xref: /illumos-gate/usr/src/common/util/string.c (revision 584b574a)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 * Copyright 2014 Joyent, Inc.  All rights reserved.
 */

/*
 * Copyright (c) 2016 by Delphix. All rights reserved.
 * Copyright 2018 Nexenta Systems, Inc.
 */

/*
 * Implementations of the functions described in vsnprintf(3C) and string(3C),
 * for use by the kernel, the standalone, and kmdb.  Unless otherwise specified,
 * these functions match the section 3C manpages.
 */

#include <sys/types.h>
#include <sys/null.h>
#include <sys/varargs.h>

#if defined(_KERNEL)
#include <sys/systm.h>
#include <sys/debug.h>
#elif !defined(_BOOT)
#include <string.h>
#endif

#include "memcpy.h"
#include "string.h"

/*
 * We don't need these for x86 boot or kmdb.
 */
#if !defined(_KMDB) && (!defined(_BOOT) || defined(__sparc))

#define	ADDCHAR(c)	if (bufp++ - buf < buflen) bufp[-1] = (c)

/*
 * Given a buffer 'buf' of size 'buflen', render as much of the string
 * described by <fmt, args> as possible.  The string will always be
 * null-terminated, so the maximum string length is 'buflen - 1'.
 * Returns the number of bytes that would be necessary to render the
 * entire string, not including null terminator (just like vsnprintf(3S)).
 * To determine buffer size in advance, use vsnprintf(NULL, 0, fmt, args) + 1.
 *
 * There is no support for floating point, and the C locale is assumed.
 */
size_t
vsnprintf(char *buf, size_t buflen, const char *fmt, va_list aargs)
{
	uint64_t ul, tmp;
	char *bufp = buf;	/* current buffer pointer */
	char c, pad;
	int width, base, sign, num;
	int prec, h_count, l_count, dot_count;
	int pad_count, transfer_count, left_align;
	char *digits, *sp, *bs;
	char numbuf[65];	/* sufficient for a 64-bit binary value */
	int numwidth;
	va_list args;

	ul = 0;
	bs = NULL;
	/*
	 * Make a copy so that all our callers don't have to make a copy
	 */
	va_copy(args, aargs);

	if ((ssize_t)buflen < 0)
		buflen = 0;

	while ((c = *fmt++) != '\0') {
		if (c != '%') {
			ADDCHAR(c);
			continue;
		}

		width = prec = numwidth = 0;
		left_align = base = sign = 0;
		h_count = l_count = dot_count = 0;
		pad = ' ';
		digits = "0123456789abcdef";
next_fmt:
		if ((c = *fmt++) == '\0')
			break;

		if (c >= 'A' && c <= 'Z') {
			c += 'a' - 'A';
			digits = "0123456789ABCDEF";
		}

		switch (c) {
		case '-':
			left_align++;
			goto next_fmt;
		case '0':
			if (dot_count == 0)
				pad = '0';
			/*FALLTHROUGH*/
		case '1':
		case '2':
		case '3':
		case '4':
		case '5':
		case '6':
		case '7':
		case '8':
		case '9':
			num = 0;
			for (;;) {
				num = 10 * num + c - '0';
				c = *fmt;
				if (c < '0' || c > '9')
					break;
				else
					fmt++;
			}
			if (dot_count > 0)
				prec = num;
			else
				width = num;

