[RESEND PATCH v2 09/18] lib: sscanf: add sscanf implementation

[Anastasiia Lukianenko <vicooodin@gmail.com>]

From: Andrii Anisov <andrii_anisov@epam.com>

Port sscanf implementation from mini-os and introduce new
Kconfig option to enable it: CONFIG_SSCANF. Disable by default.

Signed-off-by: Andrii Anisov <andrii_anisov@epam.com>
Signed-off-by: Anastasiia Lukianenko <anastasiia_lukianenko@epam.com>
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
---

Changes since v1:
 - provide a test in /tests/lib
 - reduce the code size
 - add comments
 - correct code style

 include/vsprintf.h |   8 +
 lib/Kconfig        |   4 +
 lib/Makefile       |   1 +
 lib/sscanf.c       | 823 +++++++++++++++++++++++++++++++++++++++++++++
 test/lib/Makefile  |   1 +
 test/lib/sscanf.c  | 174 ++++++++++
 6 files changed, 1011 insertions(+)
 create mode 100644 lib/sscanf.c
 create mode 100644 test/lib/sscanf.c

diff --git a/include/vsprintf.h b/include/vsprintf.h
index d9fb68add0..2290083eba 100644
--- a/include/vsprintf.h
+++ b/include/vsprintf.h
@@ -234,4 +234,12 @@ char *strmhz(char *buf, unsigned long hz);
  */
 void str_to_upper(const char *in, char *out, size_t len);
 
+/**
+ * sscanf - Unformat a buffer into a list of arguments
+ * @buf:	input buffer
+ * @fmt:	formatting of buffer
+ * @...:	resulting arguments
+ */
+int sscanf(const char *buf, const char *fmt, ...);
+
 #endif
diff --git a/lib/Kconfig b/lib/Kconfig
index 2142bd06e6..efd383ea88 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -80,6 +80,10 @@ config SPL_SPRINTF
 config TPL_SPRINTF
 	bool
 
+config SSCANF
+	bool
+	default n
+
 config STRTO
 	bool
 	default y
diff --git a/lib/Makefile b/lib/Makefile
index 1dc06c57d5..0cd7bea282 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -123,6 +123,7 @@ else
 # Main U-Boot always uses the full printf support
 obj-y += vsprintf.o strto.o
 obj-$(CONFIG_OID_REGISTRY) += oid_registry.o
+obj-$(CONFIG_SSCANF) += sscanf.o
 endif
 
 obj-y += date.o
diff --git a/lib/sscanf.c b/lib/sscanf.c
new file mode 100644
index 0000000000..d1e2dc272c
--- /dev/null
+++ b/lib/sscanf.c
@@ -0,0 +1,823 @@
+// SPDX-License-Identifier: BSD-3-Clause
+/*
+ * Copyright (c) 1990, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Chris Torek.
+ *
+ * Copyright (c) 2011 The FreeBSD Foundation
+ * All rights reserved.
+ * Portions of this software were developed by David Chisnall
+ * under sponsorship from the FreeBSD Foundation.
+ *
+ * Author: Juergen Gross <jgross@suse.com>
+ * Date: Jun 2016
+ */
+
+#if !defined HAVE_LIBC
+
+#include <os.h>
+#include <linux/kernel.h>
+#include <linux/ctype.h>
+#include <vsprintf.h>
+#include <linux/string.h>
+#include <malloc.h>
+#define __DECONST(type, var)    ((type)(uintptr_t)(const void *)(var))
+
+/**
+ * struct str_info - Input string parameters
+ * @neg: negative number or not
+ *	 0 - not negative
+ *	 1 - negative
+ * @any: set any if any `digits' consumed; make it negative to indicate
+ *	 overflow
+ * @acc: accumulated value
+ */
+struct str_info {
+	int neg, any;
+	u64 acc;
+};
+
+/**
+ * str_to_int_convert() - Write string data to structure
+ * @nptr: pointer to string
+ * @base: number's base
+ * @unsign: describes what integer is expected
+ *	    0 - not unsigned
+ *	    1 - unsigned
+ *
+ * Ignores `locale' stuff.  Assumes that the upper and lower case
+ * alphabets and digits are each contiguous.
+ *
+ * Return: struct str_info *, which contains string data to future process
+ */
+static struct str_info *
+str_to_int_convert(const char **nptr, int base, unsigned int unsign)
+{
+	const char *s = *nptr;
+	u64 acc;
+	unsigned char c;
+	u64 cutoff;
+	int neg, any, cutlim;
+	u64 qbase;
+	struct str_info *info;
+
+	/*
+	 * Skip white space and pick up leading +/- sign if any.
