Filesystem: Add readv/writev handlers

The readv() and writev() support was implemented in terms of multiple
calls to the read and write handlers.  This imposes a problem on device
files which use an IO vector as single request entity.  For example a
low-level network device (e.g. BPF(4)) may use an IO vector to create
one frame from multiple protocol layers each with its own IO vector
entry.

4 files changed, 78 insertions, 41 deletions

diff --git a/cpukit/libcsupport/include/rtems/libio.h b/cpukit/libcsupport/include/rtems/libio.h
index 21d57ebddf..4bfa02a3a5 100644
--- a/cpukit/libcsupport/include/rtems/libio.h
+++ b/cpukit/libcsupport/include/rtems/libio.h
@@ -29,6 +29,7 @@
 #include <sys/stat.h>
 #include <sys/ioctl.h>
 #include <sys/statvfs.h>
+#include <sys/uio.h>
 
 #include <unistd.h>
 #include <termios.h>
@@ -808,6 +809,29 @@ typedef ssize_t (*rtems_filesystem_read_t)(
 );
 
 /**
+ * @brief Reads an IO vector from a node.
+ *
+ * This handler is responsible to update the offset field of the IO descriptor.
+ *
+ * @param[in, out] iop The IO pointer.
+ * @param[in] iov The IO vector with buffer for read data.  The caller must
+ * ensure that the IO vector values are valid.
+ * @param[in] iovcnt The count of buffers in the IO vector.
+ * @param[in] total The total count of bytes in the buffers in the IO vector.
+ *
+ * @retval non-negative Count of read characters.
+ * @retval -1 An error occurred.  The errno is set to indicate the error.
+ *
+ * @see rtems_filesystem_default_readv().
+ */
+typedef ssize_t (*rtems_filesystem_readv_t)(
+  rtems_libio_t      *iop,
+  const struct iovec *iov,
+  int                 iovcnt,
+  ssize_t             total
+);
+
+/**
  * @brief Writes to a node.
  *
  * This handler is responsible to update the offset field of the IO descriptor.
@@ -828,6 +852,29 @@ typedef ssize_t (*rtems_filesystem_write_t)(
 );
 
 /**
+ * @brief Writes an IO vector to a node.
+ *
+ * This handler is responsible to update the offset field of the IO descriptor.
+ *
+ * @param[in, out] iop The IO pointer.
+ * @param[in] iov The IO vector with buffer for write data.  The caller must
+ * ensure that the IO vector values are valid.
+ * @param[in] iovcnt The count of buffers in the IO vector.
+ * @param[in] total The total count of bytes in the buffers in the IO vector.
+ *
+ * @retval non-negative Count of written characters.
+ * @retval -1 An error occurred.  The errno is set to indicate the error.
+ *
+ * @see rtems_filesystem_default_writev().
+ */
+typedef ssize_t (*rtems_filesystem_writev_t)(
+  rtems_libio_t      *iop,
+  const struct iovec *iov,
+  int                 iovcnt,
+  ssize_t             total
+);
+
+/**
  * @brief IO control of a node.
  *
  * @param[in, out] iop The IO pointer.
@@ -992,6 +1039,8 @@ struct _rtems_filesystem_file_handlers_r {
   rtems_filesystem_fcntl_t fcntl_h;
   rtems_filesystem_poll_t poll_h;
   rtems_filesystem_kqfilter_t kqfilter_h;
+  rtems_filesystem_readv_t readv_h;
+  rtems_filesystem_writev_t writev_h;
 };
 
 /**
@@ -1033,6 +1082,18 @@ ssize_t rtems_filesystem_default_read(
 );
 
 /**
+ * @brief Calls the read handler for each IO vector entry.
+ *
+ * @see rtems_filesystem_readv_t.
+ */
+ssize_t rtems_filesystem_default_readv(
+  rtems_libio_t      *iop,
+  const struct iovec *iov,
+  int                 iovcnt,
+  ssize_t             total
+);
+
+/**
  * @retval -1 Always.  The errno is set to ENOTSUP.
  *
  * @see rtems_filesystem_write_t.
@@ -1044,6 +1105,18 @@ ssize_t rtems_filesystem_default_write(
 );
 
