commit 4c6f35ea529ebca9b2dfb6d7c79cade30118fd75
author Elliott Hughes <enh@google.com> Tue Jul 09 09:49:12 2019 -0700
committer Rob Landley <rob@landley.net> Tue Jul 09 16:22:59 2019 -0500
tree d315ec75d91d9e1a75286d6674b90535aedae30a
parent a5da2e966ad67c2f3667d75b4600c5d4e6ea0c53

dd: fix seek= on stdout.

tests/dd.test

diff --git a/tests/dd.test b/tests/dd.test
index 3ad15f2..d2d6033 100644
--- a/tests/dd.test
+++ b/tests/dd.test
@@ -92,3 +92,6 @@
 # status=noxfer|none
 testing "status=noxfer" "dd if=input status=noxfer ibs=1 2>&1" "input\n6+0 records in\n0+1 records out\n" "input\n" ""
 testing "status=none" "dd if=input status=none ibs=1 2>&1" "input\n" "input\n" ""
+
+testing "seek stdout" "yes 2> /dev/null | dd bs=8 seek=2 count=1 > out 2> /dev/null && xxd -p out" \
+  "00000000000000000000000000000000790a790a790a790a\n" "" ""

toys/pending/dd.c

diff --git a/toys/pending/dd.c b/toys/pending/dd.c
index e37f8b2..0c447f7 100644
--- a/toys/pending/dd.c
+++ b/toys/pending/dd.c
@@ -188,7 +188,7 @@
 
   // seek/truncate as necessary. We handled position zero truncate with
   // O_TRUNC on open, so output to /dev/null and such doesn't error.
-  if (TT.out.fd!=1 && (bs = TT.out.offset*TT.out.sz)) {
+  if ((bs = TT.out.offset*TT.out.sz)) {
     xlseek(TT.out.fd, bs, SEEK_CUR);
     if (trunc && ftruncate(TT.out.fd, bs)) perror_exit("ftruncate");
   }