[hackers] [sbase] dd: Always move excess to beginning of buffer after read/write loops || Michael Forney

[git]

commit 4b76652eff2b6f7d23c800dbc48c509792c726b3
Author:     Michael Forney <mfor...@mforney.org>
AuthorDate: Wed Apr 28 01:41:26 2021 -0700
Commit:     Michael Forney <mfor...@mforney.org>
CommitDate: Fri May 21 12:16:41 2021 -0700

    dd: Always move excess to beginning of buffer after read/write loops
    
    Otherwise, while we may have enough room for at least one input
    block, we may not have enough room for an output block.

diff --git a/dd.c b/dd.c
index 5522db5..6061048 100644
--- a/dd.c
+++ b/dd.c
@@ -222,11 +222,10 @@ main(int argc, char *argv[])
                                ofull++;
                        opos += ret;
                } while ((eof && ipos < opos) || (!eof && ipos - opos >= obs));
-               if (len - ipos < ibs) {
+               if (opos < ipos)
                        memmove(buf, buf + opos, ipos - opos);
-                       ipos -= opos;
-                       opos = 0;
-               }
+               ipos -= opos;
+               opos = 0;
        }
        summary();