In support of #8305 (implement cache).

Add Truncate() method to nsIFileSpec and implement in nsFileSpecImpl

[Mac Implementation: sdagley, r: sfraser]
[Win implementation: fur, r:rogerl]
[Unix implementation: yixiong.zue@intel.com, r: fur]


git-svn-id: svn://10.0.0.236/trunk@53948 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/xpcom/io/nsFileSpec.h

@@ -506,6 +506,7 @@ class NS_COM nsFileSpec
         void                    CreateDir(int mode = 0700) { CreateDirectory(mode); }
                                    // workaround for yet another VC++ bug with long identifiers.
         void                    Delete(PRBool inRecursive) const;
+        nsresult                Truncate(PRInt32 aNewLength) const;
         void                    RecursiveCopy(nsFileSpec newDir) const;
         
         nsresult                Rename(const char* inNewName); // not const: gets updated

mozilla/xpcom/io/nsFileSpecImpl.cpp

@@ -384,6 +384,13 @@ NS_IMETHODIMP nsFileSpecImpl::CreateDir()
 	return mFileSpec.Error();
 }
 
+//----------------------------------------------------------------------------------------
+NS_IMETHODIMP nsFileSpecImpl::Truncate(PRInt32 aNewLength)
+//----------------------------------------------------------------------------------------
+{
+	return mFileSpec.Truncate(aNewLength);
+}
+
 //----------------------------------------------------------------------------------------
 NS_IMETHODIMP nsFileSpecImpl::Rename(const char *newLeafName)
 //----------------------------------------------------------------------------------------

mozilla/xpcom/io/nsFileSpecMac.cpp

@@ -1031,6 +1031,32 @@ void nsFileSpec::RecursiveCopy(nsFileSpec newDir) const
 	}
 } // nsFileSpec::RecursiveCopy
 
+//----------------------------------------------------------------------------------------
+nsresult nsFileSpec::Truncate(PRInt32 aNewLength) const
+//----------------------------------------------------------------------------------------
+{
+    short   refNum;
+    OSErr   err;
+        
+    // First see if we have an internal error set
+    if (NS_FAILED(mError))
+        return mError;
+        
+    // Need to open the file to trunc
+    if (::FSpOpenDF(&mSpec, fsWrPerm, &refNum) != noErr)
+        return NS_FILE_FAILURE;
+
+    err = ::SetEOF(refNum, aNewLength);
+        
+    // Close the file unless we got an error that it was already closed
+    if (err != fnOpnErr)
+        (void)::FSClose(refNum);
+        
+    if (err != noErr)
+        return NS_FILE_FAILURE;
+        
+    return NS_OK;
+} // nsFileSpec::Truncate
 
 //----------------------------------------------------------------------------------------
 nsresult nsFileSpec::Rename(const char* inNewName)

mozilla/xpcom/io/nsFileSpecUnix.cpp

@@ -341,6 +341,22 @@ void nsFileSpec::RecursiveCopy(nsFileSpec newDir) const
 } // nsFileSpec::RecursiveCopy
 
 
+//----------------------------------------------------------------------------------------
+nsresult nsFileSpec::Truncate(const PRInt32 offset) const
+//----------------------------------------------------------------------------------------
+{
+    char* Path = nsCRT::strdup(mPath);
+
+    int rv = truncate(Path, offset) ;
+
+    nsCRT::free(Path) ;
+
+    if(!rv) 
+        return NS_OK ;
+    else
+        return NS_ERROR_FAILURE ;
+} // nsFileSpec::Truncate
+
 //----------------------------------------------------------------------------------------
 nsresult nsFileSpec::Rename(const char* inNewName)
 //----------------------------------------------------------------------------------------

mozilla/xpcom/io/nsFileSpecWin.cpp

@@ -1,4 +1,4 @@
-/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  *
  * The contents of this file are subject to the Netscape Public
  * License Version 1.1 (the "License"); you may not use this file
@@ -19,7 +19,7 @@
  *
  * Contributor(s): 
  */
- 
+
 //	This file is included by nsFileSpec.cp, and includes the Windows-specific
 //	implementations.
 
@@ -471,6 +471,46 @@ void nsFileSpec::RecursiveCopy(nsFileSpec newDir) const
     }
 } // nsFileSpec::RecursiveCopy
 
+//----------------------------------------------------------------------------------------
+nsresult
+nsFileSpec::Truncate(const PRInt32 aNewFileLength) const
+//----------------------------------------------------------------------------------------
+{
+    DWORD status;
+    HANDLE hFile;
+
+    // Leave it to Microsoft to open an existing file with a function
+    // named "CreateFile".
+    hFile = CreateFile(mPath,
+                       GENERIC_WRITE, 
+                       FILE_SHARE_READ, 
+                       NULL, 
+                       OPEN_EXISTING, 
+                       FILE_FLAG_NO_BUFFERING | FILE_FLAG_OVERLAPPED, 
+                       NULL); 
+    if (hFile == INVALID_HANDLE_VALUE)
+        return NS_FILE_FAILURE;
+
+    // Seek to new, desired end of file
+    status = SetFilePointer(hFile, aNewFileLength, NULL, FILE_BEGIN);
+    if (status == 0xffffffff)
+        goto error;
+
+    // Truncate file at current cursor position
+    if (!SetEndOfFile(hFile))
+        goto error;
+
+    if (!CloseHandle(hFile))
+        return NS_FILE_FAILURE;
+
+    return NS_OK;
+
+ error:
+    CloseHandle(hFile);
+    return NS_FILE_FAILURE;
+
+} // nsFileSpec::Truncate
+
 //----------------------------------------------------------------------------------------
 nsresult nsFileSpec::Rename(const char* inNewName)
 //----------------------------------------------------------------------------------------

mozilla/xpcom/io/nsIFileSpec.idl

@@ -102,6 +102,7 @@ interface nsIFileSpec : nsISupports
 	boolean isSymlink();
 	void resolveSymlink();
 
+    void truncate(in long aNewLength);
 	void rename([const] in string newLeafName);
 	void copyToDir([const] in nsIFileSpec newParentDir);
 	void moveToDir([const] in nsIFileSpec newParentDir);