tee: exit early if no more writable outputs

* src/tee.c (main): Don't continue reading if we can't
output anywhere.
* tests/misc/tee.sh: Ensure we exit when no more outputs.
* NEWS: Mention the change in behavior.

1 files changed, 25 insertions, 0 deletions

diff --git a/tests/misc/tee.sh b/tests/misc/tee.sh
index 3c3fd11d7..5f2eeda7b 100755
--- a/tests/misc/tee.sh
+++ b/tests/misc/tee.sh
@@ -31,4 +31,29 @@ for n in 0 $nums; do
         done
 done
 
+
+# Ensure tee exits early if no more writable outputs
+if test -w /dev/full && test -c /dev/full; then
+  yes | returns_ 1 timeout 10 tee /dev/full 2>err >/dev/full || fail=1
+  # Ensure an error for each of the 2 outputs
+  # (and no redundant errors for stdout).
+  test $(wc -l < err) = 2 || { cat err; fail=1; }
+
+
+  # Ensure we continue with outputs that are OK
+  seq 10000 > multi_read || framework_failure_
+
+  returns_ 1 tee /dev/full out2 2>err >out1 <multi_read || fail=1
+  cmp multi_read out1 || fail=1
+  cmp multi_read out2 || fail=1
+  # Ensure an error for failing output
+  test $(wc -l < err) = 1 || { cat err; fail=1; }
+
+  returns_ 1 tee out1 out2 2>err >/dev/full <multi_read || fail=1
+  cmp multi_read out1 || fail=1
+  cmp multi_read out2 || fail=1
+  # Ensure an error for failing output
+  test $(wc -l < err) = 1 || { cat err; fail=1; }
+fi
+
 Exit $fail