The following Makefile illustrates the issue:
$ cat >Makefile <<EOF
all:
echo "abc" | grep "b"
.PHONY: all
$ make all # works as expected
$ make all > /dev/null
grep: (standard input): Invalid argument
make: *** [Makefile:2: all] Error 2
The bug was introduced by commit 4fa6f48b573267e758650e114ec158d97916411e
(introducing the usage of splice), which was first released in grep version
2.27.
My environment:
$ make --version
GNU Make 4.2.1
Built for x86_64-pc-linux-gnu
Copyright (C) 1988-2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html
>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
$ grep --version
grep (GNU grep) 2.27
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html
>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by Mike Haertel and others, see <
http://git.sv.gnu.org/cgit/grep.git/tree/AUTHORS>.
Patch attached.
--
Benno Fünfstück
diff --git a/src/grep.c b/src/grep.c
index f28f3c2..3e8e662 100644
--- a/src/grep.c
+++ b/src/grep.c
@@ -1729,10 +1729,19 @@ drain_input (int fd, struct stat const *st)
#ifdef SPLICE_F_MOVE
/* Should be faster, since it need not copy data to user space. */
while ((nbytes = splice (fd, NULL, STDOUT_FILENO, NULL,
- INITIAL_BUFSIZE, SPLICE_F_MOVE)))
- if (nbytes < 0)
- return false;
- return true;
+ INITIAL_BUFSIZE, SPLICE_F_MOVE)) > 0)
+ continue;
+
+ if(nbytes == 0) return true;
+
+ /* STDOUT might have been opened with O_APPEND (gnumake sets this flag for example).
+ * In this case, splice fails with EINVAL.
+ *
+ * In that case, the safe_read still works so instead of returning with an error here,
+ * we just fall through to the safe_read variant.
+ */
+ if(nbytes < 0 && errno != EINVAL) return false;
+
#endif
}
while ((nbytes = safe_read (fd, buffer, bufalloc)))
