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 <[email protected]>
---
  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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