[libdvdcss-devel] [PATCH] Add dvdcss_open_stream() API function

From: Thomas Guillem <[email protected]>

This allows opening a DVD device using external read/seek callbacks.
---

A fresh version of the patch, rebased on top of my cleanup and with most
of my review comments addressed so that we have a cleaner basis for
further discussion.

 NEWS                |   2 +
 src/device.c        | 109 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 src/dvdcss/dvdcss.h |  12 ++++++
 src/libdvdcss.c     |  30 +++++++++++++++
 src/libdvdcss.h     |   3 ++
 5 files changed, 154 insertions(+), 2 deletions(-)

diff --git a/NEWS b/NEWS
index d3fdaed..e542020 100644
--- a/NEWS
+++ b/NEWS
@@ -7,6 +7,8 @@ Changes between 1.2.13 and 1.3.0:
     - the variable dvdcss_interface_2
   * Support for Android
   * Drop support for HP-UX, Solaris, BeOS, QNX, OS/2, and Windows 9x.
+  * Add dvdcss_open_stream() to public API. This allows installing custom
+    callback functions for accessing DVD, e.g. over the network.
   * Miscellaneous cleanups to code, documentation, build system.
 
 
diff --git a/src/device.c b/src/device.c
index ed2b710..8b4a50e 100644
--- a/src/device.c
+++ b/src/device.c
@@ -74,6 +74,10 @@ static int libc_seek  ( dvdcss_t, int );
 static int libc_read  ( dvdcss_t, void *, int );
 static int libc_readv ( dvdcss_t, struct iovec *, int );
 
+static int stream_seek  ( dvdcss_t, int );
+static int stream_read  ( dvdcss_t, void *, int );
+static int stream_readv ( dvdcss_t, struct iovec *, int );
+
 #ifdef WIN32
 static int win2k_open  ( dvdcss_t, const char * );
 static int win2k_seek  ( dvdcss_t, int );
@@ -83,6 +87,9 @@ static int win2k_readv ( dvdcss_t, struct iovec *, int );
 
 int dvdcss_use_ioctls( dvdcss_t dvdcss )
 {
+    if( dvdcss->p_stream )
+        return 0;
+
 #if defined( WIN32 )
     if( dvdcss->b_file )
     {
@@ -141,8 +148,8 @@ void dvdcss_check_device ( dvdcss_t dvdcss )
     int i, i_fd;
 #endif
 
-    /* If the device name is non-null, return */
-    if( dvdcss->psz_device[0] )
+    /* If the device name is non-NULL or stream is set, return. */
+    if( dvdcss->psz_device[0] || dvdcss->p_stream )
     {
         return;
     }
@@ -273,6 +280,16 @@ int dvdcss_open_device ( dvdcss_t dvdcss )
 
     print_debug( dvdcss, "opening target `%s'", psz_device );
 
+    /* if callback functions are initialized */
+    if( dvdcss->p_stream )
+    {
+        print_debug( dvdcss, "using stream API for access" );
+        dvdcss->pf_seek  = stream_seek;
+        dvdcss->pf_read  = stream_read;
+        dvdcss->pf_readv = stream_readv;
+        return 0;
+    }
+
 #if defined( WIN32 )
     dvdcss->b_file = 1;
     /* If device is "X:" or "X:\", we are not actually opening a file. */
@@ -446,6 +463,31 @@ static int libc_seek( dvdcss_t dvdcss, int i_blocks )
     return dvdcss->i_pos;
 }
 
