From 8f6da8d78a28b0072ee2bac071e5a6df751b0eda Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Herv=C3=A9=20Poussineau?= <hpoussin@reactos.org>
Date: Sun, 4 May 2025 21:13:46 +0200
Subject: [PATCH] [FREELDR] Fix RamDisk size determination; add some traces
 (#8399)
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CORE-14603 CORE-9023

The RamDisk path specified with `/RDPATH=` can be a path to a block
device, like a disk partition, or the current boot disk (a ReactOS
specific feature added in commit 9b70d4380c), instead of being only
a file (as with Windows' NTLDR).

In this case, the `StartingAddress` and `EndingAddress` returned by
`ArcGetFileInformation()` are, per the specs, the start and end
positions of the partition as byte offsets from the start of the disk.
Therefore, the size of the partition is `== EndingAddress - StartingAddress`.

+ Add diagnostic traces in `RamDiskLoadVirtualFile()` and `RamDiskInitialize()`.

Co-authored-by: Hermès Bélusca-Maïto <hermes.belusca-maito@reactos.org>
---
 boot/freeldr/freeldr/disk/ramdisk.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/boot/freeldr/freeldr/disk/ramdisk.c b/boot/freeldr/freeldr/disk/ramdisk.c
index 2d111d885d9..e080a7e4000 100644
--- a/boot/freeldr/freeldr/disk/ramdisk.c
+++ b/boot/freeldr/freeldr/disk/ramdisk.c
@@ -12,6 +12,9 @@
 #include <freeldr.h>
 #include "../ntldr/ntldropts.h"
 
+#include <debug.h>
+DBG_DEFAULT_CHANNEL(DISK);
+
 /* GLOBALS ********************************************************************/
 
 PVOID gInitRamDiskBase = NULL;
@@ -119,6 +122,8 @@ RamDiskLoadVirtualFile(
     UiDrawProgressBarCenter("Loading RamDisk...");
 
     /* Try opening the Ramdisk file */
+    TRACE("RamDiskLoadVirtualFile: Opening '%s', '%s'\n",
+          FileName, DefaultPath ? DefaultPath : "n/a");
     Status = FsOpenFile(FileName, DefaultPath, OpenReadOnly, &RamFileId);
     if (Status != ESUCCESS)
         return Status;
@@ -130,16 +135,24 @@ RamDiskLoadVirtualFile(
         ArcClose(RamFileId);
         return Status;
     }
+    /* NOTE: For partitions, StartingAddress/EndingAddress are the start/end
+     * positions of the partition as byte offsets from the start of the disk */
+    Information.EndingAddress.QuadPart -= Information.StartingAddress.QuadPart;
+    Information.StartingAddress.QuadPart = 0ULL;
+
+    TRACE("RAMDISK size: %I64u (High: %lu ; Low: %lu)\n",
+          Information.EndingAddress.QuadPart,
+          Information.EndingAddress.HighPart,
+          Information.EndingAddress.LowPart);
 
     /* FIXME: For now, limit RAM disks to 4GB */
-    if (Information.EndingAddress.HighPart != 0)
+    if (Information.EndingAddress.HighPart != 0) // (RamDiskFileSize >= 0x100000000ULL)
     {
         ArcClose(RamFileId);
         UiMessageBox("RAM disk too big.");
         return ENOMEM;
     }
     RamDiskFileSize = Information.EndingAddress.QuadPart;
-    ASSERT(RamDiskFileSize < 0x100000000); // See FIXME above.
 
     /* Allocate memory for it */
     ChunkSize = 8 * 1024 * 1024;
@@ -208,6 +221,11 @@ RamDiskInitialize(
     IN PCSTR LoadOptions OPTIONAL,
     IN PCSTR DefaultPath OPTIONAL)
 {
+    TRACE("RamDiskInitialize(%s, '%s', '%s')\n",
+          InitRamDisk ? "INIT" : "REGULAR",
+          LoadOptions ? LoadOptions : "n/a",
+          DefaultPath ? DefaultPath : "n/a");
+
     /* Reset the RAMDISK device */
     if ((RamDiskBase != gInitRamDiskBase) &&
         (RamDiskFileSize != gInitRamDiskSize) &&