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Forums » .NET » .NET »
Locking issue with File Operations...
Posted Date: 16 Dec 2008 Posted By: Vijay Kumar Vemula Member Level: Gold Points: 1
Responses:
2
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Hi all,
I am writing below code to access a .txt file on the hard disk.
public static FileStream OpenReadWrite(String PathNm, bool bExclusiveWrite)
{
int Sharing = FILE_SHARE_READ;
if (!bExclusiveWrite)
Sharing |= FILE_SHARE_WRITE;
SafeFileHandle FileHandle = CreateFile(PathNm, GENERIC_WRITE | GENERIC_READ, Sharing, IntPtr.Zero, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, IntPtr.Zero);
if (FileHandle.IsInvalid)
Marshal.ThrowExceptionForHR(Marshal.GetLastWin32Error());
FileStream fs = new FileStream(FileHandle, FileAccess.ReadWrite);
fs.Seek(fs.Length, SeekOrigin.Begin);
return fs;
}
[DllImport("Kernel32.dll", CharSet=CharSet.Ansi, EntryPoint = "CreateFile")]
private static extern SafeFileHandle CreateFile(System.String PathNm, uint openmode, int fileshare, IntPtr SA, int openflags, int attribs, IntPtr templFile);
private static uint GENERIC_READ = 0x80000000;
private static uint GENERIC_WRITE = 0x40000000;
private static int FILE_SHARE_READ = 0x00000001;
private static int FILE_SHARE_WRITE = 0x00000002;
private static int OPEN_ALWAYS = 4;
private static int OPEN_EXISTING = 3;
private static int FILE_ATTRIBUTE_NORMAL = 0x00000080;
I am able to access the text file with the above written code without any issue. But, where as if I want to access the file in sharing mode (while another process is using it), I am getting exception. The exception is as follows.
Invalid handle.
Parameter name: handle
Can anybody tell me what is the quick fix for this issue?
I will be waiting for your reply.... as it is urgent issue, I want its solution ASAP.
Thanks inadvance.
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Responses
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| Author: MOHAN BABU DODDAPANENI 16 Dec 2008 | Member Level: Silver | Rating:  Points: 3 |
I could see
if (!bExclusiveWrite)
Sharing |= FILE_SHARE_WRITE;
Is ! intensional.. I guess it should be
if ( bExclusiveWrite )
Sharing |= FILE_SHARE_WRITE;
is GENERIC_WRITE and GENERIC_READ in CreateFile both required for you ?
If you are opening the file just for reading..then have just read
And one more thing... don't forget to close the handle using CloseHandle
| | Author: Amit Shah 16 Dec 2008 | Member Level: Gold | Rating: Points: 6 |
close all handles after read write.
when your shared file read then no problem but if there ar writing then use lock unlock method which is provied by .net framework..
let me know if find problem !!!!!
------------------
Hi all,
I am writing below code to access a .txt file on the hard disk.
public static FileStream OpenReadWrite(String PathNm, bool bExclusiveWrite)
{
int Sharing = FILE_SHARE_READ;
if (!bExclusiveWrite)
Sharing |= FILE_SHARE_WRITE;
SafeFileHandle FileHandle = CreateFile(PathNm, GENERIC_WRITE | GENERIC_READ, Sharing, IntPtr.Zero, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, IntPtr.Zero);
if (FileHandle.IsInvalid)
Marshal.ThrowExceptionForHR(Marshal.GetLastWin32Error());
FileStream fs = new FileStream(FileHandle, FileAccess.ReadWrite);
fs.Seek(fs.Length, SeekOrigin.Begin);
return fs;
}
[DllImport("Kernel32.dll", CharSet=CharSet.Ansi, EntryPoint = "CreateFile")]
private static extern SafeFileHandle CreateFile(System.String PathNm, uint openmode, int fileshare, IntPtr SA, int openflags, int attribs, IntPtr templFile);
private static uint GENERIC_READ = 0x80000000;
private static uint GENERIC_WRITE = 0x40000000;
private static int FILE_SHARE_READ = 0x00000001;
private static int FILE_SHARE_WRITE = 0x00000002;
private static int OPEN_ALWAYS = 4;
private static int OPEN_EXISTING = 3;
private static int FILE_ATTRIBUTE_NORMAL = 0x00000080;
I am able to access the text file with the above written code without any issue. But, where as if I want to access the file in sharing mode (while another process is using it), I am getting exception. The exception is as follows.
Invalid handle.
Parameter name: handle
Can anybody tell me what is the quick fix for this issue?
I will be waiting for your reply.... as it is urgent issue, I want its solution ASAP.
Thanks inadvance.
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