stdbuf: A new program to run a command with modified stdio buffering

* AUTHORS: Register as the author.
* NEWS: Mention this change.
* README: Add stdbuf command to list.
* configure.ac: Only enable on ELF systems with GCC.
* cfg.mk (sc_system_h_headers): Use VC_LIST_EXCEPT rather than
VC_LIST, so we can add an exception, if needed.
* .x-sc_system_h_headers: New file.  Exempt libstdbuf.c.
* Makefile.am (syntax_check_exceptions): Add .x-sc_system_h_headers.
* doc/coreutils.texi (stdbuf invocation): Add stdbuf info.
* man/.gitignore: Ignore generated manpage.
* src/.gitignore: Ignore stdbuf and libstdbuf.so binaries.
* man/Makefile.am (stdbuf.1): Add dependency.
* man/stdbuf.x: New file with example usage.
* po/POTFILES.in: Reference new command and shared library sources.
* src/Makefile.am (build_if_possible__progs): Add stdbuf and libstdbuf,
(pkglib_PROGRAMS): Reference optional shared lib,
(libstdbuf_so_LDADD): Ensure we don't link with non PIC libcoreutils.a.
(libstdbuf_so_LDFLAGS): Add -shared GCC option,
(libstdbuf_so_CFLAGS): Add -fPIC GCC option.
(check-README): Exclude libstbuf.
(check-AUTHORS): ditto.
(sc_tight_scope): Exclude functions starting with __.
* src/libstdbuf.c: The LD_PRELOAD shared library to control buffering.
* src/stdbuf.c: New file to setup env variables before execing command.
* tests/Makefile.am: Reference new test file.
* tests/misc/help-version: Set expected exit codes.
* tests/misc/invalid-opt: ditto.
* tests/misc/stdbuf: Add 9 tests.

1 files changed, 86 insertions, 0 deletions

diff --git a/tests/misc/stdbuf b/tests/misc/stdbuf
new file mode 100755
index 000000000..6f79e771f
--- /dev/null
+++ b/tests/misc/stdbuf
@@ -0,0 +1,86 @@
+#!/bin/sh
+# Exercise stdbuf functionality
+
+# Copyright (C) 2009 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+if test "$VERBOSE" = yes; then
+  set -x
+  stdbuf --version
+fi
+
+. $srcdir/test-lib.sh
+getlimits_
+
+# Use a fifo rather than a pipe in the tests below
+# so that the producer (uniq) will wait until the
+# consumer (dd) opens the fifo therefore increasing
+# the chance that dd will read the data from each
+# write separately.
+mkfifo fifo || framework_failure
+
+fail=0
+
+# Verify input parameter checking
+stdbuf -o1 true || fail=1 # verify size syntax
+stdbuf -oK true || fail=1 # verify size syntax
+stdbuf -o0 true || fail=1 # verify unbuffered syntax
+stdbuf -oL true || fail=1 # verify line buffered syntax
+stdbuf -ol true && fail=1 # Capital 'L' required
+stdbuf -o$SIZE_OFLOW true && fail=1 # size too large
+stdbuf -iL true && fail=1 # line buffering stdin disallowed
+
+# Ensure line buffering stdout takes effect
+printf '1\n' > exp
+dd count=1 if=fifo > out 2> err &
+(printf '1\n'; sleep .2; printf '2\n') | stdbuf -oL uniq > fifo
+wait # for dd to complete
+compare out exp || fail=1
+
+# Ensure un buffering stdout takes effect
+printf '1\n' > exp
+dd count=1 if=fifo > out 2> err &
+(printf '1\n'; sleep .2; printf '2\n') | stdbuf -o0 uniq > fifo
+wait # for dd to complete
+compare out exp || fail=1
+
+# Ensure un buffering stdin takes effect
+#  The following works for me, but is racy. I.E. we're depending
+#  on dd to run and close the fifo before the second write by uniq.
+#  If we add a sleep, then we're just testing -oL
+    # printf '3\n' > exp
+    # dd count=1 if=fifo > /dev/null 2> err &
+    # printf '1\n\2\n3\n' | (stdbuf -i0 -oL uniq > fifo; cat) > out
+    # wait # for dd to complete
+    # compare out exp || fail=1
+#  One could remove the need for dd (used to close the fifo to get uniq to quit
+#  early), if head -n1 read stdin char by char. Note uniq | head -c2 doesn't
+#  suffice due to the buffering implicit in the pipe.  sed currently does read
+#  stdin char by char, so we can test with `sed 1q`.  However I'm wary about
+#  adding this dependency on a program outside of coreutils.
+    # printf '2\n' > exp
+    # printf '1\n2\n' | (stdbuf -i0 sed 1q >/dev/null; cat) > out
+    # compare out exp || fail=1
+
+# Ensure block buffering stdout takes effect
+# We don't currently test block buffering failures as
+# this doesn't work on on GLIBC-2.7 or GLIBC-2.9 at least.
+   # printf '1\n2\n' > exp
+   # dd count=1 if=fifo > out 2> err &
+   # (printf '1\n'; sleep .2; printf '2\n') | stdbuf -o4 uniq > fifo
+   # wait # for dd to complete
+   # compare out exp || fail=1
+
+Exit $fail