This pull request brings back FAT file system support along with multiple improvements #212
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Bytes_Total feels like it holds the size of the file, as in "total bytes of the file" but in really it's the current index in the file. And the comment associated with this field already says that it's an index: "The actual file index". Offset of File_Offset are other possible names for this field.
Otherwise an incorrect value is returned to the caller.
as opposed to handles. And pass handles as out parameters.
File and directory handles will always be used for more than one
operation. Read/Write and Close at least, so it will require to declare
a variable for them.
Handle : Any_File_Handle;
begin
Open ("/my_file". Handle);
Handle.Read (...)
Handle.Close;
vs
-- This is not practical because now I can't close the handle
Open ("/my_file").Read (...);
On the other side, one might want to just check the status code of a
function without declaring a variable to do so.
if Open ("/my_file", Handle) /= OK then
...
vs
Handle : Any_File_Handle;
Status : Status_Code;
begin
Handle := Open ("/my_file", Status);
if Status /= OK then
...
And update the native implementation.
in a package called File_IO. This hides some of the complexity of dealing with access to handle and answers some of the questions discussed in the issue #68. The package also provides the mounting interface, taken from Filesystem.VFS.
Some of the virtual filesystem are obsolete because of missing features in the new implementation.
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This function is expected to use Parent.Current_Index as opposed to a local index, as stated in the comments of this function and the calling function.
pat-rogers
approved these changes
Oct 2, 2017
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The first patches merge the FAT support with the existing interface and file systems (native and semihosting) and add two tests for FAT using a disk image.
The second part creates a "front-end" interface to read/write files. We realized in the past that it's difficult to have a good file-system driver interface (HAL.Filesystem) that would also be user friendly, in particular with regards to the handling of handles and their deallocation (#68). The front-end interface is somewhat similar to Ada.Text_IO or GNAT.OS_Lib except that standard Ada.Text_IO* rely a lot on exception which are not always available or desirable in our case.
There's also the beginning of a documentation.