+	 * If base is 0, allow 0x for hex and 0 for octal, else
+	 * assume decimal; if base is already 16, allow 0x.
+	 */
+	info = (struct str_info *)malloc(sizeof(struct str_info));
+	if (!info)
+		return NULL;
+
+	do {
+		c = *s++;
+	} while (isspace(c));
+	if (c == '-') {
+		neg = 1;
+		c = *s++;
+	} else {
+		neg = 0;
+		if (c == '+')
+			c = *s++;
+	}
+	if ((base == 0 || base == 16) &&
+	    c == '0' && (*s == 'x' || *s == 'X')) {
+		c = s[1];
+		s += 2;
+		base = 16;
+	}
+	if (base == 0)
+		base = c == '0' ? 8 : 10;
+
+	/*
+	 * Compute the cutoff value between legal numbers and illegal
+	 * numbers.  That is the largest legal value, divided by the
+	 * base.  An input number that is greater than this value, if
+	 * followed by a legal input character, is too big.  One that
+	 * is equal to this value may be valid or not; the limit
+	 * between valid and invalid numbers is then based on the last
+	 * digit.  For instance, if the range for quads is
+	 * [-9223372036854775808..9223372036854775807] and the input base
+	 * is 10, cutoff will be set to 922337203685477580 and cutlim to
+	 * either 7 (neg==0) or 8 (neg==1), meaning that if we have
+	 * accumulated a value > 922337203685477580, or equal but the
+	 * next digit is > 7 (or 8), the number is too big, and we will
+	 * return a range error.
+	 *
+	 * Set any if any `digits' consumed; make it negative to indicate
+	 * overflow.
+	 */
+	qbase = (unsigned int)base;
+
+	if (!unsign) {
+		cutoff = neg ? (u64)-(LLONG_MIN + LLONG_MAX) + LLONG_MAX : LLONG_MAX;
+		cutlim = cutoff % qbase;
+		cutoff /= qbase;
+	} else {
+		cutoff = (u64)ULLONG_MAX / qbase;
+		cutlim = (u64)ULLONG_MAX % qbase;
+	}
+
+	for (acc = 0, any = 0;; c = *s++) {
+		if (!isascii(c))
+			break;
+		if (isdigit(c))
+			c -= '0';
+		else if (isalpha(c))
+			c -= isupper(c) ? 'A' - 10 : 'a' - 10;
+		else
+			break;
+		if (c >= base)
+			break;
+		if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim)) {
+			any = -1;
+		} else {
+			any = 1;
+			acc *= qbase;
+			acc += c;
+		}
+	}
+
+	info->any = any;
+	info->neg = neg;
+	info->acc = acc;
+
+	*nptr = s;
+
+	return info;
+}
+
+/**
+ * strtoq() - Convert a string to a quad integer
+ * @nptr: pointer to string
+ * @endptr: pointer to number's end in the string
+ * @base: number's base
+ *
+ * Return: s64 quad integer number converted from input string
+ */
+static s64
+strtoq(const char *nptr, char **endptr, int base)
+{
+	const char *s = nptr;
+	u64 acc;
+	int unsign = 0;
+	struct str_info *info;
+
+	info = str_to_int_convert(&s, base, unsign);
+	if (!info)
+		return -1;
+
+	acc = info->acc;
+
+	if (info->any < 0)
+		acc = info->neg ? LLONG_MIN : LLONG_MAX;
+	else if (info->neg)
+		acc = -acc;
+	if (endptr != 0)
+		*endptr = __DECONST(char *, info->any ? s - 1 : nptr);
+
+	free(info);
+
+	return acc;
+}
+
+/**
+ * strtouq() - Convert a string to an unsigned quad integer
+ * @nptr: pointer to string
+ * @endptr: pointer to number's end in the string
+ * @base: number's base
+ *
+ * Return: s64 unsigned quad integer number converted from
+ *         input string
+ */
+u64
+strtouq(const char *nptr, char **endptr, int base)
+{
+		const char *s = nptr;
+	u64 acc;
+	int unsign = 1;
+	struct str_info *info;
+
+	info = str_to_int_convert(&s, base, unsign);
+	if (!info)
+		return -1;
+
+	acc = info->acc;
+
+	if (info->any < 0)
+		acc = ULLONG_MAX;
+	else if (info->neg)
+		acc = -acc;
+	if (endptr != 0)
+		*endptr = __DECONST(char *, info->any ? s - 1 : nptr);
+
+	free(info);
+
+	return acc;
+}
+
+/**
+ * __sccl() - Fill in the given table from the scanset at the given format
+ * (just after `[')
+ * @tab: table to fill in
+ * @fmt: format of buffer
+ *
+ * The table has a 1 wherever characters should be considered part of the
+ * scanset.
