xenstore: support building the xenstore clients statically.

This removes threading from libxenstore.a (but not libxenstore.so)
since pthreads is incompatible with static linking and none of the
command line clients require threads anyway.

It is now possible to build these utilities statically with a uclibc
toolchain which is useful for small userspace utility domains.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>

2 files changed, 85 insertions, 35 deletions

diff --git a/tools/xenstore/Makefile b/tools/xenstore/Makefile
index d0a0b518f1..b42e583118 100644
--- a/tools/xenstore/Makefile
+++ b/tools/xenstore/Makefile
@@ -24,8 +24,18 @@ XENSTORED_OBJS_$(CONFIG_NetBSD) = xenstored_netbsd.o
 
 XENSTORED_OBJS += $(XENSTORED_OBJS_y)
 
+ifneq ($(XENSTORE_STATIC_CLIENTS),y)
+LIBXENSTORE := libxenstore.so
+else
+LIBXENSTORE := libxenstore.a
+$(CLIENTS) xenstore-control xenstore-ls: CFLAGS += -static
+endif
+
 .PHONY: all
-all: libxenstore.so libxenstore.a xenstored $(CLIENTS) xs_tdb_dump xenstore-control xenstore-ls
+all: libxenstore.so libxenstore.a xenstored clients xs_tdb_dump 
+
+.PHONY: clients
+clients: $(CLIENTS) xenstore-control xenstore-ls
 
 ifeq ($(CONFIG_SunOS),y)
 xenstored_probes.h: xenstored_probes.d
@@ -42,16 +52,16 @@ endif
 xenstored: $(XENSTORED_OBJS)
 	$(CC) $(CFLAGS) $(LDFLAGS) $^ $(LDFLAGS_libxenctrl) $(SOCKET_LIBS) -o $@
 
-$(CLIENTS): xenstore-%: xenstore_%.o libxenstore.so
+$(CLIENTS): xenstore-%: xenstore_%.o $(LIBXENSTORE)
 	$(CC) $(CFLAGS) $(LDFLAGS) $< -L. -lxenstore $(SOCKET_LIBS) -o $@
 
 $(CLIENTS_OBJS): xenstore_%.o: xenstore_client.c
 	$(COMPILE.c) -DCLIENT_$(*F) -o $@ $<
 
-xenstore-control: xenstore_control.o libxenstore.so
+xenstore-control: xenstore_control.o $(LIBXENSTORE)
 	$(CC) $(CFLAGS) $(LDFLAGS) $< -L. -lxenstore $(SOCKET_LIBS) -o $@
 
-xenstore-ls: xsls.o libxenstore.so
+xenstore-ls: xsls.o $(LIBXENSTORE)
 	$(CC) $(CFLAGS) $(LDFLAGS) $< -L. -lxenstore $(SOCKET_LIBS) -o $@
 
 xs_tdb_dump: xs_tdb_dump.o utils.o tdb.o talloc.o
@@ -62,6 +72,8 @@ libxenstore.so: libxenstore.so.$(MAJOR)
 libxenstore.so.$(MAJOR): libxenstore.so.$(MAJOR).$(MINOR)
 	ln -sf $< $@
 
+xs.opic: CFLAGS += -DUSE_PTHREAD
+
 libxenstore.so.$(MAJOR).$(MINOR): xs.opic xs_lib.opic
 	$(CC) $(CFLAGS) $(LDFLAGS) -Wl,$(SONAME_LDFLAG) -Wl,libxenstore.so.$(MAJOR) $(SHLIB_CFLAGS) -o $@ $^ $(SOCKET_LIBS) -lpthread
 
diff --git a/tools/xenstore/xs.c b/tools/xenstore/xs.c
index dbbf8ef394..94db1ce45e 100644
--- a/tools/xenstore/xs.c
+++ b/tools/xenstore/xs.c
@@ -32,7 +32,6 @@
 #include <signal.h>
 #include <stdint.h>
 #include <errno.h>
-#include <pthread.h>
 #include "xs.h"
 #include "list.h"
 #include "utils.h"
@@ -43,6 +42,10 @@ struct xs_stored_msg {
 	char *body;
 };
 
+#ifdef USE_PTHREAD
+
+#include <pthread.h>
+
 struct xs_handle {
 	/* Communications channel to xenstore daemon. */
 	int fd;
@@ -78,14 +81,37 @@ struct xs_handle {
 	pthread_mutex_t request_mutex;
 };
 
-static int read_message(struct xs_handle *h);
+#define mutex_lock(m)		pthread_mutex_lock(m)
+#define mutex_unlock(m)		pthread_mutex_unlock(m)
+#define condvar_signal(c)	pthread_cond_signal(c)
+#define condvar_wait(c,m,hnd)	pthread_cond_wait(c,m)
+
 static void *read_thread(void *arg);
 
