mini/vsprintf.c

/*
 * Copyright (c) 1995 Patrick Powell.
 *
 * This code is based on code written by Patrick Powell <papowell@astart.com>.
 * It may be used for any purpose as long as this notice remains intact on all
 * source code distributions.

 * Copyright (c) 2008 Holger Weiss.
 *
 * This version of the code is maintained by Holger Weiss <holger@jhweiss.de>.
 * My changes to the code may freely be used, modified and/or redistributed for
 * any purpose.  It would be nice if additions and fixes to this file (including
 * trivial code cleanups) would be sent back in order to let me include them in
 * the version available at <http://www.jhweiss.de/software/snprintf.html>.
 * However, this is not a requirement for using or redistributing (possibly
 * modified) versions of this file, nor is leaving this notice intact mandatory.
 */

/*
 * History
 *
 * 2009-03-05 Hector Martin "marcan" <marcan@marcansoft.com>
 *
 * 	Hacked up and removed a lot of stuff including floating-point support,
 * 	a bunch of ifs and defines, locales, and tests
 *
 * 2008-01-20 Holger Weiss <holger@jhweiss.de> for C99-snprintf 1.1:
 *
 * 	Fixed the detection of infinite floating point values on IRIX (and
 * 	possibly other systems) and applied another few minor cleanups.
 *
 * 2008-01-06 Holger Weiss <holger@jhweiss.de> for C99-snprintf 1.0:
 *
 * 	Added a lot of new features, fixed many bugs, and incorporated various
 * 	improvements done by Andrew Tridgell <tridge@samba.org>, Russ Allbery
 * 	<rra@stanford.edu>, Hrvoje Niksic <hniksic@xemacs.org>, Damien Miller
 * 	<djm@mindrot.org>, and others for the Samba, INN, Wget, and OpenSSH
 * 	projects.  The additions include: support the "e", "E", "g", "G", and
 * 	"F" conversion specifiers (and use conversion style "f" or "F" for the
 * 	still unsupported "a" and "A" specifiers); support the "hh", "ll", "j",
 * 	"t", and "z" length modifiers; support the "#" flag and the (non-C99)
 * 	"'" flag; use localeconv(3) (if available) to get both the current
 * 	locale's decimal point character and the separator between groups of
 * 	digits; fix the handling of various corner cases of field width and
 * 	precision specifications; fix various floating point conversion bugs;
 * 	handle infinite and NaN floating point values; don't attempt to write to
 * 	the output buffer (which may be NULL) if a size of zero was specified;
 * 	check for integer overflow of the field width, precision, and return
 * 	values and during the floating point conversion; use the OUTCHAR() macro
 * 	instead of a function for better performance; provide asprintf(3) and
 * 	vasprintf(3) functions; add new test cases.  The replacement functions
 * 	have been renamed to use an "rpl_" prefix, the function calls in the
 * 	main project (and in this file) must be redefined accordingly for each
 * 	replacement function which is needed (by using Autoconf or other means).
 * 	Various other minor improvements have been applied and the coding style
 * 	was cleaned up for consistency.
 *
 * 2007-07-23 Holger Weiss <holger@jhweiss.de> for Mutt 1.5.13:
 *
 * 	C99 compliant snprintf(3) and vsnprintf(3) functions return the number
 * 	of characters that would have been written to a sufficiently sized
 * 	buffer (excluding the '\0').  The original code simply returned the
 * 	length of the resulting output string, so that's been fixed.
 *
 * 1998-03-05 Michael Elkins <me@mutt.org> for Mutt 0.90.8:
 *
 * 	The original code assumed that both snprintf(3) and vsnprintf(3) were
 * 	missing.  Some systems only have snprintf(3) but not vsnprintf(3), so
 * 	the code is now broken down under HAVE_SNPRINTF and HAVE_VSNPRINTF.
 *
 * 1998-01-27 Thomas Roessler <roessler@does-not-exist.org> for Mutt 0.89i:
 *
 * 	The PGP code was using unsigned hexadecimal formats.  Unfortunately,
 * 	unsigned formats simply didn't work.
 *
 * 1997-10-22 Brandon Long <blong@fiction.net> for Mutt 0.87.1:
 *
 * 	Ok, added some minimal floating point support, which means this probably
 * 	requires libm on most operating systems.  Don't yet support the exponent
 * 	(e,E) and sigfig (g,G).  Also, fmtint() was pretty badly broken, it just
 * 	wasn't being exercised in ways which showed it, so that's been fixed.
 * 	Also, formatted the code to Mutt conventions, and removed dead code left
 * 	over from the original.  Also, there is now a builtin-test, run with:
 * 	gcc -DTEST_SNPRINTF -o snprintf snprintf.c -lm && ./snprintf
 *
 * 2996-09-15 Brandon Long <blong@fiction.net> for Mutt 0.43:
 *
 * 	This was ugly.  It is still ugly.  I opted out of floating point
 * 	numbers, but the formatter understands just about everything from the
 * 	normal C string format, at least as far as I can tell from the Solaris
 * 	2.5 printf(3S) man page.
 */