+ *
+ * Return: pointer to the character past the closing `]'
+ */
+static const u_char *
+__sccl(char *tab, const u_char *fmt)
+{
+	int c, n, v;
+
+	/* first `clear' the whole table */
+	c = *fmt++;             /* first char hat => negated scanset */
+	if (c == '^') {
+		v = 1;          /* default => accept */
+		c = *fmt++;     /* get new first char */
+	} else {
+		v = 0;          /* default => reject */
+	}
+
+	/* XXX: Will not work if sizeof(tab*) > sizeof(char) */
+	for (n = 0; n < 256; n++)
+		tab[n] = v;        /* memset(tab, v, 256) */
+
+	if (c == 0)
+		return (fmt - 1);/* format ended before closing ] */
+
+	/*
+	 * Now set the entries corresponding to the actual scanset
+	 * to the opposite of the above.
+	 *
+	 * The first character may be ']' (or '-') without being special;
+	 * the last character may be '-'.
+	 */
+	v = 1 - v;
+	for (;;) {
+		tab[c] = v;             /* take character c */
+doswitch:
+		n = *fmt++;             /* and examine the next */
+		switch (n) {
+		case 0:                 /* format ended too soon */
+			return (fmt - 1);
+
+		case '-':
+			/*
+			 * A scanset of the form
+			 *      [01+-]
+			 * is defined as `the digit 0, the digit 1,
+			 * the character +, the character -', but
+			 * the effect of a scanset such as
+			 *      [a-zA-Z0-9]
+			 * is implementation defined.  The V7 Unix
+			 * scanf treats `a-z' as `the letters a through
+			 * z', but treats `a-a' as `the letter a, the
+			 * character -, and the letter a'.
+			 *
+			 * For compatibility, the `-' is not considerd
+			 * to define a range if the character following
+			 * it is either a close bracket (required by ANSI)
+			 * or is not numerically greater than the character
+			 * we just stored in the table (c).
+			 */
+			n = *fmt;
+			if (n == ']' || n < c) {
+				c = '-';
+				break;  /* resume the for(;;) */
+			}
+			fmt++;
+			/* fill in the range */
+			do {
+				tab[++c] = v;
+			} while (c < n);
+			c = n;
+			/*
+			 * Alas, the V7 Unix scanf also treats formats
+			 * such as [a-c-e] as `the letters a through e'.
+			 * This too is permitted by the standard....
+			 */
+			goto doswitch;
+			break;
+
+		case ']':               /* end of scanset */
+			return (fmt);
+
+		default:                /* just another character */
+			c = n;
+			break;
+		}
+	}
+	/* NOTREACHED */
+}
+
+/**
+ * vsscanf - Unformat a buffer into a list of arguments
+ * @buf:	input buffer
+ * @fmt:	format of buffer
+ * @args:	arguments
+ */
+#define BUF             32      /* Maximum length of numeric string. */
+
+/*
+ * Flags used during conversion.
+ */
+#define LONG            0x01    /* l: long or double */
+#define SHORT           0x04    /* h: short */
+#define SUPPRESS        0x08    /* suppress assignment */
+#define POINTER         0x10    /* weird %p pointer (`fake hex') */
+#define NOSKIP          0x20    /* do not skip blanks */
+#define QUAD            0x400
+#define SHORTSHORT      0x4000  /** hh: char */
+
+/*
+ * The following are used in numeric conversions only:
+ * SIGNOK, NDIGITS, DPTOK, and EXPOK are for floating point;
+ * SIGNOK, NDIGITS, PFXOK, and NZDIGITS are for integral.
+ */
+#define SIGNOK          0x40    /* +/- is (still) legal */
+#define NDIGITS         0x80    /* no digits detected */
+
+#define DPTOK           0x100   /* (float) decimal point is still legal */
+#define EXPOK           0x200   /* (float) exponent (e+3, etc) still legal */
+
+#define PFXOK           0x100   /* 0x prefix is (still) legal */
+#define NZDIGITS        0x200   /* no zero digits detected */
+
+/*
+ * Conversion types.
