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printf.c revision 1.3 
      1 /*
      2  * Copyright (c) 1989 The Regents of the University of California.
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #ifndef lint
     35 char copyright[] =
     36 "@(#) Copyright (c) 1989 The Regents of the University of California.\n\
     37  All rights reserved.\n";
     38 #endif /* not lint */
     39 
     40 #ifndef lint
     41 /*static char sccsid[] = "from: @(#)printf.c	5.9 (Berkeley) 6/1/90";*/
     42 static char rcsid[] = "$Id: printf.c,v 1.3 1993/08/01 18:10:03 mycroft Exp $";
     43 #endif /* not lint */
     44 
     45 #include <sys/types.h>
     46 #include <stdio.h>
     47 #include <string.h>
     48 
     49 #define PF(f, func) { \
     50 	if (fieldwidth) \
     51 		if (precision) \
     52 			(void)printf(f, fieldwidth, precision, func); \
     53 		else \
     54 			(void)printf(f, fieldwidth, func); \
     55 	else if (precision) \
     56 		(void)printf(f, precision, func); \
     57 	else \
     58 		(void)printf(f, func); \
     59 }
     60 
     61 char **gargv;
     62 
     63 main(argc, argv)
     64 	int argc;
     65 	char **argv;
     66 {
     67 	static char *skip1, *skip2;
     68 	register char *format, *fmt, *start;
     69 	register int end, fieldwidth, precision;
     70 	char convch, nextch, *getstr(), *mklong();
     71 	double getdouble();
     72 	long getlong();
     73 
     74 	if (argc < 2) {
     75 		fprintf(stderr, "usage: printf format [arg ...]\n");
     76 		exit(1);
     77 	}
     78 
     79 	/*
     80 	 * Basic algorithm is to scan the format string for conversion
     81 	 * specifications -- once one is found, find out if the field
     82 	 * width or precision is a '*'; if it is, gather up value.  Note,
     83 	 * format strings are reused as necessary to use up the provided
     84 	 * arguments, arguments of zero/null string are provided to use
     85 	 * up the format string.
     86 	 */
     87 	skip1 = "#-+ 0";
     88 	skip2 = "*0123456789";
     89 
     90 	escape(fmt = format = *++argv);		/* backslash interpretation */
     91 	gargv = ++argv;
     92 	for (;;) {
     93 		end = 0;
     94 		/* find next format specification */
     95 next:		for (start = fmt;; ++fmt) {
     96 			if (!*fmt) {
     97 				/* avoid infinite loop */
     98 				if (end == 1) {
     99 					fprintf(stderr,
    100 					    "printf: missing format character.\n");
    101 					exit(1);
    102 				}
    103 				end = 1;
    104 				if (fmt > start)
    105 					(void)printf("%s", start);
    106 				if (!*gargv)
    107 					exit(0);
    108 				fmt = format;
    109 				goto next;
    110 			}
    111 			/* %% prints a % */
    112 			if (*fmt == '%') {
    113 				if (*++fmt != '%')
    114 					break;
    115 				*fmt++ = '\0';
    116 				(void)printf("%s", start);
    117 				goto next;
    118 			}
    119 		}
    120 
    121 		/* skip to field width */
    122 		for (; index(skip1, *fmt); ++fmt);
    123 		fieldwidth = *fmt == '*' ? getint() : 0;
    124 
    125 		/* skip to possible '.', get following precision */
    126 		for (; index(skip2, *fmt); ++fmt);
    127 		if (*fmt == '.')
