a

kern/parse.c

@@ -0,0 +1,113 @@
+#include	"u.h"
+#include	"lib.h"
+#include	"dat.h"
+#include	"fns.h"
+#include	"error.h"
+
+/*
+ * Generous estimate of number of fields, including terminal nil pointer
+ */
+static int
+ncmdfield(char *p, int n)
+{
+	int white, nwhite;
+	char *ep;
+	int nf;
+
+	if(p == nil)
+		return 1;
+
+	nf = 0;
+	ep = p+n;
+	white = 1;	/* first text will start field */
+	while(p < ep){
+		nwhite = (strchr(" \t\r\n", *p++ & 0xFF) != 0);	/* UTF is irrelevant */
+		if(white && !nwhite)	/* beginning of field */
+			nf++;
+		white = nwhite;
+	}
+	return nf+1;	/* +1 for nil */
+}
+
+/*
+ *  parse a command written to a device
+ */
+Cmdbuf*
+parsecmd(char *p, int n)
+{
+	Cmdbuf *volatile cb;
+	int nf;
+	char *sp;
+
+	nf = ncmdfield(p, n);
+
+	/* allocate Cmdbuf plus string pointers plus copy of string including \0 */
+	sp = smalloc(sizeof(*cb) + nf * sizeof(char*) + n + 1);
+	cb = (Cmdbuf*)sp;
+	cb->f = (char**)(&cb[1]);
+	cb->buf = (char*)(&cb->f[nf]);
+
+	if(up!=nil && waserror()){
+		free(cb);
+		nexterror();
+	}
+	memmove(cb->buf, p, n);
+	if(up != nil)
+		poperror();
+
+	/* dump new line and null terminate */
+	if(n > 0 && cb->buf[n-1] == '\n')
+		n--;
+	cb->buf[n] = '\0';
+
+	cb->nf = tokenize(cb->buf, cb->f, nf-1);
+	cb->f[cb->nf] = nil;
+
+	return cb;
+}
+
+/*
+ * Reconstruct original message, for error diagnostic
+ */
+void
+cmderror(Cmdbuf *cb, char *s)
+{
+	int i;
+	char *p, *e;
+
+	p = up->genbuf;
+	e = p+ERRMAX-10;
+	p = seprint(p, e, "%s \"", s);
+	for(i=0; i<cb->nf; i++){
+		if(i > 0)
+			p = seprint(p, e, " ");
+		p = seprint(p, e, "%q", cb->f[i]);
+	}
+	strcpy(p, "\"");
+	error(up->genbuf);
+}
+
+/*
+ * Look up entry in table
+ */
+Cmdtab*
+lookupcmd(Cmdbuf *cb, Cmdtab *ctab, int nctab)
+{
+	int i;
+	Cmdtab *ct;
+
+	if(cb->nf == 0)
+		error("empty control message");
+
+	for(ct = ctab, i=0; i<nctab; i++, ct++){
+		if(strcmp(ct->cmd, "*") !=0)	/* wildcard always matches */
+		if(strcmp(ct->cmd, cb->f[0]) != 0)
+			continue;
+		if(ct->narg != 0 && ct->narg != cb->nf)
+			cmderror(cb, Ecmdargs);
+		return ct;
+	}
+
+	cmderror(cb, "unknown control message");
+	return nil;
+}