isolate: give up and die on file unavailability

client/archiver/directory.go

Index: client/archiver/directory.go
diff --git a/client/archiver/directory.go b/client/archiver/directory.go
index 961849fd63193c75a0febb609b58d95baf798f12..24c91afd19394b1bfafcb721bc9654b7b5f009c0 100644
--- a/client/archiver/directory.go
+++ b/client/archiver/directory.go
@@ -69,7 +69,7 @@ func walk(root string, blacklist []string, c chan<- *walkItem) {
 	err := filepath.Walk(root, func(p string, info os.FileInfo, err error) error {
 		total++
 		if err != nil {
-			return fmt.Errorf("walk(%s): %s", p, err)
+			return fmt.Errorf("walk(%q): %v", p, err)

[mithro, 2016/11/29 03:43:44]

This will cause the binary to fail if it tries to walk a directory with a
permission denied error...

I think that is probably the right solution, but we should just double check?

[djd-OOO-Apr2017, 2016/11/29 03:51:55]

Do you have a suggestion on how to check that? Also, it doesn't look like this
change would affect the ultimate behaviour for this type of failure: such an
error is already been reported from walk and ultimately/hopefully cancelling the
upload.

 		}
 		if len(p) <= rootLen {
 			// Root directory.
@@ -98,7 +98,8 @@ func walk(root string, blacklist []string, c chan<- *walkItem) {
 		return nil
 	})
 	if err != nil {
-		c <- &walkItem{err: err}
+		// No point continuing if an error occurred during walk.
+		log.Fatalf("Unable to walk %q: %v", root, err)

[tandrii(chromium), 2016/11/30 14:35:08]

1. a test for this would be nice anyway - panic can be caught...
2. have you seen this
https://bugs.chromium.org/p/chromium/issues/detail?id=480558#c5? It'd be really
awesome to exit with the right error code.

[M-A Ruel, 2016/11/30 15:39:14]

I'm not enthusiastic about hard failing vs cleanly propagating the error up, but
I'm not concerned enough to block the CL as propagating the error would require
a fair amount of refactoring.

log.Fatal() calls os.Exit(1) and doesn't panic. It could be worth calling
log.Printf() + os.Exit(3) or something.

(Sorry for not commenting about this earlier)

 	}
 }