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

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

 tools/include/nolibc/stdio.h                 | 93 ++++++++++++++++++++++++++++
 tools/testing/selftests/kselftest.h          |  5 --
 tools/testing/selftests/nolibc/nolibc-test.c | 59 ++++++++++++++++++
 3 files changed, 152 insertions(+), 5 deletions(-)
---
base-commit: ae1f550efc11eaf1496c431d9c6e784cb49124c5
change-id: 20240414-nolibc-scanf-f1db6930d0c6

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

[PATCH 1/2] 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>
---
 tools/include/nolibc/stdio.h                 | 93 ++++++++++++++++++++++++++++
 tools/testing/selftests/nolibc/nolibc-test.c | 59 ++++++++++++++++++
 2 files changed, 152 insertions(+)

diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h
index c968dbbc4ef8..d63c45c06d8e 100644
--- a/tools/include/nolibc/stdio.h
+++ b/tools/include/nolibc/stdio.h
@@ -348,6 +348,99 @@ 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 == '%') {
+			lpref = 0;
+			format++;
+
+			if (*format == 'l') {
+				lpref = 1;
+				format++;
+				if (*format == 'l') {
+					lpref = 2;
+					format++;
+				}
+			}
+
+			if (*format == '%') {
+				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)) {
+			while (isspace(*format))
+				format++;
+			while (isspace(*str))
+				str++;
+		} else if (*format == *str) {
+			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 093d0512f4c5..addbceb0b276 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -1277,6 +1277,64 @@ 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;
+
+	if (sscanf("", "foo") != EOF)
+		return 1;
+
+	if (sscanf("foo", "foo") != 0)
+		return 2;
+
+	if (sscanf("123", "%d", &i) != 1)
+		return 3;
+
+	if (i != 123)
+		return 4;
+
+	if (sscanf("a123b456c0x90", "a%db%uc%p", &i, &u, &p) != 3)
+		return 5;
+
+	if (i != 123)
+		return 6;
+
+	if (u != 456)
+		return 7;
+
+	if (p != (void *)0x90)
+		return 8;
+
+	if (sscanf("a    b1", "a b%d", &i) != 1)
+		return 9;
+
+	if (i != 1)
+		return 10;
+
+	if (sscanf("a%1", "a%%%d", &i) != 1)
+		return 11;
+
+	if (i != 1)
+		return 12;
+
+	if (sscanf("1|2|3|4|5|6",
+		   "%d|%ld|%lld|%u|%lu|%llu",
+		   &i, &l, &ll, &u, &ul, &ull) != 6)
+		return 13;
+
+	if (i != 1 || l != 2 || ll != 3 ||
+	    u != 4 || ul != 5 || ull != 6)
+		return 14;
+
+	return 0;
+}
+
 static int run_vfprintf(int min, int max)
 {
 	int test;
@@ -1298,6 +1356,7 @@ 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 */

-- 
2.46.0

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

[Shuah Khan]

On 7/31/24 12:32, Thomas Weißschuh wrote:
> The implementation is limited and only supports numeric arguments.

I would like to see more information in here. Why is this needed
etc. etc.

> 
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> ---
>   tools/include/nolibc/stdio.h                 | 93 ++++++++++++++++++++++++++++
>   tools/testing/selftests/nolibc/nolibc-test.c | 59 ++++++++++++++++++
>   2 files changed, 152 insertions(+)
> 
> diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h
> index c968dbbc4ef8..d63c45c06d8e 100644
> --- a/tools/include/nolibc/stdio.h
> +++ b/tools/include/nolibc/stdio.h
> @@ -348,6 +348,99 @@ int printf(const char *fmt, ...)
>   	return ret;
>   }
>   
> +static __attribute__((unused))
> +int vsscanf(const char *str, const char *format, va_list args)

Is there a reason why you didn't use the same code in lib/vsprintf.c?
You could simply duplicate the code here?

