1 files changed, 43 insertions, 19 deletions
diff --git a/src/Main/Forms/VolumeCreationWizard.cpp b/src/Main/Forms/VolumeCreationWizard.cpp
index dd5c4dbf..37af6361 100644
--- a/src/Main/Forms/VolumeCreationWizard.cpp
+++ b/src/Main/Forms/VolumeCreationWizard.cpp
@@ -14,6 +14,7 @@
 #include "Platform/SystemInfo.h"
 #ifdef TC_UNIX
 #include <unistd.h>
+#include <sys/statvfs.h> // header for statvfs
 #include "Platform/Unix/Process.h"
 #endif
 #include "Core/RandomNumberGenerator.h"
@@ -822,15 +823,6 @@ namespace VeraCrypt
 						}
 					}
 
-					// Skip PIM
-					if (forward && OuterVolume)
-					{
-						// Use FAT to prevent problems with free space
-						QuickFormatEnabled = false;
-						SelectedFilesystemType = VolumeCreationOptions::FilesystemType::FAT;
-						return Step::CreationProgress;
-					}
-
 					if (VolumeSize > 4 * BYTES_PER_GB)
 					{
 						if (VolumeSize <= TC_MAX_FAT_SECTOR_COUNT * SectorSize)
@@ -901,15 +893,6 @@ namespace VeraCrypt
 					}
 				}
 
-
-				if (forward && OuterVolume)
-				{
-					// Use FAT to prevent problems with free space
-					QuickFormatEnabled = false;
-					SelectedFilesystemType = VolumeCreationOptions::FilesystemType::FAT;
-					return Step::CreationProgress;
-				}
-
 				if (VolumeSize > 4 * BYTES_PER_GB)
 				{
 					if (VolumeSize <= TC_MAX_FAT_SECTOR_COUNT * SectorSize)
@@ -945,6 +928,22 @@ namespace VeraCrypt
 		case Step::FormatOptions:
 			{
 				VolumeFormatOptionsWizardPage *page = dynamic_cast <VolumeFormatOptionsWizardPage *> (GetCurrentPage());
+
+				if (forward && OuterVolume)
+				{
+					if (page->GetFilesystemType() != VolumeCreationOptions::FilesystemType::FAT)
+					{
+						if (!Gui->AskYesNo (_("WARNING: You have selected a filesystem other than FAT for the outer volume.\n"
+											  "Please Note that in this case VeraCrypt can't calculate the exact maximum allowed size for the hidden volume and it will use only an estimation that can be wrong.\n"
+											  "Thus, it is your responsibility to use an adequate value for the size of the hidden volume so that it doesn\'t overlap the outer volume.\n\n"
+											  "Do you want to continue using the selected filesystem for the outer volume?")
+											, false, true))
+						{
+							return GetCurrentStep();
+						}
+					}
+				}
+
 				SelectedFilesystemType = page->GetFilesystemType();
 				QuickFormatEnabled = page->IsQuickFormatEnabled();
 
@@ -1098,12 +1097,23 @@ namespace VeraCrypt
 				// require using FUSE and loop device which cannot be used for devices with sectors larger than 512.
 
 				wxBusyCursor busy;
+				bool outerVolumeAvailableSpaceValid = false;
+				uint64 outerVolumeAvailableSpace = 0;
 				MaxHiddenVolumeSize = 0;
 
 				Gui->SetActiveFrame (this);
 
 				if (MountedOuterVolume)
 				{
+#ifdef TC_UNIX
+					const DirectoryPath &outerVolumeMountPoint = MountedOuterVolume->MountPoint;
+					struct statvfs stat;
+					if (statvfs(((string)outerVolumeMountPoint).c_str(), &stat) == 0)
+					{
+						 outerVolumeAvailableSpace = (uint64) stat.f_bsize * (uint64) stat.f_bavail;
+						 outerVolumeAvailableSpaceValid = true;
+					}
+#endif
 					Core->DismountVolume (MountedOuterVolume);
 					MountedOuterVolume.reset();
 				}
@@ -1126,7 +1136,21 @@ namespace VeraCrypt
 #endif
 
 				shared_ptr <Volume> outerVolume = Core->OpenVolume (make_shared <VolumePath> (SelectedVolumePath), true, Password, Pim, Kdf, false, Keyfiles, VolumeProtection::ReadOnly);
-				MaxHiddenVolumeSize = Core->GetMaxHiddenVolumeSize (outerVolume);
+				try
+				{
+					MaxHiddenVolumeSize = Core->GetMaxHiddenVolumeSize (outerVolume);
+				}
+				catch (ParameterIncorrect& )
+				{
+					// Outer volume not using FAT
+					// estimate maximum hidden volume size as 80% of available size of outer volume
+					if (outerVolumeAvailableSpaceValid)
+					{
+						MaxHiddenVolumeSize =(4ULL * outerVolumeAvailableSpace) / 5ULL;
+					}
+					else
+						throw;
+				}
 
 				// Add a reserve (in case the user mounts the outer volume and creates new files
 				// on it by accident or OS writes some new data behind his or her back, such as