From bfc296bc4b8e6f01e471984458fa66ad5acc2a1e Mon Sep 17 00:00:00 2001
From: Hubert Maier
Date: Mon, 7 Oct 2019 23:15:29 +0200
Subject: AMIGAOS4: Fix NULL access

---
 backends/fs/amigaos4/amigaos4-fs.cpp | 61 ++++++++++++++++++++++--------------
 1 file changed, 37 insertions(+), 24 deletions(-)

(limited to 'backends/fs')

diff --git a/backends/fs/amigaos4/amigaos4-fs.cpp b/backends/fs/amigaos4/amigaos4-fs.cpp
index 3561303b6d..624f8aaa25 100644
--- a/backends/fs/amigaos4/amigaos4-fs.cpp
+++ b/backends/fs/amigaos4/amigaos4-fs.cpp
@@ -62,13 +62,21 @@ AmigaOSFilesystemNode::AmigaOSFilesystemNode() {
 	_bIsDirectory = true;
 	_sPath = "";
 	_pFileLock = 0;
-	_nProt = 0; // Protection is ignored for the root volume
+	_nProt = 0; // Protection is ignored for the root volume.
 	LEAVE();
 }
 
 AmigaOSFilesystemNode::AmigaOSFilesystemNode(const Common::String &p) {
 	ENTER();
 
+	// We need to explicitely open dos.library and it's IDOS interface.
+	// Otherwise we'll hit an IDOS NULL pointer after compiling a shared
+	// binary with (shared) plugins.
+	// The hit will happen on loading a game from any engine, if more
+	// than one engine/plugin is available.
+	DOSBase=IExec->OpenLibrary("dos.library",0);
+	IDOS = (struct DOSIFace *)IExec->GetInterface(DOSBase, "main", 1, NULL);
+	
 	int offset = p.size();
 
 	//assert(offset > 0);
@@ -84,7 +92,7 @@ AmigaOSFilesystemNode::AmigaOSFilesystemNode(const Common::String &p) {
 	_bIsDirectory = false;
 	_bIsValid = false;
 
-	// Check whether the node exists and if it's a directory
+	// Check whether the node exists and if it's a directory.
 	struct ExamineData * pExd = IDOS->ExamineObjectTags(EX_StringNameInput,_sPath.c_str(),TAG_END);
 	if (pExd) {
 		_nProt = pExd->Protection;
@@ -93,7 +101,7 @@ AmigaOSFilesystemNode::AmigaOSFilesystemNode(const Common::String &p) {
 			_pFileLock = IDOS->Lock((CONST_STRPTR)_sPath.c_str(), SHARED_LOCK);
 			_bIsValid = (_pFileLock != 0);
 
-			// Add a trailing slash if needed
+			// Add a trailing slash if needed.
 			const char c = _sPath.lastChar();
 			if (c != '/' && c != ':')
 				_sPath += '/';
@@ -105,6 +113,10 @@ AmigaOSFilesystemNode::AmigaOSFilesystemNode(const Common::String &p) {
 		IDOS->FreeDosObject(DOS_EXAMINEDATA, pExd);
 	}
 
+	// Close dos.library and it's IDOS interface again.
+	IExec->DropInterface((struct Interface *)IDOS);
+	IExec->CloseLibrary(DOSBase);
+
 	LEAVE();
 }
 
@@ -161,7 +173,7 @@ AmigaOSFilesystemNode::AmigaOSFilesystemNode(BPTR pLock, const char *pDisplayNam
 	LEAVE();
 }
 
-// We need the custom copy constructor because of DupLock()
+// We need the custom copy constructor because of DupLock().
 AmigaOSFilesystemNode::AmigaOSFilesystemNode(const AmigaOSFilesystemNode& node)
 : AbstractFSNode() {
 	ENTER();
@@ -237,9 +249,6 @@ bool AmigaOSFilesystemNode::getChildren(AbstractFSList &myList, ListMode mode, b
 	ENTER();
 	bool ret = false;
 
-	// TODO: Honor the hidden flag
-	// There is no such thing as a hidden flag in AmigaOS...
-
 	if (!_bIsValid) {
 		debug(6, "Invalid node");
 		LEAVE();
@@ -343,9 +352,9 @@ bool AmigaOSFilesystemNode::isReadable() const {
 	if (!_bIsValid)
 		return false;
 
-	// Regular RWED protection flags are low-active or inverted, thus the negation.
-	// Moreover, a pseudo root filesystem is readable whatever the
-	// protection says.
+	// Regular RWED protection flags are low-active or inverted,
+	// thus the negation. Moreover, a pseudo root filesystem is
+	// readable whatever the protection says.
 	bool readable = !(_nProt & EXDF_OTR_READ) || isRootNode();
 
 	return readable;
@@ -355,9 +364,10 @@ bool AmigaOSFilesystemNode::isWritable() const {
 	if (!_bIsValid)
 		return false;
 
-	// Regular RWED protection flags are low-active or inverted, thus the negation.
-	// Moreover, a pseudo root filesystem is never writable whatever
-	// the protection says (Because of it's pseudo nature).
+	// Regular RWED protection flags are low-active or inverted,
+	// thus the negation. Moreover, a pseudo root filesystem is
+	// never writable whatever the protection says.
+	// (Because of it's pseudo nature).
 	bool writable = !(_nProt & EXDF_OTR_WRITE) && !isRootNode();
 
 	return writable;
@@ -385,18 +395,21 @@ AbstractFSList AmigaOSFilesystemNode::listVolumes() const {
 			dosList->dol_Port) {
 
 			// The original line was
-			//if (dosList->dol_Type == DLT_VOLUME &&
-			//dosList->dol_Name &&
-			//dosList->dol_Task) {
-			// which errored using SDK 53.24 with a 'struct dosList' has no member called 'dol_Task'
-			// The reason for that was that
-			// 1) dol_Task wasn't a task pointer, it is a message port instead
-			// 2) It was redefined to be dol_Port in dos/obsolete.h in afore mentioned SDK
-
-			// Copy name to buffer
+			//
+			//	if (dosList->dol_Type == DLT_VOLUME &&
+			//		dosList->dol_Name &&
+			//		dosList->dol_Task) {
+			//
+			// which errored using SDK 53.24 with a
+			//	'struct dosList' has no member called 'dol_Task'
+			// The reason for that was, that
+			//	1) dol_Task wasn't a task pointer, it is a message port instead.
+			//	2) it was redefined to be dol_Port in dos/obsolete.h in aforementioned SDK.
+
+			// Copy name to buffer.
 			IDOS->CopyStringBSTRToC(dosList->dol_Name, buffer, MAXPATHLEN);
 
-			// Volume name + '\0'
+			// Volume name + '\0'.
 			char *volName = new char [strlen(buffer) + 1];
 
 			strcpy(volName, buffer);
@@ -408,7 +421,7 @@ AbstractFSList AmigaOSFilesystemNode::listVolumes() const {
 
 				char *devName = new char [MAXPATHLEN];
 
-				// Find device name
+				// Find device name.
 				IDOS->DevNameFromLock(volumeLock, devName, MAXPATHLEN, DN_DEVICEONLY);
 
 				sprintf(buffer, "%s (%s)", volName, devName);
-- 
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