block_File: loads a file into a block_t

include/vlc_block.h

@@ -148,17 +148,8 @@ static inline void block_Release( block_t *p_block )
     p_block->pf_release( p_block );
 }
 
-/**
- * Creates a block from a virtual address memory mapping (mmap).
- * This is provided by LibVLC so that mmap blocks can safely be deallocated
- * even after the allocating plugin has been unloaded from memory.
- *
- * @param addr base address of the mapping (as returned by mmap)
- * @param length length (bytes) of the mapping (as passed to mmap)
- * @return NULL if addr is MAP_FAILED, or an error occurred (in the later
- * case, munmap(addr, length) is invoked before returning).
- */
 VLC_EXPORT( block_t *, block_mmap_Alloc, (void *addr, size_t length) );
+VLC_EXPORT( block_t *, block_File, (int fd) );
 
 /****************************************************************************
  * Chains of blocks functions helper

src/libvlccore.sym

@@ -41,6 +41,7 @@ block_FifoRelease
 block_FifoShow
 block_FifoSize
 block_FifoWake
+block_File
 block_Init
 block_mmap_Alloc
 block_Realloc

src/misc/block.c

@@ -29,6 +29,7 @@
 #endif
 
 #include <vlc/vlc.h>
+#include <sys/stat.h>
 #include "vlc_block.h"
 
 /*****************************************************************************
@@ -208,6 +209,16 @@ static void block_mmap_Release (block_t *block)
     free (p_sys);
 }
 
+/**
+ * Creates a block from a virtual address memory mapping (mmap).
+ * This is provided by LibVLC so that mmap blocks can safely be deallocated
+ * even after the allocating plugin has been unloaded from memory.
+ *
+ * @param addr base address of the mapping (as returned by mmap)
+ * @param length length (bytes) of the mapping (as passed to mmap)
+ * @return NULL if addr is MAP_FAILED, or an error occurred (in the later
+ * case, munmap(addr, length) is invoked before returning).
+ */
 block_t *block_mmap_Alloc (void *addr, size_t length)
 {
     if (addr == MAP_FAILED)
@@ -247,6 +258,79 @@ ssize_t pread (int fd, void *buf, size_t count, off_t offset)
 }
 #endif
 
+/**
+ * Loads a file into a block of memory. If possible a private file mapping is
+ * created. Otherwise, the file is read normally. On 32-bits platforms, this
+ * function will not work for very large files, due to memory space
+ * constraints.
+ *
+ * @param fd file descriptor to load from
+ * @return a new block with the file content at p_buffer, and file length at
+ * i_buffer (release it with block_Release()), or NULL upon error (see errno).
+ */
+block_t *block_File (int fd)
+{
+    size_t length;
+    struct stat st;
+
+    /* First, get the file size */
+    if (fstat (fd, &st))
+        return NULL;
+
+    /* st_size is meaningful for regular files, shared memory and typed memory.
+     * It's also meaning for symlinks, but that's not possible with fstat().
+     * In other cases, it's undefined, and we should really not go further. */
+#ifndef S_TYPEISSHM
+# define S_TYPEISSHM( buf ) (0)
+#endif
+    if (S_ISDIR (st.st_mode))
+    {
+        errno = EISDIR;
+        return NULL;
+    }
+    if (!S_ISREG (st.st_mode) && !S_TYPEISSHM (&st))
+    {
+        errno = ESPIPE;
+        return NULL;
+    }
+
+    /* Prevent an integer overflow in mmap() and malloc() */
+    if (st.st_size >= SIZE_MAX)
+    {
+        errno = ENOMEM;
+        return NULL;
+    }
+    length = (size_t)st.st_size;
+
+#ifdef HAVE_MMAP
+    if (length > 0)
+    {
+        void *addr;
+
+        addr = mmap (NULL, length, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
+        if (addr != MAP_FAILED)
+            return block_mmap_Alloc (addr, length);
+    }
+#endif
+
+    /* If mmap() is not implemented by the OS _or_ the filesystem... */
+    block_t *block = block_Alloc (length);
+    if (block == NULL)
+        return NULL;
+
+    for (size_t i = 0; i < length;)
+    {
+        ssize_t len = pread (fd, block->p_buffer + i, length - i, i);
+        if (len == -1)
+        {
+            block_Release (block);
+            return NULL;
+        }
+        i += len;
+    }
+    return block;
+}
+
 /*****************************************************************************
  * block_fifo_t management
  *****************************************************************************/