With all these libc functionality added, it isn't nolibc looks like :)

> +{
> +	uintmax_t uval;
> +	intmax_t ival;
> +	int base;
> +	char *endptr;
> +	int matches;
> +	int lpref;
> +
> +	matches = 0;
> +
> +	while (1) {
> +		if (*format == '%') {
> +			lpref = 0;
> +			format++;
> +
> +			if (*format == 'l') {
> +				lpref = 1;
> +				format++;
> +				if (*format == 'l') {
> +					lpref = 2;
> +					format++;
> +				}
> +			}
> +
> +			if (*format == '%') {
> +				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)) {
> +			while (isspace(*format))
> +				format++;
> +			while (isspace(*str))
> +				str++;
> +		} else if (*format == *str) {
> +			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 093d0512f4c5..addbceb0b276 100644
> --- a/tools/testing/selftests/nolibc/nolibc-test.c
> +++ b/tools/testing/selftests/nolibc/nolibc-test.c
> @@ -1277,6 +1277,64 @@ 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;
> +
> +	if (sscanf("", "foo") != EOF)
> +		return 1;
> +
> +	if (sscanf("foo", "foo") != 0)
> +		return 2;
> +
> +	if (sscanf("123", "%d", &i) != 1)
> +		return 3;
> +
> +	if (i != 123)
> +		return 4;
> +
> +	if (sscanf("a123b456c0x90", "a%db%uc%p", &i, &u, &p) != 3)
> +		return 5;
> +
> +	if (i != 123)
> +		return 6;
> +
> +	if (u != 456)
> +		return 7;
> +
> +	if (p != (void *)0x90)
> +		return 8;
> +
> +	if (sscanf("a    b1", "a b%d", &i) != 1)
> +		return 9;
> +
> +	if (i != 1)
> +		return 10;
> +
> +	if (sscanf("a%1", "a%%%d", &i) != 1)
> +		return 11;
> +
> +	if (i != 1)
> +		return 12;
> +
> +	if (sscanf("1|2|3|4|5|6",
> +		   "%d|%ld|%lld|%u|%lu|%llu",
> +		   &i, &l, &ll, &u, &ul, &ull) != 6)
> +		return 13;
> +
> +	if (i != 1 || l != 2 || ll != 3 ||
> +	    u != 4 || ul != 5 || ull != 6)
> +		return 14;
> +
> +	return 0;

Can we simplify this code? It is hard to read code with too
many conditions. Maybe defining an array test conditions
instead of a series ifs.

> +}
> +
>   static int run_vfprintf(int min, int max)
>   {
>   	int test;
> @@ -1298,6 +1356,7 @@ 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 */
> 

thanks,
-- Shuah

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

[Thomas Weißschuh]

On 2024-07-31 17:01:09+0000, Shuah Khan wrote:
> On 7/31/24 12:32, Thomas Weißschuh wrote:
> > The implementation is limited and only supports numeric arguments.
> 
> I would like to see more information in here. Why is this needed
> etc. etc.

Ack.

> > 
> > Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> > ---
> >   tools/include/nolibc/stdio.h                 | 93 ++++++++++++++++++++++++++++
> >   tools/testing/selftests/nolibc/nolibc-test.c | 59 ++++++++++++++++++
> >   2 files changed, 152 insertions(+)
> > 
> > diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h
> > index c968dbbc4ef8..d63c45c06d8e 100644
> > --- a/tools/include/nolibc/stdio.h
> > +++ b/tools/include/nolibc/stdio.h
> > @@ -348,6 +348,99 @@ int printf(const char *fmt, ...)
> >   	return ret;
> >   }
> > +static __attribute__((unused))
> > +int vsscanf(const char *str, const char *format, va_list args)
> 
> Is there a reason why you didn't use the same code in lib/vsprintf.c?
> You could simply duplicate the code here?

lib/vsprintf.c is GPL-2.0-only while nolibc is LGPL-2.1 OR MIT,
so code reuse isn't really possible.
Furthermore I think the vsprintf.c implements the custom kernel formats,
while nolibc should use posix ones.

