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Hi,

I've written a BSD licensed version of seq(1) from Plan 9 and I'd
like some feedback.  I'll commit this in several days if I don't
hear any strong objections.  Note this command is also a part of
the GNU `coreutils'.  Yes, I know that jot(1) has similar functionality.
Thanks in advance for comments.

--
Brian Ginsbach

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/*
 * Copyright (c) 2004 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Brian Ginsbach.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgment:
 *      This product includes software developed by the NetBSD
 *      Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__RCSID("$NetBSD$");

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <math.h>
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define ZERO	'0'
#define SPACE	' '

#define MAX(a, b)	(((a) < (b))? (b) : (a))
#define ISSIGN(c)	((int)(c) == '-' || (int)(c) == '+')
#define ISEXP(c)	((int)(c) == 'e' || (int)(c) == 'E')
#define ISODIGIT(c)	((int)(c) >= '0' && (int)(c) <= '7')

/* Globals */

const char *decimal_point = ".";	/* default */
char default_format[] = { "%g" };		/* default */

/* Prototypes */

double e_atof(const char *);

int decimal_places(const char *);
int main(int, char *[]);
int numeric(const char *);
int valid_format(const char *);

char *generate_format(double, double, double, int, char);
char *unescape(char *);

/*
 * The seq command will print out a numeric sequence from 1, the default,
 * to a user specified upper limit by 1.  The lower bound and increment
 * maybe indicated by the user on the command line.  The sequence can
 * be either whole, the default, or decimal numbers.
 */
int
main(int argc, char *argv[])
{
	int c = 0, errflg = 0;
	int equalize = 0;
	double first = 1.0;
	double last = 0.0;
	double incr = 0.0;
	struct lconv *locale;
	char *fmt = NULL;
	const char *sep = "\n";
	const char *term = NULL;
	char pad = ZERO;

	/* Determine the locale's decimal point. */
	locale = localeconv();
	if (locale && locale->decimal_point && locale->decimal_point[0] != '\0')
		decimal_point = locale->decimal_point;

	/*
         * Process options, but handle negative numbers separately
         * least they trip up getopt(3).
         */
	while ((optind < argc) && !numeric(argv[optind]) &&
	    (c = getopt(argc, argv, "f:hs:t:w")) != -1) {

		switch (c) {
		case 'f':	/* format (plan9) */
			fmt = optarg;
			equalize = 0;
			break;
		case 's':	/* separator (GNU) */
			sep = unescape(optarg);
			break;
		case 't':	/* terminator (new) */
			term = unescape(optarg);
			break;
		case 'w':	/* equal width (plan9) */
			if (!fmt)
				if (equalize++)
					pad = SPACE;
			break;
		case 'h':	/* help (GNU) */
		default:
			errflg++;
			break;
		}
	}

	argc -= optind;
	argv += optind;
	if (argc < 1 || argc > 3)
		errflg++;

	if (errflg) {
		fprintf(stderr,
		    "usage: %s [-f format] [-s str] [-w] [first [incr]] last\n",
		    getprogname());
		exit(1);
	}

	last = e_atof(argv[argc - 1]);

	if (argc > 1)
		first = e_atof(argv[0]);
	
	if (argc > 2) {
		incr = e_atof(argv[1]);
		/* Plan 9/GNU don't do zero */
		if (incr == 0.0)
			errx(1, "zero %screment", (first < last)? "in" : "de");
	}

	/* default is one for Plan 9/GNU work alike */
	if (incr == 0.0)
		incr = (first < last) ? 1.0 : -1.0;

	if (incr <= 0.0 && first < last)
		errx(1, "needs positive increment");

	if (incr >= 0.0 && first > last)
		errx(1, "needs negative decrement");

	if (fmt != NULL) {
		if (!valid_format(fmt))
			errx(1, "invalid format string: `%s'", fmt);
		fmt = unescape(fmt);
		/*
	         * XXX to be bug for bug compatible with Plan 9 add a
		 * newline if none found at the end of the format string.
		 */
	} else
		fmt = generate_format(first, incr, last, equalize, pad);

	if (incr > 0) {
		for (; first <= last; first += incr) {
			printf(fmt, first);
			fputs(sep, stdout);
		}
	} else {
		for (; first >= last; first += incr) {
			printf(fmt, first);
			fputs(sep, stdout);
		}
	}
	if (term != NULL)
		fputs(term, stdout);

	return (0);
}

/*
 * numeric - verify that string is numeric
 */
int
numeric(const char *s)
{
	int seen_decimal_pt, decimal_pt_len;

