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	getflags.c - 9base - revived minimalist port of Plan 9 userland to Unix
	git clone git://git.suckless.org/9base
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	---
	getflags.c (3962B)
	---
	1 /*% cyntax -DTEST % && cc -DTEST -go # %
	2 */
	3 #include "rc.h"
	4 #include "getflags.h"
	5 #include "fns.h"
	6 char *flagset[] = {"<flag>"};
	7 char **flag[NFLAG];
	8 char cmdline[NCMDLINE+1];
	9 char *cmdname;
	10 static char *flagarg="";
	11 static void reverse(char, char);
	12 static int scanflag(int, char*);
	13 static void errn(char*, int);
	14 static void errs(char*);
	15 static void errc(int);
	16 static int reason;
	17 #define RESET 1
	18 #define FEWARGS 2
	19 #define FLAGSYN 3
	20 #define BADFLAG 4
	21 static int badflag;
	22
	23 int
	24 getflags(int argc, char argv[], char flags, int stop)
	25 {
	26 char s, t;
	27 int i, j, c, count;
	28 flagarg = flags;
	29 if(cmdname==0)
	30 cmdname = argv[0];
	31 s = cmdline;
	32 for(i = 0;i!=argc;i++){
	33 for(t = argv[i];*t;t++)
	34 if(s!=&cmdline[NCMDLINE])
	35 s++=t;
	36 if(i!=argc-1 && s!=&cmdline[NCMDLINE])
	37 *s++=' ';
	38 }
	39 *s='\0';
	40 i = 1;
	41 while(i!=argc){
	42 if(argv[i][0]!='-' \|\| argv[i][1]=='\0'){
	43 if(stop)
	44 return argc;
	45 i++;
	46 continue;
	47 }
	48 s = argv[i]+1;
	49 while(*s){
	50 c=*s++;
	51 count = scanflag(c, flags);
	52 if(count==-1)
	53 return -1;
	54 if(flag[c]){ reason = RESET; badflag = c; return…
	55 if(count==0){
	56 flag[c] = flagset;
	57 if(*s=='\0'){
	58 for(j = i+1;j<=argc;j++)
	59 argv[j-1] = argv[j];
	60 --argc;
	61 }
	62 }
	63 else{
	64 if(*s=='\0'){
	65 for(j = i+1;j<=argc;j++)
	66 argv[j-1] = argv[j];
	67 --argc;
	68 s = argv[i];
	69 }
	70 if(argc-i<count){
	71 reason = FEWARGS;
	72 badflag = c;
	73 return -1;
	74 }
	75 reverse(argv+i, argv+argc);
	76 reverse(argv+i, argv+argc-count);
	77 reverse(argv+argc-count+1, argv+argc);
	78 argc-=count;
	79 flag[c] = argv+argc+1;
	80 flag[c][0] = s;
	81 s="";
	82 }
	83 }
	84 }
	85 return argc;
	86 }
	87
	88 static void
	89 reverse(char p, char q)
	90 {
	91 char *t;
	92 for(;p<q;p++,--q){ t=p; p=q; q = t; }
	93 }
	94
	95 static int
	96 scanflag(int c, char *f)
	97 {
	98 int fc, count;
	99 if(0<=c && c<NFLAG)
	100 while(*f){
	101 if(*f==' '){
	102 f++;
	103 continue;
	104 }
	105 fc=*f++;
	106 if(*f==':'){
	107 f++;
	108 if(f<'0' \|\| '9'<f){ reason = FLAGSYN; …
	109 count = 0;
	110 while('0'<=f && f<='9') count = count*…
	111 }
	112 else
	113 count = 0;
	114 if(*f=='['){
	115 do{
	116 f++;
	117 if(*f=='\0'){ reason = FLAGSYN; …
	118 }while(*f!=']');
	119 f++;
	120 }
	121 if(c==fc)
	122 return count;
	123 }
	124 reason = BADFLAG;
	125 badflag = c;
	126 return -1;
	127 }
	128
	129 void
	130 usage(char *tail)
	131 {
	132 char s, t, c;
	133 int count, nflag = 0;
	134 switch(reason){
	135 case RESET:
	136 errs("Flag -");
	137 errc(badflag);
	138 errs(": set twice\n");
	139 break;
	140 case FEWARGS:
	141 errs("Flag -");
	142 errc(badflag);
	143 errs(": too few arguments\n");
	144 break;
	145 case FLAGSYN:
	146 errs("Bad argument to getflags!\n");
	147 break;
	148 case BADFLAG:
	149 errs("Illegal flag -");
	150 errc(badflag);
	151 errc('\n');
	152 break;
	153 }
	154 errs("Usage: ");
	155 errs(cmdname);
	156 for(s = flagarg;*s;){
	157 c=*s;
	158 if(*s++==' ')
	159 continue;
	160 if(*s==':'){
	161 s++;
	162 count = 0;
	163 while('0'<=s && s<='9') count = count10+s++-…
	164 }
	165 else count = 0;
	166 if(count==0){
	167 if(nflag==0)
	168 errs(" [-");
	169 nflag++;
	170 errc(c);
	171 }
	172 if(*s=='['){
	173 s++;
	174 while(s!=']' && s!='\0') s++;
	175 if(*s==']')
	176 s++;
	177 }
	178 }
	179 if(nflag)
	180 errs("]");
	181 for(s = flagarg;*s;){
	182 c=*s;
	183 if(*s++==' ')
	184 continue;
	185 if(*s==':'){
	186 s++;
	187 count = 0;
	188 while('0'<=s && s<='9') count = count10+s++-…
	189 }
	190 else count = 0;
	191 if(count!=0){
	192 errs(" [-");
	193 errc(c);
	194 if(*s=='['){
	195 s++;
	196 t = s;
	197 while(s!=']' && s!='\0') s++;
	198 errs(" ");
	199 errn(t, s-t);
	200 if(*s==']')
	201 s++;
	202 }
	203 else
	204 while(count--) errs(" arg");
	205 errs("]");
	206 }
	207 else if(*s=='['){
	208 s++;
	209 while(s!=']' && s!='\0') s++;
	210 if(*s==']')
	211 s++;
	212 }
	213 }
	214 if(tail){
	215 errs(" ");
	216 errs(tail);
	217 }
	218 errs("\n");
	219 Exit("bad flags");
	220 }
	221
	222 static void
	223 errn(char *s, int count)
	224 {
	225 while(count){ errc(*s++); --count; }
	226 }
	227
	228 static void
	229 errs(char *s)
	230 {
	231 while(s) errc(s++);
	232 }
	233 #define NBUF 80
	234 static char buf[NBUF], *bufp = buf;
	235
	236 static void
	237 errc(int c)
	238 {
	239 *bufp++=c;
	240 if(bufp==&buf[NBUF] \|\| c=='\n'){
	241 Write(2, buf, bufp-buf);
	242 bufp = buf;
	243 }
	244 }