mem: add support for ringbuffers

Add an option to map the memory twice in contigious memory to
make it easier to deal with ringbuffers.

pinos/client/mem.c

@@ -75,18 +75,66 @@ static inline int memfd_create(const char *name, unsigned int flags) {
 
 #undef USE_MEMFD
 
+SpaResult
+pinos_memblock_map (PinosMemblock *mem)
+{
+  if (mem->ptr != NULL)
+    return SPA_RESULT_OK;
+
+  if (mem->flags & PINOS_MEMBLOCK_FLAG_MAP_READWRITE) {
+    int prot = 0;
+
+    if (mem->flags & PINOS_MEMBLOCK_FLAG_MAP_READ)
+      prot |= PROT_READ;
+    if (mem->flags & PINOS_MEMBLOCK_FLAG_MAP_WRITE)
+      prot |= PROT_WRITE;
+
+    if (mem->flags & PINOS_MEMBLOCK_FLAG_MAP_TWICE) {
+      void *ptr;
+
+      mem->ptr = mmap (NULL, mem->size << 1, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+      if (mem->ptr == MAP_FAILED)
+        return SPA_RESULT_NO_MEMORY;
+
+      ptr = mmap (mem->ptr, mem->size, prot, MAP_FIXED | MAP_SHARED, mem->fd, mem->offset);
+      if (ptr != mem->ptr) {
+        munmap (mem->ptr, mem->size << 1);
+        return SPA_RESULT_NO_MEMORY;
+      }
+
+      ptr = mmap (mem->ptr + mem->size, mem->size, prot, MAP_FIXED | MAP_SHARED, mem->fd, mem->offset);
+      if (ptr != mem->ptr + mem->size) {
+        munmap (mem->ptr, mem->size << 1);
+        return SPA_RESULT_NO_MEMORY;
+      }
+    } else {
+      mem->ptr = mmap (NULL, mem->size, prot, MAP_SHARED, mem->fd, 0);
+      if (mem->ptr == MAP_FAILED)
+        return SPA_RESULT_NO_MEMORY;
+    }
+  } else {
+    mem->ptr = NULL;
+  }
+  return SPA_RESULT_OK;
+}
+
 SpaResult
 pinos_memblock_alloc (PinosMemblockFlags  flags,
                       size_t              size,
                       PinosMemblock      *mem)
 {
+  bool use_fd;
+
   if (mem == NULL || size == 0)
     return SPA_RESULT_INVALID_ARGUMENTS;
 
+  mem->offset = 0;
   mem->flags = flags;
   mem->size = size;
 
-  if (flags & PINOS_MEMBLOCK_FLAG_WITH_FD) {
+  use_fd = !!(flags & (PINOS_MEMBLOCK_FLAG_MAP_TWICE | PINOS_MEMBLOCK_FLAG_WITH_FD));
+
+  if (use_fd) {
 #ifdef USE_MEMFD
     mem->fd = memfd_create ("pinos-memfd", MFD_CLOEXEC | MFD_ALLOW_SEALING);
     if (mem->fd == -1) {
@@ -116,27 +164,23 @@ pinos_memblock_alloc (PinosMemblockFlags  flags,
       }
     }
 #endif
-    if (flags & PINOS_MEMBLOCK_FLAG_MAP_READWRITE) {
+    if (pinos_memblock_map (mem) != SPA_RESULT_OK)
-      int prot = 0;
+      goto mmap_failed;
-
-      if (flags & PINOS_MEMBLOCK_FLAG_MAP_READ)
-        prot |= PROT_READ;
-      if (flags & PINOS_MEMBLOCK_FLAG_MAP_WRITE)
-        prot |= PROT_WRITE;
-
-      mem->ptr = mmap (NULL, size, prot, MAP_SHARED, mem->fd, 0);
-      if (mem->ptr == MAP_FAILED)
-        return SPA_RESULT_NO_MEMORY;
-    } else {
-      mem->ptr = NULL;
-    }
   } else {
     mem->ptr = malloc (size);
     if (mem->ptr == NULL)
       return SPA_RESULT_NO_MEMORY;
     mem->fd = -1;
   }
+  if (!(flags & PINOS_MEMBLOCK_FLAG_WITH_FD) && mem->fd != -1) {
+    close (mem->fd);
+    mem->fd = -1;
+  }
   return SPA_RESULT_OK;
+
+mmap_failed:
+  close (mem->fd);
+  return SPA_RESULT_NO_MEMORY;
 }
 