#include <stdarg.h>
#include "types.h"

#define VA_START(ap, last) va_start(ap, last)
#define VA_SHIFT(ap, value, type) /* No-op for ANSI C. */

#define ULLONG unsigned long
#define UINTMAX_T unsigned long
#define UINTMAX_MAX ULONG_MAX
#define LLONG long
#define INTMAX_T long

/* Support for uintptr_t. */
#ifndef UINTPTR_T
#if HAVE_UINTPTR_T || defined(uintptr_t)
#define UINTPTR_T uintptr_t
#else
#define UINTPTR_T unsigned long int
#endif	/* HAVE_UINTPTR_T || defined(uintptr_t) */
#endif	/* !defined(UINTPTR_T) */

/* Support for ptrdiff_t. */
#ifndef PTRDIFF_T
#if HAVE_PTRDIFF_T || defined(ptrdiff_t)
#define PTRDIFF_T ptrdiff_t
#else
#define PTRDIFF_T long int
#endif	/* HAVE_PTRDIFF_T || defined(ptrdiff_t) */
#endif	/* !defined(PTRDIFF_T) */

/*
 * We need an unsigned integer type corresponding to ptrdiff_t (cf. C99:
 * 7.19.6.1, 7).  However, we'll simply use PTRDIFF_T and convert it to an
 * unsigned type if necessary.  This should work just fine in practice.
 */
#ifndef UPTRDIFF_T
#define UPTRDIFF_T PTRDIFF_T
#endif	/* !defined(UPTRDIFF_T) */

/*
 * We need a signed integer type corresponding to size_t (cf. C99: 7.19.6.1, 7).
 * However, we'll simply use size_t and convert it to a signed type if
 * necessary.  This should work just fine in practice.
 */
#ifndef SSIZE_T
#define SSIZE_T size_t
#endif	/* !defined(SSIZE_T) */


/*
 * Buffer size to hold the octal string representation of UINT128_MAX without
 * nul-termination ("3777777777777777777777777777777777777777777").
 */
#ifdef MAX_CONVERT_LENGTH
#undef MAX_CONVERT_LENGTH
#endif	/* defined(MAX_CONVERT_LENGTH) */
#define MAX_CONVERT_LENGTH      43

/* Format read states. */
#define PRINT_S_DEFAULT         0
#define PRINT_S_FLAGS           1
#define PRINT_S_WIDTH           2
#define PRINT_S_DOT             3
#define PRINT_S_PRECISION       4
#define PRINT_S_MOD             5
#define PRINT_S_CONV            6

/* Format flags. */
#define PRINT_F_MINUS           (1 << 0)
#define PRINT_F_PLUS            (1 << 1)
#define PRINT_F_SPACE           (1 << 2)
#define PRINT_F_NUM             (1 << 3)
#define PRINT_F_ZERO            (1 << 4)
#define PRINT_F_QUOTE           (1 << 5)
#define PRINT_F_UP              (1 << 6)
#define PRINT_F_UNSIGNED        (1 << 7)
#define PRINT_F_TYPE_G          (1 << 8)
#define PRINT_F_TYPE_E          (1 << 9)

