tparse.c - plan9port - [fork] Plan 9 from user space
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       tparse.c (2049B)
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            1 #include <u.h>
            2 #include <libc.h>
            3 #include <fcall.h>
            4 #include <thread.h>
            5 #include <9p.h>
            6 
            7 /*
            8  * Generous estimate of number of fields, including terminal nil pointer
            9  */
           10 static int
           11 ncmdfield(char *p, int n)
           12 {
           13         int white, nwhite;
           14         char *ep;
           15         int nf;
           16 
           17         if(p == nil)
           18                 return 1;
           19 
           20         nf = 0;
           21         ep = p+n;
           22         white = 1;        /* first text will start field */
           23         while(p < ep){
           24                 nwhite = (strchr(" \t\r\n", *p++ & 0xFF) != 0);        /* UTF is irrelevant */
           25                 if(white && !nwhite)        /* beginning of field */
           26                         nf++;
           27                 white = nwhite;
           28         }
           29         return nf+1;        /* +1 for nil */
           30 }
           31 
           32 /*
           33  *  parse a command written to a device
           34  */
           35 Cmdbuf*
           36 parsecmd(char *p, int n)
           37 {
           38         Cmdbuf *cb;
           39         int nf;
           40         char *sp;
           41 
           42         nf = ncmdfield(p, n);
           43 
           44         /* allocate Cmdbuf plus string pointers plus copy of string including \0 */
           45         sp = emalloc9p(sizeof(*cb) + nf * sizeof(char*) + n + 1);
           46         cb = (Cmdbuf*)sp;
           47         cb->f = (char**)(&cb[1]);
           48         cb->buf = (char*)(&cb->f[nf]);
           49 
           50         memmove(cb->buf, p, n);
           51 
           52         /* dump new line and null terminate */
           53         if(n > 0 && cb->buf[n-1] == '\n')
           54                 n--;
           55         cb->buf[n] = '\0';
           56 
           57         cb->nf = tokenize(cb->buf, cb->f, nf-1);
           58         cb->f[cb->nf] = nil;
           59 
           60         return cb;
           61 }
           62 
           63 /*
           64  * Reconstruct original message, for error diagnostic
           65  */
           66 void
           67 respondcmderror(Req *r, Cmdbuf *cb, char *fmt, ...)
           68 {
           69         int i;
           70         va_list arg;
           71         char *p, *e;
           72         char err[ERRMAX];
           73 
           74         e = err+ERRMAX-10;
           75         va_start(arg, fmt);
           76         p = vseprint(err, e, fmt, arg);
           77         va_end(arg);
           78         p = seprint(p, e, ": \"");
           79         for(i=0; i<cb->nf; i++){
           80                 if(i > 0)
           81                         p = seprint(p, e, " ");
           82                 p = seprint(p, e, "%q", cb->f[i]);
           83         }
           84         strcpy(p, "\"");
           85         respond(r, err);
           86 }
           87 
           88 /*
           89  * Look up entry in table
           90  */
           91 Cmdtab*
           92 lookupcmd(Cmdbuf *cb, Cmdtab *ctab, int nctab)
           93 {
           94         int i;
           95         Cmdtab *ct;
           96 
           97         if(cb->nf == 0){
           98                 werrstr("empty control message");
           99                 return nil;
          100         }
          101 
          102         for(ct = ctab, i=0; i<nctab; i++, ct++){
          103                 if(strcmp(ct->cmd, "*") !=0)        /* wildcard always matches */
          104                 if(strcmp(ct->cmd, cb->f[0]) != 0)
          105                         continue;
          106                 if(ct->narg != 0 && ct->narg != cb->nf){
          107                         werrstr("bad # args to command");
          108                         return nil;
          109                 }
          110                 return ct;
          111         }
          112 
          113         werrstr("unknown control message");
          114         return nil;
          115 }