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Message-ID: <5db920e0-51e8-48d9-b0ae-95479e875fad@t-8ch.de>
Date: Fri, 2 Aug 2024 17:48:13 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Shuah Khan <skhan@...uxfoundation.org>
Cc: Willy Tarreau <w@....eu>, Shuah Khan <shuah@...nel.org>,
linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 1/2] tools/nolibc: add support for [v]sscanf()
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@...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?
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
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