Fix specs EFI_FILE_PROTOCOL.Read() non-compliance for directory listing

* Closes #4.
pbatard · Apr 11, 2023 · 6982701 · 6982701
1 parent 50324b7
commit 6982701
Showing 1 changed file with 11 additions and 3 deletions.
diff --git a/uefi-driver/uefi_file.c b/uefi-driver/uefi_file.c
@@ -1,6 +1,6 @@
 /* uefi_file.c - SimpleFileIo Interface */
 /*
- * Copyright © 2014-2021 Pete Batard <pete@akeo.ie>
+ * Copyright © 2014-2023 Pete Batard <pete@akeo.ie>
  * Based on iPXE's efi_driver.c and efi_file.c:
  * Copyright © 2011,2013 Michael Brown <mbrown@fensystems.co.uk>.
  *
@@ -306,6 +306,12 @@ static INT32 DirHook(VOID* Data, CONST CHAR16* Name,
  FS_ASSERT(NameLen < 256);
 
  if (HookData->Info->Size < ((UINT64)NameLen + 1) * sizeof(CHAR16)) {
+ /*
+ * Per specs: If the buffer is not large enough to hold the current directory
+ * entry, EFI_BUFFER_TOO_SMALL is returned and Len is set to the size of the
+ * buffer needed to read the entry.
+ */
+ HookData->Info->Size = ((UINT64)NameLen + 1) * sizeof(CHAR16);
  NtfsSetErrno(EFI_BUFFER_TOO_SMALL);
  return -1;
  }
@@ -342,16 +348,18 @@ FileReadDir(EFI_NTFS_FILE* File, UINTN* Len, VOID* Data)
 
  HookData.Info->Size = *Len;
  Status = NtfsReadDirectory(File, DirHook, &HookData);
+ *Len = (UINTN)HookData.Info->Size;
+
  if (EFI_ERROR(Status)) {
  if (Status == EFI_END_OF_FILE) {
  *Len = 0;
  return EFI_SUCCESS;
  }
- PrintStatusError(Status, L"Directory listing failed");
+ if (Status != EFI_BUFFER_TOO_SMALL)
+ PrintStatusError(Status, L"Directory listing failed");
  return Status;
  }
 
- *Len = (UINTN)HookData.Info->Size;
  return EFI_SUCCESS;
 }