1 files changed, 125 insertions, 0 deletions
diff --git a/appl/alphabet/fs/mode.b b/appl/alphabet/fs/mode.b
new file mode 100644
index 00000000..974885c7
--- /dev/null
+++ b/appl/alphabet/fs/mode.b
@@ -0,0 +1,125 @@
+implement Mode, Fsmodule;
+include "sys.m";
+	sys: Sys;
+include "draw.m";
+include "sh.m";
+include "alphabet/reports.m";
+	Report: import Reports;
+include "alphabet/fs.m";
+	fs: Fs;
+	Value: import fs;
+	Fschan, Fsdata, Entrychan, Entry,
+	Gatechan, Gatequery, Nilentry, Option,
+	Next, Down, Skip, Quit: import Fs;
+
+Mode: module {};
+
+# XXX implement octal modes.
+
+User:	con 8r700;
+Group:	con 8r070;
+Other:	con 8r007;
+All:	con User | Group | Other;
+
+Read:	con 8r444;
+Write:	con 8r222;
+Exec:	con 8r111;
+
+types(): string
+{
+	return "ps";
+}
+
+badmod(p: string)
+{
+	sys->fprint(sys->fildes(2), "fs: size: cannot load %s: %r\n", p);
+	raise "fail:bad module";
+}
+
+init()
+{
+	sys = load Sys Sys->PATH;
+	fs = load Fs Fs->PATH;
+	if(fs == nil)
+		badmod(Fs->PATH);
+	fs->init();
+}
+
+run(nil: ref Draw->Context, nil: ref Report,
+			nil: list of Option, args: list of ref Value): ref Value
+{
+	spec := (hd args).s().i;
+	(ok, mask, mode) := parsemode(spec);
+	if(ok == 0){
+		sys->fprint(sys->fildes(2), "fs: mode: bad mode %#q\n", spec);
+		return nil;
+	}
+	c := chan of Gatequery;
+	spawn modegate(c, mask, mode);
+	return ref Value.Vp(c);
+}
+
+modegate(c: Gatechan, mask, mode: int)
+{
+	m := mode & mask;
+	while((((d, nil, nil), reply) := <-c).t0.t0 != nil)
+		reply <-= ((d.mode & mask) ^ m) == 0;
+}
+
+# stolen from /appl/cmd/chmod.b
+parsemode(spec: string): (int, int, int)
+{
+	mask := Sys->DMAPPEND | Sys->DMEXCL | Sys->DMDIR | Sys->DMAUTH;
+loop:
+	for(i := 0; i < len spec; i++){
+		case spec[i] {
+		'u' =>
+			mask |= User;
+		'g' =>
+			mask |= Group;
+		'o' =>
+			mask |= Other;
+		'a' =>
+			mask |= All;
+		* =>
+			break loop;
+		}
+	}
+	if(i == len spec)
+		return (0, 0, 0);
+	if(i == 0)
+		mask |= All;
+
+	op := spec[i++];
+	if(op != '+' && op != '-' && op != '=')
+		return (0, 0, 0);
+
+	mode := 0;
+	for(; i < len spec; i++){
+		case spec[i]{
+		'r' =>
+			mode |= Read;
+		'w' =>
+			mode |= Write;
+		'x' =>
+			mode |= Exec;
+		'a' =>
+			mode |= Sys->DMAPPEND;
+		'l' =>
+			mode |= Sys->DMEXCL;
+		'd' =>
+			mode |= Sys->DMDIR;
+		'A' =>
+			mode |= Sys->DMAUTH;
+		* =>
+			return (0, 0, 0);
+		}
+	}
+	if(op == '+' || op == '-')
+		mask &= mode;
+	if(op == '-')
+		mode = ~mode;
+	return (1, mask, mode);
+}
+
+