Re: Truncate a file from the beginning to the current position

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#1247

From: Ted Lyngmo
Date: Wed, 17 Oct 2007 16:10

40 lines
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"Mehmet Caner" <mcaner40@hotmail.com> wrote:
 >
 > is it possible to truncate a file from the beginning ?

Maybe something like this can work for you? It's potentially very 
dangerous, but if you wanna shorten extremely large logfiles with 
content that is not crucial to your business, it may be worth a try.

Best regards,
Ted Lyngmo

void remove_first_bytes( char *filename, size_t bytes ) {
   FILE *fin, *fout;
   char buf[BUFSIZ];
   size_t rco, new_end=-1;

   fin = fopen( filename, "r+b" );
   if( fin ) {
     fout = fopen( filename, "r+b" );
     if( fout ) {
       fseek( fin, bytes, SEEK_SET );

       while( !feof( fin ) ) {
         rco = fread( buf, 1, BUFSIZ, fin );
         if( (rco>0) && (rco != fwrite( buf, 1, rco, fout )) ) {
           // big trouble, file destroyed
         }
       }

       new_end = ftell( fout );

       fclose( fout );
     }
     fclose( fin );

     if( new_end>0 ) {
       // Now use SetEndOfFile( ..., new_end );
     }
   }
}

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<4715d331@newsgroups.borland.com> <4715df73@newsgroups.borland.com> <47161c7b@newsgroups.borland.com> <m89ch3h2tophqsg72tk7on1p092qsb9u3l@4ax.com>

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Date: Wed, 17 Oct 2007 18:10:26 +0200
From: Ted Lyngmo <tedREMOVETHIS@lyncon.se>
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