6.16-stable review patch. If anyone has any objections, please let me know.
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From: Thomas Weißschuh thomas.weissschuh@linutronix.de
[ Upstream commit 4a40129087a4c32135bb1177a57bbbe6ee646f1a ]
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 thomas.weissschuh@linutronix.de Acked-by: Willy Tarreau w@1wt.eu Link: https://lore.kernel.org/r/20250704-nolibc-printf-error-v1-2-74b7a092433b@lin... Signed-off-by: Thomas Weißschuh linux@weissschuh.net Signed-off-by: Sasha Levin sashal@kernel.org --- 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 c470d334ef3f..7630234408c5 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 dbe13000fb1a..b5c04c137249 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -1646,6 +1646,28 @@ 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; @@ -1675,6 +1697,7 @@ 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 */