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[PXEXT] Avoid queueing zero-length buffers in posix_io.c

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read_user() assumes that zero-length buffers don't exist, and optimises
around this.
This commit is contained in:
Michael Brown
2008-03-25 21:10:21 +00:00
parent 92d15eff30
commit 96edbd128f
1 changed files with 12 additions and 6 deletions
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14
src/core/posix_io.c
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@@ -114,7 +114,7 @@ static void posix_file_xfer_close ( struct xfer_interface *xfer, int rc ) {
static int static int
posix_file_xfer_deliver_iob ( struct xfer_interface *xfer, posix_file_xfer_deliver_iob ( struct xfer_interface *xfer,
struct io_buffer *iobuf, struct io_buffer *iobuf,
struct xfer_metadata *meta __unused ) { struct xfer_metadata *meta ) {
struct posix_file *file = struct posix_file *file =
container_of ( xfer, struct posix_file, xfer ); container_of ( xfer, struct posix_file, xfer );
@@ -125,7 +125,12 @@ posix_file_xfer_deliver_iob ( struct xfer_interface *xfer,
if ( file->filesize < file->pos ) if ( file->filesize < file->pos )
file->filesize = file->pos; file->filesize = file->pos;
if ( iob_len ( iobuf ) ) {
list_add_tail ( &iobuf->list, &file->data ); list_add_tail ( &iobuf->list, &file->data );
} else {
free_iob ( iobuf );
}
return 0; return 0;
} }
@@ -293,14 +298,15 @@ ssize_t read_user ( int fd, userptr_t buffer, off_t offset, size_t max_len ) {
free_iob ( iobuf ); free_iob ( iobuf );
} }
file->pos += len; file->pos += len;
if ( len ) assert ( len != 0 );
return len; return len;
break;
} }
/* If file has completed, return (after returning all data) */ /* If file has completed, return (after returning all data) */
if ( file->rc != -EINPROGRESS ) if ( file->rc != -EINPROGRESS ) {
assert ( list_empty ( &file->data ) );
return file->rc; return file->rc;
}
/* No data ready and file still in progress; return -WOULDBLOCK */ /* No data ready and file still in progress; return -WOULDBLOCK */
return -EWOULDBLOCK; return -EWOULDBLOCK;