git: c35334b08561 - stable/14 - lib/libc/tests/string: add extended unit tests for strcmp()

From: Robert Clausecker <fuz_at_FreeBSD.org>
Date: Thu, 28 Dec 2023 17:20:10 UTC
The branch stable/14 has been updated by fuz:

URL: https://cgit.FreeBSD.org/src/commit/?id=c35334b085616c8ad9a567a04cb1a5cbf6b76a80

commit c35334b085616c8ad9a567a04cb1a5cbf6b76a80
Author:     Robert Clausecker <fuz@FreeBSD.org>
AuthorDate: 2023-09-22 20:42:00 +0000
Commit:     Robert Clausecker <fuz@FreeBSD.org>
CommitDate: 2023-12-28 17:02:40 +0000

    lib/libc/tests/string: add extended unit tests for strcmp()
    
    This changeset add a new set of tests that comprehensively test strcmp() on
    various alignments of the input. This made it easy to smoke out many
    exciting new bugs in the new SSE strcmp() implementation from D41971.
    
    MFC after:      1 week
    Reviewed by:    ngie
    Sponsored by:   The FreeBSD Foundation
    Differential Revision: https://reviews.freebsd.org/D41970
    
    (cherry picked from commit b49596de2622a51e5673ba2c0b3718cd88a2aa41)
---
 lib/libc/tests/string/Makefile      |   2 +
 lib/libc/tests/string/strcmp_test.c | 132 ++++++++++++++++++++++++++++++++++++
 2 files changed, 134 insertions(+)

diff --git a/lib/libc/tests/string/Makefile b/lib/libc/tests/string/Makefile
index 1994b128ab57..e9b066cacac7 100644
--- a/lib/libc/tests/string/Makefile
+++ b/lib/libc/tests/string/Makefile
@@ -11,6 +11,7 @@ ATF_TESTS_C+=		flsll_test
 ATF_TESTS_C+=		memcmp_test
 ATF_TESTS_C+=		memset_s_test
 ATF_TESTS_C+=		stpncpy_test
+ATF_TESTS_C+=		strcmp2_test
 ATF_TESTS_C+=		strcspn_test
 ATF_TESTS_C+=		strerror2_test
 ATF_TESTS_C+=		strspn_test
@@ -37,6 +38,7 @@ NETBSD_ATF_TESTS_C+=	strpbrk_test
 NETBSD_ATF_TESTS_C+=	strrchr_test
 NETBSD_ATF_TESTS_C+=	swab_test
 
+SRCS.strcmp2_test=	strcmp_test.c
 SRCS.strerror2_test=	strerror_test.c
 
 .include "../Makefile.netbsd-tests"
diff --git a/lib/libc/tests/string/strcmp_test.c b/lib/libc/tests/string/strcmp_test.c
new file mode 100644
index 000000000000..75ebcbcadda2
--- /dev/null
+++ b/lib/libc/tests/string/strcmp_test.c
@@ -0,0 +1,132 @@
+/*-
+ * Copyright (c) 2023 The FreeBSD Foundation
+ *
+ * This software was developed by Robert Clausecker <fuz@FreeBSD.org>
+ * under sponsorship from the FreeBSD Foundation.
+ *
+ * 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
+ */
+
+#include <sys/cdefs.h>
+
+#include <atf-c.h>
+#include <dlfcn.h>
+#include <string.h>
+
+int (*volatile strcmp_fn)(const char *, const char *);
+
+ATF_TC(strcmp_alignments);
+ATF_TC_HEAD(strcmp_alignments, tc)
+{
+	atf_tc_set_md_var(tc, "descr", "Test strcmp(3) with various alignments");
+}
+
+static void
+alignment_testcase(char *a, char *b, int want)
+{
+	int res;
+
+	res = strcmp_fn(a, b);
+	ATF_CHECK_MSG(want == (res > 0) - (res < 0),
+	    "strcmp(%p \"%s\", %p \"%s\") = %d != %d",
+	    (void *)a, a, (void *)b, b, res, want);
+}
+
+static void
+check_strcmp_alignments(char a[], char b[],
+    size_t a_off, size_t b_off, size_t len, size_t pos)
+{
+	char *a_str, *b_str, a_orig, b_orig;
+
+	a[a_off] = '\0';
+	b[b_off] = '\0';
+
+	a_str = a + a_off + 1;
+	b_str = b + b_off + 1;
+
+	a_str[len] = '\0';
+	b_str[len] = '\0';
+	a_str[len+1] = 'A';
+	b_str[len+1] = 'B';
+
+	a_orig = a_str[pos];
+	b_orig = b_str[pos];
+
+	alignment_testcase(a_str, b_str, 0);
+
+	if (pos < len) {
+		a_str[pos] = '\0';
+		alignment_testcase(a_str, b_str, -1);
+		a_str[pos] = a_orig;
+		b_str[pos] = '\0';
+		alignment_testcase(a_str, b_str, 1);
+		b_str[pos] = b_orig;
+	}
+
+	a_str[pos] = 'X';
+	alignment_testcase(a_str, b_str, 1);
+	a_str[pos] = a_orig;
+	b_str[pos] = 'X';
+	alignment_testcase(a_str, b_str, -1);
+	b_str[pos] = b_orig;
+
+	a[a_off] = '-';
+	b[b_off] = '-';
+	a_str[len] = '-';
+	b_str[len] = '-';
+	a_str[len+1] = '-';
+	b_str[len+1] = '-';
+}
+
+ATF_TC_BODY(strcmp_alignments, tc)
+{
+	size_t a_off, b_off, len, pos;
+	/* 16B alignment offset + 64B buffer + sentinel before/after + NUL */
+	char a[64+16+3], b[64+16+3];
+
+	memset(a, '-', sizeof(a));
+	memset(b, '-', sizeof(b));
+	a[sizeof(a) - 1] = '\0';
+	b[sizeof(b) - 1] = '\0';
+
+	/* check alignment offsets relevant for SSE routines */
+	for (a_off = 0; a_off < 16; a_off++)
+		for (b_off = 0; b_off < 16; b_off++)
+			/* ensure main loop (@ 32B) is completed at least once */
+			for (len = 1; len <= 64; len++)
+				for (pos = 0; pos <= len; pos++)
+					check_strcmp_alignments(a, b, a_off, b_off, len, pos);
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+	void *dl_handle;
+
+	dl_handle = dlopen(NULL, RTLD_LAZY);
+	strcmp_fn = dlsym(dl_handle, "test_strcmp");
+	if (strcmp_fn == NULL)
+		strcmp_fn = strcmp;
+
+	ATF_TP_ADD_TC(tp, strcmp_alignments);
+
+	return atf_no_error();
+}