/* Conversion flags. */
#define PRINT_C_CHAR            1
#define PRINT_C_SHORT           2
#define PRINT_C_LONG            3
#define PRINT_C_LLONG           4
//#define PRINT_C_LDOUBLE         5
#define PRINT_C_SIZE            6
#define PRINT_C_PTRDIFF         7
#define PRINT_C_INTMAX          8

#ifndef MAX
#define MAX(x, y) ((x >= y) ? x : y)
#endif	/* !defined(MAX) */
#ifndef CHARTOINT
#define CHARTOINT(ch) (ch - '0')
#endif	/* !defined(CHARTOINT) */
#ifndef ISDIGIT
#define ISDIGIT(ch) ('0' <= (unsigned char)ch && (unsigned char)ch <= '9')
#endif	/* !defined(ISDIGIT) */

#define OUTCHAR(str, len, size, ch)                                          \
do {                                                                         \
	if (len + 1 < size)                                                  \
		str[len] = ch;                                               \
	(len)++;                                                             \
} while (/* CONSTCOND */ 0)

static void fmtstr(char *, size_t *, size_t, const char *, int, int, int);
static void fmtint(char *, size_t *, size_t, INTMAX_T, int, int, int, int);
static void printsep(char *, size_t *, size_t);
static int getnumsep(int);
static int convert(UINTMAX_T, char *, size_t, int, int);

int vsnprintf(char *str, size_t size, const char *format, va_list args)
{
	INTMAX_T value;
	unsigned char cvalue;
	const char *strvalue;
	INTMAX_T *intmaxptr;
	PTRDIFF_T *ptrdiffptr;
	SSIZE_T *sizeptr;
	LLONG *llongptr;
	long int *longptr;
	int *intptr;
	short int *shortptr;
	signed char *charptr;
	size_t len = 0;
	int overflow = 0;
	int base = 0;
	int cflags = 0;
	int flags = 0;
	int width = 0;
	int precision = -1;
	int state = PRINT_S_DEFAULT;
	char ch = *format++;

	/*
	 * C99 says: "If `n' is zero, nothing is written, and `s' may be a null
	 * pointer." (7.19.6.5, 2)  We're forgiving and allow a NULL pointer
	 * even if a size larger than zero was specified.  At least NetBSD's
	 * snprintf(3) does the same, as well as other versions of this file.
	 * (Though some of these versions will write to a non-NULL buffer even
	 * if a size of zero was specified, which violates the standard.)
	 */
	if (str == NULL && size != 0)
		size = 0;

