ipcpd, lib: Add flow down events

This adds the flow down event to Ouroboros. In the shim-eth-llc, a
netlink socket is opened which listens to device up/down events. For
each event the flow is then adjusted with fccntl to notify the user
the flow is down or back up again. In the normal IPCP an event is
thrown if a write reports that the flow is down.

1 files changed, 36 insertions, 16 deletions

diff --git a/src/lib/shm_rbuff_pthr.c b/src/lib/shm_rbuff_pthr.c
index 9567762f..fb183d8f 100644
--- a/src/lib/shm_rbuff_pthr.c
+++ b/src/lib/shm_rbuff_pthr.c
@@ -26,6 +26,7 @@
 #include <ouroboros/lockfile.h>
 #include <ouroboros/time_utils.h>
 #include <ouroboros/errno.h>
+#include <ouroboros/fccntl.h>
 
 #include <pthread.h>
 #include <sys/mman.h>
@@ -41,8 +42,6 @@
 #include <stdbool.h>
 
 #define FN_MAX_CHARS 255
-#define RB_OPEN 0
-#define RB_CLOSED 1
 
 #define SHM_RBUFF_FILE_SIZE ((SHM_BUFFER_SIZE) * sizeof(ssize_t)          \
                              + 3 * sizeof(size_t)                         \
@@ -138,7 +137,7 @@ struct shm_rbuff * shm_rbuff_create(pid_t api, int port_id)
         pthread_cond_init(rb->add, &cattr);
         pthread_cond_init(rb->del, &cattr);
 
-        *rb->acl = RB_OPEN;
+        *rb->acl  = ACL_RDWR;
         *rb->head = 0;
         *rb->tail = 0;
 
@@ -226,8 +225,11 @@ void shm_rbuff_destroy(struct shm_rbuff * rb)
         free(rb);
 }
 
-int shm_rbuff_write(struct shm_rbuff * rb, size_t idx)
+int shm_rbuff_write(struct shm_rbuff * rb,
+                    size_t             idx)
 {
+        int ret = 0;
+
         assert(rb);
         assert(idx < SHM_BUFFER_SIZE);
 
@@ -237,14 +239,18 @@ int shm_rbuff_write(struct shm_rbuff * rb, size_t idx)
         if (pthread_mutex_lock(rb->lock) == EOWNERDEAD)
                 pthread_mutex_consistent(rb->lock);
 #endif
-        if (*rb->acl == RB_CLOSED) {
-                pthread_mutex_unlock(rb->lock);
-                return -ENOTALLOC;
+
+        if (*rb->acl != ACL_RDWR) {
+                if (*rb->acl & ACL_FLOWDOWN)
+                        ret = -EFLOWDOWN;
+                else if (*rb->acl & ACL_RDONLY)
+                        ret = -ENOTALLOC;
+                goto err;
         }
 
         if (!shm_rbuff_free(rb)) {
-                pthread_mutex_unlock(rb->lock);
-                return -EAGAIN;
+                ret = -EAGAIN;
+                goto err;
         }
 
         if (shm_rbuff_empty(rb))
@@ -256,6 +262,9 @@ int shm_rbuff_write(struct shm_rbuff * rb, size_t idx)
         pthread_mutex_unlock(rb->lock);
 
         return 0;
+ err:
+        pthread_mutex_unlock(rb->lock);
+        return ret;
 }
 
 ssize_t shm_rbuff_read(struct shm_rbuff * rb)
@@ -270,9 +279,11 @@ ssize_t shm_rbuff_read(struct shm_rbuff * rb)
         if (pthread_mutex_lock(rb->lock) == EOWNERDEAD)
                 pthread_mutex_consistent(rb->lock);
 #endif
+
         if (shm_rbuff_empty(rb)) {
+                ret = *rb->acl & ACL_FLOWDOWN ? -EFLOWDOWN : -EAGAIN;
                 pthread_mutex_unlock(rb->lock);
-                return -EAGAIN;
+                return ret;
         }
 
         ret = *tail_el_ptr(rb);
@@ -297,6 +308,12 @@ ssize_t shm_rbuff_read_b(struct shm_rbuff *      rb,
         if (pthread_mutex_lock(rb->lock) == EOWNERDEAD)
                 pthread_mutex_consistent(rb->lock);
 #endif
+
+        if (shm_rbuff_empty(rb) && (*rb->acl & ACL_FLOWDOWN)) {
+                pthread_mutex_unlock(rb->lock);
+                return -EFLOWDOWN;
+        }
+
         pthread_cleanup_push((void(*)(void *))pthread_mutex_unlock,
                              (void *) rb->lock);
 
@@ -324,7 +341,8 @@ ssize_t shm_rbuff_read_b(struct shm_rbuff *      rb,
         return idx;
 }
 
-void shm_rbuff_block(struct shm_rbuff * rb)
+void shm_rbuff_set_acl(struct shm_rbuff * rb,
+                       uint32_t           flags)
 {
         assert(rb);
 
@@ -334,13 +352,15 @@ void shm_rbuff_block(struct shm_rbuff * rb)
         if (pthread_mutex_lock(rb->lock) == EOWNERDEAD)
                 pthread_mutex_consistent(rb->lock);
 #endif
-        *rb->acl = RB_CLOSED;
+        *rb->acl = (size_t) flags;
 
         pthread_mutex_unlock(rb->lock);
 }
 
-void shm_rbuff_unblock(struct shm_rbuff * rb)
+uint32_t shm_rbuff_get_acl(struct shm_rbuff * rb)
 {
+        uint32_t flags;
+
         assert(rb);
 
 #ifndef HAVE_ROBUST_MUTEX
@@ -349,9 +369,11 @@ void shm_rbuff_unblock(struct shm_rbuff * rb)
         if (pthread_mutex_lock(rb->lock) == EOWNERDEAD)
                 pthread_mutex_consistent(rb->lock);
 #endif
-        *rb->acl = RB_OPEN;
+        flags = (uint32_t) *rb->acl;
 
         pthread_mutex_unlock(rb->lock);
+
+        return flags;
 }
 
 void shm_rbuff_fini(struct shm_rbuff * rb)
@@ -364,8 +386,6 @@ void shm_rbuff_fini(struct shm_rbuff * rb)
         if (pthread_mutex_lock(rb->lock) == EOWNERDEAD)
                 pthread_mutex_consistent(rb->lock);
 #endif
-        assert(*rb->acl == RB_CLOSED);
-
         pthread_cleanup_push((void(*)(void *))pthread_mutex_unlock,
                              (void *) rb->lock);