tests: check decoding of chown syscall

* tests/chown.c: New file.
* tests/chown.test: New test.
* tests/xchownx.c: New file.
* tests/.gitignore: Add chown.
* tests/Makefile.am (check_PROGRAMS): Likewise.
(DECODER_TESTS): Add chown.test.
(EXTRA_DIST): Add xchownx.c.
diff --git a/tests/.gitignore b/tests/.gitignore
index 6aae5de..ad27043 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -16,6 +16,7 @@
 bpf
 caps
 chmod
+chown
 chroot
 clock_nanosleep
 clock_xettime
diff --git a/tests/Makefile.am b/tests/Makefile.am
index c7e884d..0a2ac1c 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -68,6 +68,7 @@
 	bpf \
 	caps \
 	chmod \
+	chown \
 	chroot \
 	clock_nanosleep \
 	clock_xettime \
@@ -276,6 +277,7 @@
 	bpf.test \
 	caps.test \
 	chmod.test \
+	chown.test \
 	chroot.test \
 	clock_nanosleep.test \
 	clock_xettime.test \
@@ -504,6 +506,7 @@
 	     umovestr.expected \
 	     wait.expected \
 	     xattr.expected \
+	     xchownx.c \
 	     xselect.c \
 	     xstatx.c \
 	     $(TESTS)
diff --git a/tests/chown.c b/tests/chown.c
new file mode 100644
index 0000000..59a4d63
--- /dev/null
+++ b/tests/chown.c
@@ -0,0 +1,19 @@
+#include "tests.h"
+#include <sys/syscall.h>
+
+#ifdef __NR_chown
+
+# define SYSCALL_NR __NR_chown
+# define SYSCALL_NAME "chown"
+
+# if defined __NR_chown32 && __NR_chown != __NR_chown32
+#  define UGID_TYPE_IS_SHORT
+# endif
+
+# include "xchownx.c"
+
+#else
+
+SKIP_MAIN_UNDEFINED("__NR_chown")
+
+#endif
diff --git a/tests/chown.test b/tests/chown.test
new file mode 100755
index 0000000..1a94c32
--- /dev/null
+++ b/tests/chown.test
@@ -0,0 +1,6 @@
+#!/bin/sh
+
+# Check chown syscall decoding.
+
+. "${srcdir=.}/init.sh"
+run_strace_match_diff -a29
diff --git a/tests/xchownx.c b/tests/xchownx.c
new file mode 100644
index 0000000..fdf476e
--- /dev/null
+++ b/tests/xchownx.c
@@ -0,0 +1,173 @@
+/*
+ * Check decoding of chown/chown32/lchown/lchown32/fchown/fchown32 syscalls.
+ *
+ * Copyright (c) 2016 Dmitry V. Levin <ldv@altlinux.org>
+ * 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.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#ifdef UGID_TYPE_IS_SHORT
+# define UGID_TYPE	short
+# define GETEUID	syscall(__NR_geteuid)
+# define GETEGID	syscall(__NR_getegid)
+# define CHECK_OVERFLOWUID(arg)	check_overflowuid(arg)
+# define CHECK_OVERFLOWGID(arg)	check_overflowgid(arg)
+#else
+# define UGID_TYPE	int
+# define GETEUID	geteuid()
+# define GETEGID	getegid()
+# define CHECK_OVERFLOWUID(arg)
+# define CHECK_OVERFLOWGID(arg)
+#endif
+
+#define UNLINK_SAMPLE \
+	if (unlink(sample)) perror_msg_and_fail("unlink")
+#define CLOSE_SAMPLE \
+	if (close(fd)) perror_msg_and_fail("close")
+
+#ifdef ACCESS_BY_DESCRIPTOR
+# define SYSCALL_ARG1 fd
+# define FMT_ARG1 "%d"
+# define ERRNO_STR "EBADF"
+# define EOK_CMD CLOSE_SAMPLE
+# define CLEANUP_CMD UNLINK_SAMPLE
+#else
+# define SYSCALL_ARG1 sample
+# define FMT_ARG1 "\"%s\""
+# define ERRNO_STR "ENOENT"
+# define EOK_CMD UNLINK_SAMPLE
+# define CLEANUP_CMD CLOSE_SAMPLE
+#endif
+
+static int
+ugid2int(const unsigned UGID_TYPE id)
+{
+	if ((unsigned UGID_TYPE) -1U == id)
+		return -1;
+	else
+		return id;
+}
+
+static void
+print_int(const unsigned int num)
+{
+	if (num == -1U)
+		printf(", -1");
+	else
+		printf(", %u", num);
+}
+
+static int
+num_matches_id(const unsigned int num, const unsigned int id)
+{
+	return num == id || num == -1U;
+}
+
+#define PAIR(val)	{ val, gid }, { uid, val }
+
+int
+main(void)
+{
+	static const char sample[] = SYSCALL_NAME "_sample";
+
+	unsigned int uid = GETEUID;
+	CHECK_OVERFLOWUID(uid);
+	unsigned int gid = GETEGID;
+	CHECK_OVERFLOWUID(gid);
+
+	const struct {
+		const long uid, gid;
+	} tests[] = {
+		{ uid, gid },
+		{ (unsigned long) 0xffffffff00000000ULL | uid, gid },
+		{ uid, (unsigned long) 0xffffffff00000000ULL | gid },
+		PAIR(-1U),
+		PAIR(-1L),
+		{ 0xffff0000U | uid, gid },
+		{ uid, 0xffff0000U | gid },
+		PAIR(0xffff),
+		PAIR(0xc0deffffU),
+		PAIR(0xfacefeedU),
+		PAIR((long) 0xfacefeeddeadbeefULL)
+	};
+
+	int fd = open(sample, O_RDONLY | O_CREAT, 0400);
+	if (fd < 0)
+		perror_msg_and_fail("open");
+
+	CLEANUP_CMD;
+
+	unsigned int i;
+	long expected = 0;
+
+	for (i = 0; i < ARRAY_SIZE(tests); ++i) {
+		const unsigned int unum = ugid2int(tests[i].uid);
+		const unsigned int gnum = ugid2int(tests[i].gid);
+
+		if (num_matches_id(unum, uid) &&
+		    num_matches_id(gnum, gid)) {
+			if (expected)
+				continue;
+		} else {
+			if (!expected) {
+				expected = -1;
+				EOK_CMD;
+			}
+		}
+
+		const long rc = syscall(SYSCALL_NR, SYSCALL_ARG1,
+					tests[i].uid, tests[i].gid);
+		int saved_errno = errno;
+		if (rc != expected) {
+			if (!i && ENOSYS == errno) {
+				printf("%s(" FMT_ARG1 ", %u, %u)"
+				       " = -1 ENOSYS (%m)\n",
+				       SYSCALL_NAME, SYSCALL_ARG1, uid, gid);
+				break;
+			}
+			perror_msg_and_fail("%s(" FMT_ARG1
+					    ", %#lx, %#lx) != %ld",
+					    SYSCALL_NAME, SYSCALL_ARG1,
+					    tests[i].uid, tests[i].gid,
+					    expected);
+		}
+
+		printf("%s(" FMT_ARG1, SYSCALL_NAME, SYSCALL_ARG1);
+		print_int(unum);
+		print_int(gnum);
+		errno = saved_errno;
+		if (expected)
+			printf(") = %ld " ERRNO_STR " (%m)\n", expected);
+		else
+			printf(") = 0\n");
+	}
+
+	puts("+++ exited with 0 +++");
+	return 0;
+}