	while (ch != '\0')
		switch (state) {
		case PRINT_S_DEFAULT:
			if (ch == '%')
				state = PRINT_S_FLAGS;
			else
				OUTCHAR(str, len, size, ch);
			ch = *format++;
			break;
		case PRINT_S_FLAGS:
			switch (ch) {
			case '-':
				flags |= PRINT_F_MINUS;
				ch = *format++;
				break;
			case '+':
				flags |= PRINT_F_PLUS;
				ch = *format++;
				break;
			case ' ':
				flags |= PRINT_F_SPACE;
				ch = *format++;
				break;
			case '#':
				flags |= PRINT_F_NUM;
				ch = *format++;
				break;
			case '0':
				flags |= PRINT_F_ZERO;
				ch = *format++;
				break;
			case '\'':	/* SUSv2 flag (not in C99). */
				flags |= PRINT_F_QUOTE;
				ch = *format++;
				break;
			default:
				state = PRINT_S_WIDTH;
				break;
			}
			break;
		case PRINT_S_WIDTH:
			if (ISDIGIT(ch)) {
				ch = CHARTOINT(ch);
				if (width > (INT_MAX - ch) / 10) {
					overflow = 1;
					goto out;
				}
				width = 10 * width + ch;
				ch = *format++;
			} else if (ch == '*') {
				/*
				 * C99 says: "A negative field width argument is
				 * taken as a `-' flag followed by a positive
				 * field width." (7.19.6.1, 5)
				 */
				if ((width = va_arg(args, int)) < 0) {
					flags |= PRINT_F_MINUS;
					width = -width;
				}
				ch = *format++;
				state = PRINT_S_DOT;
			} else
				state = PRINT_S_DOT;
			break;
		case PRINT_S_DOT:
			if (ch == '.') {
				state = PRINT_S_PRECISION;
				ch = *format++;
			} else
				state = PRINT_S_MOD;
			break;
		case PRINT_S_PRECISION:
			if (precision == -1)
				precision = 0;
			if (ISDIGIT(ch)) {
				ch = CHARTOINT(ch);
				if (precision > (INT_MAX - ch) / 10) {
					overflow = 1;
					goto out;
				}
				precision = 10 * precision + ch;
				ch = *format++;
			} else if (ch == '*') {
				/*
				 * C99 says: "A negative precision argument is
				 * taken as if the precision were omitted."
				 * (7.19.6.1, 5)
				 */
				if ((precision = va_arg(args, int)) < 0)
					precision = -1;
				ch = *format++;
				state = PRINT_S_MOD;
			} else
				state = PRINT_S_MOD;
			break;
		case PRINT_S_MOD:
			switch (ch) {
			case 'h':
				ch = *format++;
				if (ch == 'h') {	/* It's a char. */
					ch = *format++;
					cflags = PRINT_C_CHAR;
				} else
					cflags = PRINT_C_SHORT;
				break;
			case 'l':
				ch = *format++;
				if (ch == 'l') {	/* It's a long long. */
					ch = *format++;
					cflags = PRINT_C_LLONG;
				} else
					cflags = PRINT_C_LONG;
				break;
			case 'j':
				cflags = PRINT_C_INTMAX;
				ch = *format++;
				break;
			case 't':
				cflags = PRINT_C_PTRDIFF;
				ch = *format++;
				break;
			case 'z':
				cflags = PRINT_C_SIZE;
				ch = *format++;
				break;
			}
			state = PRINT_S_CONV;
			break;
		case PRINT_S_CONV:
			switch (ch) {
			case 'd':
				/* FALLTHROUGH */
			case 'i':
				switch (cflags) {
				case PRINT_C_CHAR:
					value = (signed char)va_arg(args, int);
					break;
				case PRINT_C_SHORT:
					value = (short int)va_arg(args, int);
					break;
				case PRINT_C_LONG:
					value = va_arg(args, long int);
					break;
				case PRINT_C_LLONG:
					value = va_arg(args, LLONG);
					break;
				case PRINT_C_SIZE:
					value = va_arg(args, SSIZE_T);
					break;
				case PRINT_C_INTMAX:
					value = va_arg(args, INTMAX_T);
					break;
				case PRINT_C_PTRDIFF:
					value = va_arg(args, PTRDIFF_T);
					break;
				default:
					value = va_arg(args, int);
					break;
				}
				fmtint(str, &len, size, value, 10, width,
				    precision, flags);
				break;
			case 'X':
				flags |= PRINT_F_UP;
				/* FALLTHROUGH */
			case 'x':
				base = 16;
				/* FALLTHROUGH */
			case 'o':
				if (base == 0)
					base = 8;
				/* FALLTHROUGH */
			case 'u':
				if (base == 0)
					base = 10;
				flags |= PRINT_F_UNSIGNED;
				switch (cflags) {
				case PRINT_C_CHAR:
					value = (unsigned char)va_arg(args,
					    unsigned int);
					break;
				case PRINT_C_SHORT:
					value = (unsigned short int)va_arg(args,
					    unsigned int);
					break;
				case PRINT_C_LONG:
					value = va_arg(args, unsigned long int);
					break;
				case PRINT_C_LLONG:
					value = va_arg(args, ULLONG);
					break;
				case PRINT_C_SIZE:
					value = va_arg(args, size_t);
					break;
				case PRINT_C_INTMAX:
					value = va_arg(args, UINTMAX_T);
					break;
				case PRINT_C_PTRDIFF:
					value = va_arg(args, UPTRDIFF_T);
					break;
				default:
					value = va_arg(args, unsigned int);
					break;
				}
				fmtint(str, &len, size, value, base, width,
				    precision, flags);
				break;
			case 'c':
				cvalue = va_arg(args, int);
				OUTCHAR(str, len, size, cvalue);
				break;
			case 's':
				strvalue = va_arg(args, char *);
				fmtstr(str, &len, size, strvalue, width,
				    precision, flags);
				break;
			case 'p':
				/*
				 * C99 says: "The value of the pointer is
				 * converted to a sequence of printing
				 * characters, in an implementation-defined
				 * manner." (C99: 7.19.6.1, 8)
				 */
				if ((strvalue = va_arg(args, void *)) == NULL)
					/*
					 * We use the glibc format.  BSD prints
					 * "0x0", SysV "0".
					 */
					fmtstr(str, &len, size, "(nil)", width,
					    -1, flags);
				else {
					/*
					 * We use the BSD/glibc format.  SysV
					 * omits the "0x" prefix (which we emit
					 * using the PRINT_F_NUM flag).
					 */
					flags |= PRINT_F_NUM;
					flags |= PRINT_F_UNSIGNED;
					fmtint(str, &len, size,
					    (UINTPTR_T)strvalue, 16, width,
					    precision, flags);
				}
				break;
			case 'n':
				switch (cflags) {
				case PRINT_C_CHAR:
					charptr = va_arg(args, signed char *);
					*charptr = len;
					break;
				case PRINT_C_SHORT:
					shortptr = va_arg(args, short int *);
					*shortptr = len;
					break;
				case PRINT_C_LONG:
					longptr = va_arg(args, long int *);
					*longptr = len;
					break;
				case PRINT_C_LLONG:
					llongptr = va_arg(args, LLONG *);
					*llongptr = len;
					break;
				case PRINT_C_SIZE:
					/*
					 * C99 says that with the "z" length
					 * modifier, "a following `n' conversion
					 * specifier applies to a pointer to a
					 * signed integer type corresponding to
					 * size_t argument." (7.19.6.1, 7)
					 */
					sizeptr = va_arg(args, SSIZE_T *);
					*sizeptr = len;
					break;
				case PRINT_C_INTMAX:
					intmaxptr = va_arg(args, INTMAX_T *);
					*intmaxptr = len;
					break;
				case PRINT_C_PTRDIFF:
					ptrdiffptr = va_arg(args, PTRDIFF_T *);
					*ptrdiffptr = len;
					break;
				default:
					intptr = va_arg(args, int *);
					*intptr = len;
					break;
				}
				break;
			case '%':	/* Print a "%" character verbatim. */
				OUTCHAR(str, len, size, ch);
				break;
			default:	/* Skip other characters. */
				break;
			}
			ch = *format++;
			state = PRINT_S_DEFAULT;
			base = cflags = flags = width = 0;
			precision = -1;
			break;
		}
out:
	if (len < size)
		str[len] = '\0';
	else if (size > 0)
		str[size - 1] = '\0';

