printf: implicate test line in failure messages

This improves the failure output by pointing to the failing line at the
top level of the test, e.g.:
      # test_number: EXPECTATION FAILED at lib/printf_kunit.c:103
  lib/printf_kunit.c:167: vsnprintf(buf, 256, "%#-12x", ...) wrote '0x1234abcd  ', expected '0x1234abce  '
      # test_number: EXPECTATION FAILED at lib/printf_kunit.c:142
  lib/printf_kunit.c:167: kvasprintf(..., "%#-12x", ...) returned '0x1234abcd  ', expected '0x1234abce  '

Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20250307-printf-kunit-convert-v6-3-4d85c361c241@gmail.com
Signed-off-by: Kees Cook <kees@kernel.org>

Author: tamird

lib/tests/printf_kunit.c

@@ -38,9 +38,9 @@ static unsigned int total_tests;
 static char *test_buffer;
 static char *alloced_buffer;
 
-static void __printf(5, 0)
-do_test(struct kunit *kunittest, int bufsize, const char *expect, int elen,
-	const char *fmt, va_list ap)
+static void __printf(7, 0)
+do_test(struct kunit *kunittest, const char *file, const int line, int bufsize, const char *expect,
+	int elen, const char *fmt, va_list ap)
 {
 	va_list aq;
 	int ret, written;
@@ -53,64 +53,70 @@ do_test(struct kunit *kunittest, int bufsize, const char *expect, int elen,
 	va_end(aq);
 
 	if (ret != elen) {
-		KUNIT_FAIL(kunittest, "vsnprintf(buf, %d, \"%s\", ...) returned %d, expected %d\n",
-			   bufsize, fmt, ret, elen);
+		KUNIT_FAIL(kunittest,
+			   "%s:%d: vsnprintf(buf, %d, \"%s\", ...) returned %d, expected %d\n",
+			   file, line, bufsize, fmt, ret, elen);
 		return;
 	}
 
 	if (memchr_inv(alloced_buffer, FILL_CHAR, PAD_SIZE)) {
-		KUNIT_FAIL(kunittest, "vsnprintf(buf, %d, \"%s\", ...) wrote before buffer\n",
-			   bufsize, fmt);
+		KUNIT_FAIL(kunittest,
+			   "%s:%d: vsnprintf(buf, %d, \"%s\", ...) wrote before buffer\n",
+			   file, line, bufsize, fmt);
 		return;
 	}
 
 	if (!bufsize) {
 		if (memchr_inv(test_buffer, FILL_CHAR, BUF_SIZE + PAD_SIZE)) {
-			KUNIT_FAIL(kunittest, "vsnprintf(buf, 0, \"%s\", ...) wrote to buffer\n", fmt);
+			KUNIT_FAIL(kunittest,
+				   "%s:%d: vsnprintf(buf, 0, \"%s\", ...) wrote to buffer\n",
+				   file, line, fmt);
 		}
 		return;
 	}
 
 	written = min(bufsize-1, elen);
 	if (test_buffer[written]) {
 		KUNIT_FAIL(kunittest,
-			   "vsnprintf(buf, %d, \"%s\", ...) did not nul-terminate buffer\n",
-			   bufsize, fmt);
+			   "%s:%d: vsnprintf(buf, %d, \"%s\", ...) did not nul-terminate buffer\n",
+			   file, line, bufsize, fmt);
 		return;
 	}
 
 	if (memchr_inv(test_buffer + written + 1, FILL_CHAR, bufsize - (written + 1))) {
 		KUNIT_FAIL(kunittest,
-			   "vsnprintf(buf, %d, \"%s\", ...) wrote beyond the nul-terminator\n",
-			   bufsize, fmt);
+			   "%s:%d: vsnprintf(buf, %d, \"%s\", ...) wrote beyond the nul-terminator\n",
+			   file, line, bufsize, fmt);
 		return;
 	}
 