			goto next_fmt;
		case '.':
			dot_count++;
			goto next_fmt;
		case '*':
			if (dot_count > 0)
				prec = (int)va_arg(args, int);
			else
				width = (int)va_arg(args, int);
			goto next_fmt;
		case 'l':
			l_count++;
			goto next_fmt;
		case 'h':
			h_count++;
			goto next_fmt;
		case 'd':
			sign = 1;
			/*FALLTHROUGH*/
		case 'u':
			base = 10;
			break;
		case 'p':
			l_count = 1;
			/*FALLTHROUGH*/
		case 'x':
			base = 16;
			break;
		case 'o':
			base = 8;
			break;
		case 'b':
			l_count = 0;
			base = 1;
			break;
		case 'c':
			c = (char)va_arg(args, int);
			ADDCHAR(c);
			break;
		case 's':
			sp = va_arg(args, char *);
			if (sp == NULL) {
				sp = "<null string>";
				/* avoid truncation */
				prec = strlen(sp);
			}
			/*
			 * Handle simple case specially to avoid
			 * performance hit of strlen()
			 */
			if (prec == 0 && width == 0) {
				while ((c = *sp++) != 0)
					ADDCHAR(c);
				break;
			}
			if (prec > 0) {
				transfer_count = strnlen(sp, prec);
				/* widen field if too narrow */
				if (prec > width)
					width = prec;
			} else
				transfer_count = strlen(sp);
			if (width > transfer_count)
				pad_count = width - transfer_count;
			else
				pad_count = 0;
			while ((!left_align) && (pad_count-- > 0))
				ADDCHAR(' ');
			/* ADDCHAR() evaluates arg at most once */
			while (transfer_count-- > 0)
				ADDCHAR(*sp++);
			while ((left_align) && (pad_count-- > 0))
				ADDCHAR(' ');
			break;
		case '%':
			ADDCHAR('%');
			break;
		}

		if (base == 0)
			continue;

		if (h_count == 0 && l_count == 0)
			if (sign)
				ul = (int64_t)va_arg(args, int);
			else
				ul = (int64_t)va_arg(args, unsigned int);
		else if (l_count > 1)
			if (sign)
				ul = (int64_t)va_arg(args, int64_t);
			else
				ul = (int64_t)va_arg(args, uint64_t);
		else if (l_count > 0)
			if (sign)
				ul = (int64_t)va_arg(args, long);
			else
				ul = (int64_t)va_arg(args, unsigned long);
		else if (h_count > 1)
			if (sign)
				ul = (int64_t)((char)va_arg(args, int));
			else
				ul = (int64_t)((unsigned char)va_arg(args,
				    int));
		else if (h_count > 0)
			if (sign)
				ul = (int64_t)((short)va_arg(args, int));
			else
				ul = (int64_t)((unsigned short)va_arg(args,
				    int));

		if (sign && (int64_t)ul < 0)
			ul = -ul;
		else
			sign = 0;

		if (c == 'b') {
			bs = va_arg(args, char *);
			base = *bs++;
		}

		/*
		 * Fill in the number string buffer and calculate the
		 * number string length.
		 */
		tmp = ul;
		sp = numbuf;
		do {
			*sp++ = digits[tmp % base];
			numwidth++;
		} while ((tmp /= base) != 0);

		/*
		 * Reduce the total field width by precision or the number
		 * string length depending on which one is bigger, and sign.
		 */
		if (prec >= numwidth)
			width -= prec;
		else
			width -= numwidth;
		width -= sign;

		/* Add the sign if width is '0'-padded */
		if (sign && pad == '0')
			ADDCHAR('-');

		/* If not left-aligned, add the width padding */
		if (!left_align) {
			while (width-- > 0)
				ADDCHAR(pad);
		}

		/* Add the sign if width is NOT '0'-padded */
		if (sign && pad != '0')
			ADDCHAR('-');

		/* Add the precision '0'-padding */
		while (prec-- > numwidth)
			ADDCHAR('0');

		/* Print out the number */
		while (sp > numbuf) {
			sp--;
			ADDCHAR(*sp);
		}

		/* Add left-alignment padding */
		while (width-- > 0)
			ADDCHAR(' ');

		if (c == 'b' && ul != 0) {
			int any = 0;
			c = *bs++;
			while (c != 0) {
				if (ul & (1 << (c - 1))) {
					if (any++ == 0)
						ADDCHAR('<');
					while ((c = *bs++) >= 32)
						ADDCHAR(c);
					ADDCHAR(',');
				} else {
					while ((c = *bs++) >= 32)
						continue;
				}
			}
			if (any) {
				bufp--;
				ADDCHAR('>');
			}
		}
	}
	if (bufp - buf < buflen)
		bufp[0] = c;
	else if (buflen != 0)
		buf[buflen - 1] = c;

	va_end(args);

	return (bufp - buf);
}

/*PRINTFLIKE3*/
size_t
snprintf(char *buf, size_t buflen, const char *fmt, ...)
{
	va_list args;

	va_start(args, fmt);
	buflen = vsnprintf(buf, buflen, fmt, args);
	va_end(args);

	return (buflen);
}