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 <li...@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


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