--- coreutils-5.2.1/src/dd.c	2005-06-26 22:31:51.000000000 +0200
+++ ../coreutils-mine/build-tree/coreutils-5.2.1/src/dd.c	2005-06-23 22:49:33.000000000 +0200
@@ -80,6 +80,7 @@
 #define C_SYNC 02000
 /* Use separate input and output buffers, and combine partial input blocks. */
 #define C_TWOBUFS 04000
+#define C_SPARSE 010000
 
 /* The name this program was run with. */
 char *program_name;
@@ -168,9 +169,12 @@
   {"noerror", C_NOERROR},       /* Ignore i/o errors. */
   {"notrunc", C_NOTRUNC},       /* Do not truncate output file. */
   {"sync", C_SYNC},             /* Pad input records to ibs with NULs. */
+  {"sparse", C_SPARSE},		/* Generate sparse file */
   {NULL, 0}
 };
 
+size_t sparseblocksize;
+const char *zeroblock;
 
 /* Translation table formed by applying successive transformations. */
 static unsigned char trans_table[256];
@@ -1079,7 +1083,41 @@
 
       if (ibuf == obuf)		/* If not C_TWOBUFS. */
 	{
-	  size_t nwritten = full_write (STDOUT_FILENO, obuf, n_bytes_read);
+	  size_t nwritten;
+
+	  if (conversions_mask & C_SPARSE && (n_bytes_read % sparseblocksize) == 0)
+	    {
+	      size_t towrite = 0;
+	      nwritten = 0;
+	      if (memcmp(obuf, zeroblock, sparseblocksize))
+		goto firstnotzero;
+	      while (nwritten < n_bytes_read) {
+		do {
+		  towrite += sparseblocksize;
+		} while (nwritten + towrite < n_bytes_read &&
+		    !memcmp (obuf + nwritten + towrite, zeroblock, sparseblocksize));
+		if (lseek (STDOUT_FILENO, towrite, SEEK_CUR) == -1)
+		  {
+		    error (0, errno, _("seeking %s"), quote (output_file));
+		    quit (EXIT_FAILURE);
+		  }
+		nwritten += towrite;
+		if (nwritten == n_bytes_read)
+		  break;
+		towrite = 0;
+firstnotzero:
+		do {
+		  towrite += sparseblocksize;
+		} while (nwritten + towrite < n_bytes_read &&
+		    memcmp (obuf + nwritten + towrite, zeroblock, sparseblocksize));
+		if (full_write (STDOUT_FILENO, obuf + nwritten, towrite) != towrite)
+		  break;
+		nwritten += towrite;
+		towrite = 0;
+	      }
+	    }
+	  else
+	    nwritten = full_write (STDOUT_FILENO, obuf, n_bytes_read);
 
 	  st.bytes += nwritten;
 	  
@@ -1261,6 +1299,18 @@
       output_file = _("standard output");
     }
 
+  if (conversions_mask & C_SPARSE)
+    {
+      struct stat stdout_stat;
+
+    if (fstat (STDOUT_FILENO, &stdout_stat) != 0)
+      error (EXIT_FAILURE, errno, _("cannot fstat %s"),
+	     quote (output_file));
+
+      sparseblocksize = stdout_stat.st_blksize;
+      zeroblock = calloc(1,sparseblocksize);
+    }
+
   install_handler (SIGINT, interrupt_handler);
   install_handler (SIGQUIT, interrupt_handler);
   install_handler (SIGPIPE, interrupt_handler);