+ */
+#define CT_CHAR         0       /* %c conversion */
+#define CT_CCL          1       /* %[...] conversion */
+#define CT_STRING       2       /* %s conversion */
+#define CT_INT          3       /* integer, i.e., strtoq or strtouq */
+typedef u64 (*ccfntype)(const char *, char **, int);
+
+int
+vsscanf(const char *inp, char const *fmt0, va_list ap)
+{
+	int inr;
+	const u_char *fmt = (const u_char *)fmt0;
+	int c;                  /* character from format, or conversion */
+	size_t width;           /* field width, or 0 */
+	char *p;                /* points into all kinds of strings */
+	int n;                  /* handy integer */
+	int flags;              /* flags as defined above */
+	char *p0;               /* saves original value of p when necessary */
+	int nassigned;          /* number of fields assigned */
+	int nconversions;       /* number of conversions */
+	int nread;              /* number of characters consumed from fp */
+	int base;               /* base argument to strtoq/strtouq */
+	ccfntype ccfn;          /* conversion function (strtoq/strtouq) */
+	char ccltab[256];       /* character class table for %[...] */
+	char buf[BUF];          /* buffer for numeric conversions */
+
+	/* `basefix' is used to avoid `if' tests in the integer scanner */
+	static short basefix[17] = { 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
+				     12, 13, 14, 15, 16 };
+
+	inr = strlen(inp);
+
+	nassigned = 0;
+	nconversions = 0;
+	nread = 0;
+	base = 0;               /* XXX just to keep gcc happy */
+	ccfn = NULL;            /* XXX just to keep gcc happy */
+	for (;;) {
+		c = *fmt++;
+		if (c == 0)
+			return (nassigned);
+		if (isspace(c)) {
+			while (inr > 0 && isspace(*inp))
+				nread++, inr--, inp++;
+			continue;
+		}
+		if (c != '%')
+			goto literal;
+		width = 0;
+		flags = 0;
+		/*
+		 * switch on the format.  continue if done;
+		 * break once format type is derived.
+		 */
+again:          c = *fmt++;
+		switch (c) {
+		case '%':
+literal:
+			if (inr <= 0)
+				goto input_failure;
+			if (*inp != c)
+				goto match_failure;
+			inr--, inp++;
+			nread++;
+			continue;
+
+		case '*':
+			flags |= SUPPRESS;
+			goto again;
+		case 'l':
+			if (flags & LONG) {
+				flags &= ~LONG;
+				flags |= QUAD;
+			} else {
+				flags |= LONG;
+			}
+			goto again;
+		case 'q':
+			flags |= QUAD;
+			goto again;
+		case 'h':
+			if (flags & SHORT) {
+				flags &= ~SHORT;
+				flags |= SHORTSHORT;
+			} else {
+				flags |= SHORT;
+			}
+			goto again;
+
+		case '0': case '1': case '2': case '3': case '4':
+		case '5': case '6': case '7': case '8': case '9':
+			width = width * 10 + c - '0';
+			goto again;
+
+		/*
+		 * Conversions.
+		 *
+		 */
+		case 'd':
+			c = CT_INT;
+			ccfn = (ccfntype)strtoq;
+			base = 10;
+			break;
+
+		case 'i':
+			c = CT_INT;
+			ccfn = (ccfntype)strtoq;
+			base = 0;
+			break;
+
+		case 'o':
+			c = CT_INT;
+			ccfn = strtouq;
+			base = 8;
+			break;
+
+		case 'u':
+			c = CT_INT;
+			ccfn = strtouq;
+			base = 10;
+			break;
+
+		case 'x':
+			flags |= PFXOK; /* enable 0x prefixing */
+			c = CT_INT;
+			ccfn = strtouq;
+			base = 16;
+			break;
+
+		case 's':
+			c = CT_STRING;
+			break;
+
+		case '[':
+			fmt = __sccl(ccltab, fmt);
+			flags |= NOSKIP;
+			c = CT_CCL;
+			break;
+
+		case 'c':
+			flags |= NOSKIP;
+			c = CT_CHAR;
+			break;
+
+		case 'p':       /* pointer format is like hex */
+			flags |= POINTER | PFXOK;
+			c = CT_INT;
+			ccfn = strtouq;
+			base = 16;
+			break;
+
+		case 'n':
+			nconversions++;
+			if (flags & SUPPRESS)   /* ??? */
+				continue;
+			if (flags & SHORTSHORT)
+				*va_arg(ap, char *) = nread;
+			else if (flags & SHORT)
+				*va_arg(ap, short *) = nread;
+			else if (flags & LONG)
+				*va_arg(ap, long *) = nread;
+			else if (flags & QUAD)
+				*va_arg(ap, s64 *) = nread;
+			else
+				*va_arg(ap, int *) = nread;
+			continue;
+		}
+
+		/*
+		 * We have a conversion that requires input.
