For use by the EFI LoadImage boot service, implement support of opening a file within an EFI simple file system by its barebox-generated EFI device path.
Signed-off-by: Ahmad Fatoum <[email protected]> --- efi/loader/protocols/file.c | 67 +++++++++++++++++++++++++++++++++++++ include/efi/loader/file.h | 3 ++ 2 files changed, 70 insertions(+) diff --git a/efi/loader/protocols/file.c b/efi/loader/protocols/file.c index 3858cd3e1682..03d2dc3a0d38 100644 --- a/efi/loader/protocols/file.c +++ b/efi/loader/protocols/file.c @@ -922,6 +922,73 @@ static const struct efi_file_handle efi_file_handle_protocol = { .flush_ex = efi_file_flush_ex, }; +/** + * efi_file_from_path() - open file via device path + * + * @fp: device path + * Return: EFI_FILE_PROTOCOL for the file or NULL + */ +struct efi_file_handle *efi_file_from_path(struct efi_device_path *fp) +{ + struct efi_simple_file_system_protocol *v; + struct efi_file_handle *f; + efi_status_t efiret; + + v = efi_fs_from_path(fp); + if (!v) + return NULL; + + efiret = v->open_volume(v, &f); + if (efiret != EFI_SUCCESS) + return NULL; + + /* Skip over device-path nodes before the file path. */ + while (fp && !EFI_DP_TYPE(fp, MEDIA_DEVICE, FILE_PATH)) + fp = efi_dp_next(fp); + + /* + * Step through the nodes of the directory path until the actual file + * node is reached which is the final node in the device path. + */ + while (fp) { + struct efi_device_path_file_path *fdp = + container_of(fp, struct efi_device_path_file_path, header); + struct efi_file_handle *f2; + efi_char16_t *filename; + size_t filename_sz; + + if (!EFI_DP_TYPE(fp, MEDIA_DEVICE, FILE_PATH)) { + pr_warn("bad file path!\n"); + f->close(f); + return NULL; + } + + /* + * UEFI specification requires pointers that are passed to + * protocol member functions to be aligned. So memcpy it + * unconditionally + */ + if (fdp->header.length <= offsetof(struct efi_device_path_file_path, path_name)) + return NULL; + filename_sz = fdp->header.length - + offsetof(struct efi_device_path_file_path, path_name); + filename = memdup(fdp->path_name, filename_sz); + if (!filename) + return NULL; + efiret = f->open(f, &f2, filename, EFI_FILE_MODE_READ, 0); + free(filename); + if (efiret != EFI_SUCCESS) + return NULL; + + fp = efi_dp_next(fp); + + f->close(f); + f = f2; + } + + return f; +} + static efi_status_t EFIAPI efi_open_volume(struct efi_simple_file_system_protocol *this, struct efi_file_handle **root) diff --git a/include/efi/loader/file.h b/include/efi/loader/file.h index ce52cc5df8aa..a4f071f97817 100644 --- a/include/efi/loader/file.h +++ b/include/efi/loader/file.h @@ -12,6 +12,9 @@ struct efi_file_handle; struct efi_simple_file_system_protocol * efi_fs_from_path(struct efi_device_path *fp); +/* open file from device-path: */ +struct efi_file_handle *efi_file_from_path(struct efi_device_path *fp); + efi_status_t efi_file_size(struct efi_file_handle *fh, efi_uintn_t *size); /** -- 2.47.3
