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	rc.c - 9base - revived minimalist port of Plan 9 userland to Unix
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	rc.c (3271B)
	---
	1 #include "mk.h"
	2
	3 /*
	4 * This file contains functions that depend on rc's syntax. Most
	5 * of the routines extract strings observing rc's escape conventi…
	6 */
	7
	8
	9 /*
	10 * skip a token in single quotes.
	11 */
	12 static char *
	13 squote(char *cp)
	14 {
	15 Rune r;
	16 int n;
	17
	18 while(*cp){
	19 n = chartorune(&r, cp);
	20 if(r == '\'') {
	21 n += chartorune(&r, cp+n);
	22 if(r != '\'')
	23 return(cp);
	24 }
	25 cp += n;
	26 }
	27 SYNERR(-1); /* should never occur */
	28 fprint(2, "missing closing '\n");
	29 return 0;
	30 }
	31
	32 /*
	33 * search a string for characters in a pattern set
	34 * characters in quotes and variable generators are escaped
	35 */
	36 char *
	37 rccharin(char cp, char pat)
	38 {
	39 Rune r;
	40 int n, vargen;
	41
	42 vargen = 0;
	43 while(*cp){
	44 n = chartorune(&r, cp);
	45 switch(r){
	46 case '\'': /* skip quoted string …
	47 cp = squote(cp+1); /* n must = 1 */
	48 if(!cp)
	49 return 0;
	50 break;
	51 case '$':
	52 if(*(cp+1) == '{')
	53 vargen = 1;
	54 break;
	55 case '}':
	56 if(vargen)
	57 vargen = 0;
	58 else if(utfrune(pat, r))
	59 return cp;
	60 break;
	61 default:
	62 if(vargen == 0 && utfrune(pat, r))
	63 return cp;
	64 break;
	65 }
	66 cp += n;
	67 }
	68 if(vargen){
	69 SYNERR(-1);
	70 fprint(2, "missing closing } in pattern generator\n");
	71 }
	72 return 0;
	73 }
	74
	75 /*
	76 * extract an escaped token. Possible escape chars are single-qu…
	77 * double-quote,and backslash. Only the first is valid for rc. t…
	78 * others are just inserted into the receiving buffer.
	79 */
	80 char*
	81 rcexpandquote(char s, Rune r, Bufblock b)
	82 {
	83 if (r != '\'') {
	84 rinsert(b, r);
	85 return s;
	86 }
	87
	88 while(*s){
	89 s += chartorune(&r, s);
	90 if(r == '\'') {
	91 if(*s == '\'')
	92 s++;
	93 else
	94 return s;
	95 }
	96 rinsert(b, r);
	97 }
	98 return 0;
	99 }
	100
	101 /*
	102 * Input an escaped token. Possible escape chars are single-quot…
	103 * double-quote and backslash. Only the first is a valid escape …
	104 * rc; the others are just inserted into the receiving buffer.
	105 */
	106 int
	107 rcescapetoken(Biobuf bp, Bufblock buf, int preserve, int esc)
	108 {
	109 int c, line;
	110
	111 if(esc != '\'')
	112 return 1;
	113
	114 line = mkinline;
	115 while((c = nextrune(bp, 0)) > 0){
	116 if(c == '\''){
	117 if(preserve)
	118 rinsert(buf, c);
	119 c = Bgetrune(bp);
	120 if (c < 0)
	121 break;
	122 if(c != '\''){
	123 Bungetrune(bp);
	124 return 1;
	125 }
	126 }
	127 rinsert(buf, c);
	128 }
	129 SYNERR(line); fprint(2, "missing closing %c\n", esc);
	130 return 0;
	131 }
	132
	133 /*
	134 * copy a single-quoted string; s points to char after opening qu…
	135 */
	136 static char *
	137 copysingle(char s, Bufblock buf)
	138 {
	139 Rune r;
	140
	141 while(*s){
	142 s += chartorune(&r, s);
	143 rinsert(buf, r);
	144 if(r == '\'')
	145 break;
	146 }
	147 return s;
	148 }
	149 /*
	150 * check for quoted strings. backquotes are handled here; single…
	151 * s points to char after opening quote, q.
	152 */
	153 char *
	154 rccopyq(char s, Rune q, Bufblock buf)
	155 {
	156 if(q == '\'') /* copy quoted stri…
	157 return copysingle(s, buf);
	158
	159 if(q != '`') /* not quoted */
	160 return s;
	161
	162 while(s){ / copy backquoted str…
	163 s += chartorune(&q, s);
	164 rinsert(buf, q);
	165 if(q == '}')
	166 break;
	167 if(q == '\'')
	168 s = copysingle(s, buf); /* copy quoted st…
	169 }
	170 return s;
	171 }
	172
	173 static int
	174 rcmatchname(char *name)
	175 {
	176 char *p;
	177
	178 if((p = strrchr(name, '/')) != nil)
	179 name = p+1;
	180 if(name[0] == 'r' && name[1] == 'c')
	181 return 1;
	182 return 0;
	183 }
	184
	185 Shell rcshell = {
	186 "rc",
	187 "'= \t",
	188 '\1',
	189 rccharin,
	190 rcexpandquote,
	191 rcescapetoken,
	192 rccopyq,
	193 rcmatchname
	194 };