lib/libc/tests/string/stpncpy_test.c: extend for upcoming SSE implementation

This adds additional unit tests validating the function for
All possible alignment offsets of source and destination.

Also extend the test to allow testing of an external stpncpy
implementation, which greatly simplifies the development of
custom implementations.

Sponsored by:	The FreeBSD Foundation
Tested by:	developers@, exp-run
Approved by:	mjg
MFC after:	1 month
MFC to:		stable/14
PR:		275785
Differential Revision:	https://reviews.freebsd.org/D42519

1 files changed, 85 insertions, 14 deletions

diff --git a/lib/libc/tests/string/stpncpy_test.c b/lib/libc/tests/string/stpncpy_test.c
index 8154237eb8c2..8574b2d591be 100644
--- a/lib/libc/tests/string/stpncpy_test.c
+++ b/lib/libc/tests/string/stpncpy_test.c
@@ -1,7 +1,11 @@
 /*-
  * Copyright (c) 2009 David Schultz <das@FreeBSD.org>
+ * Copyright (c) 2023 The FreeBSD Foundation
  * All rights reserved.
  *
+ * Portions of this software were 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:
@@ -27,12 +31,15 @@
 #include <sys/param.h>
 #include <sys/mman.h>
 #include <assert.h>
+#include <dlfcn.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include <atf-c.h>
 
+static char *(*stpncpy_fn)(char *restrict, const char *restrict, size_t);
+
 static char *
 makebuf(size_t len, int guard_at_end)
 {
@@ -69,7 +76,7 @@ test_stpncpy(const char *s)
 				dst = makebuf(bufsize, j);
 				memset(dst, 'X', bufsize);
 				len = (bufsize < size) ? bufsize : size - 1;
-				assert(stpncpy(dst, src, bufsize) == dst+len);
+				assert(stpncpy_fn(dst, src, bufsize) == dst+len);
 				assert(memcmp(src, dst, len) == 0);
 				for (x = len; x < bufsize; x++)
 					assert(dst[x] == '\0');
@@ -78,33 +85,97 @@ test_stpncpy(const char *s)
 	}
 }
 
-ATF_TC_WITHOUT_HEAD(nul);
-ATF_TC_BODY(nul, tc)
+static void
+test_sentinel(char *dest, char *src, size_t destlen, size_t srclen)
 {
+	size_t i;
+	const char *res, *wantres;
+	const char *fail = NULL;
+
+	for (i = 0; i < srclen; i++)
+		/* src will never include (){} */
+		src[i] = '0' + i;
+	src[srclen] = '\0';
+
+	/* source sentinels: not to be copied */
+	src[-1] = '(';
+	src[srclen+1] = ')';
+
+	memset(dest, 0xee, destlen);
+
+	/* destination sentinels: not to be touched */
+	dest[-1] = '{';
+	dest[destlen] = '}';
+
+	wantres = dest + (srclen > destlen ? destlen : srclen);
+	res = stpncpy_fn(dest, src, destlen);
+
+	if (dest[-1] != '{')
+		fail = "start sentinel overwritten";
+	else if (dest[destlen] != '}')
+		fail = "end sentinel overwritten";
+	else if (strncmp(src, dest, destlen) != 0)
+		fail = "string not copied correctly";
+	else if (res != wantres)
+		fail = "incorrect return value";
+	else for (i = srclen; i < destlen; i++)
+		if (dest[i] != '\0') {
+			fail = "incomplete NUL padding";
+			break;
+		}
 
-	test_stpncpy("");
+	if (fail)
+		atf_tc_fail_nonfatal("%s\n"
+		    "stpncpy(%p \"%s\", %p \"%s\", %zu) = %p (want %p)\n",
+		    fail, dest, dest, src, src, destlen, res, wantres);
 }
 
-ATF_TC_WITHOUT_HEAD(foo);
-ATF_TC_BODY(foo, tc)
+ATF_TC_WITHOUT_HEAD(null);
+ATF_TC_BODY(null, tc)
 {
-
-	test_stpncpy("foo");
+	ATF_CHECK_EQ(stpncpy_fn(NULL, NULL, 0), NULL);
 }
 
-ATF_TC_WITHOUT_HEAD(glorp);
-ATF_TC_BODY(glorp, tc)
+ATF_TC_WITHOUT_HEAD(bounds);
+ATF_TC_BODY(bounds, tc)
 {
+	size_t i;
+	char buf[64+1];
 
-	test_stpncpy("glorp");
+	for (i = 0; i < sizeof(buf) - 1; i++) {
+		buf[i] = ' ' + i;
+		buf[i+1] = '\0';
+		test_stpncpy(buf);
+	}
+}
+
+ATF_TC_WITHOUT_HEAD(alignments);
+ATF_TC_BODY(alignments, tc)
+{
+	size_t srcalign, destalign, srclen, destlen;
+	char src[15+3+64]; /* 15 offsets + 64 max length + NUL + sentinels */
+	char dest[15+2+64]; /* 15 offsets + 64 max length + sentinels */
+
+	for (srcalign = 0; srcalign < 16; srcalign++)
+		for (destalign = 0; destalign < 16; destalign++)
+			for (srclen = 0; srclen < 64; srclen++)
+				for (destlen = 0; destlen < 64; destlen++)
+					test_sentinel(dest+destalign+1,
+					    src+srcalign+1, destlen, srclen);
 }
 
 ATF_TP_ADD_TCS(tp)
 {
+	void *dl_handle;
+
+	dl_handle = dlopen(NULL, RTLD_LAZY);
+	stpncpy_fn = dlsym(dl_handle, "test_stpncpy");
+	if (stpncpy_fn == NULL)
+		stpncpy_fn = stpncpy;
 
-	ATF_TP_ADD_TC(tp, nul);
-	ATF_TP_ADD_TC(tp, foo);
-	ATF_TP_ADD_TC(tp, glorp);
+	ATF_TP_ADD_TC(tp, null);
+	ATF_TP_ADD_TC(tp, bounds);
+	ATF_TP_ADD_TC(tp, alignments);
 
 	return (atf_no_error());
 }