+		 */
+		if (inr <= 0)
+			goto input_failure;
+
+		/*
+		 * Consume leading white space, except for formats
+		 * that suppress this.
+		 */
+		if ((flags & NOSKIP) == 0) {
+			while (isspace(*inp)) {
+				nread++;
+				if (--inr > 0)
+					inp++;
+				else
+					goto input_failure;
+			}
+			/*
+			 * Note that there is at least one character in
+			 * the buffer, so conversions that do not set NOSKIP
+			 * can no longer result in an input failure.
+			 */
+		}
+
+		/*
+		 * Do the conversion.
+		 */
+		switch (c) {
+		case CT_CHAR:
+			/* scan arbitrary characters (sets NOSKIP) */
+			if (width == 0)
+				width = 1;
+			if (flags & SUPPRESS) {
+				size_t sum = 0;
+
+				if ((n = inr) < width) {
+					sum += n;
+					width -= n;
+					inp += n;
+					if (sum == 0)
+						goto input_failure;
+				} else {
+					sum += width;
+					inr -= width;
+					inp += width;
+				}
+				nread += sum;
+			} else {
+				memcpy(va_arg(ap, char *), inp, width);
+				inr -= width;
+				inp += width;
+				nread += width;
+				nassigned++;
+			}
+			nconversions++;
+			break;
+
+		case CT_CCL:
+			/* scan a (nonempty) character class (sets NOSKIP) */
+			if (width == 0)
+				width = (size_t)~0;     /* `infinity' */
+			/* take only those things in the class */
+			if (flags & SUPPRESS) {
+				n = 0;
+				while (ccltab[(unsigned char)*inp]) {
+					n++, inr--, inp++;
+					if (--width == 0)
+						break;
+					if (inr <= 0) {
+						if (n == 0)
+							goto input_failure;
+						break;
+					}
+				}
+				if (n == 0)
+					goto match_failure;
+			} else {
+				p = va_arg(ap, char *);
+				p0 = p;
+				while (ccltab[(unsigned char)*inp]) {
+					inr--;
+					*p++ = *inp++;
+					if (--width == 0)
+						break;
+					if (inr <= 0) {
+						if (p == p0)
+							goto input_failure;
+						break;
+					}
+				}
+				n = p - p0;
+				if (n == 0)
+					goto match_failure;
+				*p = 0;
+				nassigned++;
+			}
+			nread += n;
+			nconversions++;
+			break;
+
+		case CT_STRING:
+			/* like CCL, but zero-length string OK, & no NOSKIP */
+			if (width == 0)
+				width = (size_t)~0;
+			if (flags & SUPPRESS) {
+				n = 0;
+				while (!isspace(*inp)) {
+					n++, inr--, inp++;
+					if (--width == 0)
+						break;
+					if (inr <= 0)
+						break;
+				}
+				nread += n;
+			} else {
+				p = va_arg(ap, char *);
+				p0 = p;
+				while (!isspace(*inp)) {
+					inr--;
+					*p++ = *inp++;
+					if (--width == 0)
+						break;
+					if (inr <= 0)
+						break;
+				}
+				*p = 0;
+				nread += p - p0;
+				nassigned++;
+			}
+			nconversions++;
+			continue;
+
+		case CT_INT:
+			/* scan an integer as if by strtoq/strtouq */
+#ifdef hardway
+			if (width == 0 || width > sizeof(buf) - 1)
+				width = sizeof(buf) - 1;
+#else
+			/* size_t is unsigned, hence this optimisation */
+			if (--width > sizeof(buf) - 2)
+				width = sizeof(buf) - 2;
+			width++;
+#endif
+			flags |= SIGNOK | NDIGITS | NZDIGITS;
+			for (p = buf; width; width--) {
+				c = *inp;
+				/*
+				 * Switch on the character; `goto ok'
+				 * if we accept it as a part of number.
