From 4a40129087a4c32135bb1177a57bbbe6ee646f1a Mon Sep 17 00:00:00 2001 From: =?utf8?q?Thomas=20Wei=C3=9Fschuh?= Date: Fri, 4 Jul 2025 15:43:13 +0200 Subject: [PATCH] selftests/nolibc: correctly report errors from printf() and friends MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When an error is encountered by printf() it needs to be reported. errno() is already set by the callback. sprintf() is different, but that keeps working and is already tested. Also add a new test. Fixes: 7e4346f4a3a6 ("tools/nolibc/stdio: add a minimal [vf]printf() implementation") Signed-off-by: Thomas Weißschuh Acked-by: Willy Tarreau Link: https://lore.kernel.org/r/20250704-nolibc-printf-error-v1-2-74b7a092433b@linutronix.de Signed-off-by: Thomas Weißschuh --- tools/include/nolibc/stdio.h | 4 ++-- tools/testing/selftests/nolibc/nolibc-test.c | 23 ++++++++++++++++++++ 2 files changed, 25 insertions(+), 2 deletions(-) diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h index c470d334ef3f4..7630234408c58 100644 --- a/tools/include/nolibc/stdio.h +++ b/tools/include/nolibc/stdio.h @@ -358,11 +358,11 @@ int __nolibc_printf(__nolibc_printf_cb cb, intptr_t state, size_t n, const char n -= w; while (width-- > w) { if (cb(state, " ", 1) != 0) - break; + return -1; written += 1; } if (cb(state, outstr, w) != 0) - break; + return -1; } written += len; diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index ef80861105f56..a297ee0d6d075 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -1662,6 +1662,28 @@ int test_strerror(void) return 0; } +static int test_printf_error(void) +{ + int fd, ret, saved_errno; + + fd = open("/dev/full", O_RDWR); + if (fd == -1) + return 1; + + errno = 0; + ret = dprintf(fd, "foo"); + saved_errno = errno; + close(fd); + + if (ret != -1) + return 2; + + if (saved_errno != ENOSPC) + return 3; + + return 0; +} + static int run_printf(int min, int max) { int test; @@ -1691,6 +1713,7 @@ static int run_printf(int min, int max) CASE_TEST(width_trunc); EXPECT_VFPRINTF(25, " ", "%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; case __LINE__: return ret; /* must be last */ /* note: do not set any defaults so as to permit holes above */ -- 2.47.3