Add block_shm_Alloc()

include/vlc_block.h

@@ -168,6 +168,7 @@ static inline void block_Release( block_t *p_block )
 
 VLC_API block_t *block_heap_Alloc(void *, size_t) VLC_USED VLC_MALLOC;
 VLC_API block_t *block_mmap_Alloc(void *addr, size_t length) VLC_USED VLC_MALLOC;
+VLC_API block_t * block_shm_Alloc(void *addr, size_t length) VLC_USED VLC_MALLOC;
 VLC_API block_t *block_File(int fd) VLC_USED VLC_MALLOC;
 VLC_API block_t *block_FilePath(const char *) VLC_USED VLC_MALLOC;
 

src/libvlccore.sym

@@ -32,6 +32,7 @@ block_FilePath
 block_heap_Alloc
 block_Init
 block_mmap_Alloc
+block_shm_Alloc
 block_Realloc
 config_AddIntf
 config_ChainCreate

src/misc/block.c

@@ -335,6 +335,55 @@ block_t *block_mmap_Alloc (void *addr, size_t length)
 }
 #endif
 
+#ifdef HAVE_SYS_SHM_H
+# include <sys/shm.h>
+
+typedef struct block_shm_t
+{
+    block_t     self;
+    void       *base_addr;
+} block_shm_t;
+
+static void block_shm_Release (block_t *block)
+{
+    block_shm_t *p_sys = (block_shm_t *)block;
+
+    shmdt (p_sys->base_addr);
+    free (p_sys);
+}
+
+/**
+ * Creates a block from a System V shared memory segment (shmget()).
+ * This is provided by LibVLC so that segments can safely be deallocated
+ * even after the allocating plugin has been unloaded from memory.
+ *
+ * @param addr base address of the segment (as returned by shmat())
+ * @param length length (bytes) of the segment (as passed to shmget())
+ * @return NULL if an error occurred (in that case, shmdt(addr) is invoked
+ * before returning NULL).
+ */
+block_t *block_shm_Alloc (void *addr, size_t length)
+{
+    block_shm_t *block = malloc (sizeof (*block));
+    if (unlikely(block == NULL))
+    {
+        shmdt (addr);
+        return NULL;
+    }
+
+    block_Init (&block->self, (uint8_t *)addr, length);
+    block->self.pf_release = block_shm_Release;
+    block->base_addr = addr;
+    return &block->self;
+}
+#else
+block_t *block_shm_Alloc (void *addr, size_t length)
+{
+    (void) addr; (void) length;
+    abort ();
+}
+#endif
+
 
 #ifdef WIN32
 # include <io.h>