+				 */
+				switch (c) {
+				/*
+				 * The digit 0 is always legal, but is
+				 * special.  For %i conversions, if no
+				 * digits (zero or nonzero) have been
+				 * scanned (only signs), we will have
+				 * base==0.  In that case, we should set
+				 * it to 8 and enable 0x prefixing.
+				 * Also, if we have not scanned zero digits
+				 * before this, do not turn off prefixing
+				 * (someone else will turn it off if we
+				 * have scanned any nonzero digits).
+				 */
+				case '0':
+					if (base == 0) {
+						base = 8;
+						flags |= PFXOK;
+					}
+					if (flags & NZDIGITS)
+						flags &= ~(SIGNOK | NZDIGITS | NDIGITS);
+					else
+						flags &= ~(SIGNOK | PFXOK | NDIGITS);
+					goto ok;
+
+				/* 1 through 7 always legal */
+				case '1': case '2': case '3':
+				case '4': case '5': case '6': case '7':
+					base = basefix[base];
+					flags &= ~(SIGNOK | PFXOK | NDIGITS);
+					goto ok;
+
+				/* digits 8 and 9 ok iff decimal or hex */
+				case '8': case '9':
+					base = basefix[base];
+					if (base <= 8)
+						break;  /* not legal here */
+					flags &= ~(SIGNOK | PFXOK | NDIGITS);
+					goto ok;
+
+				/* letters ok iff hex */
+				case 'A': case 'B': case 'C':
+				case 'D': case 'E': case 'F':
+				case 'a': case 'b': case 'c':
+				case 'd': case 'e': case 'f':
+					/* no need to fix base here */
+					if (base <= 10)
+						break;  /* not legal here */
+					flags &= ~(SIGNOK | PFXOK | NDIGITS);
+					goto ok;
+
+				/* sign ok only as first character */
+				case '+': case '-':
+					if (flags & SIGNOK) {
+						flags &= ~SIGNOK;
+						goto ok;
+						}
+					break;
+
+				/* x ok iff flag still set & 2nd char */
+				case 'x': case 'X':
+					if (flags & PFXOK && p == buf + 1) {
+						base = 16;      /* if %i */
+						flags &= ~PFXOK;
+						goto ok;
+					}
+					break;
+				}
+
+				/*
+				 * If we got here, c is not a legal character
+				 * for a number.  Stop accumulating digits.
+				 */
+				break;
+ok:
+				/*
+				 * c is legal: store it and look@the next.
+				 */
+				*p++ = c;
+				if (--inr > 0)
+					inp++;
+				else
+					break;          /* end of input */
+			}
+			/*
+			 * If we had only a sign, it is no good; push
+			 * back the sign.  If the number ends in `x',
+			 * it was [sign] '' 'x', so push back the x
+			 * and treat it as [sign] ''.
+			 */
+			if (flags & NDIGITS) {
+				if (p > buf) {
+					inp--;
+					inr++;
+				}
+				goto match_failure;
+			}
+			c = ((u_char *)p)[-1];
+			if (c == 'x' || c == 'X') {
+				--p;
+				inp--;
+				inr++;
+			}
+			if ((flags & SUPPRESS) == 0) {
+				u64 res;
+
+				*p = 0;
+				res = (*ccfn)(buf, (char **)NULL, base);
+				if (flags & POINTER)
+					*va_arg(ap, void **) =
+					(void *)(uintptr_t)res;
+				else if (flags & SHORTSHORT)
+					*va_arg(ap, char *) = res;
+				else if (flags & SHORT)
+					*va_arg(ap, short *) = res;
+				else if (flags & LONG)
+					*va_arg(ap, long *) = res;
+				else if (flags & QUAD)
+					*va_arg(ap, s64 *) = res;
+				else
+					*va_arg(ap, int *) = res;
+				nassigned++;
+			}
+			nread += p - buf;
+			nconversions++;
+			break;
+		}
+	}
+input_failure:
+		return (nconversions != 0 ? nassigned : -1);
+match_failure:
+		return (nassigned);
+}
+
+/**
+ * sscanf - Unformat a buffer into a list of arguments
+ * @buf:	input buffer
+ * @fmt:	formatting of buffer
+ * @...:	resulting arguments
+ */
+int sscanf(const char *buf, const char *fmt, ...)
