[sane-devel] [RFC][PATCH] scanimage --batch="| pipe > %d.img" extension

[Taisuke Yamada]

Hi.

I have created a patch to make "scanimage --batch=" accept
command pipeline in addition to plain filename, and wondering
if this could be merged back to the original. I'm currently
scanning thousands of pages with ADF, and this extension
increases overall processing speed significantly.

Check out the following:

  $ time ./scanimage --batch=%.3d.pnm --batch-count=1
  Scanning 1 pages, incrementing by 1, numbering from 1
  Scanning page 1
  Scanned page 1. (scanner status = 5)
  real    0m14.579s
  user    0m0.088s
  sys     0m0.060s

  $ time ./scanimage --batch='| pnmflip -cw > %.3d.pnm' --batch-count=1
  Scanning page 1
  Scanned page 1. (scanner status = 5)
  real    0m14.931s
  user    0m4.740s
  sys     0m0.160s

  $ time sh -c './scanimage --batch=%.3d.pnm --batch-count=1; pnmflip -cw < 001.pnm > a && mv a 001.pnm'
  Scanning 1 pages, incrementing by 1, numbering from 1
  Scanning page 1
  Scanned page 1. (scanner status = 5)
  real    0m19.348s
  user    0m4.736s
  sys     0m0.140s

As you can see, doing on-the-fly conversion brings speed
advantage of nearly 25%, and it also reduces both disk I/O
and space requirement by 50%.

This is similar to scanadf extension posted some time ago, but
since scanimage is more flexible than scanadf, it'd be great
if this gets included as well.

Best Regards,
--
Taisuke Yamada <tyamadajp at spam.rakugaki.org>
2268 E9A2 D4F9 014E F11D  1DF7 DCA3 83BC 78E5 CD3A

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-------------- next part --------------
--- scanimage.c.orig	2006-09-10 13:21:41.000000000 +0900
+++ scanimage.c	2006-09-10 13:21:45.000000000 +0900
@@ -2117,7 +2117,7 @@
 	{
 	  char path[PATH_MAX];
 	  if (batch)		/* format is NULL unless batch mode */
-	    sprintf (path, format, n);	/* love --(C++) */
+	    sprintf (path, format, n, n, n, n, n);	/* love --(C++) */
 
 
 	  if (batch)
@@ -2146,15 +2146,21 @@
 	    {
 	      fprintf (stderr, "%s: sane_start: %s\n",
 		       prog_name, sane_strstatus (status));
-	      fclose (stdout);
 	      break;
 	    }
 
-	  if (batch && NULL == freopen (path, "w", stdout))
+	  if (batch)
 	    {
-	      fprintf (stderr, "cannot open %s\n", path);
-	      sane_cancel (device);
-	      return SANE_STATUS_ACCESS_DENIED;
+	      FILE *tmp = (path[0] == '|')
+		? popen (&path[1], "w") : freopen (path, "w", stdout);
+
+	      if (tmp == NULL)
+		{
+		  fprintf (stderr, "cannot open %s\n", path);
+		  sane_cancel (device);
+		  return SANE_STATUS_ACCESS_DENIED;
+		}
+	      stdout = tmp;
 	    }
 
 	  status = scan_it ();
@@ -2179,6 +2185,14 @@
 		}
 	      break;
 	    }			/* switch */
+
+	  {
+	    struct stat buf;
+	    fstat (fileno (stdout), &buf);
+	    if (S_ISFIFO (buf.st_mode))
+	      pclose (stdout);
+	  }
+
 	  n += batch_increment;
 	}
       while ((batch