 	if (memchr_inv(test_buffer + bufsize, FILL_CHAR, BUF_SIZE + PAD_SIZE - bufsize)) {
-		KUNIT_FAIL(kunittest, "vsnprintf(buf, %d, \"%s\", ...) wrote beyond buffer\n",
-			   bufsize, fmt);
+		KUNIT_FAIL(kunittest,
+			   "%s:%d: vsnprintf(buf, %d, \"%s\", ...) wrote beyond buffer\n",
+			   file, line, bufsize, fmt);
 		return;
 	}
 
 	if (memcmp(test_buffer, expect, written)) {
 		KUNIT_FAIL(kunittest,
-			   "vsnprintf(buf, %d, \"%s\", ...) wrote '%s', expected '%.*s'\n",
-			   bufsize, fmt, test_buffer, written, expect);
+			   "%s:%d: vsnprintf(buf, %d, \"%s\", ...) wrote '%s', expected '%.*s'\n",
+			   file, line, bufsize, fmt, test_buffer, written, expect);
 		return;
 	}
 }
 
-static void __printf(4, 5)
-__test(struct kunit *kunittest, const char *expect, int elen, const char *fmt, ...)
+static void __printf(6, 7)
+__test(struct kunit *kunittest, const char *file, const int line, const char *expect, int elen,
+	const char *fmt, ...)
 {
 	va_list ap;
 	int rand;
 	char *p;
 
 	if (elen >= BUF_SIZE) {
 		KUNIT_FAIL(kunittest,
-			   "error in test suite: expected length (%d) >= BUF_SIZE (%d). fmt=\"%s\"\n",
-			   elen, BUF_SIZE, fmt);
+			   "%s:%d: error in test suite: expected length (%d) >= BUF_SIZE (%d). fmt=\"%s\"\n",
+			   file, line, elen, BUF_SIZE, fmt);
 		return;
 	}
 
@@ -122,27 +128,27 @@ __test(struct kunit *kunittest, const char *expect, int elen, const char *fmt, .
 	 * enough and 0), and then we also test that kvasprintf would
 	 * be able to print it as expected.
 	 */
-	do_test(kunittest, BUF_SIZE, expect, elen, fmt, ap);
+	do_test(kunittest, file, line, BUF_SIZE, expect, elen, fmt, ap);
 	rand = get_random_u32_inclusive(1, elen + 1);
 	/* Since elen < BUF_SIZE, we have 1 <= rand <= BUF_SIZE. */
-	do_test(kunittest, rand, expect, elen, fmt, ap);
-	do_test(kunittest, 0, expect, elen, fmt, ap);
+	do_test(kunittest, file, line, rand, expect, elen, fmt, ap);
+	do_test(kunittest, file, line, 0, expect, elen, fmt, ap);
 
 	p = kvasprintf(GFP_KERNEL, fmt, ap);
 	if (p) {
 		total_tests++;
 		if (memcmp(p, expect, elen+1)) {
 			KUNIT_FAIL(kunittest,
-				   "kvasprintf(..., \"%s\", ...) returned '%s', expected '%s'\n",
-				   fmt, p, expect);
+				   "%s:%d: kvasprintf(..., \"%s\", ...) returned '%s', expected '%s'\n",
+				   file, line, fmt, p, expect);
 		}
 		kfree(p);
 	}
 	va_end(ap);
 }
 
 #define test(expect, fmt, ...)					\
-	__test(kunittest, expect, strlen(expect), fmt, ##__VA_ARGS__)
+	__test(kunittest, __FILE__, __LINE__, expect, strlen(expect), fmt, ##__VA_ARGS__)
 
 static void
 test_basic(struct kunit *kunittest)
@@ -153,7 +159,7 @@ test_basic(struct kunit *kunittest)
 	test("", &nul);
 	test("100%", "100%%");
 	test("xxx%yyy", "xxx%cyyy", '%');
-	__test(kunittest, "xxx\0yyy", 7, "xxx%cyyy", '\0');
+	__test(kunittest, __FILE__, __LINE__, "xxx\0yyy", 7, "xxx%cyyy", '\0');
 }
 
 static void