929466 - mar.c:177:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]

Status: RESOLVED FIXED

(Toolkit :: Application Update, defect)

Description

[Daniel Holbert [:dholbert]]

Build warning:
{
modules/libmar/tool/mar.c: In function ‘main’:
modules/libmar/tool/mar.c:177:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                (argv[1][2] == '0' + certCount ||
                            ^
}

argv is a char**, so argv[1][2] is of type "char". (signed)

certCount is of type uint32_t, so ('0' + certCount) is of type uint32_t. ('0' gets promoted for the purpose of the addition)

So we end up comparing a signed expression on the left to an unsigned expression on the right.

We can fix this by making certCount a signed variable (possibly type "char", so that the two sides of this equality-check actually match?)

Comment 1

[Daniel Holbert [:dholbert]]

Alternately, we can just cast '0' + certCount to be a char. Slightly hackier, but cleaner / more targeted, and it looks like that's essentially what the code is expecting to happen.

(Note that the surrounding code prevents certCount from exceeding MAX_SIGNATURES, which is 8, so we're in no danger of actually wrapping past CHAR_MAX.)

Comment 2

[Daniel Holbert [:dholbert]]

Attachment: fix v1

This just adds a (char) cast, per prev comment.

Comment 3

[Brian R. Bondy [:bbondy]]

Comment on attachment 820335 [details] [diff] [review]
fix v1

Review of attachment 820335 [details] [diff] [review]:
-----------------------------------------------------------------

Thanks!

Comment 4

[Daniel Holbert [:dholbert]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/f87879d36aef

Comment 5

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/f87879d36aef