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printf.c revision 1.2 
      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[] = "@(#)printf.c	5.9 (Berkeley) 6/1/90";
     42 #endif /* not lint */
     43 
     44 #include <sys/types.h>
     45 #include <stdio.h>
     46 #include <string.h>
     47 
     48 #define PF(f, func) { \
     49 	if (fieldwidth) \
     50 		if (precision) \
     51 			(void)printf(f, fieldwidth, precision, func); \
     52 		else \
     53 			(void)printf(f, fieldwidth, func); \
     54 	else if (precision) \
     55 		(void)printf(f, precision, func); \
     56 	else \
     57 		(void)printf(f, func); \
     58 }
     59 
     60 char **gargv;
     61 
     62 main(argc, argv)
     63 	int argc;
     64 	char **argv;
     65 {
     66 	static char *skip1, *skip2;
     67 	register char *format, *fmt, *start;
     68 	register int end, fieldwidth, precision;
     69 	char convch, nextch, *getstr(), *mklong();
     70 	double getdouble();
     71 	long getlong();
     72 
     73 	if (argc < 2) {
     74 		fprintf(stderr, "usage: printf format [arg ...]\n");
     75 		exit(1);
     76 	}
     77 
     78 	/*
     79 	 * Basic algorithm is to scan the format string for conversion
     80 	 * specifications -- once one is found, find out if the field
     81 	 * width or precision is a '*'; if it is, gather up value.  Note,
     82 	 * format strings are reused as necessary to use up the provided
     83 	 * arguments, arguments of zero/null string are provided to use
     84 	 * up the format string.
     85 	 */
     86 	skip1 = "#-+ 0";
     87 	skip2 = "*0123456789";
     88 
     89 	escape(fmt = format = *++argv);		/* backslash interpretation */
     90 	gargv = ++argv;
     91 	for (;;) {
     92 		end = 0;
     93 		/* find next format specification */
     94 next:		for (start = fmt;; ++fmt) {
     95 			if (!*fmt) {
     96 				/* avoid infinite loop */
     97 				if (end == 1) {
     98 					fprintf(stderr,
     99 					    "printf: missing format character.\n");
    100 					exit(1);
    101 				}
    102 				end = 1;
    103 				if (fmt > start)
    104 					(void)printf("%s", start);
    105 				if (!*gargv)
    106 					exit(0);
    107 				fmt = format;
    108 				goto next;
    109 			}
    110 			/* %% prints a % */
    111 			if (*fmt == '%') {
    112 				if (*++fmt != '%')
    113 					break;
    114 				*fmt++ = '\0';
    115 				(void)printf("%s", start);
    116 				goto next;
    117 			}
    118 		}
    119 
    120 		/* skip to field width */
    121 		for (; index(skip1, *fmt); ++fmt);
    122 		fieldwidth = *fmt == '*' ? getint() : 0;
    123 
    124 		/* skip to possible '.', get following precision */
    125 		for (; index(skip2, *fmt); ++fmt);
    126 		if (*fmt == '.')