+static int stream_seek( dvdcss_t dvdcss, int i_blocks )
+{
+    off_t i_seek = i_blocks * DVDCSS_BLOCK_SIZE;
+
+    if( !dvdcss->p_stream_cb->pf_seek )
+        return -1;
+
+    if( dvdcss->i_pos == i_blocks )
+    {
+        /* We are already in position */
+        return i_blocks;
+    }
+
+    if( dvdcss->p_stream_cb->pf_seek( dvdcss->p_stream, i_seek ) != 0 )
+    {
+        print_error( dvdcss, "seek error" );
+        dvdcss->i_pos = -1;
+        return -1;
+    }
+
+    dvdcss->i_pos = i_blocks;
+
+    return dvdcss->i_pos;
+}
+
 #if defined( WIN32 )
 static int win2k_seek( dvdcss_t dvdcss, int i_blocks )
 {
@@ -514,6 +556,46 @@ static int libc_read ( dvdcss_t dvdcss, void *p_buffer, int i_blocks )
     return i_ret_blocks;
 }
 
+static int stream_read ( dvdcss_t dvdcss, void *p_buffer, int i_blocks )
+{
+    off_t i_size, i_ret, i_ret_blocks;
+
+    i_size = i_blocks * DVDCSS_BLOCK_SIZE;
+
+    if( !dvdcss->p_stream_cb->pf_read )
+        return -1;
+
+    i_ret = dvdcss->p_stream_cb->pf_read( dvdcss->p_stream, p_buffer, i_size );
+
+    if( i_ret < 0 )
+    {
+        print_error( dvdcss, "read error" );
+        dvdcss->i_pos = -1;
+        return i_ret;
+    }
+
+    i_ret_blocks = i_ret / DVDCSS_BLOCK_SIZE;
+
+    /* Handle partial reads */
+    if( i_ret != i_size )
+    {
+        int i_seek;
+
+        dvdcss->i_pos = -1;
+        i_seek = stream_seek( dvdcss, i_ret_blocks );
+        if( i_seek < 0 )
+        {
+            return i_seek;
+        }
+
+        /* We have to return now so that i_pos isn't clobbered */
+        return i_ret_blocks;
+    }
+
+    dvdcss->i_pos += i_ret_blocks;
+    return i_ret_blocks;
+}
+
 #if defined( WIN32 )
 static int win2k_read ( dvdcss_t dvdcss, void *p_buffer, int i_blocks )
 {
@@ -605,6 +687,29 @@ static int libc_readv ( dvdcss_t dvdcss, struct iovec *p_iovec, int i_blocks )
 #endif
 }
 
+/*****************************************************************************
+ * stream_readv: vectored read
+ *****************************************************************************/
+static int stream_readv ( dvdcss_t dvdcss, struct iovec *p_iovec, int i_blocks )
+{
+    int i_read;
+
+    if( !dvdcss->p_stream_cb->pf_readv )
+        return -1;
+
+    i_read = dvdcss->p_stream_cb->pf_readv( dvdcss->p_stream, p_iovec,
+                                            i_blocks );
+
+    if( i_read < 0 )
+    {
+        dvdcss->i_pos = -1;
+        return i_read;
+    }
+
+    dvdcss->i_pos += i_read / DVDCSS_BLOCK_SIZE;
+    return i_read / DVDCSS_BLOCK_SIZE;
+}
+
 #if defined( WIN32 )
 /*****************************************************************************
  * win2k_readv: vectored read using ReadFile for Win2K
diff --git a/src/dvdcss/dvdcss.h b/src/dvdcss/dvdcss.h
index 64f95cf..5e1a77b 100644
--- a/src/dvdcss/dvdcss.h
+++ b/src/dvdcss/dvdcss.h
@@ -31,6 +31,8 @@
 #define DVDCSS_DVDCSS_H 1
 #endif
 
+#include <stdint.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -38,6 +40,14 @@ extern "C" {
 /** Library instance handle, to be used for each library call. */
 typedef struct dvdcss_s* dvdcss_t;
 
+struct dvdcss_stream_cb
+{
+    int ( *pf_seek )  ( void *p_stream, uint64_t i_pos);
+    int ( *pf_read )  ( void *p_stream, void *buffer, int i_read);
+    int ( *pf_readv ) ( void *p_stream, void *p_iovec, int i_blocks);
+};
+typedef struct dvdcss_stream_cb dvdcss_stream_cb;
+
 
