textutils "sort" patch

[Michael L Maraist]

Starting somewhere after version 2.0.11, there was a change to at least the 
src/sort.c program reguarding file operations.  I first noticed this on Red 
Hat 7.2 (which used 2.0.14).

The functional problem is:
ll /tmp/file*
-rw-rw-r--    1 maraist  maraist         0 Feb  9 15:23 /tmp/file1
-rw-rw-r--    1 maraist  maraist         6 Feb  8 13:30 /tmp/file2

sort -m /tmp/file1 /tmp/file2
Segmentation fault

More detailed analysis shows that if n files are provided, if any of 0 .. n-1 
files are zero bytes in size, the system cores during merging.

The problem was that during the merge, a pass is made through all the files 
reading the first line.. If a file is empty, the file-name is removed from 
the list, BUT, nothing is done about the file-handles.  This took me several 
days to fix, but here's a patch based on version 2.0.19:

--- sort.c      Sat Dec  1 12:29:26 2001
+++ sort_good.c Sat Feb  9 16:41:18 2002
@@ -1649,5 +1649,5 @@

   /* Read initial lines from each input file. */
-  for (i = 0; i < nfiles; ++i)
+  for (i = 0; i < nfiles; )
     {
       fps[i] = xfopen (files[i], "r");
@@ -1655,5 +1655,5 @@
               MAX (merge_buffer_size, sort_size / nfiles));
       /* If a file is empty, eliminate it from future consideration. */
-      while (i < nfiles && !fillbuf (&buffer[i], fps[i], files[i]))
+      if (i < nfiles && !fillbuf (&buffer[i], fps[i], files[i]))
        {
          xfclose (fps[i], files[i]);
@@ -1662,4 +1662,6 @@
          for (j = i; j < nfiles; ++j)
            files[j] = files[j + 1];
+
+          continue; // redo this loop
        }
       if (i == nfiles)
@@ -1671,4 +1673,5 @@
          base[i] = linelim - buffer[i].nlines;
        }
+      i++;
     }

--- sort.c	Sat Dec  1 12:29:26 2001
+++ sort_good.c	Sat Feb  9 16:41:18 2002
@@ -1649,5 +1649,5 @@
 
   /* Read initial lines from each input file. */
-  for (i = 0; i < nfiles; ++i)
+  for (i = 0; i < nfiles; )
     {
       fps[i] = xfopen (files[i], "r");
@@ -1655,5 +1655,5 @@
 	       MAX (merge_buffer_size, sort_size / nfiles));
       /* If a file is empty, eliminate it from future consideration. */
-      while (i < nfiles && !fillbuf (&buffer[i], fps[i], files[i]))
+      if (i < nfiles && !fillbuf (&buffer[i], fps[i], files[i]))
 	{
 	  xfclose (fps[i], files[i]);
@@ -1662,4 +1662,6 @@
 	  for (j = i; j < nfiles; ++j)
 	    files[j] = files[j + 1];
+
+          continue; // redo this loop
 	}
       if (i == nfiles)
@@ -1671,4 +1673,5 @@
 	  base[i] = linelim - buffer[i].nlines;
 	}
+      i++;
     }