device/client: make device_get_list() allocate the result buffer itself

Using device_get_count() and device_get_list() separately can return different
device counts in case there are devices added to the list inbetween these two
function calls. To prevent this, device_get_list() will allocate the buffer by
itself.

3 files changed, 26 insertions, 25 deletions

diff --git a/src/client.c b/src/client.c
index d4719c3..5a70edb 100644
--- a/src/client.c
+++ b/src/client.c
@@ -267,23 +267,21 @@ static int send_device_list(struct mux_client *client, uint32_t tag)
         plist_t dict = plist_new_dict();
         plist_t devices = plist_new_array();
 
-        int count = device_get_count(0);
-        if (count > 0) {
-                struct device_info *devs;
-                struct device_info *dev;
-                int i;
-
-                devs = malloc(sizeof(struct device_info) * count);
-                count = device_get_list(0, devs);
-                dev = devs;
-                for (i = 0; i < count; i++) {
-                        plist_t device = create_device_attached_plist(dev++);
-                        if (device) {
-                                plist_array_append_item(devices, device);
-                        }
+        struct device_info *devs = NULL;
+        struct device_info *dev;
+        int i;
+
+        int count = device_get_list(0, &devs);
+        dev = devs;
+        for (i = 0; devs && i < count; i++) {
+                plist_t device = create_device_attached_plist(dev++);
+                if (device) {
+                        plist_array_append_item(devices, device);
                 }
-                free(devs);
         }
+        if (devs)
+                free(devs);
+
         plist_dict_insert_item(dict, "DeviceList", devices);
         res = send_plist_pkt(client, tag, dict);
         plist_free(dict);
@@ -369,25 +367,23 @@ static int notify_device_remove(struct mux_client *client, uint32_t device_id)
 
 static int start_listen(struct mux_client *client)
 {
-        struct device_info *devs;
+        struct device_info *devs = NULL;
         struct device_info *dev;
         int count, i;
 
         client->state = CLIENT_LISTEN;
-        count = device_get_count(0);
-        if(!count)
-                return 0;
-        devs = malloc(sizeof(struct device_info) * count);
-        count = device_get_list(0, devs);
 
+        count = device_get_list(0, &devs);
         dev = devs;
-        for(i=0; i<count; i++) {
+        for(i=0; devs && i < count; i++) {
                 if(notify_device_add(client, dev++) < 0) {
                         free(devs);
                         return -1;
                 }
         }
-        free(devs);
+        if (devs)
+                free(devs);
+
         return count;
 }
 
diff --git a/src/device.c b/src/device.c
index 29be9d1..0844499 100644
--- a/src/device.c
+++ b/src/device.c
@@ -746,10 +746,15 @@ int device_get_count(int include_hidden)
         return count;
 }
 
-int device_get_list(int include_hidden, struct device_info *p)
+int device_get_list(int include_hidden, struct device_info **devices)
 {
         int count = 0;
         pthread_mutex_lock(&device_list_mutex);
+
+        int total_count = collection_count(&device_list);
+        *devices = malloc(sizeof(struct device_info) * total_count);
+        struct device_info *p = *devices;
+
         FOREACH(struct mux_device *dev, &device_list) {
                 if((dev->state == MUXDEV_ACTIVE) && (include_hidden || dev->visible)) {
                         p->id = dev->id;
diff --git a/src/device.h b/src/device.h
index 95d470e..cb5bc24 100644
--- a/src/device.h
+++ b/src/device.h
@@ -44,7 +44,7 @@ void device_set_visible(int device_id);
 void device_set_preflight_cb_data(int device_id, void* data);
 
 int device_get_count(int include_hidden);
-int device_get_list(int include_hidden, struct device_info *p);
+int device_get_list(int include_hidden, struct device_info **devices);
 
 int device_get_timeout(void);
 void device_check_timeouts(void);