	/* skip any sign */
	if (ISSIGN((unsigned char)*s))
		s++;

	seen_decimal_pt = 0;
	decimal_pt_len = strlen(decimal_point);
	while (*s) {
		if (!isdigit((unsigned char)*s)) {
			if (!seen_decimal_pt &&
			    strncmp(s, decimal_point, decimal_pt_len) == 0) {
				s += decimal_pt_len;
				seen_decimal_pt = 1;
				continue;
			}
			if (ISEXP((unsigned char)*s)) {
				s++;
				if (ISSIGN((unsigned char)*s)) {
					s++;
					continue;
				}
			}
			break;
		}
		s++;
	}
	return (*s == '\0');
}

/*
 * valid_format - validate user specified format string
 */
int
valid_format(const char *fmt)
{
	int conversions = 0;

	while (*fmt != '\0') {
		/* scan for conversions */
		if (*fmt != '\0' && *fmt != '%') {
			do {
				fmt++;
			} while (*fmt != '\0' && *fmt != '%');
		}
		/* scan a conversion */
		if (*fmt != '\0') {
			do {
				fmt++;

				/* ok %% */
				if (*fmt == '%') {
					fmt++;
					break;
				}
				/* valid conversions */
				if (strchr("eEfgG", *fmt) &&
				    conversions++ < 1) {
					fmt++;
					break;
				}
				/* flags, width and precsision */
				if (isdigit((unsigned char)*fmt) ||
				    strchr("+- 0#.", *fmt))
					continue;

				/* oops! bad conversion format! */
				return (0);
			} while (*fmt != '\0');
		}
	}

	return (conversions <= 1);
}

/*
 * unescape - handle C escapes in a string
 */
char *
unescape(char *orig)
{
	char c, *cp, *new = orig;
	int i;

	for (cp = orig; (*orig = *cp); cp++, orig++) {
		if (*cp != '\\')
			continue;

		switch (*++cp) {
		case 'a':	/* alert (bell) */
			*orig = '\a';
			continue;
		case 'b':	/* backspace */
			*orig = '\b';
			continue;
		case 'e':	/* escape */
			*orig = '\e';
			continue;
		case 'f':	/* formfeed */
			*orig = '\f';
			continue;
		case 'n':	/* newline */
			*orig = '\n';
			continue;
		case 'r':	/* carriage return */
			*orig = '\r';
			continue;
		case 't':	/* horizontal tab */
			*orig = '\t';
			continue;
		case 'v':	/* vertical tab */
			*orig = '\v';
			continue;
		case '\\':	/* backslash */
			*orig = '\\';
			continue;
		case '\'':	/* single quote */
			*orig = '\'';
			continue;
		case '\"':	/* double quote */
			*orig = '"';
			continue;
		case '0':
		case '1':
		case '2':
		case '3':	/* octal */
		case '4':
		case '5':
		case '6':
		case '7':	/* number */
			for (i = 0, c = 0;
			     ISODIGIT((unsigned char)*cp) && i < 3;
			     i++, cp++) {
				c <<= 3;
				c |= (*cp - '0');
			}
			*orig = c;
			continue;
		case 'x':	/* hexidecimal number */
			cp++;	/* skip 'x' */
			for (i = 0, c = 0;
			     isxdigit((unsigned char)*cp) && i < 2;
			     i++, cp++) {
				c <<= 4;
				if (isdigit((unsigned char)*cp))
					c |= (*cp - '0');
				else
					c |= ((toupper((unsigned char)*cp) -
					    'A') + 10);
			}
			*orig = c;
			continue;
		default:
			--cp;
			break;
		}
	}

	return (new);
}

/*
 * e_atof - convert an ASCII string to a double
 *	exit if string is not a valid double, or if converted value would
 *	cause overflow or underflow
 */
double
e_atof(const char *num)
{
	char *endp;
	double dbl;

	errno = 0;
	dbl = strtod(num, &endp);

	if (errno == ERANGE)
		/* under or overflow */
		err(2, "%s", num);
	else if (*endp != '\0')
		/* "junk" left in number */
		errx(2, "invalid floating point argument: %s", num);

	/* zero shall have no sign */
	if (dbl == -0.0)
		dbl = 0;
	return (dbl);
}

/*
 * decimal_places - count decimal places in a number (string)
 */
int
decimal_places(const char *number)
{
	int places = 0;
	char *dp;

	/* look for a decimal point */
	if ((dp = strstr(number, decimal_point))) {
		dp += strlen(decimal_point);

		while (isdigit((unsigned char)*dp++))
			places++;
	}
	return (places);
}

/*
 * generate_format - create a format string
 *
 * XXX to be bug for bug compatable with Plan9 and GNU return "%g"
 * when "%g" prints as "%e" (this way no width adjustments are made)
 */
char *
generate_format(double first, double incr, double last, int equalize, char pad)
{
	static char buf[256];
	char cc = '\0';
	int precision, width1, width2, places;

	if (equalize == 0)
		return (default_format);