	if (overflow || len >= INT_MAX) {
		return -1;
	}
	return (int)len;
}

static void
fmtstr(char *str, size_t *len, size_t size, const char *value, int width,
       int precision, int flags)
{
	int padlen, strln;	/* Amount to pad. */
	int noprecision = (precision == -1);

	if (value == NULL)	/* We're forgiving. */
		value = "(null)";

	/* If a precision was specified, don't read the string past it. */
	for (strln = 0; value[strln] != '\0' &&
	    (noprecision || strln < precision); strln++)
		continue;

	if ((padlen = width - strln) < 0)
		padlen = 0;
	if (flags & PRINT_F_MINUS)	/* Left justify. */
		padlen = -padlen;

	while (padlen > 0) {	/* Leading spaces. */
		OUTCHAR(str, *len, size, ' ');
		padlen--;
	}
	while (*value != '\0' && (noprecision || precision-- > 0)) {
		OUTCHAR(str, *len, size, *value);
		value++;
	}
	while (padlen < 0) {	/* Trailing spaces. */
		OUTCHAR(str, *len, size, ' ');
		padlen++;
	}
}

static void
fmtint(char *str, size_t *len, size_t size, INTMAX_T value, int base, int width,
       int precision, int flags)
{
	UINTMAX_T uvalue;
	char iconvert[MAX_CONVERT_LENGTH];
	char sign = 0;
	char hexprefix = 0;
	int spadlen = 0;	/* Amount to space pad. */
	int zpadlen = 0;	/* Amount to zero pad. */
	int pos;
	int separators = (flags & PRINT_F_QUOTE);
	int noprecision = (precision == -1);

