X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fmisc%2Fblock.c;h=0a408cc26d15766b7d531542638b7a36cd2f65b4;hb=8b0dd8cfdff0d9697fb44e7849764c9274965adb;hp=069628ab230addee58ba76d6b7ae2b942bb4322e;hpb=3afcc0bb1f929748cc7de65531d0adbdd97098c4;p=vlc

diff --git a/src/misc/block.c b/src/misc/block.c
index 069628ab23..0a408cc26d 100644
--- a/src/misc/block.c
+++ b/src/misc/block.c
@@ -31,9 +31,7 @@
 #include <sys/stat.h>
 #include <assert.h>
 #include <errno.h>
-#ifdef HAVE_UNISTD_H
-# include <unistd.h>
-#endif
+#include <unistd.h>
 #include <fcntl.h>
 
 #include <vlc_common.h>
@@ -117,11 +115,15 @@ static void BlockMetaCopy( block_t *restrict out, const block_t *in )
     out->i_length  = in->i_length;
 }
 
-/* Memory alignment (must be a multiple of sizeof(void*) and a power of two) */
-#define BLOCK_ALIGN        16
-/* Initial reserved header and footer size (must be multiple of alignment) */
+/** Initial memory alignment of data block.
+ * @note This must be a multiple of sizeof(void*) and a power of two.
+ * libavcodec AVX optimizations require at least 32-bytes. */
+#define BLOCK_ALIGN        32
+
+/** Initial reserved header and footer size. */
 #define BLOCK_PADDING      32
-/* Maximum size of reserved footer before we release with realloc() */
+
+/* Maximum size of reserved footer before shrinking with realloc(). */
 #define BLOCK_WASTE_SIZE   2048
 
 block_t *block_Alloc (size_t size)
@@ -335,8 +337,57 @@ 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);
+}
 
-#ifdef WIN32
+/**
+ * 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>
 
 static
@@ -397,7 +448,7 @@ block_t *block_File (int fd)
     }
 
     /* Prevent an integer overflow in mmap() and malloc() */
-    if (st.st_size >= SIZE_MAX)
+    if ((uintmax_t)st.st_size >= SIZE_MAX)
     {
         errno = ENOMEM;
         return NULL;
@@ -672,14 +723,24 @@ block_t *block_FifoShow( block_fifo_t *p_fifo )
     return b;
 }
 
-/* FIXME: not thread-safe */
-size_t block_FifoSize( const block_fifo_t *p_fifo )
+/* FIXME: not (really) thread-safe */
+size_t block_FifoSize (block_fifo_t *fifo)
 {
-    return p_fifo->i_size;
+    size_t size;
+
+    vlc_mutex_lock (&fifo->lock);
+    size = fifo->i_size;
+    vlc_mutex_unlock (&fifo->lock);
+    return size;
 }
 
-/* FIXME: not thread-safe */
-size_t block_FifoCount( const block_fifo_t *p_fifo )
+/* FIXME: not (really) thread-safe */
+size_t block_FifoCount (block_fifo_t *fifo)
 {
-    return p_fifo->i_depth;
+    size_t depth;
+
+    vlc_mutex_lock (&fifo->lock);
+    depth = fifo->i_depth;
+    vlc_mutex_unlock (&fifo->lock);
+    return depth;
 }