OvmfPkg/VirtioFsDxe: convert FUSE inode attributes to EFI_FILE_INFO

Introduce the VirtioFsFuseAttrToEfiFileInfo() function, for converting
FUSE inode attributes to EFI_FILE_INFO.

The EpochToEfiTime() function from EmbeddedPkg's TimeBaseLib proves
invaluable for converting the file access times.

This is the first time we consume TimeBaseLib in OvmfPkg, so add the
necessary lib class resolution. We need not modify any ArmVirtPkg DSC
files: see commit af5fed90bf ("ArmPlatformPkg,ArmVirtPkg: delete
redundant PL031 functions", 2017-05-10).

Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3097
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20201216211125.19496-22-lersek@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@arm.com>

OvmfPkg/Include/IndustryStandard/VirtioFs.h

@@ -84,6 +84,9 @@ typedef struct {
 //
 // File mode bitmasks.
 //
+#define VIRTIO_FS_FUSE_MODE_TYPE_MASK 0170000u
+#define VIRTIO_FS_FUSE_MODE_TYPE_REG  0100000u
+#define VIRTIO_FS_FUSE_MODE_TYPE_DIR  0040000u
 #define VIRTIO_FS_FUSE_MODE_PERM_RWXU 0000700u
 #define VIRTIO_FS_FUSE_MODE_PERM_RUSR 0000400u
 #define VIRTIO_FS_FUSE_MODE_PERM_WUSR 0000200u

OvmfPkg/OvmfPkgIa32.dsc

@@ -125,6 +125,7 @@
   BaseMemoryLib|MdePkg/Library/BaseMemoryLibRepStr/BaseMemoryLibRepStr.inf
   BaseLib|MdePkg/Library/BaseLib/BaseLib.inf
   SafeIntLib|MdePkg/Library/BaseSafeIntLib/BaseSafeIntLib.inf
+  TimeBaseLib|EmbeddedPkg/Library/TimeBaseLib/TimeBaseLib.inf
   BmpSupportLib|MdeModulePkg/Library/BaseBmpSupportLib/BaseBmpSupportLib.inf
   SynchronizationLib|MdePkg/Library/BaseSynchronizationLib/BaseSynchronizationLib.inf
   CpuLib|MdePkg/Library/BaseCpuLib/BaseCpuLib.inf

OvmfPkg/OvmfPkgIa32X64.dsc

@@ -129,6 +129,7 @@
   BaseMemoryLib|MdePkg/Library/BaseMemoryLibRepStr/BaseMemoryLibRepStr.inf
   BaseLib|MdePkg/Library/BaseLib/BaseLib.inf
   SafeIntLib|MdePkg/Library/BaseSafeIntLib/BaseSafeIntLib.inf
+  TimeBaseLib|EmbeddedPkg/Library/TimeBaseLib/TimeBaseLib.inf
   BmpSupportLib|MdeModulePkg/Library/BaseBmpSupportLib/BaseBmpSupportLib.inf
   SynchronizationLib|MdePkg/Library/BaseSynchronizationLib/BaseSynchronizationLib.inf
   CpuLib|MdePkg/Library/BaseCpuLib/BaseCpuLib.inf

OvmfPkg/OvmfPkgX64.dsc

@@ -129,6 +129,7 @@
   BaseMemoryLib|MdePkg/Library/BaseMemoryLibRepStr/BaseMemoryLibRepStr.inf
   BaseLib|MdePkg/Library/BaseLib/BaseLib.inf
   SafeIntLib|MdePkg/Library/BaseSafeIntLib/BaseSafeIntLib.inf
+  TimeBaseLib|EmbeddedPkg/Library/TimeBaseLib/TimeBaseLib.inf
   BmpSupportLib|MdeModulePkg/Library/BaseBmpSupportLib/BaseBmpSupportLib.inf
   SynchronizationLib|MdePkg/Library/BaseSynchronizationLib/BaseSynchronizationLib.inf
   CpuLib|MdePkg/Library/BaseCpuLib/BaseCpuLib.inf

OvmfPkg/VirtioFsDxe/Helpers.c

@@ -9,6 +9,7 @@
 #include <Library/BaseLib.h>             // StrLen()
 #include <Library/BaseMemoryLib.h>       // CopyMem()
 #include <Library/MemoryAllocationLib.h> // AllocatePool()
+#include <Library/TimeBaseLib.h>         // EpochToEfiTime()
 #include <Library/VirtioLib.h>           // Virtio10WriteFeatures()
 
