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Message-ID: <3956cee8-1623-42d6-bbc6-71b5abd67759@linuxfoundation.org>
Date: Wed, 31 Jul 2024 17:01:09 -0600
From: Shuah Khan <skhan@...uxfoundation.org>
To: Thomas Weißschuh <linux@...ssschuh.net>,
Willy Tarreau <w@....eu>, Shuah Khan <shuah@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH 1/2] tools/nolibc: add support for [v]sscanf()
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@...ssschuh.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
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