+{
+	va_list args;
+	int i;
+
+	va_start(args, fmt);
+	i = vsscanf(buf, fmt, args);
+	va_end(args);
+	return i;
+}
+
+#endif
diff --git a/test/lib/Makefile b/test/lib/Makefile
index 6ccc2c41bc..b6a0a208c5 100644
--- a/test/lib/Makefile
+++ b/test/lib/Makefile
@@ -6,6 +6,7 @@ obj-y += cmd_ut_lib.o
 obj-$(CONFIG_EFI_SECURE_BOOT) += efi_image_region.o
 obj-y += hexdump.o
 obj-y += lmb.o
+obj-y += sscanf.o
 obj-y += string.o
 obj-$(CONFIG_ERRNO_STR) += test_errno_str.o
 obj-$(CONFIG_UT_LIB_ASN1) += asn1.o
diff --git a/test/lib/sscanf.c b/test/lib/sscanf.c
new file mode 100644
index 0000000000..772e4b9204
--- /dev/null
+++ b/test/lib/sscanf.c
@@ -0,0 +1,174 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2002, Uwe Bonnes
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2016, The Tor Project, Inc.
+ * Copyright (c) 2020, EPAM Systems Inc.
+ *
+ * Unit tests for sscanf() function
+ */
+
+#include <common.h>
+#include <command.h>
+#include <log.h>
+#include <test/lib.h>
+#include <test/test.h>
+#include <test/ut.h>
+
+#define EOF -1
+
+/**
+ * lib_sscanf() - unit test for sscanf()
+ * @uts: unit test state
+ *
+ * Test sscanf() with varied parameters in different combinations passed
+ * as arguments.
+ *
+ * Return: 0 - success
+ *	   1 - failure
+ */
+static int lib_sscanf(struct unit_test_state *uts)
+{
+	char buffer[100], buffer1[100];
+	int result, ret;
+	static const char pname[] = " Hello World!\n";
+	int hour = 21, min = 59, sec = 20;
+	int number, number_so_far;
+	unsigned int u1, u2, u3;
+	char s1[20], s2[10], s3[10], ch;
+	int r, int1, int2;
+	long lng1;
+
+	/* check EOF */
+	strcpy(buffer, "");
+	ret = sscanf(buffer, "%d", &result);
+	ut_asserteq(ret, EOF);
+
+	/* check %x */
+	strcpy(buffer, "0x519");
+	ut_asserteq(sscanf(buffer, "%x", &result), 1);
+	ut_asserteq(result, 0x519);
+
+	strcpy(buffer, "0x51a");
+	ut_asserteq(sscanf(buffer, "%x", &result), 1);
+	ut_asserteq(result, 0x51a);
+
+	strcpy(buffer, "0x51g");
+	ut_asserteq(sscanf(buffer, "%x", &result), 1);
+	ut_asserteq(result, 0x51);
+
+	/* check strings */
+	ret = sprintf(buffer, " %s", pname);
+	ret = sscanf(buffer, "%*c%[^\n]", buffer1);
+	ut_asserteq(ret, 1);
+	ut_asserteq(strncmp(pname, buffer1, strlen(buffer1)), 0);
+
+	/* check digits */
+	ret = sprintf(buffer, "%d:%d:%d", hour, min, sec);
+	ret = sscanf(buffer, "%d%n", &number, &number_so_far);
+	ut_asserteq(ret, 1);
+	ut_asserteq(number, hour);
+	ut_asserteq(number_so_far, 2);
+
+	ret = sscanf(buffer + 2, "%*c%n", &number_so_far);
+	ut_asserteq(ret, 0);
+	ut_asserteq(number_so_far, 1);
+
+	/* Check %i */
+	strcpy(buffer, "123");
+	ret = sscanf(buffer, "%i", &result);
+	ut_asserteq(ret, 1);
+	ut_asserteq(result, 123);
+	ret = sscanf(buffer, "%d", &result);
+	ut_asserteq(ret, 1);
+	ut_asserteq(result, 123);
+
+	ut_asserteq(0, sscanf("hello world", "hello world"));
+	ut_asserteq(0, sscanf("hello world", "good bye"));
+	/* Excess data */
+	ut_asserteq(0, sscanf("hello 3", "%u", &u1));  /* have to match the start */
