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[tpg/acess2.git] / KernelLand / Kernel / vfs / memfile.c

diff --git a/KernelLand/Kernel/vfs/memfile.c b/KernelLand/Kernel/vfs/memfile.c
new file mode 100644 (file)
index 0000000..14b3948
--- /dev/null
+++ b/KernelLand/Kernel/vfs/memfile.c
@@ -0,0 +1,135 @@
+/* 
+ * Acess 2
+ * Virtual File System
+ * - Memory Pseudo Files
+ */
+#include <acess.h>
+#include <vfs.h>
+
+// === PROTOTYPES ===
+tVFS_Node      *VFS_MemFile_Create(const char *Path);
+void   VFS_MemFile_Close(tVFS_Node *Node);
+Uint64 VFS_MemFile_Read(tVFS_Node *Node, Uint64 Offset, Uint64 Length, void *Buffer);
+Uint64 VFS_MemFile_Write(tVFS_Node *Node, Uint64 Offset, Uint64 Length, const void *Buffer);
+
+// === GLOBALS ===
+tVFS_NodeType  gVFS_MemFileType = {
+       .Close = VFS_MemFile_Close,
+       .Read = VFS_MemFile_Read,
+       .Write = VFS_MemFile_Write
+       };
+
+// === CODE ===
+/**
+ * \fn tVFS_Node *VFS_MemFile_Create(const char *Path)
+ */
+tVFS_Node *VFS_MemFile_Create(const char *Path)
+{
+       Uint    base, size;
+       const char      *str = Path;
+       tVFS_Node       *ret;
+       
+       str++;  // Eat '$'
+       
+       // Read Base address
+       base = 0;
+       for( ; ('0' <= *str && *str <= '9') || ('A' <= *str && *str <= 'F'); str++ )
+       {
+               base *= 16;
+               if('A' <= *str && *str <= 'F')
+                       base += *str - 'A' + 10;
+               else
+                       base += *str - '0';
+       }
+       
+       // Check separator
+       if(*str++ != ':')       return NULL;
+       
+       // Read buffer size
+       size = 0;
+       for( ; ('0' <= *str && *str <= '9') || ('A' <= *str && *str <= 'F'); str++ )
+       {
+               size *= 16;
+               if('A' <= *str && *str <= 'F')
+                       size += *str - 'A' + 10;
+               else
+                       size += *str - '0';
+       }
+       
+       // Check for NULL byte
+       if(*str != '\0')        return NULL;
+       
+       // Allocate and fill node
+       ret = malloc(sizeof(tVFS_Node));
+       memset(ret, 0, sizeof(tVFS_Node));
+       
+       // State
+       ret->ImplPtr = (void*)base;
+       ret->Size = size;
+       
+       // ACLs
+       ret->NumACLs = 1;
+       ret->ACLs = &gVFS_ACL_EveryoneRWX;
+       
+       // Functions
+       ret->Type = &gVFS_MemFileType;
+       
+       return ret;
+}
+
+/**
+ * \fn void VFS_MemFile_Close(tVFS_Node *Node)
+ * \brief Dereference and clean up a memory file
+ */
+void VFS_MemFile_Close(tVFS_Node *Node)
+{
+       Node->ReferenceCount --;
+       if( Node->ReferenceCount == 0 ) {
+               Node->ImplPtr = NULL;
+               free(Node);
+       }
+}
+
+/**
+ * \fn Uint64 VFS_MemFile_Read(tVFS_Node *Node, Uint64 Offset, Uint64 Length, void *Buffer)
+ * \brief Read from a memory file
+ */
+Uint64 VFS_MemFile_Read(tVFS_Node *Node, Uint64 Offset, Uint64 Length, void *Buffer)
+{
+       // Check for use of free'd file
+       if(Node->ImplPtr == NULL)       return 0;
+       
+       // Check for out of bounds read
+       if(Offset > Node->Size) return 0;
+       
+       // Truncate data read if needed
+       if(Offset + Length > Node->Size)
+               Length = Node->Size - Offset;
+       
+       // Copy Data
+       memcpy(Buffer, (Uint8*)Node->ImplPtr + Offset, Length);
+       
+       return Length;
+}
+
+/**
+ * \fn Uint64 VFS_MemFile_Write(tVFS_Node *Node, Uint64 Offset, Uint64 Length, void *Buffer)
+ * \brief Write to a memory file
+ */
+Uint64 VFS_MemFile_Write(tVFS_Node *Node, Uint64 Offset, Uint64 Length, const void *Buffer)
+{
+       // Check for use of free'd file
+       if(Node->ImplPtr == NULL)       return 0;
+       
+       // Check for out of bounds read
+       if(Offset > Node->Size) return 0;
+       
+       // Truncate data read if needed
+       if(Offset + Length > Node->Size)
+               Length = Node->Size - Offset;
+       
+       // Copy Data
+       memcpy((Uint8*)Node->ImplPtr + Offset, Buffer, Length);
+       
+       return Length;
+}