}
+
+	printf("me_key after create before join (%p): %u, me value after create before join: %zu\n", &me_key, me_key, (size_t) pthread_getspecific(me_key));
+	printf("you_key after create before join (%p): %u, you value after create before join: %zu\n", &you_key, you_key, (size_t) pthread_getspecific(you_key));
+	printf("them_key after create before join (%p): %u, them value beafter create before join: %zu\n", &them_key, them_key, (size_t) pthread_getspecific(them_key));
+	pthread_join(new, NULL);
+	printf("me_key after join (%p): %u, me value after join: %zu\n", &me_key, me_key, (size_t) pthread_getspecific(me_key));
+	printf("you_key after join (%p): %u, you value after join: %zu\n", &you_key, you_key, (size_t) pthread_getspecific(you_key));
+	printf("them_key after join (%p): %u, them value after join: %zu\n", &them_key, them_key, (size_t) pthread_getspecific(them_key));
+
+	/* This is really not required, but we call it for API completeness. */
+	pthread_key_delete(me_key);
+	pthread_key_delete(you_key);
+	pthread_key_delete(them_key);
+
+	return 0;
+}