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| author | David Laight <david.laight.linux@gmail.com> | 2026-03-02 13:17:56 +0300 |
|---|---|---|
| committer | Thomas Weißschuh <linux@weissschuh.net> | 2026-03-20 19:46:02 +0300 |
| commit | 9aa8a4afd4e6407a4d4521c325855c4467a88b73 (patch) | |
| tree | cc1665cf37f15c17eac0fb5588ac122d0540d738 | |
| parent | b42f02da2bf99460a7b1c5c25008f2e4a65ea4e3 (diff) | |
| download | linux-9aa8a4afd4e6407a4d4521c325855c4467a88b73.tar.xz | |
selftests/nolibc: check vsnprintf() output buffer before the length
Check the string matches before checking the returned length.
Only print the string once when it matches.
Makes it a lot easier to diagnose any incorrect output.
Signed-off-by: David Laight <david.laight.linux@gmail.com>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://patch.msgid.link/20260302101815.3043-5-david.laight.linux@gmail.com
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
| -rw-r--r-- | tools/testing/selftests/nolibc/nolibc-test.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index 7588212df124..bfe793caa963 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -1676,25 +1676,27 @@ static int expect_vfprintf(int llen, int c, const char *expected, const char *fm char buf[100]; va_list args; ssize_t w; - int ret; - va_start(args, fmt); /* Only allow writing 21 bytes, to test truncation */ w = vsnprintf(buf, 21, fmt, args); va_end(args); + llen += printf(" \"%s\"", buf); + if (strncmp(expected, buf, c)) { + llen += printf(" should be \"%s\"", expected); + result(llen, FAIL); + return 1; + } + if (w != c) { llen += printf(" written(%d) != %d", (int)w, c); result(llen, FAIL); return 1; } - llen += printf(" \"%s\" = \"%s\"", expected, buf); - ret = strncmp(expected, buf, c) != 0; - - result(llen, ret ? FAIL : OK); - return ret; + result(llen, OK); + return 0; } static int test_scanf(void) |