> With all these libc functionality added, it isn't nolibc looks like :)

Well :-)

The main motivation is to provide kselftests compatibility.
Maybe Willy disagrees.

> > +{
> > +	uintmax_t uval;
> > +	intmax_t ival;
> > +	int base;
> > +	char *endptr;
> > +	int matches;
> > +	int lpref;
> > +
> > +	matches = 0;
> > +
> > +	while (1) {
> > +		if (*format == '%') {
> > +			lpref = 0;
> > +			format++;
> > +
> > +			if (*format == 'l') {
> > +				lpref = 1;
> > +				format++;
> > +				if (*format == 'l') {
> > +					lpref = 2;
> > +					format++;
> > +				}
> > +			}
> > +
> > +			if (*format == '%') {
> > +				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)) {
> > +			while (isspace(*format))
> > +				format++;
> > +			while (isspace(*str))
> > +				str++;
> > +		} else if (*format == *str) {
> > +			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 093d0512f4c5..addbceb0b276 100644
> > --- a/tools/testing/selftests/nolibc/nolibc-test.c
> > +++ b/tools/testing/selftests/nolibc/nolibc-test.c
> > @@ -1277,6 +1277,64 @@ 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;
> > +
> > +	if (sscanf("", "foo") != EOF)
> > +		return 1;
> > +
> > +	if (sscanf("foo", "foo") != 0)
> > +		return 2;
> > +
> > +	if (sscanf("123", "%d", &i) != 1)
> > +		return 3;
> > +
> > +	if (i != 123)
> > +		return 4;
> > +
> > +	if (sscanf("a123b456c0x90", "a%db%uc%p", &i, &u, &p) != 3)
> > +		return 5;
> > +
> > +	if (i != 123)
> > +		return 6;
> > +
> > +	if (u != 456)
> > +		return 7;
> > +
> > +	if (p != (void *)0x90)
> > +		return 8;
> > +
> > +	if (sscanf("a    b1", "a b%d", &i) != 1)
> > +		return 9;
> > +
> > +	if (i != 1)
> > +		return 10;
> > +
> > +	if (sscanf("a%1", "a%%%d", &i) != 1)
> > +		return 11;
> > +
> > +	if (i != 1)
> > +		return 12;
> > +
> > +	if (sscanf("1|2|3|4|5|6",
> > +		   "%d|%ld|%lld|%u|%lu|%llu",
> > +		   &i, &l, &ll, &u, &ul, &ull) != 6)
> > +		return 13;
> > +
> > +	if (i != 1 || l != 2 || ll != 3 ||
> > +	    u != 4 || ul != 5 || ull != 6)
> > +		return 14;
> > +
> > +	return 0;
> 
> Can we simplify this code? It is hard to read code with too
> many conditions. Maybe defining an array test conditions
> instead of a series ifs.

I tried that and didn't find a way.
Any pointers are welcome.

> > +
> > +
> >   static int run_vfprintf(int min, int max)
> >   {
> >   	int test;
> > @@ -1298,6 +1356,7 @@ 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 */
> > 
> 
> thanks,
> -- Shuah

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

[Shuah Khan]

On 8/2/24 09:48, Thomas Weißschuh wrote:
> On 2024-07-31 17:01:09+0000, Shuah Khan wrote:
>> On 7/31/24 12:32, Thomas Weißschuh wrote:
>>> The implementation is limited and only supports numeric arguments.
>>
>> I would like to see more information in here. Why is this needed
>> etc. etc.
> 
> Ack.
> 
>>>
>>> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
>>> ---
>>>    tools/include/nolibc/stdio.h                 | 93 ++++++++++++++++++++++++++++
>>>    tools/testing/selftests/nolibc/nolibc-test.c | 59 ++++++++++++++++++
>>>    2 files changed, 152 insertions(+)
>>>
>>> diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h
>>> index c968dbbc4ef8..d63c45c06d8e 100644
>>> --- a/tools/include/nolibc/stdio.h
>>> +++ b/tools/include/nolibc/stdio.h
>>> @@ -348,6 +348,99 @@ int printf(const char *fmt, ...)
>>>    	return ret;
>>>    }
>>> +static __attribute__((unused))
>>> +int vsscanf(const char *str, const char *format, va_list args)
>>
>> Is there a reason why you didn't use the same code in lib/vsprintf.c?
>> You could simply duplicate the code here?
> 
> lib/vsprintf.c is GPL-2.0-only while nolibc is LGPL-2.1 OR MIT,
> so code reuse isn't really possible.
> Furthermore I think the vsprintf.c implements the custom kernel formats,
> while nolibc should use posix ones.

