Re: [PATCH v3] submodule: port subcommand 'set-branch' from shell to C

Johannes Schindelin [off-list ref] writes:

quoted

+	config_set_in_gitmodules_file_gently(config_name, opt_branch);

What happens if this fails? E.g. when the permission is denied or disk is
full? This C code would then still `return 0`, pretending that it
succeeded. But the original shell script calls `git submodule--helper
config [...]` which calls `module_config()`, which in turn passes through
the return value of the `config_set_in_gitmodules_file_gently()` call.

In other words, you need something like this:

	int ret;

	[...]

	ret = config_set_in_gitmodules_file_gently(config_name, opt_branch);

	free(config_name);
	return ret;

Making sure we check the return value of helper functions we call is
a good discipline, but this is not quite enough.

So I think we'll also need this (it's unrelated to your patch, at least
unrelated enough that it merits its own, separate patch):

-                       return commands[i].fn(argc - 1, argv + 1, prefix);
+                       return !!commands[i].fn(argc - 1, argv + 1, prefix);

I checked (not all but most of the) functions in that commands[]
table and they all seem to return 0 for success and positive
non-zero for failure.

config_set_in_gitmodules_file_gently() takes the return value of a
helper function in its 'ret', gives an warning if it is negative,
and returns that 'ret' literally to the caller.  You suggestion
allows module_set_branch() return a negative value as-is.  You'd
need to return !!ret from there.

The "unrelated" change becomes only necessary if you do not do the
!!ret in module_set_branch(); otherwise it is unneeded, I think.

Thanks.