From 82f44a2107d7eb79f1e3a4af196e2e007a166e57 Mon Sep 17 00:00:00 2001
From: Pierre Schweitzer <pierre@reactos.org>
Date: Thu, 4 Jan 2018 21:47:59 +0100
Subject: [PATCH] [USETUP] When overwriting a file, if open fails, it might be
 because the file is readonly. In such situation, try to drop the readonly
 attribute before overwritting the file.

This fixes setup not being able to overwrite FAT bootcode when reusing a FAT partition
already installed without reformatting.

CORE-14158
---
 base/setup/usetup/filesup.c | 68 +++++++++++++++++++++++++++++++++++--
 1 file changed, 66 insertions(+), 2 deletions(-)

diff --git a/base/setup/usetup/filesup.c b/base/setup/usetup/filesup.c
index bed30c418d6..65a372a3377 100644
--- a/base/setup/usetup/filesup.c
+++ b/base/setup/usetup/filesup.c
@@ -348,8 +348,72 @@ SetupCopyFile(
                           0);
     if (!NT_SUCCESS(Status))
     {
-        DPRINT1("NtCreateFile failed: %x, %wZ\n", Status, &FileName);
-        goto unmapsrcsec;
+        /* Open may have failed because the file to overwrite
+         * is in readonly mode
+         */
+        if (Status == STATUS_ACCESS_DENIED)
+        {
+            FILE_BASIC_INFORMATION FileBasicInfo;
+
+            /* Reattempt to open it */
+            Status = NtCreateFile(&FileHandleDest,
+                                  GENERIC_WRITE | SYNCHRONIZE,
+                                  &ObjectAttributes,
+                                  &IoStatusBlock,
+                                  NULL,
+                                  FILE_ATTRIBUTE_NORMAL,
+                                  0,
+                                  FILE_OPEN,
+                                  FILE_NO_INTERMEDIATE_BUFFERING |
+                                  FILE_SEQUENTIAL_ONLY |
+                                  FILE_SYNCHRONOUS_IO_NONALERT,
+                                  NULL,
+                                  0);
+            /* Fail for real if we cannot open it that way
+             * XXX: actually, we should try to refine access rights
+             * to only have write_attributes, should be enough
+             */
+            if (!NT_SUCCESS(Status))
+            {
+                DPRINT1("NtCreateFile failed: %x, %wZ\n", Status, &FileName);
+                goto unmapsrcsec;
+            }
+
+            /* Zero our basic info, just to set attributes */
+            RtlZeroMemory(&FileBasicInfo, sizeof(FileBasicInfo));
+            /* Reset attributes to normal, no read-only */
+            FileBasicInfo.FileAttributes = FILE_ATTRIBUTE_NORMAL;
+            /* We basically don't care about whether it succeed:
+             * if it didn't, later open will fail
+             */
+            NtSetInformationFile(FileHandleDest, &IoStatusBlock, &FileBasicInfo,
+                                 sizeof(FileBasicInfo), FileBasicInformation);
+
+            /* Close file */
+            NtClose(FileHandleDest);
+
+            /* And re-attempt overwrite */
+            Status = NtCreateFile(&FileHandleDest,
+                                  GENERIC_WRITE | SYNCHRONIZE,
+                                  &ObjectAttributes,
+                                  &IoStatusBlock,
+                                  NULL,
+                                  FILE_ATTRIBUTE_NORMAL,
+                                  0,
+                                  FILE_OVERWRITE_IF,
+                                  FILE_NO_INTERMEDIATE_BUFFERING |
+                                  FILE_SEQUENTIAL_ONLY |
+                                  FILE_SYNCHRONOUS_IO_NONALERT,
+                                  NULL,
+                                  0);
+        }
+
+        /* We failed */
+        if (!NT_SUCCESS(Status))
+        {
+            DPRINT1("NtCreateFile failed: %x, %wZ\n", Status, &FileName);
+            goto unmapsrcsec;
+        }
     }
 
     RegionSize = (ULONG)PAGE_ROUND_UP(FileStandard.EndOfFile.u.LowPart);
-- 
2.17.1