Ack.

> 
>> With all these libc functionality added, it isn't nolibc looks like :)
> 
> Well :-)
> 
> The main motivation is to provide kselftests compatibility.
> Maybe Willy disagrees.
> 
>>> +{

>>> +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 093d0512f4c5..addbceb0b276 100644
>>> --- a/tools/testing/selftests/nolibc/nolibc-test.c
>>> +++ b/tools/testing/selftests/nolibc/nolibc-test.c
>>> @@ -1277,6 +1277,64 @@ static int expect_vfprintf(int llen, int c, const char *expected, const char *fm
>>>    	return ret;
>>>    }
>>> +static int test_scanf(void)

Is there a rationale for the return values 1 - 14. It will be
easier to understand if there are comments in the code.

>>> +{
>>> +	unsigned long long ull;
>>> +	unsigned long ul;
>>> +	unsigned int u;
>>> +	long long ll;
>>> +	long l;
>>> +	void *p;
>>> +	int i;
>>> +
>>> +	if (sscanf("", "foo") != EOF)
>>> +		return 1;
>>> +
>>> +	if (sscanf("foo", "foo") != 0)
>>> +		return 2;
>>> +
>>> +	if (sscanf("123", "%d", &i) != 1)
>>> +		return 3;>>> +
>>> +	if (i != 123)
>>> +		return 4;
>>> +
>>> +	if (sscanf("a123b456c0x90", "a%db%uc%p", &i, &u, &p) != 3)
>>> +		return 5;
>>> +
>>> +	if (i != 123)
>>> +		return 6;
>>> +
>>> +	if (u != 456)
>>> +		return 7;
>>> +
>>> +	if (p != (void *)0x90)
>>> +		return 8;
>>> +
>>> +	if (sscanf("a    b1", "a b%d", &i) != 1)
>>> +		return 9;
>>> +
>>> +	if (i != 1)
>>> +		return 10;
>>> +
>>> +	if (sscanf("a%1", "a%%%d", &i) != 1)
>>> +		return 11;
>>> +
>>> +	if (i != 1)
>>> +		return 12;
>>> +
>>> +	if (sscanf("1|2|3|4|5|6",
>>> +		   "%d|%ld|%lld|%u|%lu|%llu",
>>> +		   &i, &l, &ll, &u, &ul, &ull) != 6)
>>> +		return 13;
>>> +
>>> +	if (i != 1 || l != 2 || ll != 3 ||
>>> +	    u != 4 || ul != 5 || ull != 6)
>>> +		return 14;
>>> +
>>> +	return 0;
>>
>> Can we simplify this code? It is hard to read code with too
>> many conditions. Maybe defining an array test conditions
>> instead of a series ifs.
> 
> I tried that and didn't find a way.
> Any pointers are welcome.

I played with this some and couldn't think of way to simplify
this without making it hard to read. It would help adding
comments though.

thanks,
-- Shuah

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

[Willy Tarreau]

On Fri, Aug 02, 2024 at 05:48:13PM +0200, Thomas Weißschuh wrote:
> > With all these libc functionality added, it isn't nolibc looks like :)
> 
> Well :-)
> 
> The main motivation is to provide kselftests compatibility.
> Maybe Willy disagrees.