+#else /* !defined(USE_PTHREAD) */
+
+struct xs_handle {
+	int fd;
+	struct list_head reply_list;
+	struct list_head watch_list;
+	/* Clients can select() on this pipe to wait for a watch to fire. */
+	int watch_pipe[2];
+};
+
+#define mutex_lock(m)		((void)0)
+#define mutex_unlock(m)		((void)0)
+#define condvar_signal(c)	((void)0)
+#define condvar_wait(c,m,hnd)	read_message(hnd)
+
+#endif
+
+static int read_message(struct xs_handle *h);
+
 int xs_fileno(struct xs_handle *h)
 {
 	char c = 0;
 
-	pthread_mutex_lock(&h->watch_mutex);
+	mutex_lock(&h->watch_mutex);
 
 	if ((h->watch_pipe[0] == -1) && (pipe(h->watch_pipe) != -1)) {
 		/* Kick things off if the watch list is already non-empty. */
@@ -94,7 +120,7 @@ int xs_fileno(struct xs_handle *h)
 				continue;
 	}
 
-	pthread_mutex_unlock(&h->watch_mutex);
+	mutex_unlock(&h->watch_mutex);
 
 	return h->watch_pipe[0];
 }
@@ -163,18 +189,21 @@ static struct xs_handle *get_handle(const char *connect_to)
 
 	h->fd = fd;
 
+	INIT_LIST_HEAD(&h->reply_list);
+	INIT_LIST_HEAD(&h->watch_list);
+
 	/* Watch pipe is allocated on demand in xs_fileno(). */
 	h->watch_pipe[0] = h->watch_pipe[1] = -1;
 
-	INIT_LIST_HEAD(&h->watch_list);
+#ifdef USE_PTHREAD
 	pthread_mutex_init(&h->watch_mutex, NULL);
 	pthread_cond_init(&h->watch_condvar, NULL);
 
-	INIT_LIST_HEAD(&h->reply_list);
 	pthread_mutex_init(&h->reply_mutex, NULL);
 	pthread_cond_init(&h->reply_condvar, NULL);
 
 	pthread_mutex_init(&h->request_mutex, NULL);
+#endif
 
 	return h;
 }
@@ -198,15 +227,17 @@ void xs_daemon_close(struct xs_handle *h)
 {
 	struct xs_stored_msg *msg, *tmsg;
 
-	pthread_mutex_lock(&h->request_mutex);
-	pthread_mutex_lock(&h->reply_mutex);
-	pthread_mutex_lock(&h->watch_mutex);
+	mutex_lock(&h->request_mutex);
+	mutex_lock(&h->reply_mutex);
+	mutex_lock(&h->watch_mutex);
 
+#ifdef USE_PTHREAD
 	if (h->read_thr_exists) {
 		/* XXX FIXME: May leak an unpublished message buffer. */
 		pthread_cancel(h->read_thr);
 		pthread_join(h->read_thr, NULL);
 	}
+#endif
 
 	list_for_each_entry_safe(msg, tmsg, &h->reply_list, list) {
 		free(msg->body);
@@ -218,9 +249,9 @@ void xs_daemon_close(struct xs_handle *h)
 		free(msg);
 	}
 
-	pthread_mutex_unlock(&h->request_mutex);
-	pthread_mutex_unlock(&h->reply_mutex);
-	pthread_mutex_unlock(&h->watch_mutex);
+	mutex_unlock(&h->request_mutex);
+	mutex_unlock(&h->reply_mutex);
+	mutex_unlock(&h->watch_mutex);
 
 	if (h->watch_pipe[0] != -1) {
 		close(h->watch_pipe[0]);
@@ -277,17 +308,19 @@ static void *read_reply(
 	struct xs_stored_msg *msg;
 	char *body;
 
+#ifdef USE_PTHREAD
 	/* Read from comms channel ourselves if there is no reader thread. */
 	if (!h->read_thr_exists && (read_message(h) == -1))
 		return NULL;
+#endif
 
-	pthread_mutex_lock(&h->reply_mutex);
+	mutex_lock(&h->reply_mutex);
 	while (list_empty(&h->reply_list))
-		pthread_cond_wait(&h->reply_condvar, &h->reply_mutex);
+		condvar_wait(&h->reply_condvar, &h->reply_mutex, h);
 	msg = list_top(&h->reply_list, struct xs_stored_msg, list);
 	list_del(&msg->list);
 	assert(list_empty(&h->reply_list));
-	pthread_mutex_unlock(&h->reply_mutex);
+	mutex_unlock(&h->reply_mutex);
 
 	*type = msg->hdr.type;
 	if (len)
@@ -329,7 +362,7 @@ static void *xs_talkv(struct xs_handle *h, xs_transaction_t t,
 	ignorepipe.sa_flags = 0;
 	sigaction(SIGPIPE, &ignorepipe, &oldact);
 
