/* * $Id: //pentools/main/datemath/datemath.c#5 $ * * written by:  Stephen J. Friedl *              Software Consultant *              Tustin, California USA *              steve@unixwiz.net * *	This tool's home page is * *		http://www.unixwiz.net/tools/datemath.html * *	This is the main driver for the datemath program.  The very *	large bulk of the code is in the lex scanner specifiction *	file "lex.l" and in the yacc grammer file "gram.y", so this *	file is little more than a wrapper. It will, however, serve *	as an anchor for the documentation. * *	This program performs various operations on mm/dd/yy, mm/yy, *	and YYMM dates, and it sends the results to the standard *	output.  This function will most often be used in shell *	scripts surrounded by `` characters: * *		END_DATE=`datemath $YYMM + 3`	# add three months * *	Datemath is fairly smart about converting from one kind *	of date to another when it makes sense, and most operations *	can apply to any kind of date.  mm/yy and yymm dates are *	both converted to yymm internally, and are used synonymously. * *	The most common usage will be: * *		datemath date + num *		datemath date - num *		datemath date - date * *	The first two add or subtract the specified number of days/months *	for mm/dd/yy or mm/yy dates, and output the same kind of date. *	The third form outputs the number of days/months between the *	two specified dates in integer form. * *	This program also supports functions that operate on dates, and *	they are: * *		fday(date)		return mm/dd/yy of first day of month *		lday(date)		return mm/dd/yy of last  day of month *		ndays(date)		return # of days in this month *		year(date)		return year (19YY format) *		month(date)		return month of this date *		day(date)		return day of this date (mm/dd/yy only) *		yymm(date)		convert mm/dd/yy to mm/yy * *	All expressions have a type: mm/dd/yy, yymm, and integer, and they *	can be nested arbitrarily and grouped with parenthesis.  For example *	we want to run program "foo" with two mm/dd/yy dates, but all we *	have is a mm/yy date in $YYMM.  We would do this with: * *		foo `datemath fday(yymm)` `datemath lday(yymm+2)` * *	If we needed to see how many days is in this span, we would do: * *		datemath '( lday(yymm+2) - fday(yymm) ) + 1' * *	The string can be separate arguments or a single arg, but *	the user must take care to quote characters special to the *	shell. * *	Dates themselves can be in any of the following formats: * *		mm/yy *		yymm *		mmddyy *		mmddyyyy *		mm/dd/yy *		mm/dd/yyyy * *	and full range checking is done on them to make sure the *	dates given are plausible. * *	Currently, "syntax error" is the only indication of most failures, *	although some semantic errors (such as the wrong date type) will *	be identified.  Exit value is 0 if all is OK and nonzero on error. * * COMMAND LINE * *	Other than the expression parsed, a few command-line params *	are allowed with the traditional "dash" notation. * *	-L	This runs only the lexer, not the parser: it's used *		for testing the flex code by reading and printing *		one token at a time. It does no date math. * *	-V	print the version of this program. * *	-9 yy	two-digit years from yy..99 are 1900, and all *		else is 2000. Default = 40 * *	-2	output two-digit years * *	-4	output four-digit years (default) * *	-C	output dates in Y/M/D format * * BUGS *	> limited error checking of plausible dates *	> very poor syntax error recovery *	> should be a way to output yymm dates as mm/yy *	> no way to do collated date *input* */#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <string.h>#include <malloc.h>#include "defs.h"static const char	Version[] =	"datemath 2.0.10 - 2003-06-20 - steve@unixwiz.net";const char	*ProgName = NULL;int		year_digits   = 4,		collate_order = FALSE;static void usage(const char *argv0) __attribute__((noreturn));int main(int argc, char **argv){int	c, i, len;char	*exprbuf;int	lextest = FALSE;	ProgName = argv[0];	setbuf(stdout, (char *)0);	while ( (c = getopt(argc, argv, "VL9:24C")) != EOF )	{		switch (c)		{		  default:			usage(argv[0]);		  case '4':			year_digits = 4;			break;		  case '2':			year_digits = 2;			break;		  case 'C':			collate_order = TRUE;			break;		  case '9':			century19_year = atoi(optarg);			break;		  case 'L':			lextest = TRUE;			break;		  case 'V':		/* version */			fprintf(stderr, "%s\n", Version);			exit(EXIT_SUCCESS);		}	}	/*----------------------------------------------------------------	 * BUILD EXPRESSION STRING	 *	 * Figure out how much space we need for the whole string,	 * allocate it, then fill the buffer with it.	 */	len = 0;	for (i = optind; i < argc; i++ )	{		len += strlen(argv[i]) + 1;	}	if ( len == 0 )	{		fprintf(stderr, "ERROR: missing datemath expression\n");		usage(argv[0]);	}	len += 2; /* good measure */	if ( (exprbuf = malloc(len)) == 0 )		die("ERROR: cannot get %d bytes of memory", len);	for ( ; optind < argc; )	{		strcat(exprbuf, argv[optind++]);		strcat(exprbuf, " ");	}	init_scan(exprbuf);	if ( lextest )	{	int	tok;		while ( (tok = yylex()) != 0 )			printf("got token %d [%s]\n", tok, yytext);		exit(EXIT_SUCCESS);	}	else	{		exit( yyparse() == 0 ? EXIT_SUCCESS : EXIT_FAILURE);	}}void yyerror(const char *msg){	die("syntax error in command line: %s", msg);}static void usage(const char *argv0){const char *const *p;static const char * const text[] = {"","  -V        Report version information to stderr and exit","  -4        Output dates with four-digit years (default)","  -2        Output dates with two-digit years","  -9 ##     Two-digit years starting with ## are 19xx, else 20xx","  -C        Collate mode: output dates in year/month/day format","","Expression keywords:","""today tomorrow yesterday -- the obvious dates","fday(date) - the first day of the month","lday(date) - the last day of the month","ndays(date) - number of days in the month",0};	fprintf(stderr, "%s\n\n", Version);	fprintf(stderr, "usage: %s [options] date-expression\n", argv0);	for (p = text; *p; p++)	{		fprintf(stderr, "%s\n", *p);	}	exit(EXIT_FAILURE);}