	/* figure out "last" value printed */
	if (first > last)
		last = first - incr * floor((first - last) / incr);
	else
		last = first + incr * floor((last - first) / incr);

	sprintf(buf, "%g", incr);
	if (strchr(buf, 'e'))
		cc = 'e';
	precision = decimal_places(buf);

	width1 = sprintf(buf, "%g", first);
	if (strchr(buf, 'e'))
		cc = 'e';
	if ((places = decimal_places(buf)))
		width1 -= (places + strlen(decimal_point));

	precision = MAX(places, precision);

	width2 = sprintf(buf, "%g", last);
	if (strchr(buf, 'e'))
		cc = 'e';
	if ((places = decimal_places(buf)))
		width2 -= (places + strlen(decimal_point));

	if (precision) {
		sprintf(buf, "%%%c%d.%d%c", pad,
		    MAX(width1, width2) + (int) strlen(decimal_point) +
		    precision, precision, (cc) ? cc : 'f');
	} else {
		sprintf(buf, "%%%c%d%c", pad, MAX(width1, width2),
		    (cc) ? cc : 'g');
	}

	return (buf);
}

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.\"
.\"
.\" Copyright (c) 2004 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" Brian Ginsbach.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgment:
.\"     This product includes software developed by The NetBSD
.\"     Foundation, Inc. and its contributors.
.\" 4. Neither the name of The NetBSD Foundation nor the names of its
.\"    contributors may be used to endorse or promote products derived
.\"    from this software without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.\"
.Dd November 17, 2004
.Dt SEQ 1
.Os
.Sh NAME
.Nm seq
.Nd print sequences of numbers
.Sh SYNOPSIS
.Nm
.Op Fl f Ar format
.Op Fl s Ar string
.Op Fl t Ar string
.Op Fl w
.Op Ar first Op Ar incr
.Ar last
.Sh DESCRIPTION
The
.Nm
utility prints a sequence of numbers, one per line
.Pq default ,
from
.Ar first 
.Pq default 1 ,
to near
.Ar last
as possible, in increments of
.Ar incr
.Pq default 1 .
When
.Ar first
is larger than
.Ar last
the default
.Ar incr
is -1.
.Pp
All numbers are interpreted as floating point.
.Pp
Normally integer values are printed as decimal integers.
.Pp
The
.Nm
utility accepts the following options:
.Bl -tag -width Ar
.It Fl f Ar format
Use a
.Xr printf 3
style
.Ar format
to print each number.  Only the
.Cm e ,
.Cm E ,
.Cm f ,
.Cm g ,
.Cm G ,
and
.Cm %
conversion characters are valid, along with any optional
flags and an optional numeric mimimum field width or precision.
The
.Ar format
can contain character escape sequences in backslash notation as
defined in 
.St -ansiC .
The default is
.Cm %g .
.It Fl s Ar string
Use
.Ar string
to separate numbers.
The
.Ar string
can contain character escape sequences in backslash notation as
defined in 
.St -ansiC .
The default is
.Cm \en .
.It Fl t Ar string
Use
.Ar string
to terminate sequence of numbers.
The
.Ar string
can contain character escape sequences in backslash notation as
defined in 
.St -ansiC .
This option is useful when the default separator
does not contain a
.Cm \en .
.It Fl w
Equalize the widths of all numbers by padding with zeros as necessary.
This option has no effect with the
.Fl f
option.
If any sequence numbers will be printed in exponential notation,
the default conversion is changed to
.Cm %e .
.El
.Pp
The
.Nm
utility exits 0 on success and non-zero if an error occurs.
.Sh EXAMPLES
.Bd -literal -offset indent
seq 1 3
1
2
3

seq 3 1
3
2
1

seq -w 0 .05 .1
0.00
0.05
0.10
.Ed
.Sh SEE ALSO
.Xr jot 1 ,
.Xr printf 1 ,
.Xr printf 3
.Sh HISTORY
The
.Nm
command first appeared in
.Tn "Plan 9 from Bell Labs" .
.Sh AUTHORS
The 
.Nm
command for
.Nx
was written by Brian Ginsbach.
.Sh BUGS
The 
.Fl w
option does not handle the transition from pure floating point
to exponent representation very well.
The
.Nm
command is not bug for bug compatible with the
.Tn "Plan 9 from Bell Labs"
or 
.Tn GNU
versions of
.Nm .

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