support for sendfile with offset

6 files changed, 75 insertions, 6 deletions

diff --git a/ChangeLog b/ChangeLog
index 81376826..96c787d1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,6 @@
+Sun Dec 19 19:54:15 CET 2010
+        Added 'MHD_create_response_from_fd_at_offset'. -CG
+
 Sun Dec 19 15:16:16 CET 2010
         Fixing --enable and --disable configure options to behave properly. -CG
 
diff --git a/doc/microhttpd.texi b/doc/microhttpd.texi
index 883018f1..0298dfde 100644
--- a/doc/microhttpd.texi
+++ b/doc/microhttpd.texi
@@ -1287,11 +1287,37 @@ header information and then it can be used any number of times.
 
 @table @var
 @item size
-size of the data portion of the response, @code{-1} for unknown;
+size of the data portion of the response (should be smaller or equal to the
+size of the file)
+
+@item fd
+file descriptor referring to a file on disk with the data; will be
+closed when response is destroyed; note that 'fd' must be an actual 
+file descriptor (not a pipe or socket) since MHD might use 'sendfile' 
+or 'seek' on it
+@end table
+
+Return @mynull{} on error (i.e. invalid arguments, out of memory).
+@end deftypefun
+
+
+@deftypefun {struct MHD_Response *} MHD_create_response_from_fd_at_offset (uint64_t size, int fd, off_t offset)
+Create a response object.  The response object can be extended with
+header information and then it can be used any number of times.
+
+@table @var
+@item size
+size of the data portion of the response (number of bytes to transmit from the
+file starting at offset).
 
 @item fd
 file descriptor referring to a file on disk with the data; will be
-closed when response is destroyed
+closed when response is destroyed; note that 'fd' must be an actual 
+file descriptor (not a pipe or socket) since MHD might use 'sendfile' 
+or 'seek' on it
+
+@item offset
+offset to start reading from in the file
 @end table
 
 Return @mynull{} on error (i.e. invalid arguments, out of memory).
diff --git a/src/daemon/daemon.c b/src/daemon/daemon.c
index 558954d6..31a87bf0 100644
--- a/src/daemon/daemon.c
+++ b/src/daemon/daemon.c
@@ -701,7 +701,7 @@ send_param_adapter (struct MHD_Connection *connection,
        (-1 != (fd = connection->response->fd)) )
     {
       /* can use sendfile */
-      offset = (off_t) connection->response_write_position;
+      offset = (off_t) connection->response_write_position + connection->response->fd_off;
       ret = sendfile (connection->socket_fd, 
                       fd,
                       &offset,
diff --git a/src/daemon/internal.h b/src/daemon/internal.h
index be476f4b..2ff69472 100644
--- a/src/daemon/internal.h
+++ b/src/daemon/internal.h
@@ -229,6 +229,11 @@ struct MHD_Response
   uint64_t data_start;
 
   /**
+   * Offset to start reading from when using 'fd'.
+   */
+  off_t fd_off;
+
+  /**
    * Size of data.
    */
   size_t data_size;
diff --git a/src/daemon/response.c b/src/daemon/response.c
index e630019c..7d9ae17c 100644
--- a/src/daemon/response.c
+++ b/src/daemon/response.c
@@ -273,7 +273,7 @@ file_reader (void *cls, uint64_t pos, char *buf, size_t max)
   int ret;
 
   pthread_mutex_lock (&response->mutex);
-  (void) lseek (response->fd, pos, SEEK_SET);
+  (void) lseek (response->fd, pos + response->fd_off, SEEK_SET);
   ret = read (response->fd, buf, max);
   pthread_mutex_unlock (&response->mutex);
   return ret;
@@ -301,10 +301,12 @@ free_callback (void *cls)
  *
  * @param size size of the data portion of the response
  * @param fd file descriptor referring to a file on disk with the data
+ * @param off offset to start reading from in the file
  * @return NULL on error (i.e. invalid arguments, out of memory)
  */
-struct MHD_Response *MHD_create_response_from_fd (size_t size,
-                                                  int fd)
+struct MHD_Response *MHD_create_response_from_fd_at_offset (size_t size,
+                                                            int fd,
+                                                            off_t offset)
 {
   struct MHD_Response *ret;
 
@@ -316,11 +318,29 @@ struct MHD_Response *MHD_create_response_from_fd (size_t size,
   if (ret == NULL)
     return NULL;
   ret->fd = fd;
+  ret->fd_off = offset;
   ret->crc_cls = ret;
   return ret;
 }
 
 
+
+
+/**
+ * Create a response object.  The response object can be extended with
+ * header information and then be used any number of times.
+ *
+ * @param size size of the data portion of the response
+ * @param fd file descriptor referring to a file on disk with the data
+ * @return NULL on error (i.e. invalid arguments, out of memory)
+ */
+struct MHD_Response *MHD_create_response_from_fd (size_t size,
+                                                  int fd)
+{
+  return MHD_create_response_from_fd_at_offset (size, fd, 0);
+}
+
+
 /**
  * Create a response object.  The response object can be extended with
  * header information and then be used any number of times.
diff --git a/src/include/microhttpd.h b/src/include/microhttpd.h
index 4e133786..5edf8f98 100644
--- a/src/include/microhttpd.h
+++ b/src/include/microhttpd.h
@@ -1201,6 +1201,21 @@ struct MHD_Response *MHD_create_response_from_data (size_t size,
 struct MHD_Response *MHD_create_response_from_fd (size_t size,
                                                   int fd);
 
+
+/**
+ * Create a response object.  The response object can be extended with
+ * header information and then be used any number of times.
+ *
+ * @param size size of the data portion of the response
+ * @param fd file descriptor referring to a file on disk with the data; will be closed when response is destroyed
+ * @param off offset to start reading from in the file
+ * @return NULL on error (i.e. invalid arguments, out of memory)
+ */
+struct MHD_Response *MHD_create_response_from_fd_at_offset (size_t size,
+                                                            int fd,
+                                                            off_t offset);
+
+
 /**
  * Destroy a response object and associated resources.  Note that
  * libmicrohttpd may keep some of the resources around if the response