1 files changed, 86 insertions, 0 deletions
diff --git a/utils.c b/utils.c
new file mode 100644
index 00000000..02722294
--- /dev/null
+++ b/utils.c
@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: BSD-2-Clause-Patent
+
+#include "shim.h"
+
+EFI_STATUS
+get_file_size(EFI_FILE_HANDLE fh, UINTN *retsize)
+{
+	EFI_STATUS efi_status;
+	void *buffer = NULL;
+	UINTN bs = 0;
+
+	/* The API here is "Call it once with bs=0, it fills in bs,
+	 * then allocate a buffer and ask again to get it filled. */
+	efi_status = fh->GetInfo(fh, &EFI_FILE_INFO_GUID, &bs, NULL);
+	if (EFI_ERROR(efi_status) && efi_status != EFI_BUFFER_TOO_SMALL)
+		return efi_status;
+	if (bs == 0)
+		return EFI_SUCCESS;
+
+	buffer = AllocateZeroPool(bs);
+	if (!buffer) {
+		console_print(L"Could not allocate memory\n");
+		return EFI_OUT_OF_RESOURCES;
+	}
+	efi_status = fh->GetInfo(fh, &EFI_FILE_INFO_GUID, &bs, buffer);
+	/* This checks *either* the error from the first GetInfo, if it isn't
+	 * the EFI_BUFFER_TOO_SMALL we're expecting, or the second GetInfo
+	 * call in *any* case. */
+	if (EFI_ERROR(efi_status)) {
+		console_print(L"Could not get file info: %r\n", efi_status);
+		if (buffer)
+			FreePool(buffer);
+		return efi_status;
+	}
+	EFI_FILE_INFO *fi = buffer;
+	*retsize = fi->FileSize;
+	FreePool(buffer);
+	return EFI_SUCCESS;
+}
+
+EFI_STATUS
+read_file(EFI_FILE_HANDLE fh, CHAR16 *fullpath, CHAR16 **buffer, UINT64 *bs)
+{
+	EFI_FILE_HANDLE fh2;
+	EFI_STATUS efi_status;
+
+	efi_status = fh->Open(fh, &fh2, fullpath, EFI_FILE_READ_ONLY, 0);
+	if (EFI_ERROR(efi_status)) {
+		console_print(L"Couldn't open \"%s\": %r\n", fullpath, efi_status);
+		return efi_status;
+	}
+
+	UINTN len = 0;
+	CHAR16 *b = NULL;
+	efi_status = get_file_size(fh2, &len);
+	if (EFI_ERROR(efi_status)) {
+		console_print(L"Could not get file size for \"%s\": %r\n",
+			      fullpath, efi_status);
+		fh2->Close(fh2);
+		return efi_status;
+	}
+
+	if (len > 1024 * PAGE_SIZE) {
+		fh2->Close(fh2);
+		return EFI_BAD_BUFFER_SIZE;
+	}
+
+	b = AllocateZeroPool(len + 2);
+	if (!b) {
+		console_print(L"Could not allocate memory\n");
+		fh2->Close(fh2);
+		return EFI_OUT_OF_RESOURCES;
+	}
+
+	efi_status = fh->Read(fh, &len, b);
+	if (EFI_ERROR(efi_status)) {
+		FreePool(b);
+		fh2->Close(fh2);
+		console_print(L"Could not read file: %r\n", efi_status);
+		return efi_status;
+	}
+	*buffer = b;
+	*bs = len;
+	fh2->Close(fh2);
+	return EFI_SUCCESS;
+}