Build breaks on ignored return values

[metux]

glibc has a lot of functions whose return values should not be ignored. this produces a lot of warnings, which cause the build to break when using -Werror (which *really* should be standard for any production build ;-p):

background.c:446: error: ignoring return value of 'write', declared with attribute warn_unused_result

(setting the priority to blocker, since it breaks any serious build)

branch:1897_libc_return_values
changeset:b396e0e959179f85e2a10c6d2cffb18879025e0b

[andrew_b]

Branch: 1897_libc_return_values.

-       fscanf (f, ";\n");
+       if (fscanf (f, ";\n"));

Where you've seen such way? The widely used way to suppress warings of unsed return values is

       (void) fscanf (f, ";\n");

I think we should use a common coding styles in MC codebase.

[slyfox]

Replying to andrew_b:

Branch: 1897_libc_return_values.

-       fscanf (f, ";\n");
+       if (fscanf (f, ";\n"));

Where you've seen such way?

Agreed, looks ambiguous, odd and (not yet) generates another warning:

warning: suggest braces around empty body in an 'if' statement [-Wempty-body]

The widely used way to suppress warings of unsed return values is

       (void) fscanf (f, ";\n");

I think we should use a common coding styles in MC codebase.

Agreed.

[metux]

Okay, reworked it. Please review now.

[andrew_b]

What about

(void) fscanf (f, ";\n");

[metux]

Replying to andrew_b:

What about

(void) fscanf (f, ";\n");

Doesnt work, still get the warnings with that.
The best way seems to be:

if (ffscanf (f, ";\n")) {}

Changed it this way in the branch.

Please review now. We should get in these fixes (also the #1872 branch) ASAP, since master is still broken.

[andrew_b]

Replying to metux:

The best way seems to be:

if (ffscanf (f, ";\n")) {}

The best way is not ignore return values. :p

Please review now. We should get in these fixes (also the #1872 branch) ASAP, since master is still broken.

Actually, master is not broken.

[metux]

Replying to andrew_b:

Replying to metux:

The best way seems to be:

if (ffscanf (f, ";\n")) {}

The best way is not ignore return values. :p

Right. So everybody please review and think carefully
think about whether/how to handle the results, case
by case.

Please review now. We should get in these fixes (also the #1872 branch) ASAP, since master is still broken.

Actually, master is not broken.

It doesnt build in several configs (not just due -Werror!), eg.
--without-edit or --without-vfs totally break.

[metux]

Okay boys, I've heavily reworked it.
Now the errors are actually handled.

Please review

[slavazanko]

I have commit in branch:

• cd561fff3cbe8a7e33fd168772152822f57062da: src/background.c: little fix for respect return value of read() function

Except this, all looks fine. Enrico, you made big work. Thanks.

[metux]

Replying to slavazanko:

I have commit in branch:

• cd561fff3cbe8a7e33fd168772152822f57062da: src/background.c: little fix for respect return value of read() function

Except this, all looks fine. Enrico, you made big work. Thanks.

Sorry, overlooked it when rewriting from just-ignore to actually-handling ;-o

All others folks: please review now, we need to get that in asap ;-p

[metux]

Master had several changes, so rebased it and fixed a few more of these issues.