Re: setup_git_directory_gently contract question?

"Ciprian Dorin Craciun" <ciprian.craciun@gmail.com> writes:

Most commands that work from subdirectory use setup_git_directory() interface, because major parts of the guts of the git internal want you to be at the top of the work tree (e.g. so that you grab a path out of the index, and be able to open(2) or lstat(2) that path). A normal sequence for a command is: (1) use setup_git_directory() to learn "prefix", (2) use get_pathspec() and/or prefix_path() to add "prefix" to the paths given from the command to make it a path relative to the work tree, (3) do its thing. setup_git_directory() chdir's up to the top of the work tree for this reason.

Some commands can optionally work from even outside a git repository, but they would want to operate the same way as other comands, when they are started within a git repository. In such a case, you use "gently" variant, and give a pointer to int to store an additional return value to signal you if you are inside a git repository or outside.

 * When NULL is given as nongit_ok to gently(), it does not behave gentle
   at all.  Outside a git repository it dies loudly.

 * If you are inside a git repository, it behaves pretty much the same as
   setup_git_directory().  "*nongit_ok" is set to zero to signal that you
   are inside a git repository.

 * If you are outside a git repository, *nongit_ok is set to non-zero so
   that the caller can tell that it is not in any git repository's work
   tree.  There is no need to chdir (nor a sensible place to chdir to) in
   this case, so it doesn't.

The caller thinks of the parameter as "are we operating in non-git mode?" boolean, and the callee (i.e. setup_git_directory_gently()) thinks of it as "is it ok to be called outside a git repository?" (if it is NULL, the caller expects to be inside a repository and wants it to barf otherwise). That is why caller's variable are often called "int nongit", and the callee's parameter is called "int *nongit_ok".