do the bare minimum for fuse and lftp compatability.
this allows the coraid apt repository to be automaticly
pushed to the fileserver.

both expect the "site chmod" command that does the
obvious thing.  none is diallowed from using the site
command.

Reference: /n/sources/patch/applied/ftpdfuse
Date: Sat Aug  8 22:28:59 CES 2009
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/ip/ftpd.c	Sat Aug  8 22:26:24 2009
+++ /sys/src/cmd/ip/ftpd.c	Sat Aug  8 22:26:22 2009
@@ -59,6 +59,7 @@
 int	reply(char*, ...);
 int	restartcmd(char*);
 int	retrievecmd(char*);
+int	sitecmd(char*);
 int	sizecmd(char*);
 int	storecmd(char*);
 int	storeucmd(char*);
@@ -105,6 +106,7 @@
 	{ "rmd",	delcmd,		1, },
 	{ "rnfr",	rnfrcmd,	1, },
 	{ "rnto",	rntocmd,	1, },
+	{ "site", sitecmd, 1, },
 	{ "size", 	sizecmd,	1, },
 	{ "stor", 	storecmd,	1, },
 	{ "stou", 	storeucmd,	1, },
@@ -1120,6 +1122,52 @@
 {
 	return asproc(list, arg, 1);
 }
+
+/*
+ * fuse compatability
+ */
+int
+oksiteuser(void)
+{
+	char buf[64];
+	int fd, n;
+
+	fd = open("#c/user", OREAD);
+	if(fd == -1)
+		return 1;
+	n = read(fd, buf, sizeof buf - 1);
+	if(n > 0){
+		buf[n] = 0;
+		if(strcmp(buf, "none") == 0)
+			n = -1;
+	}
+	close(fd);
+	return n > 0;
+}
+
+int
+sitecmd(char *arg)
+{
+	char *f[4];
+	int nf, r;
+	Dir *d;
+
+	nf = tokenize(arg, f, nelem(f));
+	if(nf != 3 || cistrcmp(f[0], "chmod") != 0)
+		return reply("501 bad site command");
+	if(!oksiteuser())
+		return reply("550 Permission denied");
+	d = dirstat(f[2]);
+	if(d == nil)
+		return reply("501 site chmod: file does not exist");
+	d->mode &= ~0777;
+	d->mode |=  strtoul(f[1], 0, 8) & 0777;
+	r = dirwstat(f[2], d);
+	free(d);
+	if(r == -1)
+		return reply("550 Permission denied %r");
+	return reply("200 very well, then");
+ }
 
 /*
  *  return the size of the file