Small tweaks

Lots of new code imported.

src/lib9p/parse.c

@@ -0,0 +1,115 @@
+#include <u.h>
+#include <libc.h>
+#include <fcall.h>
+#include <thread.h>
+#include <9p.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 *cb;
+	int nf;
+	char *sp;
+
+	nf = ncmdfield(p, n);
+
+	/* allocate Cmdbuf plus string pointers plus copy of string including \0 */
+	sp = emalloc9p(sizeof(*cb) + nf * sizeof(char*) + n + 1);
+	cb = (Cmdbuf*)sp;
+	cb->f = (char**)(&cb[1]);
+	cb->buf = (char*)(&cb->f[nf]);
+
+	memmove(cb->buf, p, n);
+
+	/* 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
+respondcmderror(Req *r, Cmdbuf *cb, char *fmt, ...)
+{
+	int i;
+	va_list arg;
+	char *p, *e;
+	char err[ERRMAX];
+	
+	e = err+ERRMAX-10;
+	va_start(arg, fmt);
+	p = vseprint(err, e, fmt, arg);
+	va_end(arg);
+	p = seprint(p, e, ": \"");
+	for(i=0; i<cb->nf; i++){
+		if(i > 0)
+			p = seprint(p, e, " ");
+		p = seprint(p, e, "%q", cb->f[i]);
+	}
+	strcpy(p, "\"");
+	respond(r, err);
+}
+
+/*
+ * Look up entry in table
+ */
+Cmdtab*
+lookupcmd(Cmdbuf *cb, Cmdtab *ctab, int nctab)
+{
+	int i;
+	Cmdtab *ct;
+
+	if(cb->nf == 0){
+		werrstr("empty control message");
+		return nil;
+	}
+
+	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){
+			werrstr("bad # args to command");
+			return nil;
+		}
+		return ct;
+	}
+
+	werrstr("unknown control message");
+	return nil;
+}