1235234 - Fix unintentional switch fallthrough in ipc/chromium/ found by -Wimplicit-fallthrough warning

Status: RESOLVED FIXED

(Core :: Security: Process Sandboxing, defect)

Description

[Chris Peterson [:cpeterson]]

Attachment: ipc_MOZ_FALLTHROUGH.patch

ipc/chromium/src/base/process_util_mac.mm:132:5 [-Wimplicit-fallthrough] unannotated fall-through between switch labels

This patch fixes a clang -Wimplicit-fallthrough warning (not yet enabled by default in mozilla-central) about switch cases that fall through without a break or return statement. Warnings about intentional fallthroughs can be suppressed with MOZ_FALLTHROUGH, a MFBT macro for a clang compiler annotation. MOZ_FALLTHROUGH is only needed on cases that have code:

switch (foo) {
  case 1: // These cases have no code. No fallthrough annotations are needed.
  case 2:
  case 3:
    foo = 4; // This case has code, so a fallthrough annotation is needed:
    MOZ_FALLTHROUGH;
  default:
    return foo;
}

Comment 1

[Gian-Carlo Pascutto [:gcp]]

Comment on attachment 8702096 [details] [diff] [review]
ipc_MOZ_FALLTHROUGH.patch

Review of attachment 8702096 [details] [diff] [review]:
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I'm not sure describing this as fixing a warning is appropriate. The code is 100% buggy and the warning caught it. Can you check whether upstream is fixed?

Comment 2

[Chris Peterson [:cpeterson]]

(In reply to Gian-Carlo Pascutto [:gcp] from comment #1)
> I'm not sure describing this as fixing a warning is appropriate. The code is
> 100% buggy and the warning caught it. Can you check whether upstream is
> fixed?

This function is not in the upstream process_util_mac.mm. It's a local change in mozilla-central:

https://hg.mozilla.org/mozilla-central/rev/e45446b74099

Comment 3

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/319b30f075a2

Comment 4

[Chris Peterson [:cpeterson]]

I corrected the commit message and bug summary to mention the bug fix instead of just a warning fix.

Comment 5

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/319b30f075a2