[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Possible bug in file truncation code



On Fri, Feb 25, 2005 at 05:21:41PM +0000, David Woodhouse wrote:
> On Fri, 2005-02-25 at 17:46 +0100, Andrew Lunn wrote:
> >ie if the node does not have any fragments left its marked as
> >obsolete. These appears to remove the node, but still leaves it
> >referenced in the directory. Hence the filesystem is corrupt.
> 
> Directories don't refer to data nodes. They refer to inodes. This inode
> still exists and is zero-length because it has no valid data nodes. The
> directory still refers to it -- that's fine. What's the actual problem?

The test case does the open, followed by a close then umount and then
mounts. The mount then reports:

<5>Eep. Child "TestFile.txt" (ino #10) of dir ino #1 doesn't exist!

I've attached the test case if you want to try it.

        Andrew
#include <cyg/infra/diag.h>
#include <pkgconf/fs_jffs2.h>
#include <pkgconf/io_flash.h>
#include <stdio.h>

#include <cyg/fileio/fileio.h>

void do_file(void)
{
	int err;
	FILE *TestFile;
	char Text[255];

	// mount the filesystem
	err = mount( CYGDAT_IO_FLASH_BLOCK_DEVICE_NAME_1, "/", "jffs2" );
	if( err < 0 )
	{
		diag_printf("mount jffs2: %d %s\n", err, err<0?strerror(errno):"");
		return;
	}

	// create a new file
	TestFile = fopen("TestFile.txt","w");
	if(TestFile == 0)
	{
		diag_printf("error: fopen\n");
		return;
	}
	fputs("This is a test.", TestFile);
	fclose(TestFile);

	// read the file
	TestFile = fopen("TestFile.txt","r");
	if(TestFile == 0)
	{
		diag_printf("error: fopen\n");
		return;
	}
	if( fgets( Text, sizeof(Text), TestFile ) == 0)
		diag_printf("error: fgets\n");
	else
		diag_printf(Text);
	fclose(TestFile);

	// truncate the file
	TestFile = fopen("TestFile.txt","w");
	fclose(TestFile);

	// unmount the filesystem
	err = umount( "/" );
	if( err < 0 )
	{
		diag_printf("umount jffs2: %d %s\n", err, err<0?strerror(errno):"");
		return;
	}
}

int main( int argc, char **argv )
{
	// ok
	do_file();

	// not ok
	do_file();
        return 0;
        
}