feat(kernel): implement handling symbolic links in paths

Signed-off-by: EnderIce2 <enderice2@protonmail.com>

Kernel/exec/binary_parse.cpp

@@ -100,6 +100,12 @@ namespace Execute
 	BinaryType GetBinaryType(std::string Path)
 	{
 		FileNode *node = fs->GetByPath(Path.c_str(), nullptr);
+		if (node->IsSymbolicLink())
+		{
+			char buffer[512];
+			node->ReadLink(buffer, sizeof(buffer));
+			node = fs->GetByPath(buffer, node->Parent);
+		}
 		debug("Checking binary type of %s (returning %p)", Path.c_str(), node);
 		assert(node != nullptr);
 		return GetBinaryType(node);

Kernel/exec/elf/elf_loader.cpp

@@ -335,6 +335,13 @@ namespace Execute
 			}
 			else
 			{
+				if (ifd->IsSymbolicLink())
+				{
+					char buffer[512];
+					ifd->ReadLink(buffer, sizeof(buffer));
+					ifd = fs->GetByPath(buffer, ifd->Parent);
+				}
+
 				debug("ifd: %p, interpreter: %s", ifd, interpreterPath.c_str());
 				if (GetBinaryType(interpreterPath) != BinTypeELF)
 				{
@@ -798,6 +805,14 @@ namespace Execute
 			error("Failed to open %s, errno: %d", AbsolutePath.c_str(), fd);
 			return;
 		}
+
+		if (fd->IsSymbolicLink())
+		{
+			char buffer[512];
+			fd->ReadLink(buffer, sizeof(buffer));
+			fd = fs->GetByPath(buffer, fd->Parent);
+		}
+
 		debug("Opened %s", AbsolutePath.c_str());
 
 		int argc = 0;

Kernel/exec/spawn.cpp

@@ -40,9 +40,20 @@ namespace Execute
 			return -ENOENT;
 
 		if (!fd->IsRegularFile())
-			return -ENOEXEC;
+		{
+			if (fd->IsSymbolicLink())
+			{
+				char buffer[512];
+				fd->ReadLink(buffer, sizeof(buffer));
+				fd = fs->GetByPath(buffer, fd->Parent);
+				if (fd == nullptr)
+					return -ENOENT;
+			}
+			else
+				return -ENOEXEC;
+		}
 
-		switch (GetBinaryType(Path))
+		switch (GetBinaryType(fd))
 		{
 		case BinaryType::BinTypeELF:
 		{

Kernel/storage/filesystem.cpp

@@ -161,6 +161,7 @@ namespace vfs
 		}
 
 		Inode *Node = NULL;
+		bool readSymlinks = true; /* FIXME: implement */
 		do
 		{
 			auto it = DeviceMap.find(__Parent->Node->Device);
@@ -170,6 +171,22 @@ namespace vfs
 			if (it->second.fsi->Ops.Lookup == NULL)
 				ReturnLogError(nullptr, "Lookup not supported for %d", it->first);
 
+			if (readSymlinks && __Parent->IsSymbolicLink())
+			{
+				if (it->second.fsi->Ops.ReadLink == NULL)
+					ReturnLogError(nullptr, "Readlink not supported for %d", it->first);
+
+				char buffer[256];
+				int ret = it->second.fsi->Ops.ReadLink(__Parent->Node, buffer, sizeof(buffer));
+				if (ret < 0)
+					ReturnLogError(nullptr, "Readlink for \"%s\"(%d) failed with %d", __Parent->Path.c_str(), it->first, ret);
+
+				FileNode *target = this->GetByPath(buffer, __Parent->Parent ? __Parent->Parent : __Parent);
+				if (target == nullptr)
+					ReturnLogError(nullptr, "Failed to find target for \"%s\"", __Parent->Path.c_str());
+				__Parent = target;
+			}
+
 			std::string segmentName(segment.begin, segment.size);
 			int ret = it->second.fsi->Ops.Lookup(__Parent->Node, segmentName.c_str(), &Node);
 			if (ret < 0)

Kernel/storage/fs/ustar.cpp

@@ -389,7 +389,7 @@ namespace vfs
 			Size = strlen(node->Header->link);
 
 		strncpy(Buffer, node->Header->link, Size);
-		debug("Read %d bytes from %d", Size, Node->Index);
+		debug("Read %d bytes from %d: \"%s\"", Size, Node->Index, Buffer);
 		return Size;
 	}
 

Kernel/tasking/process.cpp

@@ -113,6 +113,12 @@ namespace Tasking
 		trace("Setting exe %s to %s",
 			  this->Name, path);
 		Executable = fs->GetByPath(path, ProcDirectory);
+		if (Executable->IsSymbolicLink())
+		{
+			char buffer[512];
+			Executable->ReadLink(buffer, sizeof(buffer));
+			Executable = fs->GetByPath(buffer, Executable->Parent);
+		}
 		FileNode *exe = fs->GetByPath("exe", ProcDirectory);
 		if (exe)
 			fs->Remove(exe);