 /**
+ * @brief Calls the write handler for each IO vector entry.
+ *
+ * @see rtems_filesystem_write_t.
+ */
+ssize_t rtems_filesystem_default_writev(
+  rtems_libio_t      *iop,
+  const struct iovec *iov,
+  int                 iovcnt,
+  ssize_t             total
+);
+
+/**
  * @retval -1 Always.  The errno is set to ENOTTY.
  *
  * @see rtems_filesystem_ioctl_t.
diff --git a/cpukit/libcsupport/src/__usrenv.c b/cpukit/libcsupport/src/__usrenv.c
index 88058c4714..f8604479a5 100644
--- a/cpukit/libcsupport/src/__usrenv.c
+++ b/cpukit/libcsupport/src/__usrenv.c
@@ -54,7 +54,9 @@ const rtems_filesystem_file_handlers_r rtems_filesystem_null_handlers = {
   .ftruncate_h = rtems_filesystem_default_ftruncate,
   .fsync_h = rtems_filesystem_default_fsync_or_fdatasync,
   .fdatasync_h = rtems_filesystem_default_fsync_or_fdatasync,
-  .fcntl_h = rtems_filesystem_default_fcntl
+  .fcntl_h = rtems_filesystem_default_fcntl,
+  .readv_h = rtems_filesystem_default_readv,
+  .writev_h = rtems_filesystem_default_writev
 };
 
 static void null_op_lock_or_unlock(
diff --git a/cpukit/libcsupport/src/readv.c b/cpukit/libcsupport/src/readv.c
index e47f22850a..6a4e0579f3 100644
--- a/cpukit/libcsupport/src/readv.c
+++ b/cpukit/libcsupport/src/readv.c
@@ -36,31 +36,12 @@ ssize_t readv(
 )
 {
   ssize_t        total;
-  int            v;
   rtems_libio_t *iop;
 
   total = rtems_libio_iovec_eval( fd, iov, iovcnt, LIBIO_FLAGS_READ, &iop );
 
   if ( total > 0 ) {
-    /*
-     *  Now process the readv().
-     */
-    total = 0;
-    for ( v = 0 ; v < iovcnt ; v++ ) {
-      ssize_t bytes = ( *iop->pathinfo.handlers->read_h )(
-        iop,
-        iov[ v ].iov_base,
-        iov[ v ].iov_len
-      );
-
-      if ( bytes < 0 )
-        return -1;
-
-      total += bytes;
-
-      if ( bytes != iov[ v ].iov_len )
-        break;
-    }
+    total = ( *iop->pathinfo.handlers->readv_h )( iop, iov, iovcnt, total );
   }
 
   return total;
diff --git a/cpukit/libcsupport/src/writev.c b/cpukit/libcsupport/src/writev.c
index 4a8dc735b8..7fa55bdbe5 100644
--- a/cpukit/libcsupport/src/writev.c
+++ b/cpukit/libcsupport/src/writev.c
@@ -28,31 +28,12 @@ ssize_t writev(
 )
 {
   ssize_t        total;
-  int            v;
   rtems_libio_t *iop;
 
   total = rtems_libio_iovec_eval( fd, iov, iovcnt, LIBIO_FLAGS_WRITE, &iop );
 
   if ( total > 0 ) {
-    /*
-     *  Now process the writev().
-     */
-    total = 0;
-    for ( v = 0 ; v < iovcnt ; v++ ) {
-      ssize_t bytes = ( *iop->pathinfo.handlers->write_h )(
-        iop,
-        iov[ v ].iov_base,
-        iov[ v ].iov_len
-      );
-
-      if ( bytes < 0 )
-        return -1;
-
-      total += bytes;
-
-      if ( bytes != iov[ v ].iov_len )
-        break;
-    }
+    total = ( *iop->pathinfo.handlers->writev_h )( iop, iov, iovcnt, total );
   }
 
   return total;