[PATCH v2 0/2] tools/nolibc: add support for [v]sscanf()

[PATCH v2 0/2] tools/nolibc: add support for [v]sscanf()

[Thomas Weißschuh]

The implementation is limited and only supports numeric arguments.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
Changes in v2:
- Return __LINE__ from different testcases to directly point to the
  failed testcase
- Add some comments
- Expand commit message
- Link to v1: https://lore.kernel.org/r/20240731-nolibc-scanf-v1-0-f71bcc4abb9e@weissschuh.net

---
Thomas Weißschuh (2):
      tools/nolibc: add support for [v]sscanf()
      Revert "selftests: kselftest: Fix build failure with NOLIBC"

 tools/include/nolibc/stdio.h                 | 98 ++++++++++++++++++++++++++++
 tools/testing/selftests/kselftest.h          |  5 --
 tools/testing/selftests/nolibc/nolibc-test.c | 68 +++++++++++++++++++
 3 files changed, 166 insertions(+), 5 deletions(-)
---
base-commit: 665fa8dea90d9fbc0e7137c7e1315d6f7e15757e
change-id: 20240414-nolibc-scanf-f1db6930d0c6

Best regards,
-- 
Thomas Weißschuh <linux@weissschuh.net>

[PATCH v2 1/2] tools/nolibc: add support for [v]sscanf()

[Thomas Weißschuh]

These functions are used often, also in selftests.
sscanf() itself is also used by kselftest.h itself.

The implementation is limited and only supports numeric arguments.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 tools/include/nolibc/stdio.h                 | 98 ++++++++++++++++++++++++++++
 tools/testing/selftests/nolibc/nolibc-test.c | 68 +++++++++++++++++++
 2 files changed, 166 insertions(+)

diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h
index 3892034198dd566d21a5cc0a9f67cf097d428393..a403351dbf6098ac8292b9589ed8a054b4c5669f 100644
--- a/tools/include/nolibc/stdio.h
+++ b/tools/include/nolibc/stdio.h
@@ -349,6 +349,104 @@ int printf(const char *fmt, ...)
 	return ret;
 }
 
+static __attribute__((unused))
+int vsscanf(const char *str, const char *format, va_list args)
+{
+	uintmax_t uval;
+	intmax_t ival;
+	int base;
+	char *endptr;
+	int matches;
+	int lpref;
+
+	matches = 0;
+
+	while (1) {
+		if (*format == '%') {
+			/* start of pattern */
+			lpref = 0;
+			format++;
+
+			if (*format == 'l') {
+				/* same as in printf() */
+				lpref = 1;
+				format++;
+				if (*format == 'l') {
+					lpref = 2;
+					format++;
+				}
+			}
+
+			if (*format == '%') {
+				/* literal % */
+				if ('%' != *str)
+					goto done;
+				str++;
+				format++;
+				continue;
+			} else if (*format == 'd') {
+				ival = strtoll(str, &endptr, 10);
+				if (lpref == 0)
+					*va_arg(args, int *) = ival;
+				else if (lpref == 1)
+					*va_arg(args, long *) = ival;
+				else if (lpref == 2)
+					*va_arg(args, long long *) = ival;
+			} else if (*format == 'u' || *format == 'x' || *format == 'X') {
+				base = *format == 'u' ? 10 : 16;
+				uval = strtoull(str, &endptr, base);
+				if (lpref == 0)
+					*va_arg(args, unsigned int *) = uval;
+				else if (lpref == 1)
+					*va_arg(args, unsigned long *) = uval;
+				else if (lpref == 2)
+					*va_arg(args, unsigned long long *) = uval;
+			} else if (*format == 'p') {
+				*va_arg(args, void **) = (void *)strtoul(str, &endptr, 16);
+			} else {
+				SET_ERRNO(EILSEQ);
+				goto done;
+			}
+
+			format++;
+			str = endptr;
+			matches++;
+
+		} else if (*format == '\0') {
+			goto done;
+		} else if (isspace(*format)) {
+			/* skip spaces in format and str */
+			while (isspace(*format))
+				format++;
+			while (isspace(*str))
+				str++;
+		} else if (*format == *str) {
+			/* literal match */
+			format++;
+			str++;
+		} else {
+			if (!matches)
+				matches = EOF;
+			goto done;
+		}
+	}
+
+done:
+	return matches;
+}
+
+static __attribute__((unused, format(scanf, 2, 3)))
+int sscanf(const char *str, const char *format, ...)
+{
+	va_list args;
+	int ret;
+
+	va_start(args, format);
+	ret = vsscanf(str, format, args);
+	va_end(args);
+	return ret;
+}
+
 static __attribute__((unused))
 void perror(const char *msg)
 {
diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 798fbdcd3ff8c36b514feb3fa1c7b8d7701cccd7..81e942c7d1684a7dd59af0b05c8330378532ecc1 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -1325,6 +1325,73 @@ static int expect_vfprintf(int llen, int c, const char *expected, const char *fm
 	return ret;
 }
 