 #include "VirtioFsDxe.h"
@@ -1589,3 +1590,121 @@ FreeRhsPath8:
   FreePool (RhsPath8);
   return Status;
 }
+
+/**
+  Convert select fields of a VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE object to
+  corresponding fields in EFI_FILE_INFO.
+
+  @param[in] FuseAttr   The VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE object to
+                        convert the relevant fields from.
+
+  @param[out] FileInfo  The EFI_FILE_INFO structure to modify. Importantly, the
+                        FileInfo->Size and FileInfo->FileName fields are not
+                        overwritten.
+
+  @retval EFI_SUCCESS      Conversion successful.
+
+  @retval EFI_UNSUPPORTED  The allocated size of the file is inexpressible in
+                           EFI_FILE_INFO.
+
+  @retval EFI_UNSUPPORTED  One of the file access times is inexpressible in
+                           EFI_FILE_INFO.
+
+  @retval EFI_UNSUPPORTED  The file type is inexpressible in EFI_FILE_INFO.
+
+  @retval EFI_UNSUPPORTED  The file is a regular file that has multiple names
+                           on the host side (i.e., its hard link count is
+                           greater than one).
+**/
+EFI_STATUS
+VirtioFsFuseAttrToEfiFileInfo (
+  IN     VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE *FuseAttr,
+     OUT EFI_FILE_INFO                      *FileInfo
+  )
+{
+  UINT64   EpochTime[3];
+  EFI_TIME *ConvertedTime[ARRAY_SIZE (EpochTime)];
+  UINTN    Idx;
+
+  FileInfo->FileSize = FuseAttr->Size;
+
+  //
+  // The unit for FuseAttr->Blocks is 512B.
+  //
+  if (FuseAttr->Blocks >= BIT55) {
+    return EFI_UNSUPPORTED;
+  }
+  FileInfo->PhysicalSize = LShiftU64 (FuseAttr->Blocks, 9);
+
+  //
+  // Convert the timestamps. File creation time is not tracked by the Virtio
+  // Filesystem device, so set FileInfo->CreateTime from FuseAttr->Mtime as
+  // well.
+  //
+  EpochTime[0]     = FuseAttr->Mtime;
+  EpochTime[1]     = FuseAttr->Atime;
+  EpochTime[2]     = FuseAttr->Mtime;
+  ConvertedTime[0] = &FileInfo->CreateTime;
+  ConvertedTime[1] = &FileInfo->LastAccessTime;
+  ConvertedTime[2] = &FileInfo->ModificationTime;
+
+  for (Idx = 0; Idx < ARRAY_SIZE (EpochTime); Idx++) {
+    //
+    // EpochToEfiTime() takes a UINTN for seconds.
+    //
+    if (EpochTime[Idx] > MAX_UINTN) {
+      return EFI_UNSUPPORTED;
+    }
+    //
+    // Set the following fields in the converted time: Year, Month, Day, Hour,
+    // Minute, Second, Nanosecond.
+    //
+    EpochToEfiTime ((UINTN)EpochTime[Idx], ConvertedTime[Idx]);
+    //
+    // The times are all expressed in UTC. Consequently, they are not affected
+    // by daylight saving.
+    //
+    ConvertedTime[Idx]->TimeZone = 0;
+    ConvertedTime[Idx]->Daylight = 0;
+    //
+    // Clear the padding fields.
+    //
+    ConvertedTime[Idx]->Pad1 = 0;
+    ConvertedTime[Idx]->Pad2 = 0;
+  }
+
+  //
+  // Set the attributes.
+  //
+  switch (FuseAttr->Mode & VIRTIO_FS_FUSE_MODE_TYPE_MASK) {
+  case VIRTIO_FS_FUSE_MODE_TYPE_DIR:
+    FileInfo->Attribute = EFI_FILE_DIRECTORY;
+    break;
+  case VIRTIO_FS_FUSE_MODE_TYPE_REG:
+    FileInfo->Attribute = 0;
+    break;
+  default:
+    //
+    // Other file types are not supported.
+    //
+    return EFI_UNSUPPORTED;
+  }
+  //
+  // Report the regular file or directory as read-only if all classes lack
+  // write permission.
+  //
+  if ((FuseAttr->Mode & (VIRTIO_FS_FUSE_MODE_PERM_WUSR |
+                         VIRTIO_FS_FUSE_MODE_PERM_WGRP |
+                         VIRTIO_FS_FUSE_MODE_PERM_WOTH)) == 0) {
+    FileInfo->Attribute |= EFI_FILE_READ_ONLY;
+  }
+
+  //
+  // A hard link count greater than 1 is not supported for regular files.
+  //
+  if ((FileInfo->Attribute & EFI_FILE_DIRECTORY) == 0 && FuseAttr->Nlink > 1) {
+    return EFI_UNSUPPORTED;
+  }
+
+  return EFI_SUCCESS;
+}

OvmfPkg/VirtioFsDxe/VirtioFsDxe.h

@@ -11,6 +11,7 @@
 #define VIRTIO_FS_DXE_H_
 
 #include <Base.h>                      // SIGNATURE_64()
+#include <Guid/FileInfo.h>             // EFI_FILE_INFO
 #include <IndustryStandard/VirtioFs.h> // VIRTIO_FS_TAG_BYTES
 #include <Library/DebugLib.h>          // CR()
 #include <Protocol/SimpleFileSystem.h> // EFI_SIMPLE_FILE_SYSTEM_PROTOCOL
@@ -225,6 +226,12 @@ VirtioFsAppendPath (
      OUT BOOLEAN *RootEscape
   );
 
+EFI_STATUS
+VirtioFsFuseAttrToEfiFileInfo (
+  IN     VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE *FuseAttr,
+     OUT EFI_FILE_INFO                      *FileInfo
+  );
+
 //
 // Wrapper functions for FUSE commands (primitives).
 //

OvmfPkg/VirtioFsDxe/VirtioFsDxe.inf

@@ -77,6 +77,7 @@
   ENTRY_POINT                           = VirtioFsEntryPoint
 
 [Packages]
+  EmbeddedPkg/EmbeddedPkg.dec
   MdePkg/MdePkg.dec
   OvmfPkg/OvmfPkg.dec
 
@@ -110,6 +111,7 @@
   BaseMemoryLib
   DebugLib
   MemoryAllocationLib
+  TimeBaseLib
   UefiBootServicesTableLib
   UefiDriverEntryPoint
   VirtioLib