From f36e1ec61a6adb135d1b4021bc849c6acb96f50c Mon Sep 17 00:00:00 2001 From: David Laight Date: Mon, 2 Mar 2026 10:17:57 +0000 Subject: [PATCH] selftests/nolibc: Use length of 'expected' string to check snprintf() output MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Instead of requiring the test cases specifying both the length and expected output, take the length from the expected output. Tests that expect the output be truncated are changed to specify the un-truncated output. Change the strncmp() to a memcmp() with an extra check that the output is actually terminated. Append a '+' to the printed output (after the final ") when the output is truncated. Signed-off-by: David Laight Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260302101815.3043-6-david.laight.linux@gmail.com Signed-off-by: Thomas Weißschuh --- tools/testing/selftests/nolibc/nolibc-test.c | 67 ++++++++++++-------- 1 file changed, 41 insertions(+), 26 deletions(-) diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index bfe793caa963..154cc5711a4c 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -1668,29 +1668,44 @@ int run_stdlib(int min, int max) return ret; } -#define EXPECT_VFPRINTF(c, expected, fmt, ...) \ - ret += expect_vfprintf(llen, c, expected, fmt, ##__VA_ARGS__) +#define EXPECT_VFPRINTF(expected, fmt, ...) \ + ret += expect_vfprintf(llen, expected, fmt, ##__VA_ARGS__) -static int expect_vfprintf(int llen, int c, const char *expected, const char *fmt, ...) +#define VFPRINTF_LEN 20 +static int expect_vfprintf(int llen, const char *expected, const char *fmt, ...) { - char buf[100]; + char buf[VFPRINTF_LEN + 80]; + unsigned int cmp_len; va_list args; - ssize_t w; + ssize_t w, expected_len; va_start(args, fmt); - /* Only allow writing 21 bytes, to test truncation */ - w = vsnprintf(buf, 21, fmt, args); + /* Limit buffer length to test truncation */ + w = vsnprintf(buf, VFPRINTF_LEN + 1, fmt, args); va_end(args); llen += printf(" \"%s\"", buf); - if (strncmp(expected, buf, c)) { - llen += printf(" should be \"%s\"", expected); + + expected_len = strlen(expected); + if (expected_len > VFPRINTF_LEN) { + /* Indicate truncated in test output */ + llen += printf("+"); + cmp_len = VFPRINTF_LEN; + } else { + cmp_len = expected_len; + } + + if (memcmp(expected, buf, cmp_len) || buf[cmp_len]) { + /* Copy and truncate until "%.*s" supported */ + memcpy(buf, expected, cmp_len); + buf[cmp_len] = 0; + llen += printf(" should be \"%s\"", buf); result(llen, FAIL); return 1; } - if (w != c) { - llen += printf(" written(%d) != %d", (int)w, c); + if (w != expected_len) { + llen += printf(" written(%d) != %d", (int)w, (int)expected_len); result(llen, FAIL); return 1; } @@ -1817,21 +1832,21 @@ static int run_printf(int min, int max) * test numbers. */ switch (test + __LINE__ + 1) { - CASE_TEST(empty); EXPECT_VFPRINTF(0, "", ""); break; - CASE_TEST(simple); EXPECT_VFPRINTF(3, "foo", "foo"); break; - CASE_TEST(string); EXPECT_VFPRINTF(3, "foo", "%s", "foo"); break; - CASE_TEST(number); EXPECT_VFPRINTF(4, "1234", "%d", 1234); break; - CASE_TEST(negnumber); EXPECT_VFPRINTF(5, "-1234", "%d", -1234); break; - CASE_TEST(unsigned); EXPECT_VFPRINTF(5, "12345", "%u", 12345); break; - CASE_TEST(char); EXPECT_VFPRINTF(1, "c", "%c", 'c'); break; - CASE_TEST(hex); EXPECT_VFPRINTF(1, "f", "%x", 0xf); break; - CASE_TEST(pointer); EXPECT_VFPRINTF(3, "0x1", "%p", (void *) 0x1); break; - CASE_TEST(uintmax_t); EXPECT_VFPRINTF(20, "18446744073709551615", "%ju", 0xffffffffffffffffULL); break; - CASE_TEST(intmax_t); EXPECT_VFPRINTF(20, "-9223372036854775807", "%jd", 0x8000000000000001LL); break; - CASE_TEST(truncation); EXPECT_VFPRINTF(25, "01234567890123456789", "%s", "0123456789012345678901234"); break; - CASE_TEST(string_width); EXPECT_VFPRINTF(10, " 1", "%10s", "1"); break; - CASE_TEST(number_width); EXPECT_VFPRINTF(10, " 1", "%10d", 1); break; - CASE_TEST(width_trunc); EXPECT_VFPRINTF(25, " ", "%25d", 1); break; + CASE_TEST(empty); EXPECT_VFPRINTF("", ""); break; + CASE_TEST(simple); EXPECT_VFPRINTF("foo", "foo"); break; + CASE_TEST(string); EXPECT_VFPRINTF("foo", "%s", "foo"); break; + CASE_TEST(number); EXPECT_VFPRINTF("1234", "%d", 1234); break; + CASE_TEST(negnumber); EXPECT_VFPRINTF("-1234", "%d", -1234); break; + CASE_TEST(unsigned); EXPECT_VFPRINTF("12345", "%u", 12345); break; + CASE_TEST(char); EXPECT_VFPRINTF("c", "%c", 'c'); break; + CASE_TEST(hex); EXPECT_VFPRINTF("f", "%x", 0xf); break; + CASE_TEST(pointer); EXPECT_VFPRINTF("0x1", "%p", (void *) 0x1); break; + CASE_TEST(uintmax_t); EXPECT_VFPRINTF("18446744073709551615", "%ju", 0xffffffffffffffffULL); break; + CASE_TEST(intmax_t); EXPECT_VFPRINTF("-9223372036854775807", "%jd", 0x8000000000000001LL); break; + CASE_TEST(truncation); EXPECT_VFPRINTF("0123456789012345678901234", "%s", "0123456789012345678901234"); break; + CASE_TEST(string_width); EXPECT_VFPRINTF(" 1", "%10s", "1"); break; + CASE_TEST(number_width); EXPECT_VFPRINTF(" 1", "%10d", 1); break; + CASE_TEST(width_trunc); EXPECT_VFPRINTF(" 1", "%25d", 1); break; CASE_TEST(scanf); EXPECT_ZR(1, test_scanf()); break; CASE_TEST(strerror); EXPECT_ZR(1, test_strerror()); break; CASE_TEST(printf_error); EXPECT_ZR(1, test_printf_error()); break;