No no I'm perfectly fine with adding the functions that developers use
or need to write their test or init tools. I don't have any strong
opinion on scanf(). Just like strtok(), I stopped using it 25 years ago
when I noticed that it never survives code evolutions, lacks a lot of
flexibility and is often strongly tied to your types (more than printf
where you can cast). But I perfectly understand that others are used to
it and would appreciate to have it, for example if it helps with command
line arguments.

> > > +static int test_scanf(void)
> > > +{
> > > +	unsigned long long ull;
> > > +	unsigned long ul;
> > > +	unsigned int u;
> > > +	long long ll;
> > > +	long l;
> > > +	void *p;
> > > +	int i;
> > > +
> > > +	if (sscanf("", "foo") != EOF)
> > > +		return 1;
> > > +
> > > +	if (sscanf("foo", "foo") != 0)
> > > +		return 2;
> > > +
> > > +	if (sscanf("123", "%d", &i) != 1)
> > > +		return 3;
> > > +
> > > +	if (i != 123)
> > > +		return 4;
> > > +
> > > +	if (sscanf("a123b456c0x90", "a%db%uc%p", &i, &u, &p) != 3)
> > > +		return 5;
> > > +
> > > +	if (i != 123)
> > > +		return 6;
> > > +
> > > +	if (u != 456)
> > > +		return 7;
> > > +
> > > +	if (p != (void *)0x90)
> > > +		return 8;
> > > +
> > > +	if (sscanf("a    b1", "a b%d", &i) != 1)
> > > +		return 9;
> > > +
> > > +	if (i != 1)
> > > +		return 10;
> > > +
> > > +	if (sscanf("a%1", "a%%%d", &i) != 1)
> > > +		return 11;
> > > +
> > > +	if (i != 1)
> > > +		return 12;
> > > +
> > > +	if (sscanf("1|2|3|4|5|6",
> > > +		   "%d|%ld|%lld|%u|%lu|%llu",
> > > +		   &i, &l, &ll, &u, &ul, &ull) != 6)
> > > +		return 13;
> > > +
> > > +	if (i != 1 || l != 2 || ll != 3 ||
> > > +	    u != 4 || ul != 5 || ull != 6)
> > > +		return 14;
> > > +
> > > +	return 0;
> > 
> > Can we simplify this code? It is hard to read code with too
> > many conditions. Maybe defining an array test conditions
> > instead of a series ifs.
> 
> I tried that and didn't find a way.
> Any pointers are welcome.

I think it would be difficult by nature of varargs.

However, since you grouped some expressions, maybe a one-liner comment
between each scanf() to explain the intent of the test would make it
easier to follow. E.g:
    /* test multiple naked numbers */
    ...
    /* test numbers delimited with a character */
    ...
    /* test multiple integer types at once */

etc. This allows the reviewer to more easly re-focus on the test they
were reading.

Willy

[PATCH 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 b8967b6e29d5..f0c4f62e2949 100644
--- a/tools/testing/selftests/kselftest.h
+++ b/tools/testing/selftests/kselftest.h
@@ -426,10 +426,6 @@ 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;
 
@@ -437,7 +433,6 @@ 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 */

-- 
2.46.0

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

[Shuah Khan]

On 7/31/24 12:32, Thomas Weißschuh wrote:
> The implementation is limited and only supports numeric arguments.

It would help to add more details on why this is needed especially
in the commit log.

> 
> Signed-off-by: Thomas Weißschuh <linux@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                 | 93 ++++++++++++++++++++++++++++
>   tools/testing/selftests/kselftest.h          |  5 --
>   tools/testing/selftests/nolibc/nolibc-test.c | 59 ++++++++++++++++++
>   3 files changed, 152 insertions(+), 5 deletions(-)
> ---
> base-commit: ae1f550efc11eaf1496c431d9c6e784cb49124c5
> change-id: 20240414-nolibc-scanf-f1db6930d0c6
> 
> Best regards,