--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/libsys/sprintf/vspcore.c	Fri May 15 01:28:16 2020 +0000
@@ -0,0 +1,285 @@
+/*
+ * Embedded [v]sprintf() implementation by Mychaela Falconia,
+ * loosely based on the 4.3BSD-Tahoe version.
+ *
+ * This module contains the core of the vsprintf() function, which may
+ * be either used directly by user code or called by the sprintf()
+ * trivial wrapper.
+ */
+
+#include <sys/types.h>
+#include <ctype.h>
+#include <stdarg.h>
+#include "defs.h"
+
+extern u_char * _sprintf_integer(u_char *op, int width, int flags, int sign,
+					unsigned number, int base, int prec);
+extern u_char * _sprintf_percent_f(u_char *op, int width, int flags, int sign,
+					double number, int prec);
+
+u_char *
+_sprintf_field(u_char *op, int width, int flags, int sign,
+		u_char *body, int size, int dprec, int fpprec)
+{
+	int fieldsz;		/* field size expanded by sign, etc */
+	int realsz;		/* field size expanded by decimal precision */
+	int n;			/* scratch */
+
+	/*
+	 * All reasonable formats wind up here.  At this point,
+	 * `body' points to a string which (if not flags&LADJUST)
+	 * should be padded out to `width' places.  If
+	 * flags&ZEROPAD, it should first be prefixed by any
+	 * sign or other prefix; otherwise, it should be blank
+	 * padded before the prefix is emitted.  After any
+	 * left-hand padding and prefixing, emit zeroes
+	 * required by a decimal [diouxX] precision, then print
+	 * the string proper, then emit zeroes required by any
+	 * leftover floating precision; finally, if LADJUST,
+	 * pad with blanks.
+	 */
+
+	/*
+	 * compute actual size, so we know how much to pad
+	 * fieldsz excludes decimal prec; realsz includes it
+	 */
+	fieldsz = size + fpprec;
+	if (sign)
+		fieldsz++;
+	if (flags & HEXPREFIX)
+		fieldsz += 2;
+	realsz = dprec > fieldsz ? dprec : fieldsz;
+
+	/* right-adjusting blank padding */
+	if ((flags & (LADJUST|ZEROPAD)) == 0 && width)
+		for (n = realsz; n < width; n++)
+			*op++ = ' ';
+	/* prefix */
+	if (sign)
+		*op++ = sign;
+	if (flags & HEXPREFIX) {
+		*op++ = '0';
+		*op++ = (flags & UPPERCASE) ? 'X' : 'x';
+	}
+	/* right-adjusting zero padding */
+	if ((flags & (LADJUST|ZEROPAD)) == ZEROPAD)
+		for (n = realsz; n < width; n++)
+			*op++ = '0';
+	/* leading zeroes from decimal precision */
+	for (n = fieldsz; n < dprec; n++)
+		*op++ = '0';
+
+	/* the string or number proper */
+	bcopy(body, op, size);
+	op += size;
+	/* trailing f.p. zeroes */
+	while (--fpprec >= 0)
+		*op++ = '0';
+	/* left-adjusting padding (always blank) */
+	if (flags & LADJUST)
+		for (n = realsz; n < width; n++)
+			*op++ = ' ';
+
+	return(op);
+}
+
+int
+vsprintf(buf0, fmt0, argp)
+	u_char *buf0, *fmt0;
+	va_list argp;
+{
+	u_char *op;		/* output buffer working ptr */
+	u_char *fmt;		/* format string working ptr */
+	int ch;			/* character from fmt */
+	int n;			/* scratch integer */
+	char *t;		/* scratch pointer */
+	int flags;		/* flags as above */
+	int prec;		/* precision from format (%.3d), or -1 */
+	int width;		/* width from format (%8d), or 0 */
+	char sign;		/* sign prefix (' ', '+', '-', or \0) */
+	unsigned un;		/* unsigned number for conversion */
+
+	op = buf0;
+	for (fmt = fmt0; ; ++fmt) {
+		for (; (ch = *fmt) && ch != '%'; ++fmt)
+			*op++ = ch;
+		if (!ch) {
+out:			*op = '\0';
+			return (op - buf0);
+		}
+
+		flags = 0; width = 0;
+		prec = -1;
+		sign = '\0';
+
+rflag:		switch (*++fmt) {
+		case ' ':
+			/*
+			 * ``If the space and + flags both appear, the space
+			 * flag will be ignored.''
+			 *	-- ANSI X3J11
+			 */
+			if (!sign)
+				sign = ' ';
+			goto rflag;
+		case '#':
+			flags |= ALT;
+			goto rflag;
+		case '*':
+			/*
+			 * ``A negative field width argument is taken as a
+			 * - flag followed by a  positive field width.''
