fixed a well hidden bug in file fastbufs

diff --git a/lib/fb-file.c b/lib/fb-file.c
index 9ac57395445301012a958277a617860ba8766d32..82236230c567efcf9a846f8ed542b337dcb68a3a 100644 (file)
--- a/lib/fb-file.c
+++ b/lib/fb-file.c
@@ -102,16 +102,14 @@ long_seek:
       if ((sh_off_t)back > f->pos)
        back = f->pos;
       f->bptr = f->buffer + back;
-      read_len = back + diff - F->wlen;
+      read_len = blen;
+      f->bstop = f->buffer + read_len;
       /* Reuse part of previous window */
-      if (F->wlen && read_len < blen)
+      if (F->wlen && read_len <= back + diff && read_len > back + diff - F->wlen)
         {
-         uns keep = MIN(F->wlen, blen - read_len);
-         memmove(f->buffer + read_len, f->buffer, keep);
-         f->bstop = f->buffer + read_len + keep;
+         uns keep = read_len + F->wlen - back - diff;
+         memmove(f->buffer + read_len - keep, f->buffer, keep);
        }
-      else
-       f->bstop = f->buffer + (read_len = blen);
 seek:
       /* Do lseek() */
       F->wpos = f->pos + (f->buffer - f->bptr);