+static int test_scanf(void)
+{
+	unsigned long long ull;
+	unsigned long ul;
+	unsigned int u;
+	long long ll;
+	long l;
+	void *p;
+	int i;
+
+	/* return __LINE__ to point to the specific failure */
+
+	/* test EOF */
+	if (sscanf("", "foo") != EOF)
+		return __LINE__;
+
+	/* test simple literal without placeholder */
+	if (sscanf("foo", "foo") != 0)
+		return __LINE__;
+
+	/* test single placeholder */
+	if (sscanf("123", "%d", &i) != 1)
+		return __LINE__;
+
+	if (i != 123)
+		return __LINE__;
+
+	/* test multiple place holders and separators */
+	if (sscanf("a123b456c0x90", "a%db%uc%p", &i, &u, &p) != 3)
+		return __LINE__;
+
+	if (i != 123)
+		return __LINE__;
+
+	if (u != 456)
+		return __LINE__;
+
+	if (p != (void *)0x90)
+		return __LINE__;
+
+	/* test space handling */
+	if (sscanf("a    b1", "a b%d", &i) != 1)
+		return __LINE__;
+
+	if (i != 1)
+		return __LINE__;
+
+	/* test literal percent */
+	if (sscanf("a%1", "a%%%d", &i) != 1)
+		return __LINE__;
+
+	if (i != 1)
+		return __LINE__;
+
+	/* test stdint.h types */
+	if (sscanf("1|2|3|4|5|6",
+		   "%d|%ld|%lld|%u|%lu|%llu",
+		   &i, &l, &ll, &u, &ul, &ull) != 6)
+		return __LINE__;
+
+	if (i != 1 || l != 2 || ll != 3 ||
+	    u != 4 || ul != 5 || ull != 6)
+		return __LINE__;
+
+	return 0;
+}
+
 static int run_vfprintf(int min, int max)
 {
 	int test;
@@ -1346,6 +1413,7 @@ static int run_vfprintf(int min, int max)
 		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(scanf);        EXPECT_ZR(1, test_scanf()); break;
 		case __LINE__:
 			return ret; /* must be last */
 		/* note: do not set any defaults so as to permit holes above */

-- 
2.48.1

[PATCH v2 2/2] Revert "selftests: kselftest: Fix build failure with NOLIBC"

[Thomas Weißschuh]

This reverts commit 16767502aa990cca2cb7d1372b31d328c4c85b40.

Nolibc gained support for uname(2) and sscanf(3) which are the
dependencies of ksft_min_kernel_version().

So re-enable support for ksft_min_kernel_version() under nolibc.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 tools/testing/selftests/kselftest.h | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/tools/testing/selftests/kselftest.h b/tools/testing/selftests/kselftest.h
index cdf91b0ca40fbdc4fb825b86d4dc547b5afa673c..c3b6d2604b1e486af5a224a11386f75fe0a83495 100644
--- a/tools/testing/selftests/kselftest.h
+++ b/tools/testing/selftests/kselftest.h
@@ -444,10 +444,6 @@ static inline __noreturn __printf(1, 2) void ksft_exit_skip(const char *msg, ...
 static inline int ksft_min_kernel_version(unsigned int min_major,
 					  unsigned int min_minor)
 {
-#ifdef NOLIBC
-	ksft_print_msg("NOLIBC: Can't check kernel version: Function not implemented\n");
-	return 0;
-#else
 	unsigned int major, minor;
 	struct utsname info;
 
@@ -455,7 +451,6 @@ static inline int ksft_min_kernel_version(unsigned int min_major,
 		ksft_exit_fail_msg("Can't parse kernel version\n");
 
 	return major > min_major || (major == min_major && minor >= min_minor);
-#endif
 }
 
 #endif /* __KSELFTEST_H */

-- 
2.48.1

Re: [PATCH v2 2/2] Revert "selftests: kselftest: Fix build failure with NOLIBC"

[Shuah Khan]

On 2/9/25 13:27, Thomas Weißschuh wrote:
> This reverts commit 16767502aa990cca2cb7d1372b31d328c4c85b40.
> 
> Nolibc gained support for uname(2) and sscanf(3) which are the
> dependencies of ksft_min_kernel_version().
> 
> So re-enable support for ksft_min_kernel_version() under nolibc.
> 
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> ---
>   tools/testing/selftests/kselftest.h | 5 -----
>   1 file changed, 5 deletions(-)
> 
> diff --git a/tools/testing/selftests/kselftest.h b/tools/testing/selftests/kselftest.h
> index cdf91b0ca40fbdc4fb825b86d4dc547b5afa673c..c3b6d2604b1e486af5a224a11386f75fe0a83495 100644
> --- a/tools/testing/selftests/kselftest.h
> +++ b/tools/testing/selftests/kselftest.h
> @@ -444,10 +444,6 @@ static inline __noreturn __printf(1, 2) void ksft_exit_skip(const char *msg, ...
>   static inline int ksft_min_kernel_version(unsigned int min_major,
>   					  unsigned int min_minor)
>   {
> -#ifdef NOLIBC
> -	ksft_print_msg("NOLIBC: Can't check kernel version: Function not implemented\n");
> -	return 0;
> -#else
>   	unsigned int major, minor;
>   	struct utsname info;
>   
> @@ -455,7 +451,6 @@ static inline int ksft_min_kernel_version(unsigned int min_major,
>   		ksft_exit_fail_msg("Can't parse kernel version\n");
>   
>   	return major > min_major || (major == min_major && minor >= min_minor);
> -#endif
>   }
>   
>   #endif /* __KSELFTEST_H */
> 

Looks good to me.

Acked-by: Shuah Khan <skhan@linuxfoundation.org>

thanks,
-- Shuah

Re: [PATCH v2 0/2] tools/nolibc: add support for [v]sscanf()

[Willy Tarreau]

On Sun, Feb 09, 2025 at 09:27:11PM +0100, Thomas Weißschuh wrote:
> The implementation is limited and only supports numeric arguments.
> 
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> ---
> Changes in v2:
> - Return __LINE__ from different testcases to directly point to the
>   failed testcase
> - Add some comments
> - Expand commit message
> - Link to v1: https://lore.kernel.org/r/20240731-nolibc-scanf-v1-0-f71bcc4abb9e@weissschuh.net

Looks good. For the whole series:

Acked-by: Willy Tarreau <w@1wt.eu>

Thanks!
Willy