Add a test program for perror() that demonstrates two bugs in the

current implementation.

tools/regression/lib/libc/stdio/Makefile

@@ -0,0 +1,11 @@
+# $FreeBSD$
+
+TESTS=	test-perror
+
+.PHONY: tests
+tests: ${TESTS}
+	for p in ${TESTS}; do ${.OBJDIR}/$$p; done
+
+.PHONY: clean
+clean:
+	-rm -f ${TESTS}

tools/regression/lib/libc/stdio/test-perror.c

@@ -0,0 +1,105 @@
+/*-
+ * Copyright (c) 2002 Tim J. Robbins
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * Test program for perror() as specified by IEEE Std. 1003.1-2001 and
+ * ISO/IEC 9899:1999.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <assert.h>
+#include <err.h>
+#include <errno.h>
+#include <limits.h>
+#include <paths.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static void cleanup(void);
+static char tmpfil[PATH_MAX];
+
+int
+main(int argc, char *argv[])
+{
+	char lbuf[512];
+	int i;
+	char *s;
+
+	strcpy(tmpfil, _PATH_TMP "perror.XXXXXXXX");
+	if (mkstemp(tmpfil) < 0)
+		err(1, "mkstemp");
+	atexit(cleanup);
+	/* Reopen stderr on a file descriptor other than 2. */
+	fclose(stderr);
+	for (i = 0; i < 3; i++)
+		dup(0);
+	if (freopen(tmpfil, "r+", stderr) == NULL)
+		err(1, "%s", tmpfil);
+
+	/*
+	 * Test that perror() doesn't call strerror() (4.4BSD bug),
+	 * the two ways of omitting a program name, and the formatting when
+	 * a program name is specified.
+	 */
+	s = strerror(ENOENT);
+	assert(strcmp(s, "No such file or directory") == 0);
+	errno = EPERM;
+	perror(NULL);
+	perror("");
+	perror("test-perror");
+	assert(strcmp(s, "No such file or directory") == 0);
+
+	/*
+	 * Read it back to check...
+	 */
+	rewind(stderr);
+	s = fgets(lbuf, sizeof(lbuf), stderr);
+	assert(s != NULL);
+	assert(strcmp(s, "Operation not permitted\n") == 0);
+	s = fgets(lbuf, sizeof(lbuf), stderr);
+	assert(s != NULL);
+	assert(strcmp(s, "Operation not permitted\n") == 0);
+	s = fgets(lbuf, sizeof(lbuf), stderr);
+	assert(s != NULL);
+	assert(strcmp(s, "test-perror: Operation not permitted\n") == 0);
+	s = fgets(lbuf, sizeof(lbuf), stderr);
+	assert(s == NULL);
+	fclose(stderr);
+
+	printf("PASS perror()\n");
+
+	return (0);
+}
+
+static void
+cleanup(void)
+{
+
+	unlink(tmpfil);
+}