Provide a single central implementation of the logic for stepping
through elements of an EFI device path.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
When iPXE is downloading a file from an EFI_FILE_PROTOCOL instance
backed by an EFI_BLOCK_IO_PROTOCOL instance provided by the same iPXE
binary (e.g. via a hooked SAN device), then it is possible for step()
to be invoked as a result of the calls into the EFI_BLOCK_IO_PROTOCOL
methods. This can potentially result in efi_local_step() being run
prematurely, before the file has been opened and before the parent
interface has been attached.
Fix by deferring starting the download process until immediately prior
to returning from efi_local_open().
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The file:/ URI syntax may be used to refer to local files on the
filesystem from which the iPXE binary was loaded. This is currently
implemented by directly using the DeviceHandle recorded in our
EFI_LOADED_IMAGE_PROTOCOL.
This mechanism will fail when a USB-enabled build of iPXE is loaded
from USB storage and subsequently installs its own USB host controller
drivers, since doing so will disconnect and reconnect the existing USB
storage drivers and thereby invalidate the original storage device
handle.
Fix by recording the device path for the loaded image's DeviceHandle
at initialisation time and later using the recorded device path to
locate the appropriate device handle.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Provide access to local files via the "file://" URI scheme. There are
three syntaxes:
- An opaque URI with a relative path (e.g. "file:script.ipxe").
This will be interpreted as a path relative to the iPXE binary.
- A hierarchical URI with a non-network absolute path
(e.g. "file:/boot/script.ipxe"). This will be interpreted as a
path relative to the root of the filesystem from which the iPXE
binary was loaded.
- A hierarchical URI with a network path in which the authority is a
volume label (e.g. "file://bootdisk/script.ipxe"). This will be
interpreted as a path relative to the root of the filesystem with
the specified volume label.
Note that the potentially desirable shell mappings (e.g. "fs0:" and
"blk0:") are concepts internal to the UEFI shell binary, and do not
seem to be exposed in any way to external executables. The old
EFI_SHELL_PROTOCOL (which did provide access to these mappings) is no
longer installed by current versions of the UEFI shell.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
