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	sh.c - 9base - revived minimalist port of Plan 9 userland to Unix
	git clone git://git.suckless.org/9base
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	sh.c (3427B)
	---
	1 #include "mk.h"
	2
	3 /*
	4 * This file contains functions that depend on the shell's syntax…
	5 * of the routines extract strings observing the shell's escape c…
	6 */
	7
	8
	9 /*
	10 * skip a token in quotes.
	11 */
	12 static char *
	13 squote(char *cp, int c)
	14 {
	15 Rune r;
	16 int n;
	17
	18 while(*cp){
	19 n = chartorune(&r, cp);
	20 if(r == c)
	21 return cp;
	22 if(r == '\\')
	23 n += chartorune(&r, cp+n);
	24 cp += n;
	25 }
	26 SYNERR(-1); /* should never occur */
	27 fprint(2, "missing closing '\n");
	28 return 0;
	29 }
	30 /*
	31 * search a string for unescaped characters in a pattern set
	32 */
	33 static char *
	34 shcharin(char cp, char pat)
	35 {
	36 Rune r;
	37 int n, vargen;
	38
	39 vargen = 0;
	40 while(*cp){
	41 n = chartorune(&r, cp);
	42 switch(r){
	43 case '\\': /* skip escaped char */
	44 cp += n;
	45 n = chartorune(&r, cp);
	46 break;
	47 case '\'': /* skip quoted string …
	48 case '"':
	49 cp = squote(cp+1, r); /* n must = 1 */
	50 if(!cp)
	51 return 0;
	52 break;
	53 case '$':
	54 if(*(cp+1) == '{')
	55 vargen = 1;
	56 break;
	57 case '}':
	58 if(vargen)
	59 vargen = 0;
	60 else if(utfrune(pat, r))
	61 return cp;
	62 break;
	63 default:
	64 if(vargen == 0 && utfrune(pat, r))
	65 return cp;
	66 break;
	67 }
	68 cp += n;
	69 }
	70 if(vargen){
	71 SYNERR(-1);
	72 fprint(2, "missing closing } in pattern generator\n");
	73 }
	74 return 0;
	75 }
	76
	77 /*
	78 * extract an escaped token. Possible escape chars are single-qu…
	79 * double-quote,and backslash.
	80 */
	81 static char*
	82 shexpandquote(char s, Rune esc, Bufblock b)
	83 {
	84 Rune r;
	85
	86 if (esc == '\\') {
	87 s += chartorune(&r, s);
	88 rinsert(b, r);
	89 return s;
	90 }
	91
	92 while(*s){
	93 s += chartorune(&r, s);
	94 if(r == esc)
	95 return s;
	96 if (r == '\\') {
	97 rinsert(b, r);
	98 s += chartorune(&r, s);
	99 }
	100 rinsert(b, r);
	101 }
	102 return 0;
	103 }
	104
	105 /*
	106 * Input an escaped token. Possible escape chars are single-quot…
	107 * double-quote and backslash.
	108 */
	109 static int
	110 shescapetoken(Biobuf bp, Bufblock buf, int preserve, int esc)
	111 {
	112 int c, line;
	113
	114 if(esc == '\\') {
	115 c = Bgetrune(bp);
	116 if(c == '\r')
	117 c = Bgetrune(bp);
	118 if (c == '\n')
	119 mkinline++;
	120 rinsert(buf, c);
	121 return 1;
	122 }
	123
	124 line = mkinline;
	125 while((c = nextrune(bp, 0)) >= 0){
	126 if(c == esc){
	127 if(preserve)
	128 rinsert(buf, c);
	129 return 1;
	130 }
	131 if(c == '\\') {
	132 rinsert(buf, c);
	133 c = Bgetrune(bp);
	134 if(c == '\r')
	135 c = Bgetrune(bp);
	136 if (c < 0)
	137 break;
	138 if (c == '\n')
	139 mkinline++;
	140 }
	141 rinsert(buf, c);
	142 }
	143 SYNERR(line); fprint(2, "missing closing %c\n", esc);
	144 return 0;
	145 }
	146
	147 /*
	148 * copy a quoted string; s points to char after opening quote
	149 */
	150 static char *
	151 copysingle(char s, Rune q, Bufblock buf)
	152 {
	153 Rune r;
	154
	155 while(*s){
	156 s += chartorune(&r, s);
	157 rinsert(buf, r);
	158 if(r == q)
	159 break;
	160 }
	161 return s;
	162 }
	163 /*
	164 * check for quoted strings. backquotes are handled here; single…
	165 * s points to char after opening quote, q.
	166 */
	167 static char *
	168 shcopyq(char s, Rune q, Bufblock buf)
	169 {
	170 if(q == '\'' \|\| q == '"') /* copy quoted string */
	171 return copysingle(s, q, buf);
	172
	173 if(q != '`') /* not quoted */
	174 return s;
	175
	176 while(s){ / copy backquoted str…
	177 s += chartorune(&q, s);
	178 rinsert(buf, q);
	179 if(q == '`')
	180 break;
	181 if(q == '\'' \|\| q == '"')
	182 s = copysingle(s, q, buf); /* copy quoted…
	183 }
	184 return s;
	185 }
	186
	187 static int
	188 shmatchname(char *name)
	189 {
	190 USED(name);
	191
	192 return 1;
	193 }
	194
	195
	196 Shell shshell = {
	197 "sh",
	198 "\"'= \t", /*used in parse.c to isolate assignment attrib…
	199 ' ', /* inter-word separator in env */
	200 shcharin,
	201 shexpandquote,
	202 shescapetoken,
	203 shcopyq,
	204 shmatchname
	205 };
	206