+	ut_asserteq(1, sscanf("3 hello", "%u", &u1));  /* but trailing is alright */
+
+	/* Numbers (ie. %u) */
+	ut_asserteq(0, sscanf("hello world 3", "hello worlb %u", &u1)); /* d vs b */
+	ut_asserteq(1, sscanf("12345", "%u", &u1));
+	ut_asserteq(12345u, u1);
+	ut_asserteq(1, sscanf("0", "%u", &u1));
+	ut_asserteq(0u, u1);
+	ut_asserteq(1, sscanf("0000", "%u", &u2));
+	ut_asserteq(0u, u2);
+	ut_asserteq(0, sscanf("A", "%u", &u1)); /* bogus number */
+
+	/* Numbers with size (eg. %2u) */
+	ut_asserteq(2, sscanf("123456", "%2u%u", &u1, &u2));
+	ut_asserteq(12u, u1);
+	ut_asserteq(3456u, u2);
+	ut_asserteq(1, sscanf("123456", "%8u", &u1));
+	ut_asserteq(123456u, u1);
+	ut_asserteq(1, sscanf("123457  ", "%8u", &u1));
+	ut_asserteq(123457u, u1);
+	ut_asserteq(3, sscanf("!12:3:456", "!%2u:%2u:%3u", &u1, &u2, &u3));
+	ut_asserteq(12u, u1);
+	ut_asserteq(3u, u2);
+	ut_asserteq(456u, u3);
+	ut_asserteq(3, sscanf("67:8:099", "%2u:%2u:%3u", &u1, &u2, &u3)); /* 0s */
+	ut_asserteq(67u, u1);
+	ut_asserteq(8u, u2);
+	ut_asserteq(99u, u3);
+	/* Arbitrary amounts of 0-padding are okay */
+	ut_asserteq(3, sscanf("12:03:000000000000000099", "%2u:%2u:%u", &u1, &u2, &u3));
+	ut_asserteq(12u, u1);
+	ut_asserteq(3u, u2);
+	ut_asserteq(99u, u3);
+
+	/* Hex (ie. %x) */
+	ut_asserteq(3, sscanf("1234 02aBcdEf ff", "%x %x %x", &u1, &u2, &u3));
+	ut_asserteq(0x1234, u1);
+	ut_asserteq(0x2ABCDEF, u2);
+	ut_asserteq(0xFF, u3);
+	/* Width works on %x */
+	ut_asserteq(3, sscanf("f00dcafe444", "%4x%4x%u", &u1, &u2, &u3));
+	ut_asserteq(0xf00d, u1);
+	ut_asserteq(0xcafe, u2);
+	ut_asserteq(444, u3);
+
+	/* Literal '%' (ie. '%%') */
+	ut_asserteq(1, sscanf("99% fresh", "%3u%% fresh", &u1));
+	ut_asserteq(99, u1);
+	ut_asserteq(0, sscanf("99 fresh", "%% %3u %s", &u1, s1));
+	ut_asserteq(1, sscanf("99 fresh", "%3u%% %s", &u1, s1));
+	ut_asserteq(2, sscanf("99 fresh", "%3u %5s %%", &u1, s1));
+	ut_asserteq(99, u1);
+	ut_asserteq_str(s1, "fresh");
+	ut_asserteq(1, sscanf("% boo", "%% %3s", s1));
+	ut_asserteq_str("boo", s1);
+
+	/* Strings (ie. %s) */
+	ut_asserteq(2, sscanf("hello", "%3s%7s", s1, s2));
+	ut_asserteq_str(s1, "hel");
+	ut_asserteq_str(s2, "lo");
+	ut_asserteq(2, sscanf("WD40", "%2s%u", s3, &u1)); /* %s%u */
+	ut_asserteq_str(s3, "WD");
+	ut_asserteq(40, u1);
+	ut_asserteq(2, sscanf("WD40", "%3s%u", s3, &u1)); /* %s%u */
+	ut_asserteq_str(s3, "WD4");
+	ut_asserteq(0, u1);
+	ut_asserteq(2, sscanf("76trombones", "%6u%9s", &u1, s1)); /* %u%s */
+	ut_asserteq(76, u1);
+	ut_asserteq_str(s1, "trombones");
+
+	ut_asserteq(3, sscanf("1.2.3", "%u.%u.%u%c", &u1, &u2, &u3, &ch));
+	ut_asserteq(4, sscanf("1.2.3 foobar", "%u.%u.%u%c", &u1, &u2, &u3, &ch));
+	ut_asserteq(' ', ch);
+
+	r = sscanf("12345 -67890 -1", "%d %ld %d", &int1, &lng1, &int2);
+	ut_asserteq(r, 3);
+	ut_asserteq(int1, 12345);
+	ut_asserteq(lng1, -67890);
+	ut_asserteq(int2, -1);
+
+	return 0;
+}
+
+LIB_TEST(lib_sscanf, 0);
-- 
2.17.1