From: David Laight <david.laight.linux@gmail.com>
strerror() can be the only part of a program that has a .data section.
This requres 4k in the program file.
Add a simple implementation of strerror_r() (ignores buflen) and use
that in strerror() so that the "errno=" string is copied at run-time.
Use __builtin_memcpy() because that optimises away the input string
and just writes the required constants to the target buffer.
Ignoring buflen is unlikely to be a problem given that the output is
always short.
Code size change largely depends on whether the inlining decision for
strerror() changes.
Change the tests to use the normal EXPECT_VFPRINTF() when testing %m.
Skip the tests when !is_nolibc.
Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
v4:
- Leave the NOLIBC_IGNORE_ERRNO check in __nolibc_printf().
- Don't rename the errno parameter to strerror() in this patch.
tools/include/nolibc/stdio.h | 18 +++++++++++++++---
tools/testing/selftests/nolibc/nolibc-test.c | 20 ++------------------
2 files changed, 17 insertions(+), 21 deletions(-)
diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h
index a4df72d9a2d3..03fcd0229f90 100644
--- a/tools/include/nolibc/stdio.h
+++ b/tools/include/nolibc/stdio.h
@@ -722,14 +722,26 @@ int setvbuf(FILE *stream __attribute__((unused)),
return 0;
}
+static __attribute__((unused,))
+int strerror_r(int errnum, char *buf, size_t buflen __attribute__((unused)))
+{
+ __builtin_memcpy(buf, "errno=", 6);
+ return 6 + i64toa_r(errnum, buf + 6);
+}
+
static __attribute__((unused))
const char *strerror(int errno)
{
- static char buf[18] = "errno=";
+ static char buf[18];
+ char *b = buf;
+
+ /* Force gcc to use 'register offset' to access buf[]. */
+ _NOLIBC_OPTIMIZER_HIDE_VAR(b);
- i64toa_r(errno, &buf[6]);
+ /* Use strerror_r() to avoid having the only .data in small programs. */
+ strerror_r(errno, b, sizeof(buf));
- return buf;
+ return b;
}
#endif /* _NOLIBC_STDIO_H */
diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 9ebebe4ff253..638f18fc5123 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -1786,23 +1786,6 @@ static int test_scanf(void)
return 0;
}
-int test_strerror(void)
-{
- char buf[100];
- ssize_t ret;
-
- memset(buf, 'A', sizeof(buf));
-
- errno = EINVAL;
- ret = snprintf(buf, sizeof(buf), "%m");
- if (is_nolibc) {
- if (ret < 6 || memcmp(buf, "errno=", 6))
- return 1;
- }
-
- return 0;
-}
-
static int test_printf_error(void)
{
int fd, ret, saved_errno;
@@ -1852,8 +1835,9 @@ static int run_printf(int min, int max)
CASE_TEST(string_width); EXPECT_VFPRINTF(1, " 1", "%10s", "1"); break;
CASE_TEST(number_width); EXPECT_VFPRINTF(1, " 1", "%10d", 1); break;
CASE_TEST(width_trunc); EXPECT_VFPRINTF(1, " 1", "%25d", 1); break;
+ CASE_TEST(errno); errno = 22; EXPECT_VFPRINTF(is_nolibc, "errno=22", "%m"); break;
+ CASE_TEST(errno-neg); errno = -22; EXPECT_VFPRINTF(is_nolibc, " errno=-22", "%12m"); 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 */
--
2.39.5