new venti library.

src/libventi/root.c

@@ -0,0 +1,67 @@
+#include <u.h>
+#include <libc.h>
+#include <venti.h>
+#include "cvt.h"
+
+static int
+checksize(int n)
+{
+	if(n < 256 || n > VtMaxLumpSize) {
+		werrstr("bad block size");
+		return -1;
+	}
+	return 0;
+}
+
+void
+vtrootpack(VtRoot *r, uchar *p)
+{
+	uchar *op = p;
+
+	U16PUT(p, VtRootVersion);
+	p += 2;
+	memmove(p, r->name, sizeof(r->name));
+	p += sizeof(r->name);
+	memmove(p, r->type, sizeof(r->type));
+	p += sizeof(r->type);
+	memmove(p, r->score, VtScoreSize);
+	p +=  VtScoreSize;
+	U16PUT(p, r->blocksize);
+	p += 2;
+	memmove(p, r->prev, VtScoreSize);
+	p += VtScoreSize;
+
+	assert(p-op == VtRootSize);
+}
+
+int
+vtrootunpack(VtRoot *r, uchar *p)
+{
+	uchar *op = p;
+	uint vers;
+	memset(r, 0, sizeof(*r));
+
+	vers = U16GET(p);
+	if(vers != VtRootVersion) {
+		werrstr("unknown root version");
+		return 0;
+	}
+	p += 2;
+	memmove(r->name, p, sizeof(r->name));
+	r->name[sizeof(r->name)-1] = 0;
+	p += sizeof(r->name);
+	memmove(r->type, p, sizeof(r->type));
+	r->type[sizeof(r->type)-1] = 0;
+	p += sizeof(r->type);
+	memmove(r->score, p, VtScoreSize);
+	p +=  VtScoreSize;
+	r->blocksize = U16GET(p);
+	if(checksize(r->blocksize) < 0)
+		return -1;
+	p += 2;
+	memmove(r->prev, p, VtScoreSize);
+	p += VtScoreSize;
+
+	assert(p-op == VtRootSize);
+	return 0;
+}