+			 *	-- ANSI X3J11
+			 * They don't exclude field widths read from args.
+			 */
+			if ((width = va_arg(argp, int)) >= 0)
+				goto rflag;
+			width = -width;
+			/* FALLTHROUGH */
+		case '-':
+			flags |= LADJUST;
+			goto rflag;
+		case '+':
+			sign = '+';
+			goto rflag;
+		case '.':
+			if (*++fmt == '*')
+				n = va_arg(argp, int);
+			else {
+				n = 0;
+				while (isascii(*fmt) && isdigit(*fmt))
+					n = 10 * n + todigit(*fmt++);
+				--fmt;
+			}
+			prec = n < 0 ? -1 : n;
+			goto rflag;
+		case '0':
+			/*
+			 * ``Note that 0 is taken as a flag, not as the
+			 * beginning of a field width.''
+			 *	-- ANSI X3J11
+			 */
+			flags |= ZEROPAD;
+			goto rflag;
+		case '1': case '2': case '3': case '4':
+		case '5': case '6': case '7': case '8': case '9':
+			n = 0;
+			do {
+				n = 10 * n + todigit(*fmt);
+			} while (isascii(*++fmt) && isdigit(*fmt));
+			width = n;
+			--fmt;
+			goto rflag;
+		case 'L':
+			flags |= LONGDBL;
+			goto rflag;
+		case 'h':
+			flags |= SHORTINT;
+			goto rflag;
+		case 'l':
+			flags |= LONGINT;
+			goto rflag;
+		case 'c':
+			/*
+			 * XXX reusing a variable of type char
+			 * for an unrelated purpose
+			 */
+			sign = (char) va_arg(argp, int);
+			op = _sprintf_field(op, width, flags, 0, &sign, 1,
+						0, 0);
+			break;
+		case 'D':
+			flags |= LONGINT;
+			/*FALLTHROUGH*/
+		case 'd':
+		case 'i':
+			n = va_arg(argp, int);
+			if (n < 0) {
+				un = -n;
+				sign = '-';
+			} else
+				un = n;
+			op = _sprintf_integer(op, width, flags, sign, un, 10,
+						prec);
+			break;
+		case 'f':
+			op = _sprintf_percent_f(op, width, flags, sign,
+						va_arg(argp, double), prec);
+			break;
+		case 'n':
+			n = op - buf0;
+			if (flags & LONGINT)
+				*va_arg(argp, long *) = n;
+			else if (flags & SHORTINT)
+				*va_arg(argp, short *) = n;
+			else
+				*va_arg(argp, int *) = n;
+			break;
+		case 'O':
+			flags |= LONGINT;
+			/*FALLTHROUGH*/
+		case 'o':
+			un = va_arg(argp, unsigned);
+			op = _sprintf_integer(op, width, flags, 0, un, 8, prec);
+			break;
+		case 'p':
+			/*
+			 * ``The argument shall be a pointer to void.  The
+			 * value of the pointer is converted to a sequence
+			 * of printable characters, in an implementation-
+			 * defined manner.''
+			 *	-- ANSI X3J11
+			 */
+			/* NOSTRICT */
+			un = (unsigned)va_arg(argp, void *);
+			op = _sprintf_integer(op, width, flags | HEXPREFIX, 0,
+						un, 16, prec);
+			break;
+		case 's':
+			if (!(t = va_arg(argp, char *)))
+				t = "(null)";
+			if (prec >= 0) {
+				/*
+				 * can't use strlen; can only look for the
+				 * NUL in the first `prec' characters, and
+				 * strlen() will go further.
+				 */
+				char *p, *memchr();
+
+				if (p = memchr(t, 0, prec)) {
+					n = p - t;
+					if (n > prec)
+						n = prec;
+				} else
+					n = prec;
+			} else
+				n = strlen(t);
+			op = _sprintf_field(op, width, flags, 0, t, n, 0, 0);
+			break;
+		case 'U':
+			flags |= LONGINT;
+			/*FALLTHROUGH*/
+		case 'u':
+			un = va_arg(argp, unsigned);
+			op = _sprintf_integer(op, width, flags, 0, un, 10,
+						prec);
+			break;
+		case 'X':
+			flags |= UPPERCASE;
+			/* FALLTHROUGH */
+		case 'x':
+			un = va_arg(argp, unsigned);
+			/* leading 0x/X only if non-zero */
+			if (flags & ALT && un != 0)
+				flags |= HEXPREFIX;
+			op = _sprintf_integer(op, width, flags, 0, un, 16,
+						prec);
+			break;
+		case '\0':	/* "%?" prints ?, unless ? is NULL */
+			goto out;
+		default:
+			*op++ = *fmt;
+		}
+	}
+	/* NOTREACHED */
+}