lib: Add missing modulo calculation

Adds a missing modulo calculation that would result in index -1 being
returned instead of zero when the ringbuffer skipped back to the
beginning.

5 files changed, 24 insertions, 25 deletions

diff --git a/include/ouroboros/shm_ap_rbuff.h b/include/ouroboros/shm_ap_rbuff.h
index 0ee3e81e..956a9540 100644
--- a/include/ouroboros/shm_ap_rbuff.h
+++ b/include/ouroboros/shm_ap_rbuff.h
@@ -37,8 +37,8 @@
 struct shm_ap_rbuff;
 
 struct rb_entry {
-        size_t index;
-        int    port_id;
+        ssize_t index;
+        int     port_id;
 };
 
 struct shm_ap_rbuff * shm_ap_rbuff_create();
diff --git a/include/ouroboros/shm_du_map.h b/include/ouroboros/shm_du_map.h
index f575aa42..35d85b11 100644
--- a/include/ouroboros/shm_du_map.h
+++ b/include/ouroboros/shm_du_map.h
@@ -47,18 +47,18 @@ void                 shm_du_map_close(struct shm_du_map * dum);
 void                 shm_du_map_destroy(struct shm_du_map * dum);
 
 /* returns the index of the buffer in the DU map */
-int shm_create_du_buff(struct shm_du_map * dum,
-                       size_t              size,
-                       size_t              headspace,
-                       uint8_t           * data,
-                       size_t              len);
+ssize_t  shm_create_du_buff(struct shm_du_map * dum,
+                            size_t              size,
+                            size_t              headspace,
+                            uint8_t           * data,
+                            size_t              len);
 
 /* FIXME: revise these */
-int       shm_du_map_read_sdu(uint8_t **           dst,
-                               struct shm_du_map * dum,
-                               size_t              idx);
-int       shm_release_du_buff(struct shm_du_map  * dum, size_t idx);
-
+int       shm_du_map_read_sdu(uint8_t **          dst,
+                              struct shm_du_map * dum,
+                              ssize_t             idx);
+int       shm_release_du_buff(struct shm_du_map  * dum,
+                              ssize_t idx);
 
 /* FIXME: use shm_du_map * and index */
 uint8_t * shm_du_buff_head_alloc(struct shm_du_buff * sdb,
diff --git a/src/ipcpd/shim-udp/main.c b/src/ipcpd/shim-udp/main.c
index e3f7fcdd..0802583c 100644
--- a/src/ipcpd/shim-udp/main.c
+++ b/src/ipcpd/shim-udp/main.c
@@ -204,8 +204,7 @@ static int port_id_to_fd(int port_id)
 
 static ssize_t ipcp_udp_flow_write(int fd, void * buf, size_t count)
 {
-        /* the AP chooses the amount of headspace and tailspace */
-        size_t index;
+        ssize_t index;
         struct rb_entry e;
 
         rw_lock_rdlock(&_ipcp->state_lock);
diff --git a/src/lib/dev.c b/src/lib/dev.c
index 9b29b992..c365a17b 100644
--- a/src/lib/dev.c
+++ b/src/lib/dev.c
@@ -531,7 +531,7 @@ int flow_cntl(int fd, int cmd, int oflags)
 
 ssize_t flow_write(int fd, void * buf, size_t count)
 {
-        size_t index;
+        ssize_t index;
         struct rb_entry e;
 
         if (buf == NULL)
diff --git a/src/lib/shm_du_map.c b/src/lib/shm_du_map.c
index 7099b265..a7ec5ac9 100644
--- a/src/lib/shm_du_map.c
+++ b/src/lib/shm_du_map.c
@@ -227,11 +227,11 @@ void shm_du_map_destroy(struct shm_du_map * dum)
         free(dum);
 }
 
-int shm_create_du_buff(struct shm_du_map * dum,
-                       size_t              size,
-                       size_t              headspace,
-                       uint8_t *           data,
-                       size_t              len)
+ssize_t shm_create_du_buff(struct shm_du_map * dum,
+                           size_t              size,
+                           size_t              headspace,
+                           uint8_t *           data,
+                           size_t              len)
 {
         struct shm_du_buff * sdb;
         long                 blocks = 0;
@@ -239,7 +239,7 @@ int shm_create_du_buff(struct shm_du_map * dum,
         int                  sz2 = headspace + len + sizeof *sdb;
         uint8_t *            write_pos;
         size_t               copy_len;
-        size_t               index;
+        ssize_t              index;
 
         if (dum == NULL || data == NULL) {
                 LOG_DBGF("Bogus input, bugging out.");
@@ -294,7 +294,7 @@ int shm_create_du_buff(struct shm_du_map * dum,
                 --blocks;
         }
 
-        index = *dum->ptr_head - 1;
+        index = (*dum->ptr_head - 1) & (SHM_BLOCKS_IN_MAP - 1);
 
         pthread_mutex_unlock(dum->shm_mutex);
 
@@ -304,9 +304,9 @@ int shm_create_du_buff(struct shm_du_map * dum,
 /* FIXME: this cannot handle packets stretching beyond the ringbuffer border */
 int shm_du_map_read_sdu(uint8_t **          dst,
                         struct shm_du_map * dum,
-                        size_t              idx)
+                        ssize_t             idx)
 {
-        size_t    len = 0;
+        size_t len = 0;
 
         if (idx > SHM_BLOCKS_IN_MAP)
                 return -1;
@@ -328,7 +328,7 @@ int shm_du_map_read_sdu(uint8_t **          dst,
         return len;
 }
 
-int shm_release_du_buff(struct shm_du_map * dum, size_t idx)
+int shm_release_du_buff(struct shm_du_map * dum, ssize_t idx)
 {
         long sz;
         long blocks = 0;