    128 			++fmt;
    129 		precision = *fmt == '*' ? getint() : 0;
    130 
    131 		/* skip to conversion char */
    132 		for (; index(skip2, *fmt); ++fmt);
    133 		if (!*fmt) {
    134 			fprintf(stderr, "printf: missing format character.\n");
    135 			exit(1);
    136 		}
    137 
    138 		convch = *fmt;
    139 		nextch = *++fmt;
    140 		*fmt = '\0';
    141 		switch(convch) {
    142 		case 'c': {
    143 			char p = getchr();
    144 			PF(start, p);
    145 			break;
    146 		}
    147 		case 's': {
    148 			char *p = getstr();
    149 			PF(start, p);
    150 			break;
    151 		}
    152 		case 'd': case 'i': case 'o': case 'u': case 'x': case 'X': {
    153 			char *f = mklong(start, convch);
    154 			long p = getlong();
    155 			PF(f, p);
    156 			break;
    157 		}
    158 		case 'e': case 'E': case 'f': case 'g': case 'G': {
    159 			double p = getdouble();
    160 			PF(start, p);
    161 			break;
    162 		}
    163 		default:
    164 			fprintf(stderr, "printf: illegal format character.\n");
    165 			exit(1);
    166 		}
    167 		*fmt = nextch;
    168 	}
    169 	/* NOTREACHED */
    170 }
    171 
    172 char *
    173 mklong(str, ch)
    174 	char *str, ch;
    175 {
    176 	int len;
    177 	char *copy, *malloc();
    178 
    179 	len = strlen(str) + 2;
    180 	if (!(copy = malloc((u_int)len))) {	/* never freed; XXX */
    181 		fprintf(stderr, "printf: out of memory.\n");
    182 		exit(1);
    183 	}
    184 	bcopy(str, copy, len - 3);
    185 	copy[len - 3] = 'l';
    186 	copy[len - 2] = ch;
    187 	copy[len - 1] = '\0';
    188 	return(copy);
    189 }
    190 
    191 escape(fmt)
    192 	register char *fmt;
    193 {
    194 	register char *store;
    195 	register int value, c;
    196 
    197 	for (store = fmt; c = *fmt; ++fmt, ++store) {
    198 		if (c != '\\') {
    199 			*store = c;
    200 			continue;
    201 		}
    202 		switch (*++fmt) {
    203 		case '\0':		/* EOS, user error */
    204 			*store = '\\';
    205 			*++store = '\0';
    206 			return;
    207 		case '\\':		/* backslash */
    208 		case '\'':		/* single quote */
    209 			*store = *fmt;
    210 			break;
    211 		case 'a':		/* bell/alert */
    212 			*store = '\7';
    213 			break;
    214 		case 'b':		/* backspace */
    215 			*store = '\b';
    216 			break;
    217 		case 'f':		/* form-feed */
    218 			*store = '\f';
    219 			break;
    220 		case 'n':		/* newline */
    221 			*store = '\n';
    222 			break;
    223 		case 'r':		/* carriage-return */
    224 			*store = '\r';
    225 			break;
    226 		case 't':		/* horizontal tab */
    227 			*store = '\t';
    228 			break;
    229 		case 'v':		/* vertical tab */
    230 			*store = '\13';
    231 			break;
    232 					/* octal constant */
    233 		case '0': case '1': case '2': case '3':
    234 		case '4': case '5': case '6': case '7':
    235 			for (c = 3, value = 0;
    236 			    c-- && *fmt >= '0' && *fmt <= '7'; ++fmt) {
    237 				value <<= 3;
    238 				value += *fmt - '0';
    239 			}
    240 			--fmt;
    241 			*store = value;
    242 			break;
    243 		default:
    244 			*store = *fmt;
    245 			break;
    246 		}
    247 	}
    248 	*store = '\0';
    249 }
    250 
    251 getchr()
    252 {
    253 	if (!*gargv)
    254 		return((int)'\0');
    255 	return((int)**gargv++);
    256 }
    257 
    258 char *
    259 getstr()
    260 {
    261 	if (!*gargv)
    262 		return("");
    263 	return(*gargv++);
    264 }
    265 
    266 static char *number = "+-.0123456789";
    267 getint()
    268 {
    269 	if (!*gargv)
    270 		return(0);
    271 	if (index(number, **gargv))
    272 		return(atoi(*gargv++));
    273 	return(asciicode());
    274 }
    275 
    276 long
    277 getlong()
    278 {
    279 	long atol();
    280 
    281 	if (!*gargv)
    282 		return((long)0);
    283 	if (index(number, **gargv))
    284 		return(strtol(*gargv++, (char **)NULL, 0));
    285 	return((long)asciicode());
    286 }
    287 
    288 double
    289 getdouble()
    290 {
    291 	double atof();
    292 
    293 	if (!*gargv)
    294 		return((double)0);
    295 	if (index(number, **gargv))
    296 		return(atof(*gargv++));
    297 	return((double)asciicode());
    298 }
    299 
    300 asciicode()
    301 {
    302 	register char ch;
    303 
    304 	ch = **gargv;
    305 	if (ch == '\'' || ch == '"')
    306 		ch = (*gargv)[1];
    307 	++gargv;
    308 	return(ch);
    309 }
    310