	if (flags & PRINT_F_UNSIGNED)
		uvalue = value;
	else {
		uvalue = (value >= 0) ? value : -value;
		if (value < 0)
			sign = '-';
		else if (flags & PRINT_F_PLUS)	/* Do a sign. */
			sign = '+';
		else if (flags & PRINT_F_SPACE)
			sign = ' ';
	}

	pos = convert(uvalue, iconvert, sizeof(iconvert), base,
	    flags & PRINT_F_UP);

	if (flags & PRINT_F_NUM && uvalue != 0) {
		/*
		 * C99 says: "The result is converted to an `alternative form'.
		 * For `o' conversion, it increases the precision, if and only
		 * if necessary, to force the first digit of the result to be a
		 * zero (if the value and precision are both 0, a single 0 is
		 * printed).  For `x' (or `X') conversion, a nonzero result has
		 * `0x' (or `0X') prefixed to it." (7.19.6.1, 6)
		 */
		switch (base) {
		case 8:
			if (precision <= pos)
				precision = pos + 1;
			break;
		case 16:
			hexprefix = (flags & PRINT_F_UP) ? 'X' : 'x';
			break;
		}
	}

	if (separators)	/* Get the number of group separators we'll print. */
		separators = getnumsep(pos);

	zpadlen = precision - pos - separators;
	spadlen = width                         /* Minimum field width. */
	    - separators                        /* Number of separators. */
	    - MAX(precision, pos)               /* Number of integer digits. */
	    - ((sign != 0) ? 1 : 0)             /* Will we print a sign? */
	    - ((hexprefix != 0) ? 2 : 0);       /* Will we print a prefix? */

	if (zpadlen < 0)
		zpadlen = 0;
	if (spadlen < 0)
		spadlen = 0;

	/*
	 * C99 says: "If the `0' and `-' flags both appear, the `0' flag is
	 * ignored.  For `d', `i', `o', `u', `x', and `X' conversions, if a
	 * precision is specified, the `0' flag is ignored." (7.19.6.1, 6)
	 */
	if (flags & PRINT_F_MINUS)	/* Left justify. */
		spadlen = -spadlen;
	else if (flags & PRINT_F_ZERO && noprecision) {
		zpadlen += spadlen;
		spadlen = 0;
	}
	while (spadlen > 0) {	/* Leading spaces. */
		OUTCHAR(str, *len, size, ' ');
		spadlen--;
	}
	if (sign != 0)	/* Sign. */
		OUTCHAR(str, *len, size, sign);
	if (hexprefix != 0) {	/* A "0x" or "0X" prefix. */
		OUTCHAR(str, *len, size, '0');
		OUTCHAR(str, *len, size, hexprefix);
	}
	while (zpadlen > 0) {	/* Leading zeros. */
		OUTCHAR(str, *len, size, '0');
		zpadlen--;
	}
	while (pos > 0) {	/* The actual digits. */
		pos--;
		OUTCHAR(str, *len, size, iconvert[pos]);
		if (separators > 0 && pos > 0 && pos % 3 == 0)
			printsep(str, len, size);
	}
	while (spadlen < 0) {	/* Trailing spaces. */
		OUTCHAR(str, *len, size, ' ');
		spadlen++;
	}
}


static void
printsep(char *str, size_t *len, size_t size)
{
	OUTCHAR(str, *len, size, ',');
}

static int
getnumsep(int digits)
{
	int separators = (digits - ((digits % 3 == 0) ? 1 : 0)) / 3;
	return separators;
}

static int
convert(UINTMAX_T value, char *buf, size_t size, int base, int caps)
{
	const char *digits = caps ? "0123456789ABCDEF" : "0123456789abcdef";
	size_t pos = 0;

	/* We return an unterminated buffer with the digits in reverse order. */
	do {
		buf[pos++] = digits[value % base];
		value /= base;
	} while (value != 0 && pos < size);

	return (int)pos;
}

int vsprintf(char *buf, const char *fmt, va_list args)
{
	return vsnprintf(buf, INT_MAX, fmt, args);
}