 void

pinos/client/mem.h

@@ -31,9 +31,10 @@ typedef struct _PinosMemblock PinosMemblock;
 typedef enum {
   PINOS_MEMBLOCK_FLAG_NONE           = 0,
   PINOS_MEMBLOCK_FLAG_WITH_FD        = (1 << 0),
-  PINOS_MEMBLOCK_FLAG_MAP_READ       = (1 << 1),
+  PINOS_MEMBLOCK_FLAG_SEAL           = (1 << 1),
-  PINOS_MEMBLOCK_FLAG_MAP_WRITE      = (1 << 2),
+  PINOS_MEMBLOCK_FLAG_MAP_READ       = (1 << 2),
-  PINOS_MEMBLOCK_FLAG_SEAL           = (1 << 3),
+  PINOS_MEMBLOCK_FLAG_MAP_WRITE      = (1 << 3),
+  PINOS_MEMBLOCK_FLAG_MAP_TWICE      = (1 << 4),
 } PinosMemblockFlags;
 
 #define PINOS_MEMBLOCK_FLAG_MAP_READWRITE (PINOS_MEMBLOCK_FLAG_MAP_READ | PINOS_MEMBLOCK_FLAG_MAP_WRITE)
@@ -41,6 +42,7 @@ typedef enum {
 struct _PinosMemblock {
   PinosMemblockFlags flags;
   int                fd;
+  off_t              offset;
   void              *ptr;
   size_t             size;
 };
@@ -48,6 +50,7 @@ struct _PinosMemblock {
 SpaResult     pinos_memblock_alloc     (PinosMemblockFlags  flags,
                                         size_t              size,
                                         PinosMemblock      *mem);
+SpaResult     pinos_memblock_map       (PinosMemblock      *mem);
 void          pinos_memblock_free      (PinosMemblock      *mem);
 
 #ifdef __cplusplus

pinos/client/transport.c

@@ -57,10 +57,9 @@ transport_area_get_size (PinosTransportArea *area)
 }
 
 static void
-transport_setup_area (void *p, PinosTransport *trans, bool reset)
+transport_setup_area (void *p, PinosTransport *trans)
 {
   PinosTransportArea *a;
-  int i;
 
   trans->area = a = p;
   p = SPA_MEMBER (p, sizeof (PinosTransportArea), SpaPortIO);
@@ -82,8 +81,14 @@ transport_setup_area (void *p, PinosTransport *trans, bool reset)
 
   trans->output_data = p;
   p = SPA_MEMBER (p, OUTPUT_BUFFER_SIZE, void);
+}
+
+static void
+transport_reset_area (PinosTransport *trans)
+{
+  int i;
+  PinosTransportArea *a = trans->area;
 
-  if (reset) {
   for (i = 0; i < a->max_inputs; i++) {
     trans->inputs[i].status = SPA_RESULT_OK;
     trans->inputs[i].buffer_id = SPA_ID_INVALID;
@@ -94,7 +99,6 @@ transport_setup_area (void *p, PinosTransport *trans, bool reset)
   }
   spa_ringbuffer_init (trans->input_buffer, INPUT_BUFFER_SIZE);
   spa_ringbuffer_init (trans->output_buffer, OUTPUT_BUFFER_SIZE);
-  }
 }
 
 PinosTransport *
@@ -126,7 +130,8 @@ pinos_transport_new (uint32_t max_inputs,
                         &impl->mem);
 
   memcpy (impl->mem.ptr, &area, sizeof (PinosTransportArea));
-  transport_setup_area (impl->mem.ptr, trans, true);
+  transport_setup_area (impl->mem.ptr, trans);
+  transport_reset_area (trans);
 
   return trans;
 }
@@ -148,16 +153,16 @@ pinos_transport_new_from_info (PinosTransportInfo *info)
   impl->mem.flags = PINOS_MEMBLOCK_FLAG_MAP_READWRITE |
                     PINOS_MEMBLOCK_FLAG_WITH_FD;
   impl->mem.fd = info->memfd;
+  impl->mem.offset = info->offset;
   impl->mem.size = info->size;
-  impl->mem.ptr = mmap (NULL, info->size, PROT_READ | PROT_WRITE, MAP_SHARED, info->memfd, info->offset);
+  if (pinos_memblock_map (&impl->mem) != SPA_RESULT_OK) {
-  if (impl->mem.ptr == MAP_FAILED) {
     pinos_log_warn ("transport %p: failed to map fd %d: %s", impl, info->memfd, strerror (errno));
     goto mmap_failed;
   }
 
   impl->offset = info->offset;
 
-  transport_setup_area (impl->mem.ptr, trans, false);
+  transport_setup_area (impl->mem.ptr, trans);
 
   tmp = trans->output_buffer;
   trans->output_buffer = trans->input_buffer;