From c7cf98b0e03780f78abe5275c6fb282f71a2369f Mon Sep 17 00:00:00 2001
From: Sami Kerola <kerolasa@iki.fi>
Date: Fri, 23 Mar 2012 11:10:04 +0100
Subject: [PATCH] lib: add fileutils file with stream error checking facility

The close_stream() is copied from GNU lib. Inspiration to do this
is talk by Jim Meyering - Goodbye World! The perils of relying on
output streams in C.

Reference: http://www.irill.org/events/ghm-gnu-hackers-meeting/videos/jim-meyering-goodbye-world-the-perils-of-relying-on-output-streams-in-c
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
---
 include/fileutils.h                   |  7 +++++
 lib/.gitignore                        |  1 +
 lib/Makefile.am                       |  3 +-
 lib/fileutils.c                       | 43 +++++++++++++++++++++++++++
 testsuite/Makefile.am                 |  1 +
 testsuite/lib.test/fileutils.exp      | 19 ++++++++++++
 testsuite/lib.test/fileutils_badfd.sh |  4 +++
 testsuite/lib.test/fileutils_full.sh  |  4 +++
 8 files changed, 81 insertions(+), 1 deletion(-)
 create mode 100644 include/fileutils.h
 create mode 100644 lib/fileutils.c
 create mode 100644 testsuite/lib.test/fileutils.exp
 create mode 100755 testsuite/lib.test/fileutils_badfd.sh
 create mode 100755 testsuite/lib.test/fileutils_full.sh

diff --git a/include/fileutils.h b/include/fileutils.h
new file mode 100644
index 00000000..cfab570c
--- /dev/null
+++ b/include/fileutils.h
@@ -0,0 +1,7 @@
+#ifndef PROCPS_NG_FILEUTILS
+#define PROCPS_NG_FILEUTILS
+
+int close_stream(FILE * stream);
+void close_stdout(void);
+
+#endif
diff --git a/lib/.gitignore b/lib/.gitignore
index f4208e7a..6b7ce835 100644
--- a/lib/.gitignore
+++ b/lib/.gitignore
@@ -1,2 +1,3 @@
 .dirstamp
+test_fileutils
 test_strutils
diff --git a/lib/Makefile.am b/lib/Makefile.am
index 4216a252..9430de2e 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -2,6 +2,7 @@ AM_CPPFLAGS = -include $(top_builddir)/config.h -I$(top_srcdir)/include
 
 AM_CPPFLAGS += -DTEST_PROGRAM
 
-noinst_PROGRAMS = test_strutils
+noinst_PROGRAMS = test_strutils test_fileutils
 
 test_strutils_SOURCES = strutils.c
+test_fileutils_SOURCES = fileutils.c
diff --git a/lib/fileutils.c b/lib/fileutils.c
new file mode 100644
index 00000000..b47a9cf7
--- /dev/null
+++ b/lib/fileutils.c
@@ -0,0 +1,43 @@
+#include <errno.h>
+#include <error.h>
+#include <stdio_ext.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "nls.h"
+
+int close_stream(FILE * stream)
+{
+	const int some_pending = (__fpending(stream) != 0);
+	const int prev_fail = (ferror(stream) != 0);
+	const int fclose_fail = (fclose(stream) != 0);
+	if (prev_fail || (fclose_fail && (some_pending || errno != EBADF))) {
+		if (!fclose_fail)
+			errno = 0;
+		return EOF;
+	}
+	return 0;
+}
+
+/* Use atexit(); */
+void close_stdout(void)
+{
+	if (close_stream(stdout) != 0 && !(errno == EPIPE)) {
+		char const *write_error = _("write error");
+		error(0, errno, "%s", write_error);
+		_exit(EXIT_FAILURE);
+	}
+
+	if (close_stream(stderr) != 0)
+		_exit(EXIT_FAILURE);
+}
+
+#ifdef TEST_PROGRAM
+#include <stdio.h>
+int main(int argc, char *argv[])
+{
+	atexit(close_stdout);
+	printf("Hello, World!\n");
+	return EXIT_SUCCESS;
+}
+#endif				/* TEST_PROGRAM */
diff --git a/testsuite/Makefile.am b/testsuite/Makefile.am
index 62acfa64..0bb7fb9f 100644
--- a/testsuite/Makefile.am
+++ b/testsuite/Makefile.am
@@ -34,6 +34,7 @@ EXTRA_DIST = \
 	global-conf.exp \
     free.test/free.exp \
     kill.test/kill.exp \
+    lib.test/fileutils.exp \
     lib.test/strutils.exp \
     pgrep.test/pgrep.exp \
     pkill.test/pkill.exp \
diff --git a/testsuite/lib.test/fileutils.exp b/testsuite/lib.test/fileutils.exp
new file mode 100644
index 00000000..3fab11e2
--- /dev/null
+++ b/testsuite/lib.test/fileutils.exp
@@ -0,0 +1,19 @@
+#
+# Testsuite for lib/fileutils program
+#
+
+set noarg "${topdir}lib/test_fileutils"
+
+set test "without argument"
+spawn $noarg
+expect_pass "$test" "Hello, World!"
+
+set badfd "${topdir}testsuite/lib.test/fileutils_badfd.sh"
+set test "test bad file descriptor"
+spawn $badfd
+expect_pass "$test" "test_fileutils: write error: Bad file descriptor"
+
+set full "${topdir}testsuite/lib.test/fileutils_full.sh"
+set test "test no space left on device"
+spawn $full
+expect_pass "$test" "test_fileutils: write error: No space left on device"
diff --git a/testsuite/lib.test/fileutils_badfd.sh b/testsuite/lib.test/fileutils_badfd.sh
new file mode 100755
index 00000000..4a0d5c67
--- /dev/null
+++ b/testsuite/lib.test/fileutils_badfd.sh
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+BASEDIR=$(dirname ${0})
+${BASEDIR}/../../lib/test_fileutils >&-
diff --git a/testsuite/lib.test/fileutils_full.sh b/testsuite/lib.test/fileutils_full.sh
new file mode 100755
index 00000000..0d96a0dd
--- /dev/null
+++ b/testsuite/lib.test/fileutils_full.sh
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+BASEDIR=$(dirname ${0})
+${BASEDIR}/../../lib/test_fileutils > /dev/full