    127 			++fmt;
    128 		precision = *fmt == '*' ? getint() : 0;
    129 
    130 		/* skip to conversion char */
    131 		for (; index(skip2, *fmt); ++fmt);
    132 		if (!*fmt) {
    133 			fprintf(stderr, "printf: missing format character.\n");
    134 			exit(1);
    135 		}
    136 
    137 		convch = *fmt;
    138 		nextch = *++fmt;
    139 		*fmt = '\0';
    140 		switch(convch) {
    141 		case 'c': {
    142 			char p = getchr();
    143 			PF(start, p);
    144 			break;
    145 		}
    146 		case 's': {
    147 			char *p = getstr();
    148 			PF(start, p);
    149 			break;
    150 		}
    151 		case 'd': case 'i': case 'o': case 'u': case 'x': case 'X': {
    152 			char *f = mklong(start, convch);
    153 			long p = getlong();
    154 			PF(f, p);
    155 			break;
    156 		}
    157 		case 'e': case 'E': case 'f': case 'g': case 'G': {
    158 			double p = getdouble();
    159 			PF(start, p);
    160 			break;
    161 		}
    162 		default:
    163 			fprintf(stderr, "printf: illegal format character.\n");
    164 			exit(1);
    165 		}
    166 		*fmt = nextch;
    167 	}
    168 	/* NOTREACHED */
    169 }
    170 
    171 char *
    172 mklong(str, ch)
    173 	char *str, ch;
    174 {
    175 	int len;
    176 	char *copy, *malloc();
    177 
    178 	len = strlen(str) + 2;
    179 	if (!(copy = malloc((u_int)len))) {	/* never freed; XXX */
    180 		fprintf(stderr, "printf: out of memory.\n");
    181 		exit(1);
    182 	}
    183 	bcopy(str, copy, len - 3);
    184 	copy[len - 3] = 'l';
    185 	copy[len - 2] = ch;
    186 	copy[len - 1] = '\0';
    187 	return(copy);
    188 }
    189 
    190 escape(fmt)
    191 	register char *fmt;
    192 {
    193 	register char *store;
    194 	register int value, c;
    195 
    196 	for (store = fmt; c = *fmt; ++fmt, ++store) {
    197 		if (c != '\\') {
    198 			*store = c;
    199 			continue;
    200 		}
    201 		switch (*++fmt) {
    202 		case '\0':		/* EOS, user error */
    203 			*store = '\\';
    204 			*++store = '\0';
    205 			return;
    206 		case '\\':		/* backslash */
    207 		case '\'':		/* single quote */
    208 			*store = *fmt;
    209 			break;
    210 		case 'a':		/* bell/alert */
    211 			*store = '\7';
    212 			break;
    213 		case 'b':		/* backspace */
    214 			*store = '\b';
    215 			break;
    216 		case 'f':		/* form-feed */
    217 			*store = '\f';
    218 			break;
    219 		case 'n':		/* newline */
    220 			*store = '\n';
    221 			break;
    222 		case 'r':		/* carriage-return */
    223 			*store = '\r';
    224 			break;
    225 		case 't':		/* horizontal tab */
    226 			*store = '\t';
    227 			break;
    228 		case 'v':		/* vertical tab */
    229 			*store = '\13';
    230 			break;
    231 					/* octal constant */
    232 		case '0': case '1': case '2': case '3':
    233 		case '4': case '5': case '6': case '7':
    234 			for (c = 3, value = 0;
    235 			    c-- && *fmt >= '0' && *fmt <= '7'; ++fmt) {
    236 				value <<= 3;
    237 				value += *fmt - '0';
    238 			}
    239 			--fmt;
    240 			*store = value;
    241 			break;
    242 		default:
    243 			*store = *fmt;
    244 			break;
    245 		}
    246 	}
    247 	*store = '\0';
    248 }
    249 
    250 getchr()
    251 {
    252 	if (!*gargv)
    253 		return((int)'\0');
    254 	return((int)**gargv++);
    255 }
    256 
    257 char *
    258 getstr()
    259 {
    260 	if (!*gargv)
    261 		return("");
    262 	return(*gargv++);
    263 }
    264 
    265 static char *number = "+-.0123456789";
    266 getint()
    267 {
    268 	if (!*gargv)
    269 		return(0);
    270 	if (index(number, **gargv))
    271 		return(atoi(*gargv++));
    272 	return(asciicode());
    273 }
    274 
    275 long
    276 getlong()
    277 {
    278 	long atol();
    279 
    280 	if (!*gargv)
    281 		return((long)0);
    282 	if (index(number, **gargv))
    283 		return(strtol(*gargv++, (char **)NULL, 0));
    284 	return((long)asciicode());
    285 }
    286 
    287 double
    288 getdouble()
    289 {
    290 	double atof();
    291 
    292 	if (!*gargv)
    293 		return((double)0);
    294 	if (index(number, **gargv))
    295 		return(atof(*gargv++));
    296 	return((double)asciicode());
    297 }
    298 
    299 asciicode()
    300 {
    301 	register char ch;
    302 
    303 	ch = **gargv;
    304 	if (ch == '\'' || ch == '"')
    305 		ch = (*gargv)[1];
    306 	++gargv;
    307 	return(ch);
    308 }
    309