 /** The block size of a DVD. */
 #define DVDCSS_BLOCK_SIZE      2048
@@ -73,6 +83,8 @@ typedef struct dvdcss_s* dvdcss_t;
  * Exported prototypes.
  */
 LIBDVDCSS_EXPORT dvdcss_t dvdcss_open  ( const char *psz_target );
+LIBDVDCSS_EXPORT dvdcss_t dvdcss_open_stream( void *p_stream,
+                                              dvdcss_stream_cb *p_stream_cb );
 LIBDVDCSS_EXPORT int      dvdcss_close ( dvdcss_t );
 LIBDVDCSS_EXPORT int      dvdcss_seek  ( dvdcss_t,
                                int i_blocks,
diff --git a/src/libdvdcss.c b/src/libdvdcss.c
index ab5b665..6d622ac 100644
--- a/src/libdvdcss.c
+++ b/src/libdvdcss.c
@@ -135,6 +135,8 @@
 #define mkdir(a, b) _mkdir(a)
 #endif
 
+static dvdcss_t dvdcss_open_common ( const char *psz_target, void *p_stream,
+                                     dvdcss_stream_cb *p_stream_cb );
 static void set_verbosity( dvdcss_t dvdcss )
 {
     const char *psz_verbose = getenv( "DVDCSS_VERBOSE" );
@@ -416,6 +418,27 @@ static void create_cache_dir( dvdcss_t dvdcss, const char *psz_cache )
  */
 LIBDVDCSS_EXPORT dvdcss_t dvdcss_open ( const char *psz_target )
 {
+    return dvdcss_open_common( psz_target, NULL, NULL );
+}
+
+/**
+ * \brief Open a DVD device using dvdcss_stream_cb.
+ *
+ * \param p_stream a private handle used by p_stream_cb
+ * \param p_stream_cb a struct containing seek and read functions
+ * \return a handle to a dvdcss instance or NULL on error.
+ *
+ * \see dvdcss_open()
+ */
+LIBDVDCSS_EXPORT dvdcss_t dvdcss_open_stream ( void *p_stream,
+                                               dvdcss_stream_cb *p_stream_cb )
+{
+    return dvdcss_open_common( NULL, p_stream, p_stream_cb );
+}
+
+static dvdcss_t dvdcss_open_common ( const char *psz_target, void *p_stream,
+                                     dvdcss_stream_cb *p_stream_cb )
+{
     int i_ret;
 
     const char *psz_cache;
@@ -423,6 +446,10 @@ LIBDVDCSS_EXPORT dvdcss_t dvdcss_open ( const char *psz_target )
     const char *psz_raw_device = getenv( "DVDCSS_RAW_DEVICE" );
 #endif
 
+    if( psz_target == NULL &&
+      ( p_stream == NULL || p_stream_cb == NULL ) )
+        return NULL;
+
     /* Allocate the library structure */
     dvdcss_t dvdcss = malloc( sizeof( struct dvdcss_s ) );
     if( dvdcss == NULL )
@@ -440,6 +467,9 @@ LIBDVDCSS_EXPORT dvdcss_t dvdcss_open ( const char *psz_target )
     dvdcss->i_method = DVDCSS_METHOD_KEY;
     dvdcss->psz_cachefile[0] = '\0';
 
+    dvdcss->p_stream = p_stream;
+    dvdcss->p_stream_cb = p_stream_cb;
+
     /* Set library verbosity from DVDCSS_VERBOSE environment variable. */
     set_verbosity( dvdcss );
 
diff --git a/src/libdvdcss.h b/src/libdvdcss.h
index 4f1f4af..f2368fb 100644
--- a/src/libdvdcss.h
+++ b/src/libdvdcss.h
@@ -72,6 +72,9 @@ struct dvdcss_s
     int    i_readv_buf_size;
 #endif /* WIN32 */
 
+    void                *p_stream;
+    dvdcss_stream_cb    *p_stream_cb;
+
 #ifdef DVDCSS_RAW_OPEN
     int    i_raw_fd;
 #endif
-- 
1.9.1

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