ww: canonicalize directory package identities

internal/wwpackage/package.ww

@@ -38,6 +38,8 @@ type pkggroup = struct {
 
 type pkgplan = struct {
 	dir: str,
+	sourceroot: str,
+	identity: str,
 	root: str,
 	workdir: str,
 	buildout: str,
@@ -438,6 +440,24 @@ fn pkgmakedir(path: str) bool = {
 	return os.mkdir(path, 448i32) == 0;
 };
 
+// Resolve a directory to the kernel's symlink-free absolute spelling. The
+// coordinator is single-threaded while planning, so the temporary cwd change
+// cannot race a child process launch.
+fn pkgcanonicaldir(path: str, out: *str) bool = {
+	let before: []u8 = alloc([], os.PATH_MAX: u64)!;
+	before.len = os.PATH_MAX;
+	let bn: i64 = os.getcwd(before.ptr, before.len: u64);
+	if (bn <= 1i64 || bn > before.len: i64) { return false; };
+	if (os.chdir(path) != 0) { return false; };
+	let after: []u8 = alloc([], os.PATH_MAX: u64)!;
+	after.len = os.PATH_MAX;
+	let an: i64 = os.getcwd(after.ptr, after.len: u64);
+	let restored: i32 = os.chdir(strings.frombytes(before[0:(bn - 1i64): i32]));
+	if (restored != 0 || an <= 1i64 || an > after.len: i64) { return false; };
+	*out = strings.dup(strings.frombytes(after[0:(an - 1i64): i32]));
+	return true;
+};
+
 // The coordinator removes only its minted temp root; validating the opened
 // inode keeps a replaced path from carrying cleanup outside that ownership.
 fn pkgremoveall(path: str) bool = {
@@ -519,9 +539,8 @@ fn pkgworkescape(s: str) str = {
 	return strings.frombytes(out);
 };
 
-fn pkgworkkey(dir: str, pkg: str) str = {
-	return strings.concat("d_", pkgworkescape(dir), "_p_",
-		pkgworkescape(pkg));
+fn pkgworkkey(dir: str) str = {
+	return strings.concat("d_", pkgworkescape(dir));
 };
 
 fn pkgsetplanpaths(p: *pkgplan, groups: []pkggroup, root: str, index: i32,
@@ -531,10 +550,10 @@ fn pkgsetplanpaths(p: *pkgplan, groups: []pkggroup, root: str, index: i32,
 	if (!pkgmakedir(p.root)) { return false; };
 	p.workdir = "";
 	if (workroot.len != 0) {
-		// The request root and first byte-sorted product name make one stable
-		// escaped key for the command-scoped driver workdir.
+		// Canonical request-directory identity makes equivalent spellings and
+		// product reorderings select one command-scoped driver workdir.
 		p.workdir = strings.concat(workroot, "/",
-			pkgworkkey(p.dir, groups[p.start].pkg));
+			pkgworkkey(p.sourceroot));
 		match (os.mkdirs(p.workdir, 448)) {
 		case void => void;
 		case let e: os.oserror => return false;
@@ -601,10 +620,14 @@ fn pkgreportcommand(kind: str, g: *pkggroup, r: *exec.result) void = {
 fn pkgstartbuild(p: *pkgplan, groups: []pkggroup, builder: str, includes: []str,
 	h: *exec.process) void = {
 	let ba: []str = alloc([],
-		(8 + (p.end - p.start) * 6 + includes.len * 2): u64)!;
+		(12 + (p.end - p.start) * 6 + includes.len * 2): u64)!;
 	append(ba, builder);
 	append(ba, "test");
 	append(ba, "-c");
+	if (p.identity.len != 0) {
+		append(ba, "--ww-root-identity");
+		append(ba, p.identity);
+	};
 	let i: i32 = p.start;
 	for (i < p.end) {
 		let g: *pkggroup = &groups[i];
@@ -619,6 +642,10 @@ fn pkgstartbuild(p: *pkgplan, groups: []pkggroup, builder: str, includes: []str,
 		append(ba, g.buildok);
 		i += 1;
 	};
+	// Recursive descendants derive full identities relative to the canonical
+	// discovery root using the driver's ordinary ordered import lookup.
+	append(ba, "-I");
+	append(ba, p.sourceroot);
 	let ii: i32 = 0;
 	for (ii < includes.len) {
 		append(ba, "-I");
@@ -745,6 +772,7 @@ export fn packagecommand(args: []str) int = {
 	let timeoutarg: str = "";
 	let outname: str = "";
 	let workroot: str = "";
+	let requestidentity: str = "";
 	let builder: str = pkgdefaultbuilder();
 	let i: i32 = 0;
 	for (i < args.len) {
@@ -819,6 +847,16 @@ export fn packagecommand(args: []str) int = {
 			i += 2;
 			continue;
 		};
+		if (strings.compare(a, "--ww-root-identity") == 0) {
+			if (i + 1 >= args.len || args[i + 1].len == 0
+				|| requestidentity.len != 0) {
+				pkgusage();
+				return 2;
+			};
+			requestidentity = args[i + 1];
+			i += 2;
+			continue;
+		};
 		if (a.len != 0 && a[0] == '-') { pkgusage(); return 2; };
 		append(roots, a);
 		i += 1;
@@ -872,6 +910,11 @@ export fn packagecommand(args: []str) int = {
 		pkgfailpath(discoverroot, "directory contains no WW package sources");
 		return 1;
 	};
+	let canonicalroot: str;
+	if (!pkgcanonicaldir(discoverroot, &canonicalroot)) {
+		pkgfailpath(discoverroot, "cannot canonicalize package directory");
+		return 1;
+	};
 
 	let srcs: []pkgsource = alloc([], ds.paths.len: u64)!;
 	i = 0;
@@ -985,6 +1028,8 @@ export fn packagecommand(args: []str) int = {
 	let plans: []pkgplan = alloc([], 1u64)!;
 	let plan: pkgplan;
 	plan.dir = discoverroot;
+	plan.sourceroot = canonicalroot;
+	plan.identity = requestidentity;
 	plan.start = 0;
 	plan.end = groups.len;
 	plan.state = PKGQUEUED;