-	pthread_mutex_lock(&h->request_mutex);
+	mutex_lock(&h->request_mutex);
 
 	if (!xs_write_all(h->fd, &msg, sizeof(msg)))
 		goto fail;
@@ -342,7 +375,7 @@ static void *xs_talkv(struct xs_handle *h, xs_transaction_t t,
 	if (!ret)
 		goto fail;
 
-	pthread_mutex_unlock(&h->request_mutex);
+	mutex_unlock(&h->request_mutex);
 
 	sigaction(SIGPIPE, &oldact, NULL);
 	if (msg.type == XS_ERROR) {
@@ -362,7 +395,7 @@ static void *xs_talkv(struct xs_handle *h, xs_transaction_t t,
 fail:
 	/* We're in a bad state, so close fd. */
 	saved_errno = errno;
-	pthread_mutex_unlock(&h->request_mutex);
+	mutex_unlock(&h->request_mutex);
 	sigaction(SIGPIPE, &oldact, NULL);
 close_fd:
 	close(h->fd);
@@ -556,16 +589,18 @@ bool xs_watch(struct xs_handle *h, const char *path, const char *token)
 {
 	struct iovec iov[2];
 
+#ifdef USE_PTHREAD
 	/* We dynamically create a reader thread on demand. */
-	pthread_mutex_lock(&h->request_mutex);
+	mutex_lock(&h->request_mutex);
 	if (!h->read_thr_exists) {
 		if (pthread_create(&h->read_thr, NULL, read_thread, h) != 0) {
-			pthread_mutex_unlock(&h->request_mutex);
+			mutex_unlock(&h->request_mutex);
 			return false;
 		}
 		h->read_thr_exists = 1;
 	}
-	pthread_mutex_unlock(&h->request_mutex);
+	mutex_unlock(&h->request_mutex);
+#endif
 
 	iov[0].iov_base = (void *)path;
 	iov[0].iov_len = strlen(path) + 1;
@@ -586,11 +621,11 @@ char **xs_read_watch(struct xs_handle *h, unsigned int *num)
 	char **ret, *strings, c = 0;
 	unsigned int num_strings, i;
 
-	pthread_mutex_lock(&h->watch_mutex);
+	mutex_lock(&h->watch_mutex);
 
 	/* Wait on the condition variable for a watch to fire. */
 	while (list_empty(&h->watch_list))
-		pthread_cond_wait(&h->watch_condvar, &h->watch_mutex);
+		condvar_wait(&h->watch_condvar, &h->watch_mutex, h);
 	msg = list_top(&h->watch_list, struct xs_stored_msg, list);
 	list_del(&msg->list);
 
@@ -599,7 +634,7 @@ char **xs_read_watch(struct xs_handle *h, unsigned int *num)
 		while (read(h->watch_pipe[0], &c, 1) != 1)
 			continue;
 
-	pthread_mutex_unlock(&h->watch_mutex);
+	mutex_unlock(&h->watch_mutex);
 
 	assert(msg->hdr.type == XS_WATCH_EVENT);
 
@@ -801,7 +836,7 @@ static int read_message(struct xs_handle *h)
 	body[msg->hdr.len] = '\0';
 
 	if (msg->hdr.type == XS_WATCH_EVENT) {
-		pthread_mutex_lock(&h->watch_mutex);
+		mutex_lock(&h->watch_mutex);
 
 		/* Kick users out of their select() loop. */
 		if (list_empty(&h->watch_list) &&
@@ -810,22 +845,23 @@ static int read_message(struct xs_handle *h)
 				continue;
 
 		list_add_tail(&msg->list, &h->watch_list);
-		pthread_cond_signal(&h->watch_condvar);
 
-		pthread_mutex_unlock(&h->watch_mutex);
+		condvar_signal(&h->watch_condvar);
+
+		mutex_unlock(&h->watch_mutex);
 	} else {
-		pthread_mutex_lock(&h->reply_mutex);
+		mutex_lock(&h->reply_mutex);
 
 		/* There should only ever be one response pending! */
 		if (!list_empty(&h->reply_list)) {
-			pthread_mutex_unlock(&h->reply_mutex);
+			mutex_unlock(&h->reply_mutex);
 			goto error;
 		}
 
 		list_add_tail(&msg->list, &h->reply_list);
-		pthread_cond_signal(&h->reply_condvar);
+		condvar_signal(&h->reply_condvar);
 
-		pthread_mutex_unlock(&h->reply_mutex);
+		mutex_unlock(&h->reply_mutex);
 	}
 
 	return 0;
@@ -838,6 +874,7 @@ static int read_message(struct xs_handle *h)
 	return -1;
 }
 
+#ifdef USE_PTHREAD
 static void *read_thread(void *arg)
 {
 	struct xs_handle *h = arg;
@@ -847,6 +884,7 @@ static void *read_thread(void *arg)
 
 	return NULL;
 }
+#endif
 
 /*
  * Local variables: